src/decompress_common.c \
src/delete_image.c \
src/dentry.c \
- src/divsufsort.c \
src/encoding.c \
src/export_image.c \
src/extract.c \
src/lzms-common.c \
src/lzms-compress.c \
src/lzms-decompress.c \
+ src/lz_bt.c \
src/lz_hash.c \
- src/lz_sarray.c \
src/lzx-common.c \
src/lzx-compress.c \
src/lzx-decompress.c \
include/wimlib/decompressor_ops.h \
include/wimlib/decompress_common.h \
include/wimlib/dentry.h \
- include/wimlib/divsufsort.h \
include/wimlib/encoding.h \
include/wimlib/endianness.h \
include/wimlib/error.h \
include/wimlib/list.h \
include/wimlib/lookup_table.h \
include/wimlib/lz.h \
+ include/wimlib/lz_bt.h \
include/wimlib/lz_hash.h \
- include/wimlib/lz_optimal.h \
- include/wimlib/lz_sarray.h \
include/wimlib/lzms.h \
include/wimlib/lzx.h \
include/wimlib/metadata.h \
http://www.tuxera.com/community/ntfs-3g-download/ for more information.
The LZX decompressor (lzx-decompress.c) was originally based on code from the
-cabextract project (http://www.cabextract.org.uk) but has been rewritten.
+cabextract project (http://www.cabextract.org.uk). The LZX compressor
+(lzx-compress.c) was originally based on code written by Matthew Russotto
+(www.russotto.net/chm/). However I have since rewritten and made many
+improvements to both the decompressor and compressor.
-The LZX compressor (lzx-compress.c) was originally based on code written by
-Matthew Russotto (www.russotto.net/chm/) but has been rewritten. It now uses
-suffix array construction code from divsufsort
-(https://code.google.com/p/libdivsufsort/) and algorithms from 7-Zip as well as
-several published papers.
+lz_hash.c contains LZ77 match-finding code that uses hash chains. It is based
+on code from zlib but I have since rewritten it.
-lz_hash.c contains a hash-table-based LZ77 matchfinder that is based on code
-from zlib but has been rewritten. This code is applicable to XPRESS, LZX, and
-LZMS, all of which are partly based on LZ77 compression.
+lz_bt.c contains LZ77 match-finding code that uses binary trees. It is based on
+code from liblzma but I have since rewritten it.
A limited number of other free programs can handle some parts of the WIM
file format:
other archive formats). However, wimlib is designed specifically to handle
WIM files and provides features previously only available in Microsoft's
implementation, such as the ability to mount WIMs read-write as well as
- read-only, the ability to create LZX or XPRESS compressed WIMs, and the
- correct handling of security descriptors and hard links.
+ read-only, the ability to create compressed WIMs, and the correct handling
+ of security descriptors and hard links.
* ImagePyX (https://github.com/maxpat78/ImagePyX) is a Python program that
provides similar capabilities to wimlib-imagex. One thing to note, though,
is that it does not support compression and decompression by itself, but
with WIMGAPI Windows 8 and later, and DISM Windows 8.1 and later.
.IP ""
The default compression type and chunk size in packed resources is LZMS with
-2^25 (33554432) byte chunks. This is independent of the WIM's main compression
+2^26 (67108864) byte chunks. This is independent of the WIM's main compression
type and chunk size.
.TP
\fB--pack-chunk-size\fR=\fISIZE\fR, \fB--solid-chunk-size\fR=\fISIZE\fR
Like \fB--chunk-size\fR, but set the chunk size used in packed resources. The
-default is LZMS compression with 2^25 (33554432) byte chunks. This option only
+default is LZMS compression with 2^26 (67108864) byte chunks. This option only
has an effect when \fB--pack-streams\fR is also specified. For maximum
compatibility with the Microsoft implementation, do not use either of these
options.
.TP
\fB--pack-compress\fR=\fITYPE\fR, \fB--solid-compress\fR=\fITYPE\fR
Like \fB--compress\fR, but set the compression format used in packed resources.
-The default is LZMS compression with 2^25 (33554432) byte chunks. This option
+The default is LZMS compression with 2^26 (67108864) byte chunks. This option
only has an effect when \fB--pack-streams\fR is also specified. For maximum
compatibility with the Microsoft implementation, do not use either of these
options.
* all streams recompressed in solid mode.
*
* Currently, new solid blocks will, by default, be written using LZMS
- * compression with 32 MiB (33554432 byte) chunks. Use
+ * compression with 64 MiB (67108864 byte) chunks. Use
* wimlib_set_output_pack_compression_type() and/or
* wimlib_set_output_pack_chunk_size() to change this. This is independent of
* the WIM's main compression type and chunk size; you can have a WIM that
struct wimlib_compressor_params_header hdr;
/** Relatively fast LZX compression algorithm with a decent compression
- * ratio; the suggested default. */
+ * ratio. */
#define WIMLIB_LZX_ALGORITHM_FAST 0
/** Slower LZX compression algorithm that provides a better compression
- * ratio. */
+ * ratio. This is the default. */
#define WIMLIB_LZX_ALGORITHM_SLOW 1
/** Algorithm to use to perform the compression: either
uint32_t fast_reserved1[10];
} fast;
- /** Parameters for the slow algorithm. */
+ /** Parameters for the "slow" algorithm. */
struct wimlib_lzx_slow_params {
/** If set to 1, the compressor can output length 2
- * matches. If set 0, the compressor only outputs
+ * matches. If set 0, the compressor can only output
* matches of length 3 or greater. Suggested value: 1
*/
uint32_t use_len2_matches : 1;
* position. Suggested value: 50. */
uint32_t max_search_depth;
- /** Maximum number of potentially good matches to
- * consider for each position. Suggested value: 3. */
- uint32_t max_matches_per_pos;
+ /* Note: max_matches_per_pos has been removed and no
+ * longer has any effect. */
- uint32_t slow_reserved2[2];
+ uint32_t slow_reserved2[3];
/** Assumed cost of a main symbol with zero frequency.
* Must be at least 1 and no more than 16. Suggested
* value: 50. */
uint32_t max_search_depth;
- /** Maximum number of potentially good matches to consider at each
- * position. Suggested value: 3. */
- uint32_t max_matches_per_pos;
+ /* Note: max_matches_per_pos has been removed and no longer has any
+ * effect. */
+
+ uint32_t reserved1;
/** Length of the array for the near-optimal LZ parsing algorithm. This
* must be at least 1. Suggested value: 1024. */
+++ /dev/null
-/*
- * divsufsort.h for libdivsufsort-lite
- * Copyright (c) 2003-2008 Yuta Mori All Rights Reserved.
- *
- * Permission is hereby granted, free of charge, to any person
- * obtaining a copy of this software and associated documentation
- * files (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use,
- * copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following
- * conditions:
- *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
- * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
- * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
- * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
- * OTHER DEALINGS IN THE SOFTWARE.
- */
-
-#ifndef _DIVSUFSORT_H
-#define _DIVSUFSORT_H 1
-
-/*- Prototypes -*/
-
-/**
- * Constructs the suffix array of a given string.
- * @param T[0..n-1] The input string.
- * @param SA[0..n-1] The output array of suffixes.
- * @param n The length of the given string.
- * @param bucket_A Temporary array with 256 entries
- * @param bucket_B Temporary array with 65536 entries
- */
-extern void
-divsufsort(const unsigned char *T, int *SA, int n,
- int *bucket_A, int *bucket_B);
-
-#define DIVSUFSORT_TMP1_SIZE (256 * sizeof(saidx_t)) /* bucket_A */
-#define DIVSUFSORT_TMP2_SIZE (256 * 256 * sizeof(saidx_t)) /* bucket_B */
-
-typedef int saidx_t;
-
-#endif /* _DIVSUFSORT_H */
--- /dev/null
+/*
+ * lz_bt.h
+ *
+ * Binary tree match-finder for Lempel-Ziv compression.
+ *
+ * Author: Eric Biggers
+ * Year: 2014
+ *
+ * The author hereby releases this file into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#ifndef _WIMLIB_LZ_BT_H
+#define _WIMLIB_LZ_BT_H
+
+#include "wimlib/types.h"
+
+/* Position type for the binary tree match-finder.
+ * This can be changed to 'u16' if no window will exceed 65536 bytes. */
+typedef u32 lz_bt_pos_t;
+
+/* Match length type for the binary tree match-finder. */
+typedef unsigned lz_bt_len_t;
+
+/* The binary tree match-finder structure. */
+struct lz_bt {
+ lz_bt_pos_t *hash_tab;
+ lz_bt_pos_t *digram_tab;
+ lz_bt_pos_t *child_tab;
+ const u8 *cur_window;
+ lz_bt_pos_t cur_window_pos;
+ lz_bt_pos_t cur_window_size;
+ lz_bt_pos_t max_window_size;
+ lz_bt_len_t min_match_len;
+ lz_bt_len_t max_match_len;
+ lz_bt_len_t num_fast_bytes;
+ u32 max_search_depth;
+};
+
+struct raw_match;
+
+extern u64
+lz_bt_get_needed_memory(lz_bt_pos_t max_window_size);
+
+extern bool
+lz_bt_init(struct lz_bt *mf,
+ lz_bt_pos_t max_window_size,
+ lz_bt_len_t min_match_len,
+ lz_bt_len_t max_match_len,
+ lz_bt_len_t num_fast_bytes,
+ u32 max_search_depth);
+
+extern void
+lz_bt_load_window(struct lz_bt *mf, const u8 *window, lz_bt_pos_t window_size);
+
+extern lz_bt_len_t
+lz_bt_get_matches(struct lz_bt *mf, struct raw_match *matches);
+
+static inline lz_bt_pos_t
+lz_bt_get_position(const struct lz_bt *mf)
+{
+ return mf->cur_window_pos;
+}
+
+static inline const u8 *
+lz_bt_get_window_ptr(const struct lz_bt *mf)
+{
+ return &mf->cur_window[mf->cur_window_pos];
+}
+
+static inline lz_bt_pos_t
+lz_bt_get_remaining_size(const struct lz_bt *mf)
+{
+ return mf->cur_window_size - mf->cur_window_pos;
+}
+
+extern void
+lz_bt_skip_positions(struct lz_bt *mf, unsigned n);
+
+extern void
+lz_bt_destroy(struct lz_bt *mf);
+
+#endif /* _WIMLIB_LZ_BT_H */
+++ /dev/null
-/*
- * lz_optimal.h
- *
- * Near-optimal LZ (Lempel-Ziv) parsing, or "match choosing".
- * See lz_get_near_optimal_match() for details of the algorithm.
- *
- * This code is not concerned with actually *finding* LZ matches, as it relies
- * on an underlying match-finder implementation that can do so.
- */
-
-/*
- * Copyright (c) 2013 Eric Biggers. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
- * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
- * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
- * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-/* Define the following structures before including this header:
- *
- * LZ_COMPRESSOR
- * LZ_ADAPTIVE_STATE
- *
- * Also, the type lz_mc_cost_t can be optionally overridden by providing an
- * appropriate typedef and defining LZ_MC_COST_T_DEFINED. */
-
-#ifndef _LZ_OPTIMAL_H
-#define _LZ_OPTIMAL_H
-
-#include "wimlib/lz.h"
-
-#ifndef LZ_MC_COST_T_DEFINED
- typedef input_idx_t lz_mc_cost_t;
-#endif
-
-#define LZ_MC_INFINITE_COST (~(lz_mc_cost_t)0)
-
-struct lz_mc_pos_data;
-
-/* State of the Lempel-Ziv match-chooser.
- *
- * This is defined here for benefit of the inlined code. It's not intended for
- * code outside the match-chooser itself to read or write members from this
- * structure. */
-struct lz_match_chooser {
- /* Temporary space used for the match-choosing algorithm. The size of
- * this array must be at least one more than @nice_len but otherwise is
- * arbitrary. More space decreases the frequency at which the algorithm
- * is forced to terminate early. 4096 spaces seems sufficient for most
- * real data. */
- struct lz_mc_pos_data *optimum;
- input_idx_t array_space;
-
- /* When a match with length greater than or equal to this length is
- * found, choose it immediately without further consideration. */
- input_idx_t nice_len;
-
- /* When matches have been chosen, optimum_cur_idx is set to the position
- * in the window of the next match/literal to return and optimum_end_idx
- * is set to the position in the window at the end of the last
- * match/literal to return. */
- input_idx_t optimum_cur_idx;
- input_idx_t optimum_end_idx;
-};
-
-/*
- * Match chooser position data:
- *
- * An array of these structures is used during the match-choosing algorithm.
- * They correspond to consecutive positions in the window and are used to keep
- * track of the cost to reach each position, and the match/literal choices that
- * need to be chosen to reach that position.
- */
-struct lz_mc_pos_data {
- /* The approximate minimum cost, in bits, to reach this position in the
- * window which has been found so far. */
- lz_mc_cost_t cost;
-
- /* The union here is just for clarity, since the fields are used in two
- * slightly different ways. Initially, the @prev structure is filled in
- * first, and links go from later in the window to earlier in the
- * window. Later, @next structure is filled in and links go from
- * earlier in the window to later in the window. */
- union {
- struct {
- /* Position of the start of the match or literal that
- * was taken to get to this position in the approximate
- * minimum-cost parse. */
- input_idx_t link;
-
- /* Offset (as in an LZ (length, offset) pair) of the
- * match or literal that was taken to get to this
- * position in the approximate minimum-cost parse. */
- input_idx_t match_offset;
- } prev;
- struct {
- /* Position at which the match or literal starting at
- * this position ends in the minimum-cost parse. */
- input_idx_t link;
-
- /* Offset (as in an LZ (length, offset) pair) of the
- * match or literal starting at this position in the
- * approximate minimum-cost parse. */
- input_idx_t match_offset;
- } next;
- };
-
- /* Format-dependent adaptive state that exists after an approximate
- * minimum-cost path to reach this position is taken. For example, for
- * LZX this is the list of recently used match offsets. If the format
- * does not have any adaptive state that affects match costs,
- * LZ_ADAPTIVE_STATE could be set to a dummy structure of size 0. */
- LZ_ADAPTIVE_STATE state;
-};
-
-/* Initialize the match-chooser.
- *
- * After calling this, multiple data buffers can be scanned with it if each is
- * preceded with a call to lz_match_chooser_begin(). */
-static bool
-lz_match_chooser_init(struct lz_match_chooser *mc,
- input_idx_t array_space,
- input_idx_t nice_len, input_idx_t max_match_len)
-{
- input_idx_t extra_len = min(nice_len, max_match_len);
-
- LZ_ASSERT(array_space > 0);
- mc->optimum = MALLOC((array_space + extra_len) * sizeof(mc->optimum[0]));
- if (mc->optimum == NULL)
- return false;
- mc->array_space = array_space;
- mc->nice_len = nice_len;
- return true;
-}
-
-static inline u64
-lz_match_chooser_get_needed_memory(input_idx_t array_space,
- input_idx_t nice_len,
- input_idx_t max_match_len)
-{
- input_idx_t extra_len = min(nice_len, max_match_len);
- return ((u64)(array_space + extra_len) *
- sizeof(((struct lz_match_chooser*)0)->optimum[0]));
-}
-
-/* Free memory allocated in lz_match_chooser_init(). */
-static void
-lz_match_chooser_destroy(struct lz_match_chooser *mc)
-{
- FREE(mc->optimum);
-}
-
-/* Call this before starting to parse each new input string. */
-static void
-lz_match_chooser_begin(struct lz_match_chooser *mc)
-{
- mc->optimum_cur_idx = 0;
- mc->optimum_end_idx = 0;
-}
-
-/*
- * Reverse the linked list of near-optimal matches so that they can be returned
- * in forwards order.
- *
- * Returns the first match in the list.
- */
-static _always_inline_attribute struct raw_match
-lz_match_chooser_reverse_list(struct lz_match_chooser *mc, input_idx_t cur_pos)
-{
- unsigned prev_link, saved_prev_link;
- unsigned prev_match_offset, saved_prev_match_offset;
-
- mc->optimum_end_idx = cur_pos;
-
- saved_prev_link = mc->optimum[cur_pos].prev.link;
- saved_prev_match_offset = mc->optimum[cur_pos].prev.match_offset;
-
- do {
- prev_link = saved_prev_link;
- prev_match_offset = saved_prev_match_offset;
-
- saved_prev_link = mc->optimum[prev_link].prev.link;
- saved_prev_match_offset = mc->optimum[prev_link].prev.match_offset;
-
- mc->optimum[prev_link].next.link = cur_pos;
- mc->optimum[prev_link].next.match_offset = prev_match_offset;
-
- cur_pos = prev_link;
- } while (cur_pos != 0);
-
- mc->optimum_cur_idx = mc->optimum[0].next.link;
-
- return (struct raw_match)
- { .len = mc->optimum_cur_idx,
- .offset = mc->optimum[0].next.match_offset,
- };
-}
-
-/* Format-specific functions inlined into lz_get_near_optimal_match(). */
-
-/* Get the list of possible matches at the next position. The return value must
- * be the number of matches found (which may be 0) and a pointer to the returned
- * matches must be written into @matches_ret. Matches must be of distinct
- * lengths and sorted in decreasing order by length. Furthermore, match lengths
- * may not exceed the @max_match_len passed to lz_match_chooser_init(), and all
- * match lengths must be at least 2. */
-typedef u32 (*lz_get_matches_t)(LZ_COMPRESSOR *ctx,
- const LZ_ADAPTIVE_STATE *state,
- struct raw_match **matches_ret);
-
-/* Skip the specified number of bytes (don't search for matches at them). This
- * is expected to be faster than simply getting the matches at each position,
- * but the exact performance difference will be dependent on the match-finder
- * implementation. */
-typedef void (*lz_skip_bytes_t)(LZ_COMPRESSOR *ctx, input_idx_t n);
-
-/* Get the cost of the literal located at the position at which matches have
- * most recently been searched. This can optionally update the @state to take
- * into account format-dependent state that affects match costs, such as repeat
- * offsets. */
-typedef lz_mc_cost_t (*lz_get_prev_literal_cost_t)(LZ_COMPRESSOR *ctx,
- LZ_ADAPTIVE_STATE *state);
-
-/* Get the cost of a match. This can optionally update the @state to take into
- * account format-dependent state that affects match costs, such as repeat
- * offsets. */
-typedef lz_mc_cost_t (*lz_get_match_cost_t)(LZ_COMPRESSOR *ctx,
- LZ_ADAPTIVE_STATE *state,
- input_idx_t length,
- input_idx_t offset);
-
-/*
- * lz_get_near_optimal_match() -
- *
- * Choose an approximately optimal match or literal to use at the next position
- * in the string, or "window", being LZ-encoded.
- *
- * This is based on the algorithm used in 7-Zip's DEFLATE encoder, written by
- * Igor Pavlov. However it also attempts to account for adaptive state, such as
- * an LRU queue of recent match offsets.
- *
- * Unlike a greedy parser that always takes the longest match, or even a "lazy"
- * parser with one match/literal look-ahead like zlib, the algorithm used here
- * may look ahead many matches/literals to determine the approximately optimal
- * match/literal to code next. The motivation is that the compression ratio is
- * improved if the compressor can do things like use a shorter-than-possible
- * match in order to allow a longer match later, and also take into account the
- * estimated real cost of coding each match/literal based on the underlying
- * entropy encoding.
- *
- * Still, this is not a true optimal parser for several reasons:
- *
- * - Very long matches (at least @nice_len) are taken immediately. This is
- * because locations with long matches are likely to have many possible
- * alternatives that would cause slow optimal parsing, but also such locations
- * are already highly compressible so it is not too harmful to just grab the
- * longest match.
- *
- * - Not all possible matches at each location are considered. Users of this
- * code are expected to provide a @get_matches() function that returns a list
- * of potentially good matches at the current position, but no more than one
- * per length. It therefore must use some sort of heuristic (e.g. smallest or
- * repeat offset) to choose a good match to consider for a given length, if
- * multiple exist. Furthermore, the @get_matches() implementation may limit
- * the total number of matches returned and/or the number of computational
- * steps spent searching for matches at each position.
- *
- * - This function relies on the user-provided @get_match_cost() and
- * @get_prev_literal_cost() functions to evaluate match and literal costs,
- * respectively, but real compression formats use entropy encoding of the
- * literal/match sequence, so the real cost of coding each match or literal is
- * unknown until the parse is fully determined. It can be approximated based
- * on iterative parses, but the end result is not guaranteed to be globally
- * optimal.
- *
- * - Although this function allows @get_match_cost() and
- * @get_prev_literal_cost() to take into account adaptive state, coding
- * decisions made with respect to the adaptive state will be locally optimal
- * but will not necessarily be globally optimal. This is because the
- * algorithm only keeps the least-costly path to get to a given location and
- * does not take into account that a slightly more costly path could result in
- * a different adaptive state that ultimately results in a lower global cost.
- *
- * - The array space used by this function is bounded, so in degenerate cases it
- * is forced to start returning matches/literals before the algorithm has
- * really finished.
- *
- * Each call to this function does one of two things:
- *
- * 1. Build a sequence of near-optimal matches/literals, up to some point, that
- * will be returned by subsequent calls to this function, then return the
- * first one.
- *
- * OR
- *
- * 2. Return the next match/literal previously computed by a call to this
- * function.
- *
- * The return value is a (length, offset) pair specifying the match or literal
- * chosen. For literals, the length is 0 or 1 and the offset is meaningless.
- *
- * NOTE: this code has been factored out of the LZX compressor so that it can be
- * shared by other formats such as LZMS. It is inlined so there is no loss of
- * performance, especially with the different implementations of match-finding,
- * cost evaluation, and adaptive state.
- */
-static _always_inline_attribute struct raw_match
-lz_get_near_optimal_match(struct lz_match_chooser *mc,
- lz_get_matches_t get_matches,
- lz_skip_bytes_t skip_bytes,
- lz_get_prev_literal_cost_t get_prev_literal_cost,
- lz_get_match_cost_t get_match_cost,
- LZ_COMPRESSOR *ctx,
- const LZ_ADAPTIVE_STATE *initial_state)
-{
- u32 num_possible_matches;
- struct raw_match *possible_matches;
- struct raw_match match;
- input_idx_t longest_match_len;
-
- if (mc->optimum_cur_idx != mc->optimum_end_idx) {
- /* Case 2: Return the next match/literal already found. */
- match.len = mc->optimum[mc->optimum_cur_idx].next.link -
- mc->optimum_cur_idx;
- match.offset = mc->optimum[mc->optimum_cur_idx].next.match_offset;
-
- mc->optimum_cur_idx = mc->optimum[mc->optimum_cur_idx].next.link;
- return match;
- }
-
- /* Case 1: Compute a new list of matches/literals to return. */
-
- mc->optimum_cur_idx = 0;
- mc->optimum_end_idx = 0;
-
- /* Get matches at this position. */
- num_possible_matches = (*get_matches)(ctx,
- initial_state,
- &possible_matches);
-
- /* If no matches found, return literal. */
- if (num_possible_matches == 0)
- return (struct raw_match){ .len = 0 };
-
- /* The matches that were found are sorted in decreasing order by length.
- * Get the length of the longest one. */
- longest_match_len = possible_matches[0].len;
-
- /* Greedy heuristic: if the longest match that was found is greater
- * than nice_len, return it immediately; don't both doing more work. */
- if (longest_match_len >= mc->nice_len) {
- (*skip_bytes)(ctx, longest_match_len - 1);
- return possible_matches[0];
- }
-
- /* Calculate the cost to reach the next position by coding a literal.
- */
- mc->optimum[1].state = *initial_state;
- mc->optimum[1].cost = (*get_prev_literal_cost)(ctx, &mc->optimum[1].state);
- mc->optimum[1].prev.link = 0;
-
- /* Calculate the cost to reach any position up to and including that
- * reached by the longest match. Use the shortest available match that
- * reaches each position, assuming that @get_matches() only returned
- * shorter matches because their estimated costs were less than that of
- * the longest match. */
- for (input_idx_t len = 2, match_idx = num_possible_matches - 1;
- len <= longest_match_len; len++)
- {
-
- LZ_ASSERT(match_idx < num_possible_matches);
- LZ_ASSERT(len <= possible_matches[match_idx].len);
-
- mc->optimum[len].state = *initial_state;
- mc->optimum[len].prev.link = 0;
- mc->optimum[len].prev.match_offset = possible_matches[match_idx].offset;
- mc->optimum[len].cost = (*get_match_cost)(ctx,
- &mc->optimum[len].state,
- len,
- possible_matches[match_idx].offset);
- if (len == possible_matches[match_idx].len)
- match_idx--;
- }
-
- /* Step forward, calculating the estimated minimum cost to reach each
- * position. The algorithm may find multiple paths to reach each
- * position; only the lowest-cost path is saved.
- *
- * The progress of the parse is tracked in the @mc->optimum array, which
- * for each position contains the minimum cost to reach that position,
- * the index of the start of the match/literal taken to reach that
- * position through the minimum-cost path, the offset of the match taken
- * (not relevant for literals), and the adaptive state that will exist
- * at that position after the minimum-cost path is taken. The @cur_pos
- * variable stores the position at which the algorithm is currently
- * considering coding choices, and the @len_end variable stores the
- * greatest position at which the costs of coding choices have been
- * saved. (Actually, the algorithm guarantees that all positions up to
- * and including @len_end are reachable by at least one path.)
- *
- * The loop terminates when any one of the following conditions occurs:
- *
- * 1. A match with length greater than or equal to @nice_len is found.
- * When this occurs, the algorithm chooses this match
- * unconditionally, and consequently the near-optimal match/literal
- * sequence up to and including that match is fully determined and it
- * can begin returning the match/literal list.
- *
- * 2. @cur_pos reaches a position not overlapped by a preceding match.
- * In such cases, the near-optimal match/literal sequence up to
- * @cur_pos is fully determined and it can begin returning the
- * match/literal list.
- *
- * 3. Failing either of the above in a degenerate case, the loop
- * terminates when space in the @mc->optimum array is exhausted.
- * This terminates the algorithm and forces it to start returning
- * matches/literals even though they may not be globally optimal.
- *
- * Upon loop termination, a nonempty list of matches/literals will have
- * been produced and stored in the @optimum array. These
- * matches/literals are linked in reverse order, so the last thing this
- * function does is reverse this list and return the first
- * match/literal, leaving the rest to be returned immediately by
- * subsequent calls to this function.
- */
- input_idx_t cur_pos = 0;
- input_idx_t len_end = longest_match_len;
- for (;;) {
- /* Advance to next position. */
- cur_pos++;
-
- /* Check termination conditions (2) and (3) noted above. */
- if (cur_pos == len_end || cur_pos == mc->array_space)
- return lz_match_chooser_reverse_list(mc, cur_pos);
-
- /* Retrieve a (possibly empty) list of potentially useful
- * matches available at this position. */
- num_possible_matches = (*get_matches)(ctx,
- &mc->optimum[cur_pos].state,
- &possible_matches);
-
- if (num_possible_matches == 0)
- longest_match_len = 0;
- else
- longest_match_len = possible_matches[0].len;
-
- /* Greedy heuristic and termination condition (1) noted above:
- * if we found a match greater than @nice_len, choose it
- * unconditionally and begin returning matches/literals. */
- if (longest_match_len >= mc->nice_len) {
- /* Build the list of matches to return and get
- * the first one. */
- match = lz_match_chooser_reverse_list(mc, cur_pos);
-
- /* Append the long match to the end of the list. */
- mc->optimum[cur_pos].next.match_offset =
- possible_matches[0].offset;
- mc->optimum[cur_pos].next.link = cur_pos + longest_match_len;
- mc->optimum_end_idx = cur_pos + longest_match_len;
-
- /* Skip over the remaining bytes of the long match. */
- (*skip_bytes)(ctx, longest_match_len - 1);
-
- /* Return first match in the list. */
- return match;
- }
-
- /* Load minimum cost to reach the current position. */
- input_idx_t cur_cost = mc->optimum[cur_pos].cost;
-
- /* Consider proceeding with a literal byte. */
- {
- LZ_ADAPTIVE_STATE state;
- lz_mc_cost_t cost;
-
- state = mc->optimum[cur_pos].state;
- cost = cur_cost + (*get_prev_literal_cost)(ctx, &state);
-
- if (cost < mc->optimum[cur_pos + 1].cost) {
- mc->optimum[cur_pos + 1].cost = cost;
- mc->optimum[cur_pos + 1].prev.link = cur_pos;
- mc->optimum[cur_pos + 1].state = state;
- }
- }
-
- /* If no matches were found, continue to the next position.
- * Otherwise, consider proceeding with a match. */
-
- if (num_possible_matches == 0)
- continue;
-
- /* Initialize any uninitialized costs up to the length of the
- * longest match found. */
- while (len_end < cur_pos + longest_match_len)
- mc->optimum[++len_end].cost = LZ_MC_INFINITE_COST;
-
- /* Calculate the minimum cost to reach any position up to and
- * including that reached by the longest match. Use the
- * shortest available match that reaches each position, assuming
- * that @get_matches() only returned shorter matches because
- * their estimated costs were less than that of the longest
- * match. */
- for (input_idx_t len = 2, match_idx = num_possible_matches - 1;
- len <= longest_match_len; len++)
- {
- LZ_ASSERT(match_idx < num_possible_matches);
- LZ_ASSERT(len <= possible_matches[match_idx].len);
-
- LZ_ADAPTIVE_STATE state;
- lz_mc_cost_t cost;
-
- state = mc->optimum[cur_pos].state;
- cost = cur_cost + (*get_match_cost)(ctx,
- &state,
- len,
- possible_matches[match_idx].offset);
-
- if (cost < mc->optimum[cur_pos + len].cost) {
- mc->optimum[cur_pos + len].cost = cost;
- mc->optimum[cur_pos + len].prev.link = cur_pos;
- mc->optimum[cur_pos + len].prev.match_offset =
- possible_matches[match_idx].offset;
- mc->optimum[cur_pos + len].state = state;
- }
-
- if (len == possible_matches[match_idx].len)
- match_idx--;
- }
- }
-}
-
-#endif /* _LZ_OPTIMAL_H */
+++ /dev/null
-/*
- * lz_sarray.h
- *
- * Suffix array match-finder for Lempel-Ziv compression.
- */
-
-/*
- * Copyright (c) 2013, 2014 Eric Biggers. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
- * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
- * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
- * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifndef _WIMLIB_LZ_SARRAY_H
-#define _WIMLIB_LZ_SARRAY_H
-
-#include "wimlib/compiler.h" /* must define '_always_inline_attribute',
- 'likely()', and 'prefetch()'. */
-#include "wimlib/lz.h" /* must define 'struct raw_match' and LZ_ASSERT() */
-#include "wimlib/types.h" /* must define 'bool', 'u8', 'u16, and 'u32' */
-
-struct salink;
-
-/* Position type --- must be an unsigned type large enough to hold the length of
- * longest window for which the suffix array match-finder will be used. */
-typedef u32 lz_sarray_pos_t;
-
-/* Length type --- must be an unsigned type large enough to hold the maximum
- * match length. */
-typedef u16 lz_sarray_len_t;
-
-/* Cost type, for the user-provided match cost evaluation function. */
-typedef lz_sarray_pos_t lz_sarray_cost_t;
-
-/* Type of distances in suffix array links. A larger type would allow skipping
- * irrelevant suffixes more quickly, which is especially helpful towards the
- * start of the window. However, even a single byte allows skipping 255 at a
- * time, which where it matters is already a big improvement over the
- * alternative of searching the suffixes consecutively. */
-typedef u8 lz_sarray_delta_t;
-
-#define LZ_SARRAY_LEN_MAX ((lz_sarray_len_t)~0UL)
-#define LZ_SARRAY_POS_MAX ((lz_sarray_pos_t)~0UL)
-#define LZ_SARRAY_DELTA_MAX ((lz_sarray_delta_t)~0UL)
-#define LZ_SARRAY_INFINITE_COST ((lz_sarray_cost_t)~0UL)
-
-/* State of the suffix array LZ (Lempel-Ziv) match-finder.
- *
- * This is defined here for benefit of the inlined code. It's not intended for
- * code outside the match-finder itself to read or write members from this
- * structure. */
-struct lz_sarray {
- /* Allocated window size for the match-finder.
- *
- * Note: this match-finder does not store the window itself, as the
- * suffix array (@SA) and associated arrays (@ISA, @LCP, @salink) are
- * sufficient to find matches. This number is the maximum length of
- * those arrays, or also the maximum window (block) size that can be
- * passed to lz_sarray_load_window(). */
- lz_sarray_pos_t max_window_size;
-
- /* Minimum length of matches to return. */
- lz_sarray_len_t min_match_len;
-
- /* Maximum length of matches to return. */
- lz_sarray_len_t max_match_len;
-
- /* Maximum matches to consider at each position (max search depth). */
- u32 max_matches_to_consider;
-
- /* Maximum number of matches to return at each position. */
- u32 max_matches_to_return;
-
- /* Current position in the window. */
- lz_sarray_pos_t cur_pos;
-
- /* Current window size. */
- lz_sarray_pos_t window_size;
-
- /* Suffix array for the current window.
- * This is a mapping from suffix rank to suffix position. */
- lz_sarray_pos_t *SA;
-
- /* Inverse suffix array for the current window.
- * This is a mapping from suffix position to suffix rank.
- * If 0 <= r < window_size, then ISA[SA[r]] == r. */
- lz_sarray_pos_t *ISA;
-
- /* Suffix array links.
- *
- * During a linear scan of the input string to find matches, this array
- * used to keep track of which rank suffixes in the suffix array appear
- * before the current position. Instead of searching in the original
- * suffix array, scans for matches at a given position traverse a linked
- * list containing (usually) only suffixes that appear before that
- * position. */
- struct salink *salink;
-};
-
-/* Suffix array link. An array of these structures, one per suffix rank, is
- * used as a replacement for the raw LCP (Longest Common Prefix) array to allow
- * skipping over suffixes that appear later in the window and hence cannot be
- * used as LZ77 matches. */
-struct salink {
- union {
- /* Temporary fields used while this structure is being
- * initialized.
- *
- * Note: we want the entire `struct salink' to be only 6 bytes,
- * even though this makes "next_initial" unaligned. */
- struct {
- lz_sarray_pos_t next_initial;
- lz_sarray_len_t lcpnext_initial;
- } _packed_attribute;
-
- struct {
- /* Intially, the length, in bytes, of the longest common
- * prefix (LCP) between the suffix having this rank and
- * the suffix with the smallest larger rank that
- * starts earlier in the window than the suffix having
- * this rank. If no such suffix exists, this will be 0.
- *
- * Later, during match-finding, after the corresponding
- * suffix has entered the LZ77 dictionary, this value
- * may be updated by lz_sarray_update_salink() to refer
- * instead to a lexicographically closer (but still
- * larger) suffix that begins at a later position that
- * has entered the LZ77 dictionary. */
- lz_sarray_len_t lcpnext;
-
- /* Initially, the length, in bytes, of the longest
- * common prefix (LCP) between the suffix having this
- * rank and the suffix with the largest smaller rank
- * that starts earlier in the window than the suffix
- * having this rank. If no such suffix exists, this
- * will be 0.
- *
- * Later, during match-finding, after the corresponding
- * suffix has entered the LZ77 dictionary, this value
- * may be updated by lz_sarray_update_salink() to refer
- * instead to a lexicographically closer (but still
- * smaller) suffix that begins at a later position that
- * has entered the LZ77 dictionary. */
- lz_sarray_len_t lcpprev;
-
- /* Distance to the suffix referred to in the description
- * of "lcpnext" above, but capped to a maximum value to
- * save memory; or, 0 if no such suffix exists. If the
- * true distance was truncated, this will give the
- * distance to the rank of a suffix that is
- * lexicographically closer to the current suffix than
- * the desired suffix, but appears *later* in the window
- * and hence cannot be used as the basis for an LZ77
- * match. */
- lz_sarray_delta_t dist_to_next;
-
- /* Distance to the suffix referred to in the description
- * of "lcpprev" above, but capped to a maximum value to
- * save memory; or, 0 if no such suffix exists. If the
- * true distance was truncated, this will give the
- * distance to the rank of a suffix that is
- * lexicographically closer to the current suffix than
- * the desired suffix, but appears *later* in the window
- * and hence cannot be used as the basis for an LZ77
- * match. */
- lz_sarray_delta_t dist_to_prev;
- };
- };
-};
-
-
-/*-----------------------------------*/
-/* Functions defined in lz_sarray.c */
-/*-----------------------------------*/
-
-extern bool
-lz_sarray_init(struct lz_sarray *mf,
- lz_sarray_pos_t max_window_size,
- lz_sarray_len_t min_match_len,
- lz_sarray_len_t max_match_len,
- u32 max_matches_to_consider,
- u32 max_matches_to_return);
-
-extern u64
-lz_sarray_get_needed_memory(lz_sarray_pos_t max_window_size);
-
-extern void
-lz_sarray_destroy(struct lz_sarray *mf);
-
-extern void
-lz_sarray_load_window(struct lz_sarray *mf, const u8 T[], lz_sarray_pos_t n);
-
-/*-------------------*/
-/* Inline functions */
-/*-------------------*/
-
-static _always_inline_attribute lz_sarray_pos_t
-lz_sarray_get_pos(const struct lz_sarray *mf)
-{
- return mf->cur_pos;
-}
-
-/* Advance the suffix array match-finder to the next position. */
-static _always_inline_attribute void
-lz_sarray_update_salink(const lz_sarray_pos_t r, struct salink link[])
-{
- const lz_sarray_pos_t next = r + link[r].dist_to_next;
- const lz_sarray_pos_t prev = r - link[r].dist_to_prev;
-
- if (next != r && link[r].dist_to_next < link[next].dist_to_prev) {
- link[next].dist_to_prev = link[r].dist_to_next;
- link[next].lcpprev = link[r].lcpnext;
- }
-
- if (prev != r && link[r].dist_to_prev < link[prev].dist_to_next) {
- link[prev].dist_to_next = link[r].dist_to_prev;
- link[prev].lcpnext = link[r].lcpprev;
- }
-}
-
-/* Skip the current position in the suffix array match-finder. */
-static _always_inline_attribute void
-lz_sarray_skip_position(struct lz_sarray *mf)
-{
- LZ_ASSERT(mf->cur_pos < mf->window_size);
- lz_sarray_update_salink(mf->ISA[mf->cur_pos++], mf->salink);
-}
-
-/*
- * Use the suffix array match-finder to retrieve a list of matches at the
- * current position.
- *
- * Returns the number of matches written into @matches. The matches are
- * returned in decreasing order by length, and each will be of unique length
- * between the minimum and maximum match lengths (inclusively) passed to
- * lz_sarray_init(). Up to @max_matches_to_return (passed to lz_sarray_init())
- * matches will be returned.
- *
- * @eval_match_cost is a function for evaluating the cost of a match when
- * deciding which ones to return. It needs to be fast, and need not be exact;
- * an implementation might simply rank matches by their offset, for example,
- * although implementations may choose to take into account additional
- * information such as repeat offsets.
- */
-static _always_inline_attribute u32
-lz_sarray_get_matches(struct lz_sarray *mf,
- struct raw_match matches[],
- lz_sarray_cost_t (*eval_match_cost)
- (lz_sarray_pos_t length,
- lz_sarray_pos_t offset,
- const void *ctx),
- const void *eval_match_cost_ctx)
-{
- LZ_ASSERT(mf->cur_pos < mf->window_size);
- const lz_sarray_pos_t i = mf->cur_pos++;
-
- const lz_sarray_pos_t * const restrict SA = mf->SA;
- const lz_sarray_pos_t * const restrict ISA = mf->ISA;
- struct salink * const restrict link = mf->salink;
- const u32 max_matches_to_consider = mf->max_matches_to_consider;
- const u32 max_matches_to_return = mf->max_matches_to_return;
-
- /* r = Rank of the suffix at the current position. */
- const lz_sarray_pos_t r = ISA[i];
-
- /* Prepare for searching the current position. */
- lz_sarray_update_salink(r, link);
-
-#if 1
- /* Prefetch next position in SA and link.
- *
- * This can improve performance on large windows since the locations in
- * SA and link at which each successive search begins are in general
- * randomly distributed. */
- if (likely(i + 1 < mf->window_size)) {
- const lz_sarray_pos_t next_r = ISA[i + 1];
- prefetch(&SA[next_r]);
- prefetch(&link[next_r]);
- }
-#endif
-
- /* L = rank of next suffix to the left;
- * R = rank of next suffix to the right;
- * lenL = length of match between current position and the suffix with rank L;
- * lenR = length of match between current position and the suffix with rank R.
- *
- * This is left and right relative to the rank of the current suffix.
- * Since the suffixes in the suffix array are sorted, the longest
- * matches are immediately to the left and right (using the linked list
- * to ignore all suffixes that occur later in the window). The match
- * length decreases the farther left and right we go. We shall keep the
- * length on both sides in sync in order to choose the lowest-cost match
- * of each length.
- */
- lz_sarray_pos_t L = r - link[r].dist_to_prev;
- lz_sarray_pos_t R = r + link[r].dist_to_next;
- lz_sarray_pos_t lenL = link[r].lcpprev;
- lz_sarray_pos_t lenR = link[r].lcpnext;
-
- /* nmatches = number of matches found so far. */
- u32 nmatches = 0;
-
- /* best_cost = cost of lowest-cost match found so far.
- *
- * Shorter matches that do not have a lower cost than this are
- * discarded, since presumably it would be cheaper to output the bytes
- * from the longer match instead. */
- lz_sarray_cost_t best_cost = LZ_SARRAY_INFINITE_COST;
-
- /* count_remaining = maximum number of possible matches remaining to be
- * considered. */
- u32 count_remaining = max_matches_to_consider;
-
- /* pending_offset = offset of lowest-cost match found for the current
- * length, or 0 if none found yet. */
- lz_sarray_pos_t pending_offset = 0;
-
- /* Note: some 'goto' statements are used in the remainder of this
- * function to remove unnecessary checks and create branches that the
- * CPU may predict better. (This function is performance critical.) */
-
- if (lenL != 0 && lenL >= lenR)
- goto extend_left;
- else if (lenR != 0)
- goto extend_right;
- else
- return 0;
-
-extend_left:
- /* Search suffixes on the left until the match length has decreased
- * below the next match length on the right or to below the minimum
- * match length. */
- for (;;) {
- lz_sarray_pos_t offset;
- lz_sarray_cost_t cost;
- lz_sarray_pos_t old_L;
- lz_sarray_pos_t old_lenL;
-
- /* Check for hard cutoff on amount of work done. */
- if (count_remaining-- == 0) {
- if (pending_offset != 0) {
- /* Save pending match. */
- matches[nmatches++] = (struct raw_match){
- .len = lenL,
- .offset = pending_offset,
- };
- }
- return nmatches;
- }
-
- if (SA[L] < i) {
- /* Suffix is in LZ77 dictionary. (Check was needed
- * because the salink array caps distances to save
- * memory.) */
-
- offset = i - SA[L];
-
- /* Save match offset if it results in lower cost. */
- cost = (*eval_match_cost)(lenL, offset,
- eval_match_cost_ctx);
- if (cost < best_cost) {
- best_cost = cost;
- pending_offset = offset;
- }
- }
-
- /* Advance left to previous suffix. */
-
- old_L = L;
- old_lenL = lenL;
-
- L -= link[L].dist_to_prev;
-
- if (link[old_L].lcpprev < old_lenL) {
- /* Match length decreased. */
-
- lenL = link[old_L].lcpprev;
-
- if (old_lenL > lenR) {
- /* Neither the right side nor the left size has
- * any more matches of length @old_lenL. If a
- * pending match exists, save it. */
- if (pending_offset != 0) {
- matches[nmatches++] = (struct raw_match){
- .len = old_lenL,
- .offset = pending_offset,
- };
- if (nmatches == max_matches_to_return)
- return nmatches;
-
- pending_offset = 0;
- }
-
- if (lenL >= lenR) {
- /* New match length on left is still at
- * least as large as the next match
- * length on the right: Keep extending
- * left, unless the minimum match length
- * would be underrun. */
- if (lenL == 0)
- return nmatches;
- goto extend_left;
- }
- }
-
- /* Here we have lenL < lenR. Extend right.
- * (No check for whether the minimum match length has
- * been underrun is needed, provided that such lengths
- * are marked as 0.) */
- goto extend_right;
- }
- }
-
-extend_right:
- /* Search suffixes on the right until the match length has decreased to
- * the next match length on the left or to below the minimum match
- * length. */
- for (;;) {
- lz_sarray_pos_t offset;
- lz_sarray_cost_t cost;
- lz_sarray_pos_t old_R;
- lz_sarray_pos_t old_lenR;
-
- /* Check for hard cutoff on amount of work done. */
- if (count_remaining-- == 0) {
- if (pending_offset != 0) {
- /* Save pending match. */
- matches[nmatches++] = (struct raw_match){
- .len = lenR,
- .offset = pending_offset,
- };
- }
- return nmatches;
- }
-
- if (SA[R] < i) {
- /* Suffix is in LZ77 dictionary. (Check was needed
- * because the salink array caps distances to save
- * memory.) */
-
- offset = i - SA[R];
-
- /* Save match offset if it results in lower cost. */
- cost = (*eval_match_cost)(lenR,
- offset,
- eval_match_cost_ctx);
- if (cost < best_cost) {
- best_cost = cost;
- pending_offset = offset;
- }
- }
-
- /* Advance right to next suffix. */
-
- old_R = R;
- old_lenR = lenR;
-
- R += link[R].dist_to_next;
-
- if (link[old_R].lcpnext < lenR) {
- /* Match length decreased. */
-
- lenR = link[old_R].lcpnext;
-
- /* Neither the right side nor the left size has any more
- * matches of length @old_lenR. If a pending match
- * exists, save it. */
- if (pending_offset != 0) {
- matches[nmatches++] = (struct raw_match){
- .len = old_lenR,
- .offset = pending_offset,
- };
- if (nmatches == max_matches_to_return)
- return nmatches;
-
- pending_offset = 0;
- }
-
- if (lenL >= lenR) {
- /* lenL >= lenR: Extend left, unless the
- * minimum match length would be underrun, in
- * which case we are done. */
- if (lenL == 0)
- return nmatches;
-
- goto extend_left;
- }
- /* lenR > lenL: Keep extending right.
- * (No check for whether the minimum match length has
- * been underrun is needed, provided that such lengths
- * are marked as 0.) */
- }
- }
-}
-
-#endif /* _WIMLIB_LZ_SARRAY_H */
* the formatted offset without actually looking at the array.
*/
static inline unsigned
-lzx_get_position_slot_raw(unsigned formatted_offset)
+lzx_get_position_slot_raw(u32 formatted_offset)
{
if (formatted_offset >= 196608) {
return (formatted_offset >> 17) + 34;
.nice_match_length = 96,
.num_optim_passes = 4,
.max_search_depth = 100,
- .max_matches_per_pos = 10,
.main_nostat_cost = 15,
.len_nostat_cost = 15,
.aligned_nostat_cost = 7,
.max_match_length = UINT32_MAX,
.nice_match_length = 96,
.max_search_depth = 100,
- .max_matches_per_pos = 10,
.optim_array_length = 1024,
};
+++ /dev/null
-/*
- * divsufsort.c for libdivsufsort-lite
- * Copyright (c) 2003-2008 Yuta Mori All Rights Reserved.
- *
- * Permission is hereby granted, free of charge, to any person
- * obtaining a copy of this software and associated documentation
- * files (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use,
- * copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following
- * conditions:
- *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
- * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
- * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
- * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
- * OTHER DEALINGS IN THE SOFTWARE.
- */
-
-#define assert(x)
-
-#include "wimlib/divsufsort.h"
-#include <stddef.h>
-
-/*- Constants -*/
-#if defined(ALPHABET_SIZE) && (ALPHABET_SIZE < 1)
-# undef ALPHABET_SIZE
-#endif
-#if !defined(ALPHABET_SIZE)
-# define ALPHABET_SIZE (256)
-#endif
-#define BUCKET_A_SIZE (ALPHABET_SIZE)
-#define BUCKET_B_SIZE (ALPHABET_SIZE * ALPHABET_SIZE)
-#if defined(SS_INSERTIONSORT_THRESHOLD)
-# if SS_INSERTIONSORT_THRESHOLD < 1
-# undef SS_INSERTIONSORT_THRESHOLD
-# define SS_INSERTIONSORT_THRESHOLD (1)
-# endif
-#else
-# define SS_INSERTIONSORT_THRESHOLD (8)
-#endif
-#if defined(SS_BLOCKSIZE)
-# if SS_BLOCKSIZE < 0
-# undef SS_BLOCKSIZE
-# define SS_BLOCKSIZE (0)
-# elif 32768 <= SS_BLOCKSIZE
-# undef SS_BLOCKSIZE
-# define SS_BLOCKSIZE (32767)
-# endif
-#else
-# define SS_BLOCKSIZE (1024)
-#endif
-/* minstacksize = log(SS_BLOCKSIZE) / log(3) * 2 */
-#if SS_BLOCKSIZE == 0
-# define SS_MISORT_STACKSIZE (96)
-#elif SS_BLOCKSIZE <= 4096
-# define SS_MISORT_STACKSIZE (16)
-#else
-# define SS_MISORT_STACKSIZE (24)
-#endif
-#define SS_SMERGE_STACKSIZE (32)
-#define TR_INSERTIONSORT_THRESHOLD (8)
-#define TR_STACKSIZE (64)
-
-
-/*- Macros -*/
-#ifndef SWAP
-# define SWAP(_a, _b) do { t = (_a); (_a) = (_b); (_b) = t; } while(0)
-#endif /* SWAP */
-#ifndef MIN
-# define MIN(_a, _b) (((_a) < (_b)) ? (_a) : (_b))
-#endif /* MIN */
-#ifndef MAX
-# define MAX(_a, _b) (((_a) > (_b)) ? (_a) : (_b))
-#endif /* MAX */
-#define STACK_PUSH(_a, _b, _c, _d)\
- do {\
- assert(ssize < STACK_SIZE);\
- stack[ssize].a = (_a), stack[ssize].b = (_b),\
- stack[ssize].c = (_c), stack[ssize++].d = (_d);\
- } while(0)
-#define STACK_PUSH5(_a, _b, _c, _d, _e)\
- do {\
- assert(ssize < STACK_SIZE);\
- stack[ssize].a = (_a), stack[ssize].b = (_b),\
- stack[ssize].c = (_c), stack[ssize].d = (_d), stack[ssize++].e = (_e);\
- } while(0)
-#define STACK_POP(_a, _b, _c, _d)\
- do {\
- assert(0 <= ssize);\
- if(ssize == 0) { return; }\
- (_a) = stack[--ssize].a, (_b) = stack[ssize].b,\
- (_c) = stack[ssize].c, (_d) = stack[ssize].d;\
- } while(0)
-#define STACK_POP5(_a, _b, _c, _d, _e)\
- do {\
- assert(0 <= ssize);\
- if(ssize == 0) { return; }\
- (_a) = stack[--ssize].a, (_b) = stack[ssize].b,\
- (_c) = stack[ssize].c, (_d) = stack[ssize].d, (_e) = stack[ssize].e;\
- } while(0)
-#define BUCKET_A(_c0) bucket_A[(_c0)]
-#if ALPHABET_SIZE == 256
-#define BUCKET_B(_c0, _c1) (bucket_B[((_c1) << 8) | (_c0)])
-#define BUCKET_BSTAR(_c0, _c1) (bucket_B[((_c0) << 8) | (_c1)])
-#else
-#define BUCKET_B(_c0, _c1) (bucket_B[(_c1) * ALPHABET_SIZE + (_c0)])
-#define BUCKET_BSTAR(_c0, _c1) (bucket_B[(_c0) * ALPHABET_SIZE + (_c1)])
-#endif
-
-
-/*- Private Functions -*/
-
-static const int lg_table[256]= {
- -1,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
- 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
- 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
- 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
- 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
- 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
- 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
- 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
-};
-
-#if (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE)
-
-static inline
-int
-ss_ilg(int n) {
-#if SS_BLOCKSIZE == 0
- return (n & 0xffff0000) ?
- ((n & 0xff000000) ?
- 24 + lg_table[(n >> 24) & 0xff] :
- 16 + lg_table[(n >> 16) & 0xff]) :
- ((n & 0x0000ff00) ?
- 8 + lg_table[(n >> 8) & 0xff] :
- 0 + lg_table[(n >> 0) & 0xff]);
-#elif SS_BLOCKSIZE < 256
- return lg_table[n];
-#else
- return (n & 0xff00) ?
- 8 + lg_table[(n >> 8) & 0xff] :
- 0 + lg_table[(n >> 0) & 0xff];
-#endif
-}
-
-#endif /* (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE) */
-
-#if SS_BLOCKSIZE != 0
-
-static const int sqq_table[256] = {
- 0, 16, 22, 27, 32, 35, 39, 42, 45, 48, 50, 53, 55, 57, 59, 61,
- 64, 65, 67, 69, 71, 73, 75, 76, 78, 80, 81, 83, 84, 86, 87, 89,
- 90, 91, 93, 94, 96, 97, 98, 99, 101, 102, 103, 104, 106, 107, 108, 109,
-110, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,
-128, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142,
-143, 144, 144, 145, 146, 147, 148, 149, 150, 150, 151, 152, 153, 154, 155, 155,
-156, 157, 158, 159, 160, 160, 161, 162, 163, 163, 164, 165, 166, 167, 167, 168,
-169, 170, 170, 171, 172, 173, 173, 174, 175, 176, 176, 177, 178, 178, 179, 180,
-181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188, 189, 189, 190, 191,
-192, 192, 193, 193, 194, 195, 195, 196, 197, 197, 198, 199, 199, 200, 201, 201,
-202, 203, 203, 204, 204, 205, 206, 206, 207, 208, 208, 209, 209, 210, 211, 211,
-212, 212, 213, 214, 214, 215, 215, 216, 217, 217, 218, 218, 219, 219, 220, 221,
-221, 222, 222, 223, 224, 224, 225, 225, 226, 226, 227, 227, 228, 229, 229, 230,
-230, 231, 231, 232, 232, 233, 234, 234, 235, 235, 236, 236, 237, 237, 238, 238,
-239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 246, 246, 247,
-247, 248, 248, 249, 249, 250, 250, 251, 251, 252, 252, 253, 253, 254, 254, 255
-};
-
-static inline
-int
-ss_isqrt(int x) {
- int y, e;
-
- if(x >= (SS_BLOCKSIZE * SS_BLOCKSIZE)) { return SS_BLOCKSIZE; }
- e = (x & 0xffff0000) ?
- ((x & 0xff000000) ?
- 24 + lg_table[(x >> 24) & 0xff] :
- 16 + lg_table[(x >> 16) & 0xff]) :
- ((x & 0x0000ff00) ?
- 8 + lg_table[(x >> 8) & 0xff] :
- 0 + lg_table[(x >> 0) & 0xff]);
-
- if(e >= 16) {
- y = sqq_table[x >> ((e - 6) - (e & 1))] << ((e >> 1) - 7);
- if(e >= 24) { y = (y + 1 + x / y) >> 1; }
- y = (y + 1 + x / y) >> 1;
- } else if(e >= 8) {
- y = (sqq_table[x >> ((e - 6) - (e & 1))] >> (7 - (e >> 1))) + 1;
- } else {
- return sqq_table[x] >> 4;
- }
-
- return (x < (y * y)) ? y - 1 : y;
-}
-
-#endif /* SS_BLOCKSIZE != 0 */
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Compares two suffixes. */
-static inline
-int
-ss_compare(const unsigned char *T,
- const int *p1, const int *p2,
- int depth) {
- const unsigned char *U1, *U2, *U1n, *U2n;
-
- for(U1 = T + depth + *p1,
- U2 = T + depth + *p2,
- U1n = T + *(p1 + 1) + 2,
- U2n = T + *(p2 + 1) + 2;
- (U1 < U1n) && (U2 < U2n) && (*U1 == *U2);
- ++U1, ++U2) {
- }
-
- return U1 < U1n ?
- (U2 < U2n ? *U1 - *U2 : 1) :
- (U2 < U2n ? -1 : 0);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-#if (SS_BLOCKSIZE != 1) && (SS_INSERTIONSORT_THRESHOLD != 1)
-
-/* Insertionsort for small size groups */
-static
-void
-ss_insertionsort(const unsigned char *T, const int *PA,
- int *first, int *last, int depth) {
- int *i, *j;
- int t;
- int r;
-
- for(i = last - 2; first <= i; --i) {
- for(t = *i, j = i + 1; 0 < (r = ss_compare(T, PA + t, PA + *j, depth));) {
- do { *(j - 1) = *j; } while((++j < last) && (*j < 0));
- if(last <= j) { break; }
- }
- if(r == 0) { *j = ~*j; }
- *(j - 1) = t;
- }
-}
-
-#endif /* (SS_BLOCKSIZE != 1) && (SS_INSERTIONSORT_THRESHOLD != 1) */
-
-
-/*---------------------------------------------------------------------------*/
-
-#if (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE)
-
-static inline
-void
-ss_fixdown(const unsigned char *Td, const int *PA,
- int *SA, int i, int size) {
- int j, k;
- int v;
- int c, d, e;
-
- for(v = SA[i], c = Td[PA[v]]; (j = 2 * i + 1) < size; SA[i] = SA[k], i = k) {
- d = Td[PA[SA[k = j++]]];
- if(d < (e = Td[PA[SA[j]]])) { k = j; d = e; }
- if(d <= c) { break; }
- }
- SA[i] = v;
-}
-
-/* Simple top-down heapsort. */
-static
-void
-ss_heapsort(const unsigned char *Td, const int *PA, int *SA, int size) {
- int i, m;
- int t;
-
- m = size;
- if((size % 2) == 0) {
- m--;
- if(Td[PA[SA[m / 2]]] < Td[PA[SA[m]]]) { SWAP(SA[m], SA[m / 2]); }
- }
-
- for(i = m / 2 - 1; 0 <= i; --i) { ss_fixdown(Td, PA, SA, i, m); }
- if((size % 2) == 0) { SWAP(SA[0], SA[m]); ss_fixdown(Td, PA, SA, 0, m); }
- for(i = m - 1; 0 < i; --i) {
- t = SA[0], SA[0] = SA[i];
- ss_fixdown(Td, PA, SA, 0, i);
- SA[i] = t;
- }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Returns the median of three elements. */
-static inline
-int *
-ss_median3(const unsigned char *Td, const int *PA,
- int *v1, int *v2, int *v3) {
- int *t;
- if(Td[PA[*v1]] > Td[PA[*v2]]) { SWAP(v1, v2); }
- if(Td[PA[*v2]] > Td[PA[*v3]]) {
- if(Td[PA[*v1]] > Td[PA[*v3]]) { return v1; }
- else { return v3; }
- }
- return v2;
-}
-
-/* Returns the median of five elements. */
-static inline
-int *
-ss_median5(const unsigned char *Td, const int *PA,
- int *v1, int *v2, int *v3, int *v4, int *v5) {
- int *t;
- if(Td[PA[*v2]] > Td[PA[*v3]]) { SWAP(v2, v3); }
- if(Td[PA[*v4]] > Td[PA[*v5]]) { SWAP(v4, v5); }
- if(Td[PA[*v2]] > Td[PA[*v4]]) { SWAP(v2, v4); SWAP(v3, v5); }
- if(Td[PA[*v1]] > Td[PA[*v3]]) { SWAP(v1, v3); }
- if(Td[PA[*v1]] > Td[PA[*v4]]) { SWAP(v1, v4); SWAP(v3, v5); }
- if(Td[PA[*v3]] > Td[PA[*v4]]) { return v4; }
- return v3;
-}
-
-/* Returns the pivot element. */
-static inline
-int *
-ss_pivot(const unsigned char *Td, const int *PA, int *first, int *last) {
- int *middle;
- int t;
-
- t = last - first;
- middle = first + t / 2;
-
- if(t <= 512) {
- if(t <= 32) {
- return ss_median3(Td, PA, first, middle, last - 1);
- } else {
- t >>= 2;
- return ss_median5(Td, PA, first, first + t, middle, last - 1 - t, last - 1);
- }
- }
- t >>= 3;
- first = ss_median3(Td, PA, first, first + t, first + (t << 1));
- middle = ss_median3(Td, PA, middle - t, middle, middle + t);
- last = ss_median3(Td, PA, last - 1 - (t << 1), last - 1 - t, last - 1);
- return ss_median3(Td, PA, first, middle, last);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Binary partition for substrings. */
-static inline
-int *
-ss_partition(const int *PA,
- int *first, int *last, int depth) {
- int *a, *b;
- int t;
- for(a = first - 1, b = last;;) {
- for(; (++a < b) && ((PA[*a] + depth) >= (PA[*a + 1] + 1));) { *a = ~*a; }
- for(; (a < --b) && ((PA[*b] + depth) < (PA[*b + 1] + 1));) { }
- if(b <= a) { break; }
- t = ~*b;
- *b = *a;
- *a = t;
- }
- if(first < a) { *first = ~*first; }
- return a;
-}
-
-/* Multikey introsort for medium size groups. */
-static
-void
-ss_mintrosort(const unsigned char *T, const int *PA,
- int *first, int *last,
- int depth) {
-#define STACK_SIZE SS_MISORT_STACKSIZE
- struct { int *a, *b, c; int d; } stack[STACK_SIZE];
- const unsigned char *Td;
- int *a, *b, *c, *d, *e, *f;
- int s, t;
- int ssize;
- int limit;
- int v, x = 0;
-
- for(ssize = 0, limit = ss_ilg(last - first);;) {
-
- if((last - first) <= SS_INSERTIONSORT_THRESHOLD) {
-#if 1 < SS_INSERTIONSORT_THRESHOLD
- if(1 < (last - first)) { ss_insertionsort(T, PA, first, last, depth); }
-#endif
- STACK_POP(first, last, depth, limit);
- continue;
- }
-
- Td = T + depth;
- if(limit-- == 0) { ss_heapsort(Td, PA, first, last - first); }
- if(limit < 0) {
- for(a = first + 1, v = Td[PA[*first]]; a < last; ++a) {
- if((x = Td[PA[*a]]) != v) {
- if(1 < (a - first)) { break; }
- v = x;
- first = a;
- }
- }
- if(Td[PA[*first] - 1] < v) {
- first = ss_partition(PA, first, a, depth);
- }
- if((a - first) <= (last - a)) {
- if(1 < (a - first)) {
- STACK_PUSH(a, last, depth, -1);
- last = a, depth += 1, limit = ss_ilg(a - first);
- } else {
- first = a, limit = -1;
- }
- } else {
- if(1 < (last - a)) {
- STACK_PUSH(first, a, depth + 1, ss_ilg(a - first));
- first = a, limit = -1;
- } else {
- last = a, depth += 1, limit = ss_ilg(a - first);
- }
- }
- continue;
- }
-
- /* choose pivot */
- a = ss_pivot(Td, PA, first, last);
- v = Td[PA[*a]];
- SWAP(*first, *a);
-
- /* partition */
- for(b = first; (++b < last) && ((x = Td[PA[*b]]) == v);) { }
- if(((a = b) < last) && (x < v)) {
- for(; (++b < last) && ((x = Td[PA[*b]]) <= v);) {
- if(x == v) { SWAP(*b, *a); ++a; }
- }
- }
- for(c = last; (b < --c) && ((x = Td[PA[*c]]) == v);) { }
- if((b < (d = c)) && (x > v)) {
- for(; (b < --c) && ((x = Td[PA[*c]]) >= v);) {
- if(x == v) { SWAP(*c, *d); --d; }
- }
- }
- for(; b < c;) {
- SWAP(*b, *c);
- for(; (++b < c) && ((x = Td[PA[*b]]) <= v);) {
- if(x == v) { SWAP(*b, *a); ++a; }
- }
- for(; (b < --c) && ((x = Td[PA[*c]]) >= v);) {
- if(x == v) { SWAP(*c, *d); --d; }
- }
- }
-
- if(a <= d) {
- c = b - 1;
-
- if((s = a - first) > (t = b - a)) { s = t; }
- for(e = first, f = b - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
- if((s = d - c) > (t = last - d - 1)) { s = t; }
- for(e = b, f = last - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
-
- a = first + (b - a), c = last - (d - c);
- b = (v <= Td[PA[*a] - 1]) ? a : ss_partition(PA, a, c, depth);
-
- if((a - first) <= (last - c)) {
- if((last - c) <= (c - b)) {
- STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
- STACK_PUSH(c, last, depth, limit);
- last = a;
- } else if((a - first) <= (c - b)) {
- STACK_PUSH(c, last, depth, limit);
- STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
- last = a;
- } else {
- STACK_PUSH(c, last, depth, limit);
- STACK_PUSH(first, a, depth, limit);
- first = b, last = c, depth += 1, limit = ss_ilg(c - b);
- }
- } else {
- if((a - first) <= (c - b)) {
- STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
- STACK_PUSH(first, a, depth, limit);
- first = c;
- } else if((last - c) <= (c - b)) {
- STACK_PUSH(first, a, depth, limit);
- STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
- first = c;
- } else {
- STACK_PUSH(first, a, depth, limit);
- STACK_PUSH(c, last, depth, limit);
- first = b, last = c, depth += 1, limit = ss_ilg(c - b);
- }
- }
- } else {
- limit += 1;
- if(Td[PA[*first] - 1] < v) {
- first = ss_partition(PA, first, last, depth);
- limit = ss_ilg(last - first);
- }
- depth += 1;
- }
- }
-#undef STACK_SIZE
-}
-
-#endif /* (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE) */
-
-
-/*---------------------------------------------------------------------------*/
-
-#if SS_BLOCKSIZE != 0
-
-static inline
-void
-ss_blockswap(int *a, int *b, int n) {
- int t;
- for(; 0 < n; --n, ++a, ++b) {
- t = *a, *a = *b, *b = t;
- }
-}
-
-static inline
-void
-ss_rotate(int *first, int *middle, int *last) {
- int *a, *b, t;
- int l, r;
- l = middle - first, r = last - middle;
- for(; (0 < l) && (0 < r);) {
- if(l == r) { ss_blockswap(first, middle, l); break; }
- if(l < r) {
- a = last - 1, b = middle - 1;
- t = *a;
- do {
- *a-- = *b, *b-- = *a;
- if(b < first) {
- *a = t;
- last = a;
- if((r -= l + 1) <= l) { break; }
- a -= 1, b = middle - 1;
- t = *a;
- }
- } while(1);
- } else {
- a = first, b = middle;
- t = *a;
- do {
- *a++ = *b, *b++ = *a;
- if(last <= b) {
- *a = t;
- first = a + 1;
- if((l -= r + 1) <= r) { break; }
- a += 1, b = middle;
- t = *a;
- }
- } while(1);
- }
- }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static
-void
-ss_inplacemerge(const unsigned char *T, const int *PA,
- int *first, int *middle, int *last,
- int depth) {
- const int *p;
- int *a, *b;
- int len, half;
- int q, r;
- int x;
-
- for(;;) {
- if(*(last - 1) < 0) { x = 1; p = PA + ~*(last - 1); }
- else { x = 0; p = PA + *(last - 1); }
- for(a = first, len = middle - first, half = len >> 1, r = -1;
- 0 < len;
- len = half, half >>= 1) {
- b = a + half;
- q = ss_compare(T, PA + ((0 <= *b) ? *b : ~*b), p, depth);
- if(q < 0) {
- a = b + 1;
- half -= (len & 1) ^ 1;
- } else {
- r = q;
- }
- }
- if(a < middle) {
- if(r == 0) { *a = ~*a; }
- ss_rotate(a, middle, last);
- last -= middle - a;
- middle = a;
- if(first == middle) { break; }
- }
- --last;
- if(x != 0) { while(*--last < 0) { } }
- if(middle == last) { break; }
- }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Merge-forward with internal buffer. */
-static
-void
-ss_mergeforward(const unsigned char *T, const int *PA,
- int *first, int *middle, int *last,
- int *buf, int depth) {
- int *a, *b, *c, *bufend;
- int t;
- int r;
-
- bufend = buf + (middle - first) - 1;
- ss_blockswap(buf, first, middle - first);
-
- for(t = *(a = first), b = buf, c = middle;;) {
- r = ss_compare(T, PA + *b, PA + *c, depth);
- if(r < 0) {
- do {
- *a++ = *b;
- if(bufend <= b) { *bufend = t; return; }
- *b++ = *a;
- } while(*b < 0);
- } else if(r > 0) {
- do {
- *a++ = *c, *c++ = *a;
- if(last <= c) {
- while(b < bufend) { *a++ = *b, *b++ = *a; }
- *a = *b, *b = t;
- return;
- }
- } while(*c < 0);
- } else {
- *c = ~*c;
- do {
- *a++ = *b;
- if(bufend <= b) { *bufend = t; return; }
- *b++ = *a;
- } while(*b < 0);
-
- do {
- *a++ = *c, *c++ = *a;
- if(last <= c) {
- while(b < bufend) { *a++ = *b, *b++ = *a; }
- *a = *b, *b = t;
- return;
- }
- } while(*c < 0);
- }
- }
-}
-
-/* Merge-backward with internal buffer. */
-static
-void
-ss_mergebackward(const unsigned char *T, const int *PA,
- int *first, int *middle, int *last,
- int *buf, int depth) {
- const int *p1, *p2;
- int *a, *b, *c, *bufend;
- int t;
- int r;
- int x;
-
- bufend = buf + (last - middle) - 1;
- ss_blockswap(buf, middle, last - middle);
-
- x = 0;
- if(*bufend < 0) { p1 = PA + ~*bufend; x |= 1; }
- else { p1 = PA + *bufend; }
- if(*(middle - 1) < 0) { p2 = PA + ~*(middle - 1); x |= 2; }
- else { p2 = PA + *(middle - 1); }
- for(t = *(a = last - 1), b = bufend, c = middle - 1;;) {
- r = ss_compare(T, p1, p2, depth);
- if(0 < r) {
- if(x & 1) { do { *a-- = *b, *b-- = *a; } while(*b < 0); x ^= 1; }
- *a-- = *b;
- if(b <= buf) { *buf = t; break; }
- *b-- = *a;
- if(*b < 0) { p1 = PA + ~*b; x |= 1; }
- else { p1 = PA + *b; }
- } else if(r < 0) {
- if(x & 2) { do { *a-- = *c, *c-- = *a; } while(*c < 0); x ^= 2; }
- *a-- = *c, *c-- = *a;
- if(c < first) {
- while(buf < b) { *a-- = *b, *b-- = *a; }
- *a = *b, *b = t;
- break;
- }
- if(*c < 0) { p2 = PA + ~*c; x |= 2; }
- else { p2 = PA + *c; }
- } else {
- if(x & 1) { do { *a-- = *b, *b-- = *a; } while(*b < 0); x ^= 1; }
- *a-- = ~*b;
- if(b <= buf) { *buf = t; break; }
- *b-- = *a;
- if(x & 2) { do { *a-- = *c, *c-- = *a; } while(*c < 0); x ^= 2; }
- *a-- = *c, *c-- = *a;
- if(c < first) {
- while(buf < b) { *a-- = *b, *b-- = *a; }
- *a = *b, *b = t;
- break;
- }
- if(*b < 0) { p1 = PA + ~*b; x |= 1; }
- else { p1 = PA + *b; }
- if(*c < 0) { p2 = PA + ~*c; x |= 2; }
- else { p2 = PA + *c; }
- }
- }
-}
-
-/* D&C based merge. */
-static
-void
-ss_swapmerge(const unsigned char *T, const int *PA,
- int *first, int *middle, int *last,
- int *buf, int bufsize, int depth) {
-#define STACK_SIZE SS_SMERGE_STACKSIZE
-#define GETIDX(a) ((0 <= (a)) ? (a) : (~(a)))
-#define MERGE_CHECK(a, b, c)\
- do {\
- if(((c) & 1) ||\
- (((c) & 2) && (ss_compare(T, PA + GETIDX(*((a) - 1)), PA + *(a), depth) == 0))) {\
- *(a) = ~*(a);\
- }\
- if(((c) & 4) && ((ss_compare(T, PA + GETIDX(*((b) - 1)), PA + *(b), depth) == 0))) {\
- *(b) = ~*(b);\
- }\
- } while(0)
- struct { int *a, *b, *c; int d; } stack[STACK_SIZE];
- int *l, *r, *lm, *rm;
- int m, len, half;
- int ssize;
- int check, next;
-
- for(check = 0, ssize = 0;;) {
- if((last - middle) <= bufsize) {
- if((first < middle) && (middle < last)) {
- ss_mergebackward(T, PA, first, middle, last, buf, depth);
- }
- MERGE_CHECK(first, last, check);
- STACK_POP(first, middle, last, check);
- continue;
- }
-
- if((middle - first) <= bufsize) {
- if(first < middle) {
- ss_mergeforward(T, PA, first, middle, last, buf, depth);
- }
- MERGE_CHECK(first, last, check);
- STACK_POP(first, middle, last, check);
- continue;
- }
-
- for(m = 0, len = MIN(middle - first, last - middle), half = len >> 1;
- 0 < len;
- len = half, half >>= 1) {
- if(ss_compare(T, PA + GETIDX(*(middle + m + half)),
- PA + GETIDX(*(middle - m - half - 1)), depth) < 0) {
- m += half + 1;
- half -= (len & 1) ^ 1;
- }
- }
-
- if(0 < m) {
- lm = middle - m, rm = middle + m;
- ss_blockswap(lm, middle, m);
- l = r = middle, next = 0;
- if(rm < last) {
- if(*rm < 0) {
- *rm = ~*rm;
- if(first < lm) { for(; *--l < 0;) { } next |= 4; }
- next |= 1;
- } else if(first < lm) {
- for(; *r < 0; ++r) { }
- next |= 2;
- }
- }
-
- if((l - first) <= (last - r)) {
- STACK_PUSH(r, rm, last, (next & 3) | (check & 4));
- middle = lm, last = l, check = (check & 3) | (next & 4);
- } else {
- if((next & 2) && (r == middle)) { next ^= 6; }
- STACK_PUSH(first, lm, l, (check & 3) | (next & 4));
- first = r, middle = rm, check = (next & 3) | (check & 4);
- }
- } else {
- if(ss_compare(T, PA + GETIDX(*(middle - 1)), PA + *middle, depth) == 0) {
- *middle = ~*middle;
- }
- MERGE_CHECK(first, last, check);
- STACK_POP(first, middle, last, check);
- }
- }
-#undef STACK_SIZE
-}
-
-#endif /* SS_BLOCKSIZE != 0 */
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Substring sort */
-static
-void
-sssort(const unsigned char *T, const int *PA,
- int *first, int *last,
- int *buf, int bufsize,
- int depth, int n, int lastsuffix) {
- int *a;
-#if SS_BLOCKSIZE != 0
- int *b, *middle, *curbuf;
- int j, k, curbufsize, limit;
-#endif
- int i;
-
- if(lastsuffix != 0) { ++first; }
-
-#if SS_BLOCKSIZE == 0
- ss_mintrosort(T, PA, first, last, depth);
-#else
- if((bufsize < SS_BLOCKSIZE) &&
- (bufsize < (last - first)) &&
- (bufsize < (limit = ss_isqrt(last - first)))) {
- if(SS_BLOCKSIZE < limit) { limit = SS_BLOCKSIZE; }
- buf = middle = last - limit, bufsize = limit;
- } else {
- middle = last, limit = 0;
- }
- for(a = first, i = 0; SS_BLOCKSIZE < (middle - a); a += SS_BLOCKSIZE, ++i) {
-#if SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE
- ss_mintrosort(T, PA, a, a + SS_BLOCKSIZE, depth);
-#elif 1 < SS_BLOCKSIZE
- ss_insertionsort(T, PA, a, a + SS_BLOCKSIZE, depth);
-#endif
- curbufsize = last - (a + SS_BLOCKSIZE);
- curbuf = a + SS_BLOCKSIZE;
- if(curbufsize <= bufsize) { curbufsize = bufsize, curbuf = buf; }
- for(b = a, k = SS_BLOCKSIZE, j = i; j & 1; b -= k, k <<= 1, j >>= 1) {
- ss_swapmerge(T, PA, b - k, b, b + k, curbuf, curbufsize, depth);
- }
- }
-#if SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE
- ss_mintrosort(T, PA, a, middle, depth);
-#elif 1 < SS_BLOCKSIZE
- ss_insertionsort(T, PA, a, middle, depth);
-#endif
- for(k = SS_BLOCKSIZE; i != 0; k <<= 1, i >>= 1) {
- if(i & 1) {
- ss_swapmerge(T, PA, a - k, a, middle, buf, bufsize, depth);
- a -= k;
- }
- }
- if(limit != 0) {
-#if SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE
- ss_mintrosort(T, PA, middle, last, depth);
-#elif 1 < SS_BLOCKSIZE
- ss_insertionsort(T, PA, middle, last, depth);
-#endif
- ss_inplacemerge(T, PA, first, middle, last, depth);
- }
-#endif
-
- if(lastsuffix != 0) {
- /* Insert last type B* suffix. */
- int PAi[2]; PAi[0] = PA[*(first - 1)], PAi[1] = n - 2;
- for(a = first, i = *(first - 1);
- (a < last) && ((*a < 0) || (0 < ss_compare(T, &(PAi[0]), PA + *a, depth)));
- ++a) {
- *(a - 1) = *a;
- }
- *(a - 1) = i;
- }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static inline
-int
-tr_ilg(int n) {
- return (n & 0xffff0000) ?
- ((n & 0xff000000) ?
- 24 + lg_table[(n >> 24) & 0xff] :
- 16 + lg_table[(n >> 16) & 0xff]) :
- ((n & 0x0000ff00) ?
- 8 + lg_table[(n >> 8) & 0xff] :
- 0 + lg_table[(n >> 0) & 0xff]);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Simple insertionsort for small size groups. */
-static
-void
-tr_insertionsort(const int *ISAd, int *first, int *last) {
- int *a, *b;
- int t, r;
-
- for(a = first + 1; a < last; ++a) {
- for(t = *a, b = a - 1; 0 > (r = ISAd[t] - ISAd[*b]);) {
- do { *(b + 1) = *b; } while((first <= --b) && (*b < 0));
- if(b < first) { break; }
- }
- if(r == 0) { *b = ~*b; }
- *(b + 1) = t;
- }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static inline
-void
-tr_fixdown(const int *ISAd, int *SA, int i, int size) {
- int j, k;
- int v;
- int c, d, e;
-
- for(v = SA[i], c = ISAd[v]; (j = 2 * i + 1) < size; SA[i] = SA[k], i = k) {
- d = ISAd[SA[k = j++]];
- if(d < (e = ISAd[SA[j]])) { k = j; d = e; }
- if(d <= c) { break; }
- }
- SA[i] = v;
-}
-
-/* Simple top-down heapsort. */
-static
-void
-tr_heapsort(const int *ISAd, int *SA, int size) {
- int i, m;
- int t;
-
- m = size;
- if((size % 2) == 0) {
- m--;
- if(ISAd[SA[m / 2]] < ISAd[SA[m]]) { SWAP(SA[m], SA[m / 2]); }
- }
-
- for(i = m / 2 - 1; 0 <= i; --i) { tr_fixdown(ISAd, SA, i, m); }
- if((size % 2) == 0) { SWAP(SA[0], SA[m]); tr_fixdown(ISAd, SA, 0, m); }
- for(i = m - 1; 0 < i; --i) {
- t = SA[0], SA[0] = SA[i];
- tr_fixdown(ISAd, SA, 0, i);
- SA[i] = t;
- }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Returns the median of three elements. */
-static inline
-int *
-tr_median3(const int *ISAd, int *v1, int *v2, int *v3) {
- int *t;
- if(ISAd[*v1] > ISAd[*v2]) { SWAP(v1, v2); }
- if(ISAd[*v2] > ISAd[*v3]) {
- if(ISAd[*v1] > ISAd[*v3]) { return v1; }
- else { return v3; }
- }
- return v2;
-}
-
-/* Returns the median of five elements. */
-static inline
-int *
-tr_median5(const int *ISAd,
- int *v1, int *v2, int *v3, int *v4, int *v5) {
- int *t;
- if(ISAd[*v2] > ISAd[*v3]) { SWAP(v2, v3); }
- if(ISAd[*v4] > ISAd[*v5]) { SWAP(v4, v5); }
- if(ISAd[*v2] > ISAd[*v4]) { SWAP(v2, v4); SWAP(v3, v5); }
- if(ISAd[*v1] > ISAd[*v3]) { SWAP(v1, v3); }
- if(ISAd[*v1] > ISAd[*v4]) { SWAP(v1, v4); SWAP(v3, v5); }
- if(ISAd[*v3] > ISAd[*v4]) { return v4; }
- return v3;
-}
-
-/* Returns the pivot element. */
-static inline
-int *
-tr_pivot(const int *ISAd, int *first, int *last) {
- int *middle;
- int t;
-
- t = last - first;
- middle = first + t / 2;
-
- if(t <= 512) {
- if(t <= 32) {
- return tr_median3(ISAd, first, middle, last - 1);
- } else {
- t >>= 2;
- return tr_median5(ISAd, first, first + t, middle, last - 1 - t, last - 1);
- }
- }
- t >>= 3;
- first = tr_median3(ISAd, first, first + t, first + (t << 1));
- middle = tr_median3(ISAd, middle - t, middle, middle + t);
- last = tr_median3(ISAd, last - 1 - (t << 1), last - 1 - t, last - 1);
- return tr_median3(ISAd, first, middle, last);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-typedef struct _trbudget_t trbudget_t;
-struct _trbudget_t {
- int chance;
- int remain;
- int incval;
- int count;
-};
-
-static inline
-void
-trbudget_init(trbudget_t *budget, int chance, int incval) {
- budget->chance = chance;
- budget->remain = budget->incval = incval;
-}
-
-static inline
-int
-trbudget_check(trbudget_t *budget, int size) {
- if(size <= budget->remain) { budget->remain -= size; return 1; }
- if(budget->chance == 0) { budget->count += size; return 0; }
- budget->remain += budget->incval - size;
- budget->chance -= 1;
- return 1;
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static inline
-void
-tr_partition(const int *ISAd,
- int *first, int *middle, int *last,
- int **pa, int **pb, int v) {
- int *a, *b, *c, *d, *e, *f;
- int t, s;
- int x = 0;
-
- for(b = middle - 1; (++b < last) && ((x = ISAd[*b]) == v);) { }
- if(((a = b) < last) && (x < v)) {
- for(; (++b < last) && ((x = ISAd[*b]) <= v);) {
- if(x == v) { SWAP(*b, *a); ++a; }
- }
- }
- for(c = last; (b < --c) && ((x = ISAd[*c]) == v);) { }
- if((b < (d = c)) && (x > v)) {
- for(; (b < --c) && ((x = ISAd[*c]) >= v);) {
- if(x == v) { SWAP(*c, *d); --d; }
- }
- }
- for(; b < c;) {
- SWAP(*b, *c);
- for(; (++b < c) && ((x = ISAd[*b]) <= v);) {
- if(x == v) { SWAP(*b, *a); ++a; }
- }
- for(; (b < --c) && ((x = ISAd[*c]) >= v);) {
- if(x == v) { SWAP(*c, *d); --d; }
- }
- }
-
- if(a <= d) {
- c = b - 1;
- if((s = a - first) > (t = b - a)) { s = t; }
- for(e = first, f = b - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
- if((s = d - c) > (t = last - d - 1)) { s = t; }
- for(e = b, f = last - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
- first += (b - a), last -= (d - c);
- }
- *pa = first, *pb = last;
-}
-
-static
-void
-tr_copy(int *ISA, const int *SA,
- int *first, int *a, int *b, int *last,
- int depth) {
- /* sort suffixes of middle partition
- by using sorted order of suffixes of left and right partition. */
- int *c, *d, *e;
- int s, v;
-
- v = b - SA - 1;
- for(c = first, d = a - 1; c <= d; ++c) {
- if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
- *++d = s;
- ISA[s] = d - SA;
- }
- }
- for(c = last - 1, e = d + 1, d = b; e < d; --c) {
- if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
- *--d = s;
- ISA[s] = d - SA;
- }
- }
-}
-
-static
-void
-tr_partialcopy(int *ISA, const int *SA,
- int *first, int *a, int *b, int *last,
- int depth) {
- int *c, *d, *e;
- int s, v;
- int rank, lastrank, newrank = -1;
-
- v = b - SA - 1;
- lastrank = -1;
- for(c = first, d = a - 1; c <= d; ++c) {
- if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
- *++d = s;
- rank = ISA[s + depth];
- if(lastrank != rank) { lastrank = rank; newrank = d - SA; }
- ISA[s] = newrank;
- }
- }
-
- lastrank = -1;
- for(e = d; first <= e; --e) {
- rank = ISA[*e];
- if(lastrank != rank) { lastrank = rank; newrank = e - SA; }
- if(newrank != rank) { ISA[*e] = newrank; }
- }
-
- lastrank = -1;
- for(c = last - 1, e = d + 1, d = b; e < d; --c) {
- if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
- *--d = s;
- rank = ISA[s + depth];
- if(lastrank != rank) { lastrank = rank; newrank = d - SA; }
- ISA[s] = newrank;
- }
- }
-}
-
-static
-void
-tr_introsort(int *ISA, const int *ISAd,
- int *SA, int *first, int *last,
- trbudget_t *budget) {
-#define STACK_SIZE TR_STACKSIZE
- struct { const int *a; int *b, *c; int d, e; }stack[STACK_SIZE];
- int *a, *b, *c;
- int t;
- int v, x = 0;
- int incr = ISAd - ISA;
- int limit, next;
- int ssize, trlink = -1;
-
- for(ssize = 0, limit = tr_ilg(last - first);;) {
-
- if(limit < 0) {
- if(limit == -1) {
- /* tandem repeat partition */
- tr_partition(ISAd - incr, first, first, last, &a, &b, last - SA - 1);
-
- /* update ranks */
- if(a < last) {
- for(c = first, v = a - SA - 1; c < a; ++c) { ISA[*c] = v; }
- }
- if(b < last) {
- for(c = a, v = b - SA - 1; c < b; ++c) { ISA[*c] = v; }
- }
-
- /* push */
- if(1 < (b - a)) {
- STACK_PUSH5(NULL, a, b, 0, 0);
- STACK_PUSH5(ISAd - incr, first, last, -2, trlink);
- trlink = ssize - 2;
- }
- if((a - first) <= (last - b)) {
- if(1 < (a - first)) {
- STACK_PUSH5(ISAd, b, last, tr_ilg(last - b), trlink);
- last = a, limit = tr_ilg(a - first);
- } else if(1 < (last - b)) {
- first = b, limit = tr_ilg(last - b);
- } else {
- STACK_POP5(ISAd, first, last, limit, trlink);
- }
- } else {
- if(1 < (last - b)) {
- STACK_PUSH5(ISAd, first, a, tr_ilg(a - first), trlink);
- first = b, limit = tr_ilg(last - b);
- } else if(1 < (a - first)) {
- last = a, limit = tr_ilg(a - first);
- } else {
- STACK_POP5(ISAd, first, last, limit, trlink);
- }
- }
- } else if(limit == -2) {
- /* tandem repeat copy */
- a = stack[--ssize].b, b = stack[ssize].c;
- if(stack[ssize].d == 0) {
- tr_copy(ISA, SA, first, a, b, last, ISAd - ISA);
- } else {
- if(0 <= trlink) { stack[trlink].d = -1; }
- tr_partialcopy(ISA, SA, first, a, b, last, ISAd - ISA);
- }
- STACK_POP5(ISAd, first, last, limit, trlink);
- } else {
- /* sorted partition */
- if(0 <= *first) {
- a = first;
- do { ISA[*a] = a - SA; } while((++a < last) && (0 <= *a));
- first = a;
- }
- if(first < last) {
- a = first; do { *a = ~*a; } while(*++a < 0);
- next = (ISA[*a] != ISAd[*a]) ? tr_ilg(a - first + 1) : -1;
- if(++a < last) { for(b = first, v = a - SA - 1; b < a; ++b) { ISA[*b] = v; } }
-
- /* push */
- if(trbudget_check(budget, a - first)) {
- if((a - first) <= (last - a)) {
- STACK_PUSH5(ISAd, a, last, -3, trlink);
- ISAd += incr, last = a, limit = next;
- } else {
- if(1 < (last - a)) {
- STACK_PUSH5(ISAd + incr, first, a, next, trlink);
- first = a, limit = -3;
- } else {
- ISAd += incr, last = a, limit = next;
- }
- }
- } else {
- if(0 <= trlink) { stack[trlink].d = -1; }
- if(1 < (last - a)) {
- first = a, limit = -3;
- } else {
- STACK_POP5(ISAd, first, last, limit, trlink);
- }
- }
- } else {
- STACK_POP5(ISAd, first, last, limit, trlink);
- }
- }
- continue;
- }
-
- if((last - first) <= TR_INSERTIONSORT_THRESHOLD) {
- tr_insertionsort(ISAd, first, last);
- limit = -3;
- continue;
- }
-
- if(limit-- == 0) {
- tr_heapsort(ISAd, first, last - first);
- for(a = last - 1; first < a; a = b) {
- for(x = ISAd[*a], b = a - 1; (first <= b) && (ISAd[*b] == x); --b) { *b = ~*b; }
- }
- limit = -3;
- continue;
- }
-
- /* choose pivot */
- a = tr_pivot(ISAd, first, last);
- SWAP(*first, *a);
- v = ISAd[*first];
-
- /* partition */
- tr_partition(ISAd, first, first + 1, last, &a, &b, v);
- if((last - first) != (b - a)) {
- next = (ISA[*a] != v) ? tr_ilg(b - a) : -1;
-
- /* update ranks */
- for(c = first, v = a - SA - 1; c < a; ++c) { ISA[*c] = v; }
- if(b < last) { for(c = a, v = b - SA - 1; c < b; ++c) { ISA[*c] = v; } }
-
- /* push */
- if((1 < (b - a)) && (trbudget_check(budget, b - a))) {
- if((a - first) <= (last - b)) {
- if((last - b) <= (b - a)) {
- if(1 < (a - first)) {
- STACK_PUSH5(ISAd + incr, a, b, next, trlink);
- STACK_PUSH5(ISAd, b, last, limit, trlink);
- last = a;
- } else if(1 < (last - b)) {
- STACK_PUSH5(ISAd + incr, a, b, next, trlink);
- first = b;
- } else {
- ISAd += incr, first = a, last = b, limit = next;
- }
- } else if((a - first) <= (b - a)) {
- if(1 < (a - first)) {
- STACK_PUSH5(ISAd, b, last, limit, trlink);
- STACK_PUSH5(ISAd + incr, a, b, next, trlink);
- last = a;
- } else {
- STACK_PUSH5(ISAd, b, last, limit, trlink);
- ISAd += incr, first = a, last = b, limit = next;
- }
- } else {
- STACK_PUSH5(ISAd, b, last, limit, trlink);
- STACK_PUSH5(ISAd, first, a, limit, trlink);
- ISAd += incr, first = a, last = b, limit = next;
- }
- } else {
- if((a - first) <= (b - a)) {
- if(1 < (last - b)) {
- STACK_PUSH5(ISAd + incr, a, b, next, trlink);
- STACK_PUSH5(ISAd, first, a, limit, trlink);
- first = b;
- } else if(1 < (a - first)) {
- STACK_PUSH5(ISAd + incr, a, b, next, trlink);
- last = a;
- } else {
- ISAd += incr, first = a, last = b, limit = next;
- }
- } else if((last - b) <= (b - a)) {
- if(1 < (last - b)) {
- STACK_PUSH5(ISAd, first, a, limit, trlink);
- STACK_PUSH5(ISAd + incr, a, b, next, trlink);
- first = b;
- } else {
- STACK_PUSH5(ISAd, first, a, limit, trlink);
- ISAd += incr, first = a, last = b, limit = next;
- }
- } else {
- STACK_PUSH5(ISAd, first, a, limit, trlink);
- STACK_PUSH5(ISAd, b, last, limit, trlink);
- ISAd += incr, first = a, last = b, limit = next;
- }
- }
- } else {
- if((1 < (b - a)) && (0 <= trlink)) { stack[trlink].d = -1; }
- if((a - first) <= (last - b)) {
- if(1 < (a - first)) {
- STACK_PUSH5(ISAd, b, last, limit, trlink);
- last = a;
- } else if(1 < (last - b)) {
- first = b;
- } else {
- STACK_POP5(ISAd, first, last, limit, trlink);
- }
- } else {
- if(1 < (last - b)) {
- STACK_PUSH5(ISAd, first, a, limit, trlink);
- first = b;
- } else if(1 < (a - first)) {
- last = a;
- } else {
- STACK_POP5(ISAd, first, last, limit, trlink);
- }
- }
- }
- } else {
- if(trbudget_check(budget, last - first)) {
- limit = tr_ilg(last - first), ISAd += incr;
- } else {
- if(0 <= trlink) { stack[trlink].d = -1; }
- STACK_POP5(ISAd, first, last, limit, trlink);
- }
- }
- }
-#undef STACK_SIZE
-}
-
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Tandem repeat sort */
-static
-void
-trsort(int *ISA, int *SA, int n, int depth) {
- int *ISAd;
- int *first, *last;
- trbudget_t budget;
- int t, skip, unsorted;
-
- trbudget_init(&budget, tr_ilg(n) * 2 / 3, n);
-/* trbudget_init(&budget, tr_ilg(n) * 3 / 4, n); */
- for(ISAd = ISA + depth; -n < *SA; ISAd += ISAd - ISA) {
- first = SA;
- skip = 0;
- unsorted = 0;
- do {
- if((t = *first) < 0) { first -= t; skip += t; }
- else {
- if(skip != 0) { *(first + skip) = skip; skip = 0; }
- last = SA + ISA[t] + 1;
- if(1 < (last - first)) {
- budget.count = 0;
- tr_introsort(ISA, ISAd, SA, first, last, &budget);
- if(budget.count != 0) { unsorted += budget.count; }
- else { skip = first - last; }
- } else if((last - first) == 1) {
- skip = -1;
- }
- first = last;
- }
- } while(first < (SA + n));
- if(skip != 0) { *(first + skip) = skip; }
- if(unsorted == 0) { break; }
- }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Sorts suffixes of type B*. */
-static
-int
-sort_typeBstar(const unsigned char *T, int *SA,
- int *bucket_A, int *bucket_B,
- int n) {
- int *PAb, *ISAb, *buf;
- int i, j, k, t, m, bufsize;
- int c0, c1;
-
- /* Initialize bucket arrays. */
- for(i = 0; i < BUCKET_A_SIZE; ++i) { bucket_A[i] = 0; }
- for(i = 0; i < BUCKET_B_SIZE; ++i) { bucket_B[i] = 0; }
-
- /* Count the number of occurrences of the first one or two characters of each
- type A, B and B* suffix. Moreover, store the beginning position of all
- type B* suffixes into the array SA. */
- for(i = n - 1, m = n, c0 = T[n - 1]; 0 <= i;) {
- /* type A suffix. */
- do { ++BUCKET_A(c1 = c0); } while((0 <= --i) && ((c0 = T[i]) >= c1));
- if(0 <= i) {
- /* type B* suffix. */
- ++BUCKET_BSTAR(c0, c1);
- SA[--m] = i;
- /* type B suffix. */
- for(--i, c1 = c0; (0 <= i) && ((c0 = T[i]) <= c1); --i, c1 = c0) {
- ++BUCKET_B(c0, c1);
- }
- }
- }
- m = n - m;
-/*
-note:
- A type B* suffix is lexicographically smaller than a type B suffix that
- begins with the same first two characters.
-*/
-
- /* Calculate the index of start/end point of each bucket. */
- for(c0 = 0, i = 0, j = 0; c0 < ALPHABET_SIZE; ++c0) {
- t = i + BUCKET_A(c0);
- BUCKET_A(c0) = i + j; /* start point */
- i = t + BUCKET_B(c0, c0);
- for(c1 = c0 + 1; c1 < ALPHABET_SIZE; ++c1) {
- j += BUCKET_BSTAR(c0, c1);
- BUCKET_BSTAR(c0, c1) = j; /* end point */
- i += BUCKET_B(c0, c1);
- }
- }
-
- if(0 < m) {
- /* Sort the type B* suffixes by their first two characters. */
- PAb = SA + n - m; ISAb = SA + m;
- for(i = m - 2; 0 <= i; --i) {
- t = PAb[i], c0 = T[t], c1 = T[t + 1];
- SA[--BUCKET_BSTAR(c0, c1)] = i;
- }
- t = PAb[m - 1], c0 = T[t], c1 = T[t + 1];
- SA[--BUCKET_BSTAR(c0, c1)] = m - 1;
-
- /* Sort the type B* substrings using sssort. */
- buf = SA + m, bufsize = n - (2 * m);
- for(c0 = ALPHABET_SIZE - 2, j = m; 0 < j; --c0) {
- for(c1 = ALPHABET_SIZE - 1; c0 < c1; j = i, --c1) {
- i = BUCKET_BSTAR(c0, c1);
- if(1 < (j - i)) {
- sssort(T, PAb, SA + i, SA + j,
- buf, bufsize, 2, n, *(SA + i) == (m - 1));
- }
- }
- }
-
- /* Compute ranks of type B* substrings. */
- for(i = m - 1; 0 <= i; --i) {
- if(0 <= SA[i]) {
- j = i;
- do { ISAb[SA[i]] = i; } while((0 <= --i) && (0 <= SA[i]));
- SA[i + 1] = i - j;
- if(i <= 0) { break; }
- }
- j = i;
- do { ISAb[SA[i] = ~SA[i]] = j; } while(SA[--i] < 0);
- ISAb[SA[i]] = j;
- }
-
- /* Construct the inverse suffix array of type B* suffixes using trsort. */
- trsort(ISAb, SA, m, 1);
-
- /* Set the sorted order of tyoe B* suffixes. */
- for(i = n - 1, j = m, c0 = T[n - 1]; 0 <= i;) {
- for(--i, c1 = c0; (0 <= i) && ((c0 = T[i]) >= c1); --i, c1 = c0) { }
- if(0 <= i) {
- t = i;
- for(--i, c1 = c0; (0 <= i) && ((c0 = T[i]) <= c1); --i, c1 = c0) { }
- SA[ISAb[--j]] = ((t == 0) || (1 < (t - i))) ? t : ~t;
- }
- }
-
- /* Calculate the index of start/end point of each bucket. */
- BUCKET_B(ALPHABET_SIZE - 1, ALPHABET_SIZE - 1) = n; /* end point */
- for(c0 = ALPHABET_SIZE - 2, k = m - 1; 0 <= c0; --c0) {
- i = BUCKET_A(c0 + 1) - 1;
- for(c1 = ALPHABET_SIZE - 1; c0 < c1; --c1) {
- t = i - BUCKET_B(c0, c1);
- BUCKET_B(c0, c1) = i; /* end point */
-
- /* Move all type B* suffixes to the correct position. */
- for(i = t, j = BUCKET_BSTAR(c0, c1);
- j <= k;
- --i, --k) { SA[i] = SA[k]; }
- }
- BUCKET_BSTAR(c0, c0 + 1) = i - BUCKET_B(c0, c0) + 1; /* start point */
- BUCKET_B(c0, c0) = i; /* end point */
- }
- }
-
- return m;
-}
-
-/* Constructs the suffix array by using the sorted order of type B* suffixes. */
-static
-void
-construct_SA(const unsigned char *T, int *SA,
- int *bucket_A, int *bucket_B,
- int n, int m) {
- int *i, *j, *k;
- int s;
- int c0, c1, c2;
-
- if(0 < m) {
- /* Construct the sorted order of type B suffixes by using
- the sorted order of type B* suffixes. */
- for(c1 = ALPHABET_SIZE - 2; 0 <= c1; --c1) {
- /* Scan the suffix array from right to left. */
- for(i = SA + BUCKET_BSTAR(c1, c1 + 1),
- j = SA + BUCKET_A(c1 + 1) - 1, k = NULL, c2 = -1;
- i <= j;
- --j) {
- if(0 < (s = *j)) {
- assert(T[s] == c1);
- assert(((s + 1) < n) && (T[s] <= T[s + 1]));
- assert(T[s - 1] <= T[s]);
- *j = ~s;
- c0 = T[--s];
- if((0 < s) && (T[s - 1] > c0)) { s = ~s; }
- if(c0 != c2) {
- if(0 <= c2) { BUCKET_B(c2, c1) = k - SA; }
- k = SA + BUCKET_B(c2 = c0, c1);
- }
- assert(k < j);
- *k-- = s;
- } else {
- assert(((s == 0) && (T[s] == c1)) || (s < 0));
- *j = ~s;
- }
- }
- }
- }
-
- /* Construct the suffix array by using
- the sorted order of type B suffixes. */
- k = SA + BUCKET_A(c2 = T[n - 1]);
- *k++ = (T[n - 2] < c2) ? ~(n - 1) : (n - 1);
- /* Scan the suffix array from left to right. */
- for(i = SA, j = SA + n; i < j; ++i) {
- if(0 < (s = *i)) {
- assert(T[s - 1] >= T[s]);
- c0 = T[--s];
- if((s == 0) || (T[s - 1] < c0)) { s = ~s; }
- if(c0 != c2) {
- BUCKET_A(c2) = k - SA;
- k = SA + BUCKET_A(c2 = c0);
- }
- assert(i < k);
- *k++ = s;
- } else {
- assert(s < 0);
- *i = ~s;
- }
- }
-}
-
-/*---------------------------------------------------------------------------*/
-
-/*- Function -*/
-
-/* XXX Modified from original: use provided temporary space instead of
- * allocating it. */
-void
-divsufsort(const unsigned char *T, int *SA, int n,
- int *bucket_A, int *bucket_B)
-{
- int m;
-
- switch (n) {
- case 0:
- break;
-
- case 1:
- SA[0] = 0;
- break;
-
- case 2:
- m = (T[0] < T[1]);
- SA[m ^ 1] = 0;
- SA[m] = 1;
- break;
-
- default:
- m = sort_typeBstar(T, SA, bucket_A, bucket_B, n);
- construct_SA(T, SA, bucket_A, bucket_B, n, m);
- break;
- }
-}
--- /dev/null
+/*
+ * lz_bt.c
+ *
+ * Binary tree match-finder for Lempel-Ziv compression.
+ *
+ * Author: Eric Biggers
+ * Year: 2014
+ *
+ * The author hereby releases this file into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+/*
+ * Note: the binary tree search/update algorithm is based on code from the
+ * public domain LZMA SDK (authors: Igor Pavlov, Lasse Collin).
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "wimlib/lz.h"
+#include "wimlib/lz_bt.h"
+#include "wimlib/util.h"
+#include <string.h>
+#include <pthread.h>
+
+#define LZ_BT_HASH_BITS 16
+#define LZ_BT_HASH_SIZE (1 << LZ_BT_HASH_BITS)
+#define LZ_BT_HASH_MASK (LZ_BT_HASH_SIZE - 1)
+#define LZ_BT_DIGRAM_TAB_SIZE (256 * 256)
+
+static u32 crc32_table[256];
+static pthread_once_t crc32_table_filled = PTHREAD_ONCE_INIT;
+
+static void
+crc32_init(void)
+{
+ for (u32 b = 0; b < 256; b++) {
+ u32 r = b;
+ for (int i = 0; i < 8; i++) {
+ if (r & 1)
+ r = (r >> 1) ^ 0xEDB88320;
+ else
+ r >>= 1;
+ }
+ crc32_table[b] = r;
+ }
+}
+
+/*
+ * Compute the hash code for the next 3-byte sequence in the window.
+ *
+ * @p
+ * A pointer to the next 3-byte sequence in the window.
+ *
+ * Returns the resulting hash code.
+ */
+static inline u32
+lz_bt_hash(const u8 *p)
+{
+ u32 hash = 0;
+
+ hash ^= crc32_table[p[0]];
+ hash ^= p[1];
+ hash ^= (u32)p[2] << 8;
+
+ return hash & LZ_BT_HASH_MASK;
+}
+
+/*
+ * Compute the number of bytes of memory that would be needed to initialize a
+ * binary tree match-finder with the specified maximum window size.
+ *
+ * @max_window_size
+ * The maximum window size, in bytes, to query.
+ *
+ * Returns the number of bytes that would be allocated by lz_bt_init(),
+ * excluding the size of the 'struct lz_bt' itself.
+ */
+u64
+lz_bt_get_needed_memory(lz_bt_pos_t max_window_size)
+{
+ u64 len;
+
+ len = LZ_BT_HASH_SIZE + LZ_BT_DIGRAM_TAB_SIZE;
+ len += 2 * (u64)max_window_size;
+
+ return len * sizeof(lz_bt_pos_t);
+}
+
+/*
+ * Initialize a binary tree match-finder.
+ *
+ * @mf
+ * The match-finder structure to initialize.
+ * @max_window_size
+ * The maximum window size that shall be supported by subsequent calls to
+ * lz_bt_load_window().
+ * @min_match_len
+ * The minimum length of matches that shall be produced by subsequent calls
+ * to lz_bt_get_matches(). This must be at least 2.
+ * @max_match_len
+ * The maximum length of matches that shall be produced by subsequent calls
+ * to lz_bt_get_matches(). This must be at least @min_match_len.
+ * @num_fast_bytes
+ * The maximum length of matches that shall be produced just using the
+ * binary tree search algorithm. If the longest match has this length,
+ * then lz_bt_get_matches() will extend it up to @max_match_len. This must
+ * be at least @min_match_len and no more than @max_match_len.
+ * @max_search_depth
+ * The maximum depth to descend into the binary search tree before halting
+ * the search.
+ *
+ * Returns %true if successful; %false if out of memory.
+ */
+bool
+lz_bt_init(struct lz_bt *mf,
+ lz_bt_pos_t max_window_size,
+ lz_bt_len_t min_match_len,
+ lz_bt_len_t max_match_len,
+ lz_bt_len_t num_fast_bytes,
+ u32 max_search_depth)
+{
+ u64 len;
+
+ /* Check and set parameters. */
+ LZ_ASSERT(min_match_len >= 2);
+ LZ_ASSERT(max_match_len >= min_match_len);
+ LZ_ASSERT(num_fast_bytes >= min_match_len);
+ LZ_ASSERT(num_fast_bytes <= max_match_len);
+
+ mf->max_window_size = max_window_size;
+ mf->min_match_len = min_match_len;
+ mf->max_match_len = max_match_len;
+ mf->num_fast_bytes = num_fast_bytes;
+ mf->max_search_depth = max_search_depth;
+
+ /* Allocate space for 'hash_tab', 'digram_tab', and 'child_tab'. */
+ len = LZ_BT_HASH_SIZE + (2 * (u64)max_window_size);
+ if (mf->min_match_len <= 2)
+ len += LZ_BT_DIGRAM_TAB_SIZE;
+ len *= sizeof(lz_bt_pos_t);
+ if ((size_t)len != len || !(mf->hash_tab = MALLOC(len)))
+ return false;
+ if (mf->min_match_len <= 2) {
+ mf->digram_tab = mf->hash_tab + LZ_BT_HASH_SIZE;
+ mf->child_tab = mf->digram_tab + LZ_BT_DIGRAM_TAB_SIZE;
+ } else {
+ mf->child_tab = mf->hash_tab + LZ_BT_HASH_SIZE;
+ }
+
+ /* Fill in the CRC32 table if not done already. */
+ pthread_once(&crc32_table_filled, crc32_init);
+
+ return true;
+}
+
+/*
+ * Destroy a binary tree match-finder.
+ *
+ * @mf
+ * The match-finder structure to destroy.
+ */
+void
+lz_bt_destroy(struct lz_bt *mf)
+{
+ FREE(mf->hash_tab);
+ /* mf->hash_tab shares storage with mf->digram_tab and mf->child_tab. */
+}
+
+/*
+ * Load a window into a binary tree match-finder.
+ *
+ * @mf
+ * The match-finder structure into which to load the window.
+ * @window
+ * Pointer to the window to load. This memory must remain available,
+ * unmodified, while the match-finder is being used.
+ * @window_size
+ * The size of the window, in bytes. This can't be larger than the
+ * @max_window_size with which lz_bt_init() was called.
+ */
+void
+lz_bt_load_window(struct lz_bt *mf, const u8 *window, lz_bt_pos_t window_size)
+{
+ LZ_ASSERT(window_size <= mf->max_window_size);
+ size_t clear_len;
+
+ mf->cur_window = window;
+ mf->cur_window_pos = 0;
+ mf->cur_window_size = window_size;
+
+ /* Clear the hash and digram tables.
+ * Note: The child table need not be cleared. */
+ clear_len = LZ_BT_HASH_SIZE;
+ if (mf->min_match_len <= 2)
+ clear_len += LZ_BT_DIGRAM_TAB_SIZE;
+ memset(mf->hash_tab, 0, clear_len * sizeof(lz_bt_pos_t));
+}
+
+/*
+ * Search the binary tree of the current hash code for matches. At the same
+ * time, update this tree to add the current position in the window.
+ *
+ * @window
+ * The window being searched.
+ * @cur_window_pos
+ * The current position in the window.
+ * @min_len
+ * Ignore matches shorter than this length. This must be at least 1.
+ * @max_len
+ * Don't produce any matches longer than this length. If we find a match
+ * this long, terminate the search and return.
+ * @max_depth
+ * Stop if we reach this depth in the binary tree.
+ * @child_tab
+ * Table of child pointers for the binary tree. The children of the node
+ * for position 'i' in the window are child_tab[i * 2] and child_tab[i*2 +
+ * 1]. Zero is reserved for the 'null' value (no child). Consequently, we
+ * don't recognize matches beginning at position 0. In fact, the node for
+ * position 0 in the window will not be used at all, which is just as well
+ * because we use 0-based indices which don't work for position 0.
+ * @cur_match
+ * The position in the window at which the binary tree for the current hash
+ * code is rooted. This can be 0, which indicates that the binary tree for
+ * the current hash code is empty.
+ * @matches
+ * The array in which to produce the matches. The matches will be produced
+ * in order of increasing length and increasing offset. No more than one
+ * match shall have any given length, nor shall any match be shorter than
+ * @min_len, nor shall any match be longer than @max_len, nor shall any two
+ * matches have the same offset.
+ *
+ * Returns the number of matches found and written to @matches.
+ */
+static lz_bt_len_t
+do_search(const u8 window[restrict],
+ const lz_bt_pos_t cur_window_pos,
+ const lz_bt_len_t min_len,
+ const lz_bt_len_t max_len,
+ const u32 max_depth,
+ lz_bt_pos_t child_tab[restrict],
+ lz_bt_pos_t cur_match,
+ struct raw_match matches[restrict])
+{
+ /*
+ * Here's my explanation of how this code actually works. Beware: this
+ * algorithm is a *lot* trickier than searching for matches via hash
+ * chains. But it can be significantly better, especially when doing
+ * "optimal" parsing, which is why it gets used, e.g. in LZMA as well as
+ * here.
+ *
+ * ---------------------------------------------------------------------
+ *
+ * Data structure
+ *
+ * Basically, there is not just one binary tree, but rather one binary
+ * tree per hash code. For a given hash code, the binary tree indexes
+ * previous positions in the window that have that same hash code. The
+ * key for each node is the "string", or byte sequence, beginning at the
+ * corresponding position in the window.
+ *
+ * Each tree maintains the invariant that if node C is a child of node
+ * P, then the window position represented by node C is smaller than
+ * ("left of") the window position represented by node P. Equivalently,
+ * while descending into a tree, the match distances ("offsets") from
+ * the current position are non-decreasing --- actually strictly
+ * increasing, because each node represents a unique position.
+ *
+ * In addition, not all previous positions sharing the same hash code
+ * will necessarily be represented in each binary tree; see the
+ * "Updating" section.
+ *
+ * ---------------------------------------------------------------------
+ *
+ * Searching
+ *
+ * Suppose we want to search for LZ77-style matches with the string
+ * beginning at the current window position and extending for @max_len
+ * bytes. To do this, we can search for this string in the binary tree
+ * for this string's hash code. Each node visited during the search is
+ * a potential match. This method will find the matches efficiently
+ * because they will converge on the current string, due to the nature
+ * of the binary search.
+ *
+ * Naively, when visiting a node that represents a match of length N, we
+ * must compare N + 1 bytes in order to determine the length of that
+ * match and the lexicographic ordering of that match relative to the
+ * current string (which determines whether we need to step left or
+ * right into the next level of the tree, as per the standard binary
+ * tree search algorithm). However, as an optimization, we need not
+ * explicitly examine the full length of the match at each node. To see
+ * that this is true, suppose that we examine a node during the search,
+ * and we find that the corresponding match is less (alt. greater) than
+ * the current string. Then, because of how binary tree search
+ * operates, the match must be lexicographically greater (alt. lesser)
+ * than any ancestor node that corresponded to a match lexicographically
+ * lesser (alt. greater) than the current string. Therefore, the match
+ * must be at least as long as the match for any such ancestor node.
+ * Therefore, the lengths of lexicographically-lesser (alt. greater)
+ * matches must be non-decreasing as they are encountered by the tree
+ * search.
+ *
+ * Using this observation, we can maintain two variables,
+ * 'longest_lt_match_len' and 'longest_gt_match_len', that represent the
+ * length of the longest lexicographically lesser and greater,
+ * respectively, match that has been examined so far. Then, when
+ * examining a new match, we need only start comparing at the index
+ * min(longest_lt_match_len, longest_gt_match_len) byte. Note that we
+ * cannot know beforehand whether the match will be lexicographically
+ * lesser or greater, hence the need for taking the minimum of these two
+ * lengths.
+ *
+ * As noted earlier, as we descend into the tree, the potential matches
+ * will have strictly increasing offsets. To make things faster for
+ * higher-level parsing / match-choosing code, we do not want to return
+ * a shorter match that has a larger offset than a longer match. This
+ * is because a longer match can always be truncated to a shorter match
+ * if needed, and smaller offsets usually (depending on the compression
+ * format) take fewer bits to encode than larger offsets.
+ * Consequently, we keep a potential match only if it is longer than the
+ * previous longest match that has been found. This has the added
+ * advantage of producing the array of matches sorted by strictly
+ * increasing lengths as well as strictly decreasing offsets.
+ *
+ * In degenerate cases, the binary tree might become severely
+ * unbalanced. To prevent excessive running times, we stop immediately
+ * (and return any matches that happen to have been found so far) if the
+ * current depth exceeds @max_depth. Note that this cutoff can occur
+ * before the longest match has been found, which is usually bad for the
+ * compression ratio.
+ *
+ * ---------------------------------------------------------------------
+ *
+ * Updating
+ *
+ * I've explained how to find matches by searching the binary tree of
+ * the current hash code. But how do we get the binary tree in the
+ * first place? Since the tree is built incrementally, the real
+ * question is how do we update the tree to "add" the current window
+ * position.
+ *
+ * The tree maintains the invariant that a node's parent always has a
+ * larger position (a.k.a. smaller match offset) than itself.
+ * Therefore, the root node must always have the largest position; and
+ * since the current position is larger than any previous position, the
+ * current position must become the root of the tree.
+ *
+ * A correct, but silly, approach is to simply add the previous root as
+ * a child of the new root, using either the left or right child pointer
+ * depending on the lexicographic ordering of the strings. This works,
+ * but it really just produces a linked list, so it's not sufficient.
+ *
+ * Instead, we can initially mark the new root's left child pointer as
+ * "pending (less than)" and its right child pointer as "pending
+ * (greater than)". Then, during the search, when we examine a match
+ * that is lexicographically less than the current string, we link the
+ * "pending (less than)" pointer to the node of that match, then set the
+ * right child pointer of *that* node as "pending (less than)".
+ * Similarly, when we examine a match that is lexicographically greater
+ * than the current string, we link the "pending (greater than)" pointer
+ * to the node of that match, then set the left child pointer of *that*
+ * node as "pending (greater than)".
+ *
+ * If the search terminates before the current string is found (up to a
+ * precision of @max_len bytes), then we set "pending (less than)" and
+ * "pending (greater than)" to point to nothing. Alternatively, if the
+ * search terminates due to finding the current string (up to a
+ * precision of @max_len bytes), then we set "pending (less than)" and
+ * "pending (greater than)" to point to the appropriate children of that
+ * match.
+ *
+ * Why does this work? Well, we can think of it this way: the "pending
+ * (less than)" pointer is reserved for the next match we find that is
+ * lexicographically *less than* the current string, and the "pending
+ * (greater than)" pointer is reserved for the next match we find that
+ * is lexicographically *greater than* the current string. This
+ * explains why when we find a match that is lexicographically less than
+ * the current string, we set the "pending (less than)" pointer to point
+ * to that match. And the reason we change "pending (less than)" to the
+ * right pointer of the match in that case is because we're walking down
+ * into that subtree, and the next match lexicographically *less than*
+ * the current string is guaranteed to be lexicographically *greater
+ * than* that match, so it should be set as the right subtree of that
+ * match. But the next match in that subtree that is lexicographically
+ * *greater than* the current string will need to be moved to the
+ * "pending (greater than)" pointer farther up the tree.
+ *
+ * It's complicated, but it should make sense if you think about it.
+ * The algorithm basically just moves subtrees into the correct
+ * locations as it walks down the tree for the search. But also, if the
+ * algorithm actually finds a match of length @max_len with the current
+ * string, it no longer needs that match node and can discard it. The
+ * algorithm also will discard nodes if the search terminates due to the
+ * depth limit. For these reasons, the binary tree might not, in fact,
+ * contain all valid positions.
+ */
+
+ lz_bt_len_t num_matches = 0;
+ lz_bt_len_t longest_lt_match_len = 0;
+ lz_bt_len_t longest_gt_match_len = 0;
+ lz_bt_len_t longest_match_len = min_len - 1;
+ lz_bt_pos_t *pending_lt_ptr = &child_tab[cur_window_pos * 2 + 0];
+ lz_bt_pos_t *pending_gt_ptr = &child_tab[cur_window_pos * 2 + 1];
+ const u8 *strptr = &window[cur_window_pos];
+ u32 depth_remaining = max_depth;
+ for (;;) {
+ const u8 *matchptr;
+ lz_bt_len_t len;
+
+ if (depth_remaining-- == 0 || cur_match == 0) {
+ *pending_lt_ptr = 0;
+ *pending_gt_ptr = 0;
+ return num_matches;
+ }
+
+ matchptr = &window[cur_match];
+ len = min(longest_lt_match_len, longest_gt_match_len);
+
+ if (matchptr[len] == strptr[len]) {
+
+ while (++len != max_len)
+ if (matchptr[len] != strptr[len])
+ break;
+
+ if (len > longest_match_len) {
+ longest_match_len = len;
+
+ matches[num_matches++] = (struct raw_match) {
+ .len = len,
+ .offset = cur_window_pos - cur_match,
+ };
+
+ if (len == max_len) {
+ *pending_lt_ptr = child_tab[cur_match * 2 + 0];
+ *pending_gt_ptr = child_tab[cur_match * 2 + 1];
+ return num_matches;
+ }
+ }
+ }
+
+ if (matchptr[len] < strptr[len]) {
+ *pending_lt_ptr = cur_match;
+ pending_lt_ptr = &child_tab[cur_match * 2 + 1];
+ cur_match = *pending_lt_ptr;
+ longest_lt_match_len = len;
+ } else {
+ *pending_gt_ptr = cur_match;
+ pending_gt_ptr = &child_tab[cur_match * 2 + 0];
+ cur_match = *pending_gt_ptr;
+ longest_gt_match_len = len;
+ }
+ }
+}
+
+/*
+ * Retrieve a list of matches at the next position in the window.
+ *
+ * @mf
+ * The binary tree match-finder structure into which a window has been
+ * loaded using lz_bt_load_window().
+ * @matches
+ * The array into which the matches will be returned. The length of this
+ * array must be at least (@mf->num_fast_bytes - @mf->min_match_len + 1).
+ *
+ * The return value is the number of matches that were found and stored in the
+ * 'matches' array. The matches will be ordered by strictly increasing length
+ * and strictly increasing offset. No match shall have length less than
+ * @min_match_len, and no match shall have length greater than @max_match_len.
+ * The return value may be 0, which indicates that no matches were found.
+ *
+ * On completion, the binary tree match-finder is advanced to the next position
+ * in the window.
+ */
+lz_bt_len_t
+lz_bt_get_matches(struct lz_bt *mf, struct raw_match matches[])
+{
+ lz_bt_pos_t bytes_remaining;
+ lz_bt_len_t num_matches;
+ lz_bt_pos_t cur_match;
+ u32 hash;
+
+ LZ_ASSERT(mf->cur_window_pos < mf->cur_window_size);
+
+ bytes_remaining = lz_bt_get_remaining_size(mf);
+
+ /* If there are fewer than 3 bytes remaining, we can't even compute a
+ * hash to look up a binary tree root. If there are exactly 2 bytes
+ * remaining we could still search for a length-2 match using the digram
+ * table, but it's not worth bothering. (Note: this is also useful for
+ * LZX, since this excludes the length 2 match having the maximum
+ * offset, which isn't allowed.) */
+ if (bytes_remaining < 3) {
+ mf->cur_window_pos++;
+ return 0;
+ }
+
+ num_matches = 0;
+
+ /* Search the digram table for a length 2 match. */
+ if (mf->min_match_len <= 2) {
+ u8 c1, c2;
+ u16 digram;
+
+ c1 = mf->cur_window[mf->cur_window_pos];
+ c2 = mf->cur_window[mf->cur_window_pos + 1];
+ digram = (u16)c1 | ((u16)c2 << 8);
+ cur_match = mf->digram_tab[digram];
+ mf->digram_tab[digram] = mf->cur_window_pos;
+
+ /* We're only interested in matches of length exactly 2, since
+ * those won't be found during the binary tree search. */
+ if (cur_match != 0 && mf->cur_window[cur_match + 2] !=
+ mf->cur_window[mf->cur_window_pos + 2])
+ {
+ matches[num_matches++] = (struct raw_match) {
+ .len = 2,
+ .offset = mf->cur_window_pos - cur_match,
+ };
+ }
+ }
+
+ /* Hash the length-3 byte sequence beginning at the current position in
+ * the window. */
+ hash = lz_bt_hash(&mf->cur_window[mf->cur_window_pos]);
+
+ /* The corresponding hash bucket in 'hash_tab' contains the root of the
+ * binary tree of previous window positions that have the same hash
+ * code. */
+ cur_match = mf->hash_tab[hash];
+
+ /* Update the hash bucket to point to the binary tree rooted at the
+ * current position, which we will construct in do_search(). */
+ mf->hash_tab[hash] = mf->cur_window_pos;
+
+ /* Search the binary tree for matches. At the same time, build the
+ * binary tree rooted at the current position, which replaces the one we
+ * search. */
+ num_matches += do_search(mf->cur_window,
+ mf->cur_window_pos,
+ max(3, mf->min_match_len),
+ min(bytes_remaining, mf->num_fast_bytes),
+ mf->max_search_depth,
+ mf->child_tab,
+ cur_match,
+ &matches[num_matches]);
+
+ /* If the longest match is @num_fast_bytes in length, it may have been
+ * truncated. Try extending it up to the maximum match length. */
+ if (num_matches != 0 && matches[num_matches - 1].len == mf->num_fast_bytes) {
+ lz_bt_pos_t limit;
+ const u8 *strptr, *matchptr;
+ lz_bt_len_t len;
+
+ limit = min(bytes_remaining, mf->max_match_len);
+ strptr = &mf->cur_window[mf->cur_window_pos];
+ matchptr = strptr - matches[num_matches - 1].offset;
+ len = matches[num_matches - 1].len;
+ while (len < limit && strptr[len] == matchptr[len])
+ len++;
+ matches[num_matches - 1].len = len;
+ }
+
+#ifdef ENABLE_LZ_DEBUG
+ /* Check the matches. */
+ for (lz_bt_len_t i = 0; i < num_matches; i++) {
+ const u8 *matchptr, *strptr;
+
+ /* Length valid? */
+ LZ_ASSERT(matches[i].len >= mf->min_match_len);
+ LZ_ASSERT(matches[i].len <= min(mf->max_match_len, bytes_remaining));
+
+ /* Offset valid? */
+ LZ_ASSERT(matches[i].offset >= 1);
+ LZ_ASSERT(matches[i].offset <= lz_bt_get_position(mf));
+
+ /* Lengths and offsets strictly increasing? */
+ if (i > 0) {
+ LZ_ASSERT(matches[i].len > matches[i - 1].len);
+ LZ_ASSERT(matches[i].offset > matches[i - 1].offset);
+ }
+
+ /* Actually a match? */
+ strptr = lz_bt_get_window_ptr(mf);
+ matchptr = strptr - matches[i].offset;
+ LZ_ASSERT(!memcmp(strptr, matchptr, matches[i].len));
+
+ /* Match can't be extended further? */
+ LZ_ASSERT(matches[i].len == min(mf->max_match_len, bytes_remaining) ||
+ strptr[matches[i].len] != matchptr[matches[i].len]);
+ }
+#endif /* ENABLE_LZ_DEBUG */
+
+ /* Advance to the next position in the window. */
+ mf->cur_window_pos++;
+
+ /* Return the number of matches found. */
+ return num_matches;
+}
+
+/* This is the same as do_search(), but it does not save any matches.
+ * See do_search() for explanatory comments. */
+static void
+do_skip(const u8 window[restrict],
+ const lz_bt_pos_t cur_window_pos,
+ const lz_bt_len_t max_len,
+ u32 depth_remaining,
+ lz_bt_pos_t child_tab[restrict],
+ lz_bt_pos_t cur_match)
+{
+ lz_bt_len_t longest_lt_match_len = 0;
+ lz_bt_len_t longest_gt_match_len = 0;
+ lz_bt_pos_t *pending_lt_ptr = &child_tab[cur_window_pos * 2 + 0];
+ lz_bt_pos_t *pending_gt_ptr = &child_tab[cur_window_pos * 2 + 1];
+ const u8 * const strptr = &window[cur_window_pos];
+ for (;;) {
+ const u8 *matchptr;
+ lz_bt_len_t len;
+
+ if (depth_remaining-- == 0 || cur_match == 0) {
+ *pending_lt_ptr = 0;
+ *pending_gt_ptr = 0;
+ return;
+ }
+
+ matchptr = &window[cur_match];
+ len = min(longest_lt_match_len, longest_gt_match_len);
+
+ if (matchptr[len] == strptr[len]) {
+ do {
+ if (++len == max_len) {
+ *pending_lt_ptr = child_tab[cur_match * 2 + 0];
+ *pending_gt_ptr = child_tab[cur_match * 2 + 1];
+ return;
+ }
+ } while (matchptr[len] == strptr[len]);
+ }
+ if (matchptr[len] < strptr[len]) {
+ *pending_lt_ptr = cur_match;
+ pending_lt_ptr = &child_tab[cur_match * 2 + 1];
+ cur_match = *pending_lt_ptr;
+ longest_lt_match_len = len;
+ } else {
+ *pending_gt_ptr = cur_match;
+ pending_gt_ptr = &child_tab[cur_match * 2 + 0];
+ cur_match = *pending_gt_ptr;
+ longest_gt_match_len = len;
+ }
+ }
+}
+
+/* Skip the current position in the binary tree match-finder. */
+static void
+lz_bt_skip_position(struct lz_bt *mf)
+{
+ lz_bt_pos_t bytes_remaining;
+ u32 hash;
+ lz_bt_pos_t cur_match;
+
+ LZ_ASSERT(mf->cur_window_pos < mf->cur_window_size);
+
+ bytes_remaining = lz_bt_get_remaining_size(mf);
+
+ /* As explained in lz_bt_get_matches(), we don't search for matches if
+ * there are fewer than 3 bytes remaining in the window. */
+ if (bytes_remaining < 3) {
+ mf->cur_window_pos++;
+ return;
+ }
+
+ /* Update the digram table. */
+ if (mf->min_match_len <= 2) {
+ u8 c1, c2;
+ u16 digram;
+
+ c1 = mf->cur_window[mf->cur_window_pos];
+ c2 = mf->cur_window[mf->cur_window_pos + 1];
+ digram = (u16)c1 | ((u16)c2 << 8);
+ mf->digram_tab[digram] = mf->cur_window_pos;
+ }
+
+ /* Update the hash table. */
+ hash = lz_bt_hash(&mf->cur_window[mf->cur_window_pos]);
+ cur_match = mf->hash_tab[hash];
+ mf->hash_tab[hash] = mf->cur_window_pos;
+
+ /* Update the binary tree for the appropriate hash code. */
+ do_skip(mf->cur_window,
+ mf->cur_window_pos,
+ min(bytes_remaining, mf->num_fast_bytes),
+ mf->max_search_depth,
+ mf->child_tab,
+ cur_match);
+
+ /* Advance to the next position. */
+ mf->cur_window_pos++;
+}
+
+/* Skip 'n' positions in the binary tree match-finder. */
+void
+lz_bt_skip_positions(struct lz_bt *mf, unsigned n)
+{
+ while (n--)
+ lz_bt_skip_position(mf);
+}
+++ /dev/null
-/*
- * lz_sarray.c
- *
- * Suffix array match-finder for Lempel-Ziv compression.
- */
-
-/*
- * Copyright (c) 2013, 2014 Eric Biggers. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
- * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
- * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
- * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
-
-#include "wimlib/divsufsort.h"
-#include "wimlib/lz_sarray.h"
-#include "wimlib/util.h"
-#include <string.h>
-
-/* If ENABLE_LZ_DEBUG is defined, verify that the suffix array satisfies its
- * definition.
- *
- * @SA The constructed suffix array.
- * @T The original data.
- * @found Temporary 'bool' array of length @n.
- * @n Length of the data (length of @SA, @T, and @found arrays).
- *
- * WARNING: this is for debug use only as it does not necessarily run in linear
- * time!!! */
-static void
-verify_suffix_array(const lz_sarray_pos_t SA[restrict],
- const u8 T[restrict],
- bool found[restrict],
- lz_sarray_pos_t n)
-{
-#ifdef ENABLE_LZ_DEBUG
- /* Ensure the SA contains exactly one of each i in [0, n - 1]. */
- for (lz_sarray_pos_t i = 0; i < n; i++)
- found[i] = false;
- for (lz_sarray_pos_t r = 0; r < n; r++) {
- lz_sarray_pos_t i = SA[r];
- LZ_ASSERT(i < n);
- LZ_ASSERT(!found[i]);
- found[i] = true;
- }
-
- /* Ensure the suffix with rank r is lexicographically lesser than the
- * suffix with rank (r + 1) for all r in [0, n - 2]. */
- for (lz_sarray_pos_t r = 0; r < n - 1; r++) {
-
- lz_sarray_pos_t i1 = SA[r];
- lz_sarray_pos_t i2 = SA[r + 1];
-
- lz_sarray_pos_t n1 = n - i1;
- lz_sarray_pos_t n2 = n - i2;
-
- int res = memcmp(&T[i1], &T[i2], min(n1, n2));
- LZ_ASSERT(res < 0 || (res == 0 && n1 < n2));
- }
-#endif /* ENABLE_LZ_DEBUG */
-}
-
-/* Compute the inverse suffix array @ISA from the suffix array @SA in linear
- * time.
- *
- * Whereas the suffix array is a mapping from suffix rank to suffix position,
- * the inverse suffix array is a mapping from suffix position to suffix rank.
- */
-static void
-compute_inverse_suffix_array(lz_sarray_pos_t ISA[restrict],
- const lz_sarray_pos_t SA[restrict],
- lz_sarray_pos_t n)
-{
- lz_sarray_pos_t r;
-
- for (r = 0; r < n; r++)
- ISA[SA[r]] = r;
-}
-
-
-/* Compute the LCP (Longest Common Prefix) array in linear time.
- *
- * LCP[r] will be the length of the longest common prefix between the suffixes
- * with positions SA[r - 1] and SA[r]. LCP[0] will be undefined.
- *
- * Algorithm adapted from Kasai et al. 2001: "Linear-Time Longest-Common-Prefix
- * Computation in Suffix Arrays and Its Applications". Modified slightly to
- * take into account that with bytes in the real world, there is no unique
- * symbol at the end of the string. */
-static void
-compute_lcp_array(lz_sarray_pos_t LCP[restrict],
- const lz_sarray_pos_t SA[restrict],
- const lz_sarray_pos_t ISA[restrict],
- const u8 T[restrict],
- lz_sarray_pos_t n)
-{
- lz_sarray_pos_t h, i, r, j, lim;
-
- h = 0;
- for (i = 0; i < n; i++) {
- r = ISA[i];
- if (r > 0) {
- j = SA[r - 1];
- lim = min(n - i, n - j);
-
- while (h < lim && T[i + h] == T[j + h])
- h++;
- LCP[r] = h;
- if (h > 0)
- h--;
- }
- }
-}
-
-/* If ENABLE_LZ_DEBUG is defined, verify that the LCP (Longest Common Prefix)
- * array satisfies its definition.
- *
- * WARNING: this is for debug use only as it does not necessarily run in linear
- * time!!! */
-static void
-verify_lcp_array(lz_sarray_pos_t LCP[restrict],
- const lz_sarray_pos_t SA[restrict],
- const u8 T[restrict],
- lz_sarray_pos_t n)
-{
-#ifdef ENABLE_LZ_DEBUG
- for (lz_sarray_pos_t r = 0; r < n - 1; r++) {
- lz_sarray_pos_t i1 = SA[r];
- lz_sarray_pos_t i2 = SA[r + 1];
- lz_sarray_pos_t lcp = LCP[r + 1];
-
- lz_sarray_pos_t n1 = n - i1;
- lz_sarray_pos_t n2 = n - i2;
-
- LZ_ASSERT(lcp <= min(n1, n2));
-
- LZ_ASSERT(memcmp(&T[i1], &T[i2], lcp) == 0);
- if (lcp < min(n1, n2))
- LZ_ASSERT(T[i1 + lcp] != T[i2 + lcp]);
- }
-#endif /* ENABLE_LZ_DEBUG */
-}
-
-/* Initialize the SA link array in linear time.
- *
- * This is similar to computing the LPF (Longest Previous Factor) array, which
- * is addressed in several papers. In particular the algorithms below are based
- * on Crochemore et al. 2009: "LPF computation revisited". However, this
- * match-finder does not actually compute or use the LPF array per se. Rather,
- * this function sets up some information necessary to compute the LPF array,
- * but later lz_sarray_get_matches() actually uses this information to search
- * the suffix array directly and can keep searching beyond the first (longest)
- * match whose length would be placed in the LPF array. This difference from
- * the theoretical work is necessary because in many real compression formats
- * matches take variable numbers of bits to encode, so a decent parser needs to
- * consider more than just the longest match with unspecified offset.
- *
- * Note: We cap the lcpprev and lcpnext values to the maximum match length so
- * that the match-finder need not worry about it later, in the inner loop.
- *
- * Note: the LCP array is one of the inputs to this function, but it is used as
- * temporary space and therefore will be invalidated.
- */
-static void
-init_salink(struct salink link[restrict],
- lz_sarray_pos_t LCP[restrict],
- const lz_sarray_pos_t SA[restrict],
- const u8 T[restrict],
- lz_sarray_pos_t n,
- lz_sarray_len_t min_match_len,
- lz_sarray_len_t max_match_len)
-{
- /* Calculate salink.dist_to_next and salink.lcpnext.
- *
- * Pass 1 calculates, for each suffix rank, the corresponding
- * "next_initial" value which is the smallest larger rank that
- * corresponds to a suffix starting earlier in the string. It also
- * calculates "lcpnext_initial", which is the longest common prefix with
- * that suffix, although to eliminate checks in lz_sarray_get_matches(),
- * "lcpnext_initial" is set to 0 if it's less than the minimum match
- * length or set to the maximum match length if it's greater than the
- * maximum match length.
- *
- * Pass 2 translates each absolute "next_initial", a 4-byte value, into
- * a relative "dist_to_next", a 1-byte value. This is done to save
- * memory. In the case that the exact relative distance cannot be
- * encoded in 1 byte, it is capped to 255. This is valid as long as
- * lz_sarray_get_matches() validates each position before using it.
- * Note that "lcpnext" need not be updated in this case because it will
- * not be used until the actual next rank has been found anyway.
- */
- link[n - 1].next_initial = LZ_SARRAY_POS_MAX;
- link[n - 1].lcpnext_initial = 0;
- for (lz_sarray_pos_t r = n - 2; r != LZ_SARRAY_POS_MAX; r--) {
- lz_sarray_pos_t t = r + 1;
- lz_sarray_pos_t l = LCP[t];
- while (t != LZ_SARRAY_POS_MAX && SA[t] > SA[r]) {
- l = min(l, link[t].lcpnext_initial);
- t = link[t].next_initial;
- }
- link[r].next_initial = t;
-
- if (l < min_match_len)
- l = 0;
- else if (l > max_match_len)
- l = max_match_len;
- link[r].lcpnext_initial = l;
- }
- for (lz_sarray_pos_t r = 0; r < n; r++) {
- lz_sarray_pos_t next;
- lz_sarray_len_t l;
- lz_sarray_delta_t dist_to_next;
-
- next = link[r].next_initial;
- l = link[r].lcpnext_initial;
-
- if (next == LZ_SARRAY_POS_MAX)
- dist_to_next = 0;
- else if (next - r <= LZ_SARRAY_DELTA_MAX)
- dist_to_next = next - r;
- else
- dist_to_next = LZ_SARRAY_DELTA_MAX;
-
- link[r].lcpnext = l;
- link[r].dist_to_next = dist_to_next;
- }
-
- /* Calculate salink.dist_to_prev and salink.lcpprev.
- *
- * This is analgous to dist_to_next and lcpnext as described above, but
- * in the other direction. That is, here we're interested in, for each
- * rank, the largest smaller rank that corresponds to a suffix starting
- * earlier in the string.
- *
- * To save memory we don't have a "prev_initial" field, but rather store
- * those values in the LCP array. */
- LCP[0] = LZ_SARRAY_POS_MAX;
- link[0].lcpprev = 0;
- for (lz_sarray_pos_t r = 1; r < n; r++) {
- lz_sarray_pos_t t = r - 1;
- lz_sarray_pos_t l = LCP[r];
- while (t != LZ_SARRAY_POS_MAX && SA[t] > SA[r]) {
- l = min(l, link[t].lcpprev);
- t = LCP[t];
- }
- LCP[r] = t;
-
- if (l < min_match_len)
- l = 0;
- else if (l > max_match_len)
- l = max_match_len;
-
- link[r].lcpprev = l;
- }
- for (lz_sarray_pos_t r = 0; r < n; r++) {
-
- lz_sarray_pos_t prev = LCP[r];
-
- if (prev == LZ_SARRAY_POS_MAX)
- link[r].dist_to_prev = 0;
- else if (r - prev <= LZ_SARRAY_DELTA_MAX)
- link[r].dist_to_prev = r - prev;
- else
- link[r].dist_to_prev = LZ_SARRAY_DELTA_MAX;
- }
-}
-
-/* If ENABLE_LZ_DEBUG is defined, verify the values computed by init_salink().
- *
- * WARNING: this is for debug use only as it does not necessarily run in linear
- * time!!! */
-static void
-verify_salink(const struct salink link[],
- const lz_sarray_pos_t SA[],
- const u8 T[],
- lz_sarray_pos_t n,
- lz_sarray_len_t min_match_len,
- lz_sarray_len_t max_match_len)
-{
-#ifdef ENABLE_LZ_DEBUG
- for (lz_sarray_pos_t r = 0; r < n; r++) {
- for (lz_sarray_pos_t prev = r; ; ) {
- if (prev == 0) {
- LZ_ASSERT(link[r].dist_to_prev == 0);
- LZ_ASSERT(link[r].lcpprev == 0);
- break;
- }
-
- prev--;
-
- if (SA[prev] < SA[r]) {
- LZ_ASSERT(link[r].dist_to_prev == min(r - prev, LZ_SARRAY_DELTA_MAX));
-
- lz_sarray_pos_t lcpprev;
- for (lcpprev = 0;
- lcpprev < min(n - SA[prev], n - SA[r]) &&
- T[SA[prev] + lcpprev] == T[SA[r] + lcpprev];
- lcpprev++)
- ;
- if (lcpprev < min_match_len)
- lcpprev = 0;
- else if (lcpprev > max_match_len)
- lcpprev = max_match_len;
-
- LZ_ASSERT(lcpprev == link[r].lcpprev);
- break;
- }
- }
-
- for (lz_sarray_pos_t next = r; ; ) {
- if (next == n - 1) {
- LZ_ASSERT(link[r].dist_to_next == 0);
- LZ_ASSERT(link[r].lcpnext == 0);
- break;
- }
-
- next++;
-
- if (SA[next] < SA[r]) {
- LZ_ASSERT(link[r].dist_to_next == min(next - r, LZ_SARRAY_DELTA_MAX));
-
- lz_sarray_pos_t lcpnext;
- for (lcpnext = 0;
- lcpnext < min(n - SA[next], n - SA[r]) &&
- T[SA[next] + lcpnext] == T[SA[r] + lcpnext];
- lcpnext++)
- ;
- if (lcpnext < min_match_len)
- lcpnext = 0;
- else if (lcpnext > max_match_len)
- lcpnext = max_match_len;
-
- LZ_ASSERT(lcpnext == link[r].lcpnext);
- break;
- }
- }
- }
-#endif
-}
-
-/*
- * Initialize the suffix array match-finder.
- *
- * @mf
- * The suffix array match-finder structure to initialize. This structure
- * is expected to be zeroed before this function is called. In the case
- * that this function fails, lz_sarray_destroy() should be called to free
- * any memory that may have been allocated.
- *
- * @max_window_size
- * The maximum window size to support. This must be greater than 0.
- *
- * The amount of needed memory will depend on this value; see
- * lz_sarray_get_needed_memory() for details.
- *
- * @min_match_len
- * The minimum length of each match to be found. Must be greater than 0.
- *
- * @max_match_len
- * The maximum length of each match to be found. Must be greater than or
- * equal to @min_match_len.
- *
- * @max_matches_to_consider
- * The maximum number of matches to consider at each position. This should
- * be greater than @max_matches_to_return because @max_matches_to_consider
- * counts all the returned matches as well as matches of equal length to
- * returned matches that were not returned. This parameter bounds the
- * amount of work the match-finder does at any one position. This could be
- * anywhere from 1 to 100+ depending on the compression ratio and
- * performance desired.
- *
- * @max_matches_to_return
- * Maximum number of matches to return at each position. Because of the
- * suffix array search algorithm, the order in which matches are returned
- * will be from longest to shortest, so cut-offs due to this parameter will
- * only result in shorter matches being discarded. This parameter could be
- * anywhere from 1 to (@max_match_len - @min_match_len + 1) depending on
- * the compression performance desired. However, making it even moderately
- * large (say, greater than 3) may not be very helpful due to the property
- * that the matches are returned from longest to shortest. But the main
- * thing to keep in mind is that if the compressor decides to output a
- * shorter-than-possible match, ideally it would be best to choose the best
- * match of the desired length rather than truncate a longer match to that
- * length.
- *
- * After initialization, the suffix-array match-finder can be used for any
- * number of input strings (windows) of length less than or equal to
- * @max_window_size by successive calls to lz_sarray_load_window().
- *
- * Returns %true on success, or %false if sufficient memory could not be
- * allocated. See the note for @max_window_size above regarding the needed
- * memory size.
- */
-bool
-lz_sarray_init(struct lz_sarray *mf,
- lz_sarray_pos_t max_window_size,
- lz_sarray_len_t min_match_len,
- lz_sarray_len_t max_match_len,
- u32 max_matches_to_consider,
- u32 max_matches_to_return)
-{
- LZ_ASSERT(min_match_len > 0);
- LZ_ASSERT(max_window_size > 0);
- LZ_ASSERT(max_match_len >= min_match_len);
-
- mf->max_window_size = max_window_size;
- mf->min_match_len = min_match_len;
- mf->max_match_len = max_match_len;
- mf->max_matches_to_consider = max_matches_to_consider;
- mf->max_matches_to_return = max_matches_to_return;
-
- /* SA and ISA will share the same storage block. */
- if ((u64)2 * max_window_size * sizeof(mf->SA[0]) !=
- 2 * max_window_size * sizeof(mf->SA[0]))
- return false;
- mf->SA = MALLOC(max_window_size * sizeof(mf->SA[0]) +
- max(DIVSUFSORT_TMP1_SIZE,
- max_window_size * sizeof(mf->SA[0])));
- if (mf->SA == NULL)
- return false;
-
- if ((u64)max_window_size * sizeof(mf->salink[0]) !=
- max_window_size * sizeof(mf->salink[0]))
- return false;
- mf->salink = MALLOC(max(DIVSUFSORT_TMP2_SIZE,
- max_window_size * sizeof(mf->salink[0])));
- if (mf->salink == NULL)
- return false;
-
- return true;
-}
-
-/*
- * Return the number of bytes of memory that lz_sarray_init() would allocate for
- * the specified maximum window size.
- *
- * This should be (14 * @max_window_size) unless the type definitions have been
- * changed.
- */
-u64
-lz_sarray_get_needed_memory(lz_sarray_pos_t max_window_size)
-{
- u64 size = 0;
-
- /* SA and ISA: 8 bytes per position */
- size += (u64)max_window_size * sizeof(((struct lz_sarray*)0)->SA[0]) +
- max(DIVSUFSORT_TMP1_SIZE,
- (u64)max_window_size * sizeof(((struct lz_sarray*)0)->SA[0]));
-
- /* salink: 6 bytes per position */
- size += max(DIVSUFSORT_TMP2_SIZE,
- (u64)max_window_size * sizeof(((struct lz_sarray*)0)->salink[0]));
-
- return size;
-}
-
-/*
- * Prepare the suffix array match-finder to scan the specified window for
- * matches.
- *
- * @mf Suffix array match-finder previously initialized with lz_sarray_init().
- *
- * @T Window, or "block", in which to find matches.
- *
- * @n Size of window in bytes. This must be positive and less than or equal
- * to the @max_window_size passed to lz_sarray_init().
- *
- * This function runs in linear time (relative to @n).
- */
-void
-lz_sarray_load_window(struct lz_sarray *mf, const u8 T[], lz_sarray_pos_t n)
-{
- lz_sarray_pos_t *ISA, *LCP;
-
- LZ_ASSERT(n > 0 && n <= mf->max_window_size);
-
- /* Compute SA (Suffix Array).
- *
- * divsufsort() needs temporary space --- one array with 256 spaces and
- * one array with 65536 spaces. The implementation of divsufsort() has
- * been modified from the original to use the provided temporary space
- * instead of allocating its own.
- *
- * We also check at build-time that divsufsort() uses the same integer
- * size expected by this code. Unfortunately, divsufsort breaks if
- * 'sa_idx_t' is defined to be a 16-bit integer; however, that would
- * limit blocks to only 65536 bytes anyway. */
- BUILD_BUG_ON(sizeof(lz_sarray_pos_t) != sizeof(saidx_t));
-
- divsufsort(T, mf->SA, n, (saidx_t*)&mf->SA[n], (saidx_t*)mf->salink);
-
- BUILD_BUG_ON(sizeof(bool) > sizeof(mf->salink[0]));
- verify_suffix_array(mf->SA, T, (bool*)mf->salink, n);
-
- /* Compute ISA (Inverse Suffix Array) in a preliminary position.
- *
- * This is just a trick to save memory. Since LCP is unneeded after
- * this function, it can be computed in any available space. The
- * storage for the ISA is the best choice because the ISA can be built
- * quickly in salink for now, then re-built in its real location at the
- * end. This is probably worth it because computing the ISA from the SA
- * is very fast, and since this match-finder is memory-hungry we'd like
- * to save as much memory as possible. */
- BUILD_BUG_ON(sizeof(mf->salink[0]) < sizeof(mf->ISA[0]));
- ISA = (lz_sarray_pos_t*)mf->salink;
- compute_inverse_suffix_array(ISA, mf->SA, n);
-
- /* Compute LCP (Longest Common Prefix) array. */
- LCP = mf->SA + n;
- compute_lcp_array(LCP, mf->SA, ISA, T, n);
- verify_lcp_array(LCP, mf->SA, T, n);
-
- /* Initialize suffix array links. */
- init_salink(mf->salink, LCP, mf->SA, T, n,
- mf->min_match_len, mf->max_match_len);
- verify_salink(mf->salink, mf->SA, T, n,
- mf->min_match_len, mf->max_match_len);
-
- /* Compute ISA (Inverse Suffix Array) in its final position. */
- ISA = mf->SA + n;
- compute_inverse_suffix_array(ISA, mf->SA, n);
-
- /* Save new variables and return. */
- mf->ISA = ISA;
- mf->cur_pos = 0;
- mf->window_size = n;
-}
-
-/* Free memory allocated for the suffix array match-finder. */
-void
-lz_sarray_destroy(struct lz_sarray *mf)
-{
- FREE(mf->SA);
- FREE(mf->salink);
-}
*/
/*
- * Copyright (C) 2013 Eric Biggers
+ * Copyright (C) 2013, 2014 Eric Biggers
*
* This file is part of wimlib, a library for working with WIM files.
*
/* This a compressor for the LZMS compression format. More details about this
* format can be found in lzms-decompress.c.
*
+ * Also see lzx-compress.c for general information about match-finding and
+ * match-choosing that also applies to this LZMS compressor.
+ *
* NOTE: this compressor currently does not code any delta matches.
*/
#include "wimlib/compress_common.h"
#include "wimlib/endianness.h"
#include "wimlib/error.h"
-#include "wimlib/lz_sarray.h"
+#include "wimlib/lz.h"
+#include "wimlib/lz_bt.h"
#include "wimlib/lzms.h"
#include "wimlib/util.h"
#include <limits.h>
#include <pthread.h>
-struct lzms_compressor;
-struct lzms_adaptive_state {
- struct lzms_lz_lru_queues lru;
- u8 main_state;
- u8 match_state;
- u8 lz_match_state;
- u8 lz_repeat_match_state[LZMS_NUM_RECENT_OFFSETS - 1];
-};
-#define LZ_ADAPTIVE_STATE struct lzms_adaptive_state
-#define LZ_COMPRESSOR struct lzms_compressor
-#include "wimlib/lz_optimal.h"
-
/* Stucture used for writing raw bits to the end of the LZMS-compressed data as
* a series of 16-bit little endian coding units. */
struct lzms_output_bitstream {
/* State of the LZMS compressor. */
struct lzms_compressor {
+ struct wimlib_lzms_compressor_params params;
+
/* Pointer to a buffer holding the preprocessed data to compress. */
u8 *window;
/* Size of the data in @buffer. */
u32 window_size;
- /* Suffix array match-finder. */
- struct lz_sarray lz_sarray;
+ /* Binary tree match-finder. */
+ struct lz_bt mf;
/* Temporary space to store found matches. */
struct raw_match *matches;
- /* Match-chooser. */
- struct lz_match_chooser mc;
+ /* Match-chooser data. */
+ struct lzms_mc_pos_data *optimum;
+ unsigned optimum_cur_idx;
+ unsigned optimum_end_idx;
/* Maximum block size this compressor instantiation allows. This is the
* allocated size of @window. */
s32 last_target_usages[65536];
};
+struct lzms_mc_pos_data {
+ u32 cost;
+#define MC_INFINITE_COST ((u32)~0UL)
+ union {
+ struct {
+ u32 link;
+ u32 match_offset;
+ } prev;
+ struct {
+ u32 link;
+ u32 match_offset;
+ } next;
+ };
+ struct lzms_adaptive_state {
+ struct lzms_lz_lru_queues lru;
+ u8 main_state;
+ u8 match_state;
+ u8 lz_match_state;
+ u8 lz_repeat_match_state[LZMS_NUM_RECENT_OFFSETS - 1];
+ } state;
+};
+
/* Initialize the output bitstream @os to write forwards to the specified
* compressed data buffer @out that is @out_limit 16-bit integers long. */
static void
lzms_end_encode_item(ctx, length);
}
-/* Fast heuristic cost evaluation to use in the inner loop of the match-finder.
- * Unlike lzms_get_lz_match_cost(), which does a true cost evaluation, this
- * simply prioritize matches based on their offset. */
-static input_idx_t
-lzms_lz_match_cost_fast(input_idx_t length, input_idx_t offset, const void *_lru)
-{
- const struct lzms_lz_lru_queues *lru = _lru;
-
- for (input_idx_t i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++)
- if (offset == lru->recent_offsets[i])
- return i;
-
- return offset;
-}
-
#define LZMS_COST_SHIFT 5
/*#define LZMS_RC_COSTS_USE_FLOATING_POINT*/
}
static u32
-lzms_get_matches(struct lzms_compressor *ctx,
- const struct lzms_adaptive_state *state,
- struct raw_match **matches_ret)
+lzms_get_matches(struct lzms_compressor *ctx, struct raw_match **matches_ret)
{
*matches_ret = ctx->matches;
- return lz_sarray_get_matches(&ctx->lz_sarray,
- ctx->matches,
- lzms_lz_match_cost_fast,
- &state->lru);
+ return lz_bt_get_matches(&ctx->mf, ctx->matches);
}
static void
-lzms_skip_bytes(struct lzms_compressor *ctx, input_idx_t n)
+lzms_skip_bytes(struct lzms_compressor *ctx, u32 n)
{
- while (n--)
- lz_sarray_skip_position(&ctx->lz_sarray);
+ lz_bt_skip_positions(&ctx->mf, n);
}
static u32
-lzms_get_prev_literal_cost(struct lzms_compressor *ctx,
- struct lzms_adaptive_state *state)
+lzms_get_literal_cost(struct lzms_compressor *ctx,
+ struct lzms_adaptive_state *state, u8 literal)
{
- u8 literal = ctx->window[lz_sarray_get_pos(&ctx->lz_sarray) - 1];
u32 cost = 0;
state->lru.upcoming_offset = 0;
static u32
lzms_get_lz_match_cost(struct lzms_compressor *ctx,
struct lzms_adaptive_state *state,
- input_idx_t length, input_idx_t offset)
+ u32 length, u32 offset)
{
u32 cost = 0;
int recent_offset_idx;
return cost;
}
+static struct raw_match
+lzms_match_chooser_reverse_list(struct lzms_compressor *ctx, unsigned cur_pos)
+{
+ unsigned prev_link, saved_prev_link;
+ unsigned prev_match_offset, saved_prev_match_offset;
+
+ ctx->optimum_end_idx = cur_pos;
+
+ saved_prev_link = ctx->optimum[cur_pos].prev.link;
+ saved_prev_match_offset = ctx->optimum[cur_pos].prev.match_offset;
+
+ do {
+ prev_link = saved_prev_link;
+ prev_match_offset = saved_prev_match_offset;
+
+ saved_prev_link = ctx->optimum[prev_link].prev.link;
+ saved_prev_match_offset = ctx->optimum[prev_link].prev.match_offset;
+
+ ctx->optimum[prev_link].next.link = cur_pos;
+ ctx->optimum[prev_link].next.match_offset = prev_match_offset;
+
+ cur_pos = prev_link;
+ } while (cur_pos != 0);
+
+ ctx->optimum_cur_idx = ctx->optimum[0].next.link;
+
+ return (struct raw_match)
+ { .len = ctx->optimum_cur_idx,
+ .offset = ctx->optimum[0].next.match_offset,
+ };
+}
+
+/* This is similar to lzx_get_near_optimal_match() in lzx-compress.c.
+ * Read that one if you want to understand it. */
static struct raw_match
lzms_get_near_optimal_match(struct lzms_compressor *ctx)
{
+ u32 num_matches;
+ struct raw_match *matches;
+ struct raw_match match;
+ u32 longest_len;
+ u32 longest_rep_len;
+ u32 longest_rep_offset;
+ struct raw_match *matchptr;
+ unsigned cur_pos;
+ unsigned end_pos;
struct lzms_adaptive_state initial_state;
+ if (ctx->optimum_cur_idx != ctx->optimum_end_idx) {
+ match.len = ctx->optimum[ctx->optimum_cur_idx].next.link -
+ ctx->optimum_cur_idx;
+ match.offset = ctx->optimum[ctx->optimum_cur_idx].next.match_offset;
+
+ ctx->optimum_cur_idx = ctx->optimum[ctx->optimum_cur_idx].next.link;
+ return match;
+ }
+
+ ctx->optimum_cur_idx = 0;
+ ctx->optimum_end_idx = 0;
+
+ longest_rep_len = ctx->params.min_match_length - 1;
+ if (lz_bt_get_position(&ctx->mf) >= 1) {
+ u32 limit = min(ctx->params.max_match_length,
+ lz_bt_get_remaining_size(&ctx->mf));
+ for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++) {
+ u32 offset = ctx->lru.lz.recent_offsets[i];
+ const u8 *strptr = lz_bt_get_window_ptr(&ctx->mf);
+ const u8 *matchptr = strptr - offset;
+ u32 len = 0;
+ while (len < limit && strptr[len] == matchptr[len])
+ len++;
+ if (len > longest_rep_len) {
+ longest_rep_len = len;
+ longest_rep_offset = offset;
+ }
+ }
+ }
+
+ if (longest_rep_len >= ctx->params.nice_match_length) {
+ lzms_skip_bytes(ctx, longest_rep_len);
+ return (struct raw_match) {
+ .len = longest_rep_len,
+ .offset = longest_rep_offset,
+ };
+ }
+
+ num_matches = lzms_get_matches(ctx, &matches);
+
+ if (num_matches) {
+ longest_len = matches[num_matches - 1].len;
+ if (longest_len >= ctx->params.nice_match_length) {
+ lzms_skip_bytes(ctx, longest_len - 1);
+ return matches[num_matches - 1];
+ }
+ } else {
+ longest_len = 1;
+ }
+
initial_state.lru = ctx->lru.lz;
initial_state.main_state = ctx->main_range_encoder.state;
initial_state.match_state = ctx->match_range_encoder.state;
initial_state.lz_match_state = ctx->lz_match_range_encoder.state;
for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++)
- initial_state.lz_repeat_match_state[i] =
- ctx->lz_repeat_match_range_encoders[i].state;
- return lz_get_near_optimal_match(&ctx->mc,
- lzms_get_matches,
- lzms_skip_bytes,
- lzms_get_prev_literal_cost,
- lzms_get_lz_match_cost,
- ctx,
- &initial_state);
+ initial_state.lz_repeat_match_state[i] = ctx->lz_repeat_match_range_encoders[i].state;
+
+ ctx->optimum[1].state = initial_state;
+ ctx->optimum[1].cost = lzms_get_literal_cost(ctx,
+ &ctx->optimum[1].state,
+ *(lz_bt_get_window_ptr(&ctx->mf) - 1));
+ ctx->optimum[1].prev.link = 0;
+
+ matchptr = matches;
+ for (u32 len = 2; len <= longest_len; len++) {
+ u32 offset = matchptr->offset;
+
+ ctx->optimum[len].state = initial_state;
+ ctx->optimum[len].prev.link = 0;
+ ctx->optimum[len].prev.match_offset = offset;
+ ctx->optimum[len].cost = lzms_get_lz_match_cost(ctx,
+ &ctx->optimum[len].state,
+ len, offset);
+ if (len == matchptr->len)
+ matchptr++;
+ }
+ end_pos = longest_len;
+
+ if (longest_rep_len >= ctx->params.min_match_length) {
+ struct lzms_adaptive_state state;
+ u32 cost;
+
+ while (end_pos < longest_rep_len)
+ ctx->optimum[++end_pos].cost = MC_INFINITE_COST;
+
+ state = initial_state;
+ cost = lzms_get_lz_match_cost(ctx,
+ &state,
+ longest_rep_len,
+ longest_rep_offset);
+ if (cost <= ctx->optimum[longest_rep_len].cost) {
+ ctx->optimum[longest_rep_len].state = state;
+ ctx->optimum[longest_rep_len].prev.link = 0;
+ ctx->optimum[longest_rep_len].prev.match_offset = longest_rep_offset;
+ ctx->optimum[longest_rep_len].cost = cost;
+ }
+ }
+
+ cur_pos = 0;
+ for (;;) {
+ u32 cost;
+ struct lzms_adaptive_state state;
+
+ cur_pos++;
+
+ if (cur_pos == end_pos || cur_pos == ctx->params.optim_array_length)
+ return lzms_match_chooser_reverse_list(ctx, cur_pos);
+
+ longest_rep_len = ctx->params.min_match_length - 1;
+ u32 limit = min(ctx->params.max_match_length,
+ lz_bt_get_remaining_size(&ctx->mf));
+ for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++) {
+ u32 offset = ctx->optimum[cur_pos].state.lru.recent_offsets[i];
+ const u8 *strptr = lz_bt_get_window_ptr(&ctx->mf);
+ const u8 *matchptr = strptr - offset;
+ u32 len = 0;
+ while (len < limit && strptr[len] == matchptr[len])
+ len++;
+ if (len > longest_rep_len) {
+ longest_rep_len = len;
+ longest_rep_offset = offset;
+ }
+ }
+
+ if (longest_rep_len >= ctx->params.nice_match_length) {
+ match = lzms_match_chooser_reverse_list(ctx, cur_pos);
+
+ ctx->optimum[cur_pos].next.match_offset = longest_rep_offset;
+ ctx->optimum[cur_pos].next.link = cur_pos + longest_rep_len;
+ ctx->optimum_end_idx = cur_pos + longest_rep_len;
+
+ lzms_skip_bytes(ctx, longest_rep_len);
+
+ return match;
+ }
+
+ num_matches = lzms_get_matches(ctx, &matches);
+
+ if (num_matches) {
+ longest_len = matches[num_matches - 1].len;
+ if (longest_len >= ctx->params.nice_match_length) {
+ match = lzms_match_chooser_reverse_list(ctx, cur_pos);
+
+ ctx->optimum[cur_pos].next.match_offset =
+ matches[num_matches - 1].offset;
+ ctx->optimum[cur_pos].next.link = cur_pos + longest_len;
+ ctx->optimum_end_idx = cur_pos + longest_len;
+
+ lzms_skip_bytes(ctx, longest_len - 1);
+
+ return match;
+ }
+ } else {
+ longest_len = 1;
+ }
+
+ while (end_pos < cur_pos + longest_len)
+ ctx->optimum[++end_pos].cost = MC_INFINITE_COST;
+
+ state = ctx->optimum[cur_pos].state;
+ cost = ctx->optimum[cur_pos].cost +
+ lzms_get_literal_cost(ctx,
+ &state,
+ *(lz_bt_get_window_ptr(&ctx->mf) - 1));
+ if (cost < ctx->optimum[cur_pos + 1].cost) {
+ ctx->optimum[cur_pos + 1].state = state;
+ ctx->optimum[cur_pos + 1].cost = cost;
+ ctx->optimum[cur_pos + 1].prev.link = cur_pos;
+ }
+
+ matchptr = matches;
+ for (u32 len = 2; len <= longest_len; len++) {
+ u32 offset;
+
+ offset = matchptr->offset;
+ state = ctx->optimum[cur_pos].state;
+
+ cost = ctx->optimum[cur_pos].cost +
+ lzms_get_lz_match_cost(ctx, &state, len, offset);
+ if (cost < ctx->optimum[cur_pos + len].cost) {
+ ctx->optimum[cur_pos + len].state = state;
+ ctx->optimum[cur_pos + len].prev.link = cur_pos;
+ ctx->optimum[cur_pos + len].prev.match_offset = offset;
+ ctx->optimum[cur_pos + len].cost = cost;
+ }
+ if (len == matchptr->len)
+ matchptr++;
+ }
+
+ if (longest_rep_len >= ctx->params.min_match_length) {
+
+ while (end_pos < cur_pos + longest_rep_len)
+ ctx->optimum[++end_pos].cost = MC_INFINITE_COST;
+
+ state = ctx->optimum[cur_pos].state;
+
+ cost = ctx->optimum[cur_pos].cost +
+ lzms_get_lz_match_cost(ctx,
+ &state,
+ longest_rep_len,
+ longest_rep_offset);
+ if (cost <= ctx->optimum[cur_pos + longest_rep_len].cost) {
+ ctx->optimum[cur_pos + longest_rep_len].state =
+ state;
+ ctx->optimum[cur_pos + longest_rep_len].prev.link =
+ cur_pos;
+ ctx->optimum[cur_pos + longest_rep_len].prev.match_offset =
+ longest_rep_offset;
+ ctx->optimum[cur_pos + longest_rep_len].cost =
+ cost;
+ }
+ }
+ }
}
/*
*
* Notes:
*
- * - This uses near-optimal LZ parsing backed by a suffix-array match-finder.
- * More details can be found in the corresponding files (lz_optimal.h,
- * lz_sarray.{h,c}).
+ * - This uses near-optimal LZ parsing backed by a binary tree match-finder.
*
- * - This does not output any delta matches. It would take a specialized
- * algorithm to find them, then more code in lz_optimal.h and here to handle
- * evaluating and outputting them.
+ * - This does not output any delta matches.
*
* - The costs of literals and matches are estimated using the range encoder
* states and the semi-adaptive Huffman codes. Except for range encoding
{
struct raw_match match;
- /* Load window into suffix array match-finder. */
- lz_sarray_load_window(&ctx->lz_sarray, ctx->window, ctx->window_size);
+ /* Load window into the binary tree match-finder. */
+ lz_bt_load_window(&ctx->mf, ctx->window, ctx->window_size);
/* Reset the match-chooser. */
- lz_match_chooser_begin(&ctx->mc);
+ ctx->optimum_cur_idx = 0;
+ ctx->optimum_end_idx = 0;
while (ctx->cur_window_pos != ctx->window_size) {
match = lzms_get_near_optimal_match(ctx);
if (ctx) {
FREE(ctx->window);
FREE(ctx->matches);
- lz_sarray_destroy(&ctx->lz_sarray);
- lz_match_chooser_destroy(&ctx->mc);
+ lz_bt_destroy(&ctx->mf);
+ FREE(ctx->optimum);
FREE(ctx);
}
}
.max_match_length = UINT32_MAX,
.nice_match_length = 32,
.max_search_depth = 50,
- .max_matches_per_pos = 3,
.optim_array_length = 1024,
};
ctx->matches = MALLOC(min(params->max_match_length -
params->min_match_length + 1,
- params->max_matches_per_pos) *
+ params->max_search_depth + 2) *
sizeof(ctx->matches[0]));
if (ctx->matches == NULL)
goto oom;
- if (!lz_sarray_init(&ctx->lz_sarray, max_block_size,
- params->min_match_length,
- min(params->max_match_length, LZ_SARRAY_LEN_MAX),
- params->max_search_depth,
- params->max_matches_per_pos))
+ if (!lz_bt_init(&ctx->mf,
+ max_block_size,
+ params->min_match_length,
+ params->max_match_length,
+ params->nice_match_length,
+ params->max_search_depth))
goto oom;
- if (!lz_match_chooser_init(&ctx->mc,
- params->optim_array_length,
- params->nice_match_length,
- params->max_match_length))
+ ctx->optimum = MALLOC((params->optim_array_length +
+ min(params->nice_match_length,
+ params->max_match_length)) *
+ sizeof(ctx->optimum[0]));
+ if (!ctx->optimum)
goto oom;
/* Initialize position and length slot data if not done already. */
lzms_init_rc_costs();
ctx->max_block_size = max_block_size;
+ memcpy(&ctx->params, params, sizeof(*params));
*ctx_ret = ctx;
return 0;
size += max_block_size;
size += sizeof(struct lzms_compressor);
- size += lz_sarray_get_needed_memory(max_block_size);
- size += lz_match_chooser_get_needed_memory(params->optim_array_length,
- params->nice_match_length,
- params->max_match_length);
- size += min(params->max_match_length -
- params->min_match_length + 1,
- params->max_matches_per_pos) *
+ size += lz_bt_get_needed_memory(max_block_size);
+ size += (params->optim_array_length +
+ min(params->nice_match_length,
+ params->max_match_length)) *
+ sizeof(((struct lzms_compressor *)0)->optimum[0]);
+ size += min(params->max_match_length - params->min_match_length + 1,
+ params->max_search_depth + 2) *
sizeof(((struct lzms_compressor*)0)->matches[0]);
return size;
}
/*
* lzx-compress.c
- *
- * LZX compression routines
*/
/*
- * Copyright (C) 2012, 2013 Eric Biggers
+ * Copyright (C) 2012, 2013, 2014 Eric Biggers
*
* This file is part of wimlib, a library for working with WIM files.
*
/*
- * This file contains a compressor for the LZX compression format, as used in
- * the WIM file format.
+ * This file contains a compressor for the LZX ("Lempel-Ziv eXtended"?)
+ * compression format, as used in the WIM (Windows IMaging) file format. This
+ * code may need some slight modifications to be used outside of the WIM format.
+ * In particular, in other situations the LZX block header might be slightly
+ * different, and a sliding window rather than a fixed-size window might be
+ * required.
*
- * Format
- * ======
+ * ----------------------------------------------------------------------------
*
- * First, the primary reference for the LZX compression format is the
- * specification released by Microsoft.
+ * Format Overview
*
- * Second, the comments in lzx-decompress.c provide some more information about
- * the LZX compression format, including errors in the Microsoft specification.
+ * The primary reference for LZX is the specification released by Microsoft.
+ * However, the comments in lzx-decompress.c provide more information about LZX
+ * and note some errors in the Microsoft specification.
*
- * Do note that LZX shares many similarities with DEFLATE, the algorithm used by
- * zlib and gzip. Both LZX and DEFLATE use LZ77 matching and Huffman coding,
- * and certain other details are quite similar, such as the method for storing
- * Huffman codes. However, some of the main differences are:
+ * LZX shares many similarities with DEFLATE, the format used by zlib and gzip.
+ * Both LZX and DEFLATE use LZ77 matching and Huffman coding. Certain details
+ * are quite similar, such as the method for storing Huffman codes. However,
+ * the main differences are:
*
* - LZX preprocesses the data to attempt to make x86 machine code slightly more
* compressible before attempting to compress it further.
+ *
* - LZX uses a "main" alphabet which combines literals and matches, with the
* match symbols containing a "length header" (giving all or part of the match
* length) and a "position slot" (giving, roughly speaking, the order of
* magnitude of the match offset).
- * - LZX does not have static Huffman blocks; however it does have two types of
- * dynamic Huffman blocks ("aligned offset" and "verbatim").
+ *
+ * - LZX does not have static Huffman blocks (that is, the kind with preset
+ * Huffman codes); however it does have two types of dynamic Huffman blocks
+ * ("verbatim" and "aligned").
+ *
* - LZX has a minimum match length of 2 rather than 3.
+ *
* - In LZX, match offsets 0 through 2 actually represent entries in an LRU
* queue of match offsets. This is very useful for certain types of files,
* such as binary files that have repeating records.
*
- * Algorithms
- * ==========
+ * ----------------------------------------------------------------------------
+ *
+ * Algorithmic Overview
*
- * There are actually two distinct overall algorithms implemented here. We
- * shall refer to them as the "slow" algorithm and the "fast" algorithm. The
- * "slow" algorithm spends more time compressing to achieve a higher compression
- * ratio compared to the "fast" algorithm. More details are presented below.
+ * At a high level, any implementation of LZX compression must operate as
+ * follows:
*
- * Slow algorithm
- * --------------
+ * 1. Preprocess the input data to translate the targets of 32-bit x86 call
+ * instructions to absolute offsets. (Actually, this is required for WIM,
+ * but might not be in other places LZX is used.)
*
- * The "slow" algorithm to generate LZX-compressed data is roughly as follows:
+ * 2. Find a sequence of LZ77-style matches and literal bytes that expands to
+ * the preprocessed data.
*
- * 1. Preprocess the input data to translate the targets of x86 call
- * instructions to absolute offsets.
+ * 3. Divide the match/literal sequence into one or more LZX blocks, each of
+ * which may be "uncompressed", "verbatim", or "aligned".
*
- * 2. Build the suffix array and inverse suffix array for the input data. The
- * suffix array contains the indices of all suffixes of the input data,
- * sorted lexcographically by the corresponding suffixes. The "position" of
- * a suffix is the index of that suffix in the original string, whereas the
- * "rank" of a suffix is the index at which that suffix's position is found
- * in the suffix array.
+ * 4. Output each LZX block.
*
- * 3. Build the longest common prefix array corresponding to the suffix array.
+ * Step (1) is fairly straightforward. It requires looking for 0xe8 bytes in
+ * the input data and performing a translation on the 4 bytes following each
+ * one.
*
- * 4. For each suffix, find the highest lower ranked suffix that has a lower
- * position, the lowest higher ranked suffix that has a lower position, and
- * the length of the common prefix shared between each. This information is
- * later used to link suffix ranks into a doubly-linked list for searching
- * the suffix array.
+ * Step (4) is complicated, but it is mostly determined by the LZX format. The
+ * only real choice we have is what algorithm to use to build the length-limited
+ * canonical Huffman codes. See lzx_write_all_blocks() for details.
*
- * 5. Set a default cost model for matches/literals.
+ * That leaves steps (2) and (3) as where all the hard stuff happens. Focusing
+ * on step (2), we need to do LZ77-style parsing on the input data, or "window",
+ * to divide it into a sequence of matches and literals. Each position in the
+ * window might have multiple matches associated with it, and we need to choose
+ * which one, if any, to actually use. Therefore, the problem can really be
+ * divided into two areas of concern: (a) finding matches at a given position,
+ * which we shall call "match-finding", and (b) choosing whether to use a
+ * match or a literal at a given position, and if using a match, which one (if
+ * there is more than one available). We shall call this "match-choosing". We
+ * first consider match-finding, then match-choosing.
*
- * 6. Determine the lowest cost sequence of LZ77 matches ((offset, length)
- * pairs) and literal bytes to divide the input into. Raw match-finding is
- * done by searching the suffix array using a linked list to avoid
- * considering any suffixes that start after the current position. Each run
- * of the match-finder returns the approximate lowest-cost longest match as
- * well as any shorter matches that have even lower approximate costs. Each
- * such run also adds the suffix rank of the current position into the linked
- * list being used to search the suffix array. Parsing, or match-choosing,
- * is solved as a minimum-cost path problem using a forward "optimal parsing"
- * algorithm based on the Deflate encoder from 7-Zip. This algorithm moves
- * forward calculating the minimum cost to reach each byte until either a
- * very long match is found or until a position is found at which no matches
- * start or overlap.
+ * ----------------------------------------------------------------------------
*
- * 7. Build the Huffman codes needed to output the matches/literals.
+ * Match-finding
*
- * 8. Up to a certain number of iterations, use the resulting Huffman codes to
- * refine a cost model and go back to Step #6 to determine an improved
- * sequence of matches and literals.
+ * Given a position in the window, we want to find LZ77-style "matches" with
+ * that position at previous positions in the window. With LZX, the minimum
+ * match length is 2 and the maximum match length is 257. The only restriction
+ * on offsets is that LZX does not allow the last 2 bytes of the window to match
+ * the the beginning of the window.
*
- * 9. Output the resulting block using the match/literal sequences and the
- * Huffman codes that were computed for the block.
+ * Depending on how good a compression ratio we want (see the "Match-choosing"
+ * section), we may want to find: (a) all matches, or (b) just the longest
+ * match, or (c) just some "promising" matches that we are able to find quickly,
+ * or (d) just the longest match that we're able to find quickly. Below we
+ * introduce the match-finding methods that the code currently uses or has
+ * previously used:
*
- * Note: the algorithm does not yet attempt to split the input into multiple LZX
- * blocks; it instead uses a series of blocks of LZX_DIV_BLOCK_SIZE bytes.
+ * - Hash chains. Maintain a table that maps hash codes, computed from
+ * fixed-length byte sequences, to linked lists containing previous window
+ * positions. To search for matches, compute the hash for the current
+ * position in the window and search the appropriate hash chain. When
+ * advancing to the next position, prepend the current position to the
+ * appropriate hash list. This is a good approach for producing matches with
+ * stategy (d) and is useful for fast compression. Therefore, we provide an
+ * option to use this method for LZX compression. See lz_hash.c for the
+ * implementation.
*
- * Fast algorithm
- * --------------
+ * - Binary trees. Similar to hash chains, but each hash bucket contains a
+ * binary tree of previous window positions rather than a linked list. This
+ * is a good approach for producing matches with stategy (c) and is useful for
+ * achieving a good compression ratio. Therefore, we provide an option to use
+ * this method; see lz_bt.c for the implementation.
*
- * The fast algorithm (and the only one available in wimlib v1.5.1 and earlier)
- * spends much less time on the main bottlenecks of the compression process ---
- * that is, the match finding and match choosing. Matches are found and chosen
- * with hash chains using a greedy parse with one position of look-ahead. No
- * block splitting is done; only compressing the full input into an aligned
- * offset block is considered.
+ * - Suffix arrays. This code previously used this method to produce matches
+ * with stategy (c), but I've dropped it because it was slower than the binary
+ * trees approach, used more memory, and did not improve the compression ratio
+ * enough to compensate. Download wimlib v1.6.2 if you want the code.
+ * However, the suffix array method was basically as follows. Build the
+ * suffix array for the entire window. The suffix array contains each
+ * possible window position, sorted by the lexicographic order of the strings
+ * that begin at those positions. Find the matches at a given position by
+ * searching the suffix array outwards, in both directions, from the suffix
+ * array slot for that position. This produces the longest matches first, but
+ * "matches" that actually occur at later positions in the window must be
+ * skipped. To do this skipping, use an auxiliary array with dynamically
+ * constructed linked lists. Also, use the inverse suffix array to quickly
+ * find the suffix array slot for a given position without doing a binary
+ * search.
*
- * Acknowledgments
- * ===============
+ * ----------------------------------------------------------------------------
*
- * Acknowledgments to several open-source projects and research papers that made
- * it possible to implement this code:
+ * Match-choosing
*
- * - divsufsort (author: Yuta Mori), for the suffix array construction code,
- * located in a separate file (divsufsort.c).
+ * Usually, choosing the longest match is best because it encodes the most data
+ * in that one item. However, sometimes the longest match is not optimal
+ * because (a) choosing a long match now might prevent using an even longer
+ * match later, or (b) more generally, what we actually care about is the number
+ * of bits it will ultimately take to output each match or literal, which is
+ * actually dependent on the entropy encoding using by the underlying
+ * compression format. Consequently, a longer match usually, but not always,
+ * takes fewer bits to encode than multiple shorter matches or literals that
+ * cover the same data.
*
- * - "Linear-Time Longest-Common-Prefix Computation in Suffix Arrays and Its
- * Applications" (Kasai et al. 2001), for the LCP array computation.
+ * This problem of choosing the truly best match/literal sequence is probably
+ * impossible to solve efficiently when combined with entropy encoding. If we
+ * knew how many bits it takes to output each match/literal, then we could
+ * choose the optimal sequence using shortest-path search a la Dijkstra's
+ * algorithm. However, with entropy encoding, the chosen match/literal sequence
+ * affects its own encoding. Therefore, we can't know how many bits it will
+ * take to actually output any one match or literal until we have actually
+ * chosen the full sequence of matches and literals.
*
- * - "LPF computation revisited" (Crochemore et al. 2009) for the prev and next
- * array computations.
+ * Notwithstanding the entropy encoding problem, we also aren't guaranteed to
+ * choose the optimal match/literal sequence unless the match-finder (see
+ * section "Match-finder") provides the match-chooser with all possible matches
+ * at each position. However, this is not computationally efficient. For
+ * example, there might be many matches of the same length, and usually (but not
+ * always) the best choice is the one with the smallest offset. So in practice,
+ * it's fine to only consider the smallest offset for a given match length at a
+ * given position. (Actually, for LZX, it's also worth considering repeat
+ * offsets.)
*
- * - 7-Zip (author: Igor Pavlov) for the algorithm for forward optimal parsing
- * (match-choosing).
+ * In addition, as mentioned earlier, in LZX we have the choice of using
+ * multiple blocks, each of which resets the Huffman codes. This expands the
+ * search space even further. Therefore, to simplify the problem, we currently
+ * we don't attempt to actually choose the LZX blocks based on the data.
+ * Instead, we just divide the data into fixed-size blocks of LZX_DIV_BLOCK_SIZE
+ * bytes each, and always use verbatim or aligned blocks (never uncompressed).
+ * A previous version of this code recursively split the input data into
+ * equal-sized blocks, up to a maximum depth, and chose the lowest-cost block
+ * divisions. However, this made compression much slower and did not actually
+ * help very much. It remains an open question whether a sufficiently fast and
+ * useful block-splitting algorithm is possible for LZX. Essentially the same
+ * problem also applies to DEFLATE. The Microsoft LZX compressor seemingly does
+ * do block splitting, although I don't know how fast or useful it is,
+ * specifically.
*
- * - zlib (author: Jean-loup Gailly and Mark Adler), for the hash table
- * match-finding algorithm (used in lz77.c).
+ * Now, back to the entropy encoding problem. The "solution" is to use an
+ * iterative approach to compute a good, but not necessarily optimal,
+ * match/literal sequence. Start with a fixed assignment of symbol costs and
+ * choose an "optimal" match/literal sequence based on those costs, using
+ * shortest-path seach a la Dijkstra's algorithm. Then, for each iteration of
+ * the optimization, update the costs based on the entropy encoding of the
+ * current match/literal sequence, then choose a new match/literal sequence
+ * based on the updated costs. Usually, the actual cost to output the current
+ * match/literal sequence will decrease in each iteration until it converges on
+ * a fixed point. This result may not be the truly optimal match/literal
+ * sequence, but it usually is much better than one chosen by doing a "greedy"
+ * parse where we always chooe the longest match.
*
- * - lzx-compress (author: Matthew T. Russotto), on which some parts of this
- * code were originally based.
+ * An alternative to both greedy parsing and iterative, near-optimal parsing is
+ * "lazy" parsing. Briefly, "lazy" parsing considers just the longest match at
+ * each position, but it waits to choose that match until it has also examined
+ * the next position. This is actually a useful approach; it's used by zlib,
+ * for example. Therefore, for fast compression we combine lazy parsing with
+ * the hash chain max-finder. For normal/high compression we combine
+ * near-optimal parsing with the binary tree match-finder.
+ *
+ * Anyway, if you've read through this comment, you hopefully should have a
+ * better idea of why things are done in a certain way in this LZX compressor,
+ * as well as in other compressors for LZ77-based formats (including third-party
+ * ones). In my opinion, the phrase "compression algorithm" is often mis-used
+ * in place of "compression format", since there can be many different
+ * algorithms that all generate compressed data in the same format. The
+ * challenge is to design an algorithm that is efficient but still gives a good
+ * compression ratio.
*/
#ifdef HAVE_CONFIG_H
#include "wimlib/compress_common.h"
#include "wimlib/endianness.h"
#include "wimlib/error.h"
+#include "wimlib/lz.h"
#include "wimlib/lz_hash.h"
-#include "wimlib/lz_sarray.h"
+#include "wimlib/lz_bt.h"
#include "wimlib/lzx.h"
#include "wimlib/util.h"
#include <string.h>
# include "wimlib/decompress_common.h"
#endif
-typedef u32 block_cost_t;
-#define INFINITE_BLOCK_COST (~(block_cost_t)0)
-
#define LZX_OPTIM_ARRAY_SIZE 4096
#define LZX_DIV_BLOCK_SIZE 32768
-#define LZX_MAX_CACHE_PER_POS 10
+#define LZX_CACHE_PER_POS 10
+
+#define LZX_CACHE_LEN (LZX_DIV_BLOCK_SIZE * (LZX_CACHE_PER_POS + 1))
+#define LZX_CACHE_SIZE (LZX_CACHE_LEN * sizeof(struct raw_match))
+
+/* Dependent on behavior of lz_bt_get_matches(). */
+#define LZX_MAX_MATCHES_PER_POS (LZX_MAX_MATCH_LEN - LZX_MIN_MATCH_LEN + 1)
/* Codewords for the LZX main, length, and aligned offset Huffman codes */
struct lzx_codewords {
/* The number of bytes of uncompressed data this block represents. */
input_idx_t block_size;
- /* The position in the 'chosen_matches' array in the `struct
- * lzx_compressor' at which the match/literal specifications for
- * this block begin. */
- input_idx_t chosen_matches_start_pos;
+ /* The match/literal sequence for this block. */
+ struct lzx_match *chosen_matches;
- /* The number of match/literal specifications for this block. */
+ /* The length of the @chosen_matches sequence. */
input_idx_t num_chosen_matches;
/* Huffman codes for this block. */
struct lzx_codes codes;
};
-/* Include template for the match-choosing algorithm. */
-#define LZ_COMPRESSOR struct lzx_compressor
-#define LZ_ADAPTIVE_STATE struct lzx_lru_queue
-struct lzx_compressor;
-#include "wimlib/lz_optimal.h"
-
/* State of the LZX compressor. */
struct lzx_compressor {
/* Fast algorithm only: Array of hash table links. */
input_idx_t *prev_tab;
- /* Slow algorithm only: Suffix array match-finder. */
- struct lz_sarray lz_sarray;
+ /* Slow algorithm only: Binary tree match-finder. */
+ struct lz_bt mf;
/* Position in window of next match to return. */
input_idx_t match_window_pos;
- /* The match-finder shall ensure the length of matches does not exceed
- * this position in the input. */
+ /* The end-of-block position. We can't allow any matches to span this
+ * position. */
input_idx_t match_window_end;
/* Matches found by the match-finder are cached in the following array
* be preferred with different cost models, but seems to be a worthwhile
* speedup. */
struct raw_match *cached_matches;
- unsigned cached_matches_pos;
+ struct raw_match *cache_ptr;
bool matches_cached;
+ struct raw_match *cache_limit;
+
+ /* Match-chooser state.
+ * When matches have been chosen, optimum_cur_idx is set to the position
+ * in the window of the next match/literal to return and optimum_end_idx
+ * is set to the position in the window at the end of the last
+ * match/literal to return. */
+ struct lzx_mc_pos_data *optimum;
+ unsigned optimum_cur_idx;
+ unsigned optimum_end_idx;
+};
- /* Match chooser. */
- struct lz_match_chooser mc;
+/*
+ * Match chooser position data:
+ *
+ * An array of these structures is used during the match-choosing algorithm.
+ * They correspond to consecutive positions in the window and are used to keep
+ * track of the cost to reach each position, and the match/literal choices that
+ * need to be chosen to reach that position.
+ */
+struct lzx_mc_pos_data {
+ /* The approximate minimum cost, in bits, to reach this position in the
+ * window which has been found so far. */
+ u32 cost;
+#define MC_INFINITE_COST ((u32)~0UL)
+
+ /* The union here is just for clarity, since the fields are used in two
+ * slightly different ways. Initially, the @prev structure is filled in
+ * first, and links go from later in the window to earlier in the
+ * window. Later, @next structure is filled in and links go from
+ * earlier in the window to later in the window. */
+ union {
+ struct {
+ /* Position of the start of the match or literal that
+ * was taken to get to this position in the approximate
+ * minimum-cost parse. */
+ input_idx_t link;
+
+ /* Offset (as in an LZ (length, offset) pair) of the
+ * match or literal that was taken to get to this
+ * position in the approximate minimum-cost parse. */
+ input_idx_t match_offset;
+ } prev;
+ struct {
+ /* Position at which the match or literal starting at
+ * this position ends in the minimum-cost parse. */
+ input_idx_t link;
+
+ /* Offset (as in an LZ (length, offset) pair) of the
+ * match or literal starting at this position in the
+ * approximate minimum-cost parse. */
+ input_idx_t match_offset;
+ } next;
+ };
+
+ /* Adaptive state that exists after an approximate minimum-cost path to
+ * reach this position is taken. */
+ struct lzx_lru_queue queue;
};
/* Returns the LZX position slot that corresponds to a given match offset,
* taking into account the recent offset queue and updating it if the offset is
* found in it. */
static unsigned
-lzx_get_position_slot(unsigned offset, struct lzx_lru_queue *queue)
+lzx_get_position_slot(u32 offset, struct lzx_lru_queue *queue)
{
unsigned position_slot;
/* See if the offset was recently used. */
- for (unsigned i = 0; i < LZX_NUM_RECENT_OFFSETS; i++) {
+ for (int i = 0; i < LZX_NUM_RECENT_OFFSETS; i++) {
if (offset == queue->R[i]) {
/* Found it. */
position_slot = lzx_get_position_slot_raw(offset + LZX_OFFSET_OFFSET);
/* Bring the new offset to the front of the queue. */
- for (unsigned i = LZX_NUM_RECENT_OFFSETS - 1; i > 0; i--)
+ for (int i = LZX_NUM_RECENT_OFFSETS - 1; i > 0; i--)
queue->R[i] = queue->R[i - 1];
queue->R[0] = offset;
spec->block_size,
ctx->max_window_size,
ctx->num_main_syms,
- &ctx->chosen_matches[spec->chosen_matches_start_pos],
+ spec->chosen_matches,
spec->num_chosen_matches,
&spec->codes,
prev_codes,
* alphabets. The return value is a 32-bit number that provides the match in an
* intermediate representation documented below. */
static u32
-lzx_tally_match(unsigned match_len, unsigned match_offset,
+lzx_tally_match(unsigned match_len, u32 match_offset,
struct lzx_freqs *freqs, struct lzx_lru_queue *queue)
{
unsigned position_slot;
/* Returns the cost, in bits, to output a literal byte using the specified cost
* model. */
-static unsigned
+static u32
lzx_literal_cost(u8 c, const struct lzx_costs * costs)
{
return costs->main[c];
* codes, return the approximate number of bits it will take to represent this
* match in the compressed output. Take into account the match offset LRU
* queue and optionally update it. */
-static unsigned
-lzx_match_cost(unsigned length, unsigned offset, const struct lzx_costs *costs,
+static u32
+lzx_match_cost(unsigned length, u32 offset, const struct lzx_costs *costs,
struct lzx_lru_queue *queue)
{
unsigned position_slot;
unsigned len_header, main_symbol;
- unsigned cost = 0;
+ unsigned num_extra_bits;
+ u32 cost = 0;
position_slot = lzx_get_position_slot(offset, queue);
cost += costs->main[main_symbol];
/* Account for extra position information. */
- unsigned num_extra_bits = lzx_get_num_extra_bits(position_slot);
+ num_extra_bits = lzx_get_num_extra_bits(position_slot);
if (num_extra_bits >= 3) {
cost += num_extra_bits - 3;
cost += costs->aligned[(offset + LZX_OFFSET_OFFSET) & 7];
}
-/* Fast heuristic cost evaluation to use in the inner loop of the match-finder.
- * Unlike lzx_match_cost() which does a true cost evaluation, this simply
- * prioritize matches based on their offset. */
-static input_idx_t
-lzx_match_cost_fast(input_idx_t length, input_idx_t offset, const void *_queue)
-{
- const struct lzx_lru_queue *queue = _queue;
-
- /* It seems well worth it to take the time to give priority to recently
- * used offsets. */
- for (input_idx_t i = 0; i < LZX_NUM_RECENT_OFFSETS; i++)
- if (offset == queue->R[i])
- return i;
-
- return offset;
-}
-
/* Set the cost model @ctx->costs from the Huffman codeword lengths specified in
* @lens.
*
}
}
-/* Tell the match-finder to skip the specified number of bytes (@n) in the
- * input. */
-static void
-lzx_lz_skip_bytes(struct lzx_compressor *ctx, input_idx_t n)
-{
- LZX_ASSERT(n <= ctx->match_window_end - ctx->match_window_pos);
- if (ctx->matches_cached) {
- ctx->match_window_pos += n;
- while (n--) {
- ctx->cached_matches_pos +=
- ctx->cached_matches[ctx->cached_matches_pos].len + 1;
- }
- } else {
- while (n--) {
- ctx->cached_matches[ctx->cached_matches_pos++].len = 0;
- lz_sarray_skip_position(&ctx->lz_sarray);
- ctx->match_window_pos++;
- }
- LZX_ASSERT(lz_sarray_get_pos(&ctx->lz_sarray) == ctx->match_window_pos);
- }
-}
-
/* Retrieve a list of matches available at the next position in the input.
*
* A pointer to the matches array is written into @matches_ret, and the return
* value is the number of matches found. */
-static u32
-lzx_lz_get_matches_caching(struct lzx_compressor *ctx,
- const struct lzx_lru_queue *queue,
- struct raw_match **matches_ret)
+static unsigned
+lzx_get_matches(struct lzx_compressor *ctx,
+ const struct raw_match **matches_ret)
{
- u32 num_matches;
+ struct raw_match *cache_ptr;
struct raw_match *matches;
+ unsigned num_matches;
- LZX_ASSERT(ctx->match_window_pos <= ctx->match_window_end);
-
- matches = &ctx->cached_matches[ctx->cached_matches_pos + 1];
+ LZX_ASSERT(ctx->match_window_pos < ctx->match_window_end);
+ cache_ptr = ctx->cache_ptr;
+ matches = cache_ptr + 1;
if (ctx->matches_cached) {
- num_matches = matches[-1].len;
+ num_matches = cache_ptr->len;
} else {
- LZX_ASSERT(lz_sarray_get_pos(&ctx->lz_sarray) == ctx->match_window_pos);
- num_matches = lz_sarray_get_matches(&ctx->lz_sarray,
- matches,
- lzx_match_cost_fast,
- queue);
- matches[-1].len = num_matches;
+ num_matches = lz_bt_get_matches(&ctx->mf, matches);
+ cache_ptr->len = num_matches;
}
- ctx->cached_matches_pos += num_matches + 1;
- *matches_ret = matches;
- /* Cap the length of returned matches to the number of bytes remaining,
- * if it is not the whole window. */
- if (ctx->match_window_end < ctx->window_size) {
- unsigned maxlen = ctx->match_window_end - ctx->match_window_pos;
- for (u32 i = 0; i < num_matches; i++)
- if (matches[i].len > maxlen)
- matches[i].len = maxlen;
+ /* Don't allow matches to span the end of an LZX block. */
+ if (ctx->match_window_end < ctx->window_size && num_matches != 0) {
+ unsigned limit = ctx->match_window_end - ctx->match_window_pos;
+
+ if (limit >= LZX_MIN_MATCH_LEN) {
+
+ unsigned i = num_matches - 1;
+ do {
+ if (matches[i].len >= limit) {
+ matches[i].len = limit;
+
+ /* Truncation might produce multiple
+ * matches with length 'limit'. Keep at
+ * most 1. */
+ num_matches = i + 1;
+ }
+ } while (i--);
+ } else {
+ num_matches = 0;
+ }
+ cache_ptr->len = num_matches;
}
+
#if 0
fprintf(stderr, "Pos %u/%u: %u matches\n",
- ctx->match_window_pos, ctx->match_window_end, num_matches);
+ ctx->match_window_pos, ctx->window_size, num_matches);
for (unsigned i = 0; i < num_matches; i++)
fprintf(stderr, "\tLen %u Offset %u\n", matches[i].len, matches[i].offset);
#endif
#ifdef ENABLE_LZX_DEBUG
- for (u32 i = 0; i < num_matches; i++) {
+ for (unsigned i = 0; i < num_matches; i++) {
LZX_ASSERT(matches[i].len >= LZX_MIN_MATCH_LEN);
LZX_ASSERT(matches[i].len <= LZX_MAX_MATCH_LEN);
LZX_ASSERT(matches[i].len <= ctx->match_window_end - ctx->match_window_pos);
LZX_ASSERT(!memcmp(&ctx->window[ctx->match_window_pos],
&ctx->window[ctx->match_window_pos - matches[i].offset],
matches[i].len));
+ if (i) {
+ LZX_ASSERT(matches[i].len > matches[i - 1].len);
+ LZX_ASSERT(matches[i].offset > matches[i - 1].offset);
+ }
}
#endif
-
ctx->match_window_pos++;
+ ctx->cache_ptr = matches + num_matches;
+ *matches_ret = matches;
return num_matches;
}
-static u32
-lzx_get_prev_literal_cost(struct lzx_compressor *ctx,
- struct lzx_lru_queue *queue)
+static void
+lzx_skip_bytes(struct lzx_compressor *ctx, unsigned n)
{
- return lzx_literal_cost(ctx->window[ctx->match_window_pos - 1],
- &ctx->costs);
+ struct raw_match *cache_ptr;
+
+ LZX_ASSERT(n <= ctx->match_window_end - ctx->match_window_pos);
+
+ cache_ptr = ctx->cache_ptr;
+ ctx->match_window_pos += n;
+ if (ctx->matches_cached) {
+ while (n--)
+ cache_ptr += 1 + cache_ptr->len;
+ } else {
+ lz_bt_skip_positions(&ctx->mf, n);
+ while (n--) {
+ cache_ptr->len = 0;
+ cache_ptr += 1;
+ }
+ }
+ ctx->cache_ptr = cache_ptr;
}
-static u32
-lzx_get_match_cost(struct lzx_compressor *ctx,
- struct lzx_lru_queue *queue,
- input_idx_t length, input_idx_t offset)
+/*
+ * Reverse the linked list of near-optimal matches so that they can be returned
+ * in forwards order.
+ *
+ * Returns the first match in the list.
+ */
+static struct raw_match
+lzx_match_chooser_reverse_list(struct lzx_compressor *ctx, unsigned cur_pos)
{
- return lzx_match_cost(length, offset, &ctx->costs, queue);
+ unsigned prev_link, saved_prev_link;
+ unsigned prev_match_offset, saved_prev_match_offset;
+
+ ctx->optimum_end_idx = cur_pos;
+
+ saved_prev_link = ctx->optimum[cur_pos].prev.link;
+ saved_prev_match_offset = ctx->optimum[cur_pos].prev.match_offset;
+
+ do {
+ prev_link = saved_prev_link;
+ prev_match_offset = saved_prev_match_offset;
+
+ saved_prev_link = ctx->optimum[prev_link].prev.link;
+ saved_prev_match_offset = ctx->optimum[prev_link].prev.match_offset;
+
+ ctx->optimum[prev_link].next.link = cur_pos;
+ ctx->optimum[prev_link].next.match_offset = prev_match_offset;
+
+ cur_pos = prev_link;
+ } while (cur_pos != 0);
+
+ ctx->optimum_cur_idx = ctx->optimum[0].next.link;
+
+ return (struct raw_match)
+ { .len = ctx->optimum_cur_idx,
+ .offset = ctx->optimum[0].next.match_offset,
+ };
}
+/*
+ * lzx_get_near_optimal_match() -
+ *
+ * Choose an approximately optimal match or literal to use at the next position
+ * in the string, or "window", being LZ-encoded.
+ *
+ * This is based on algorithms used in 7-Zip, including the DEFLATE encoder
+ * and the LZMA encoder, written by Igor Pavlov.
+ *
+ * Unlike a greedy parser that always takes the longest match, or even a "lazy"
+ * parser with one match/literal look-ahead like zlib, the algorithm used here
+ * may look ahead many matches/literals to determine the approximately optimal
+ * match/literal to code next. The motivation is that the compression ratio is
+ * improved if the compressor can do things like use a shorter-than-possible
+ * match in order to allow a longer match later, and also take into account the
+ * estimated real cost of coding each match/literal based on the underlying
+ * entropy encoding.
+ *
+ * Still, this is not a true optimal parser for several reasons:
+ *
+ * - Real compression formats use entropy encoding of the literal/match
+ * sequence, so the real cost of coding each match or literal is unknown until
+ * the parse is fully determined. It can be approximated based on iterative
+ * parses, but the end result is not guaranteed to be globally optimal.
+ *
+ * - Very long matches are chosen immediately. This is because locations with
+ * long matches are likely to have many possible alternatives that would cause
+ * slow optimal parsing, but also such locations are already highly
+ * compressible so it is not too harmful to just grab the longest match.
+ *
+ * - Not all possible matches at each location are considered because the
+ * underlying match-finder limits the number and type of matches produced at
+ * each position. For example, for a given match length it's usually not
+ * worth it to only consider matches other than the lowest-offset match,
+ * except in the case of a repeat offset.
+ *
+ * - Although we take into account the adaptive state (in LZX, the recent offset
+ * queue), coding decisions made with respect to the adaptive state will be
+ * locally optimal but will not necessarily be globally optimal. This is
+ * because the algorithm only keeps the least-costly path to get to a given
+ * location and does not take into account that a slightly more costly path
+ * could result in a different adaptive state that ultimately results in a
+ * lower global cost.
+ *
+ * - The array space used by this function is bounded, so in degenerate cases it
+ * is forced to start returning matches/literals before the algorithm has
+ * really finished.
+ *
+ * Each call to this function does one of two things:
+ *
+ * 1. Build a sequence of near-optimal matches/literals, up to some point, that
+ * will be returned by subsequent calls to this function, then return the
+ * first one.
+ *
+ * OR
+ *
+ * 2. Return the next match/literal previously computed by a call to this
+ * function.
+ *
+ * The return value is a (length, offset) pair specifying the match or literal
+ * chosen. For literals, the length is 0 or 1 and the offset is meaningless.
+ */
static struct raw_match
-lzx_lz_get_near_optimal_match(struct lzx_compressor *ctx)
+lzx_get_near_optimal_match(struct lzx_compressor *ctx)
{
- return lz_get_near_optimal_match(&ctx->mc,
- lzx_lz_get_matches_caching,
- lzx_lz_skip_bytes,
- lzx_get_prev_literal_cost,
- lzx_get_match_cost,
- ctx,
- &ctx->queue);
+ unsigned num_matches;
+ const struct raw_match *matches;
+ const struct raw_match *matchptr;
+ struct raw_match match;
+ unsigned longest_len;
+ unsigned longest_rep_len;
+ u32 longest_rep_offset;
+ unsigned cur_pos;
+ unsigned end_pos;
+
+ if (ctx->optimum_cur_idx != ctx->optimum_end_idx) {
+ /* Case 2: Return the next match/literal already found. */
+ match.len = ctx->optimum[ctx->optimum_cur_idx].next.link -
+ ctx->optimum_cur_idx;
+ match.offset = ctx->optimum[ctx->optimum_cur_idx].next.match_offset;
+
+ ctx->optimum_cur_idx = ctx->optimum[ctx->optimum_cur_idx].next.link;
+ return match;
+ }
+
+ /* Case 1: Compute a new list of matches/literals to return. */
+
+ ctx->optimum_cur_idx = 0;
+ ctx->optimum_end_idx = 0;
+
+ /* Search for matches at recent offsets. Only keep the one with the
+ * longest match length. */
+ longest_rep_len = LZX_MIN_MATCH_LEN - 1;
+ if (ctx->match_window_pos >= 1) {
+ unsigned limit = min(LZX_MAX_MATCH_LEN,
+ ctx->match_window_end - ctx->match_window_pos);
+ for (int i = 0; i < LZX_NUM_RECENT_OFFSETS; i++) {
+ u32 offset = ctx->queue.R[i];
+ const u8 *strptr = &ctx->window[ctx->match_window_pos];
+ const u8 *matchptr = strptr - offset;
+ unsigned len = 0;
+ while (len < limit && strptr[len] == matchptr[len])
+ len++;
+ if (len > longest_rep_len) {
+ longest_rep_len = len;
+ longest_rep_offset = offset;
+ }
+ }
+ }
+
+ /* If there's a long match with a recent offset, take it. */
+ if (longest_rep_len >= ctx->params.alg_params.slow.nice_match_length) {
+ lzx_skip_bytes(ctx, longest_rep_len);
+ return (struct raw_match) {
+ .len = longest_rep_len,
+ .offset = longest_rep_offset,
+ };
+ }
+
+ /* Search other matches. */
+ num_matches = lzx_get_matches(ctx, &matches);
+
+ /* If there's a long match, take it. */
+ if (num_matches) {
+ longest_len = matches[num_matches - 1].len;
+ if (longest_len >= ctx->params.alg_params.slow.nice_match_length) {
+ lzx_skip_bytes(ctx, longest_len - 1);
+ return matches[num_matches - 1];
+ }
+ } else {
+ longest_len = 1;
+ }
+
+ /* Calculate the cost to reach the next position by coding a literal.
+ */
+ ctx->optimum[1].queue = ctx->queue;
+ ctx->optimum[1].cost = lzx_literal_cost(ctx->window[ctx->match_window_pos - 1],
+ &ctx->costs);
+ ctx->optimum[1].prev.link = 0;
+
+ /* Calculate the cost to reach any position up to and including that
+ * reached by the longest match. */
+ matchptr = matches;
+ for (unsigned len = 2; len <= longest_len; len++) {
+ u32 offset = matchptr->offset;
+
+ ctx->optimum[len].queue = ctx->queue;
+ ctx->optimum[len].prev.link = 0;
+ ctx->optimum[len].prev.match_offset = offset;
+ ctx->optimum[len].cost = lzx_match_cost(len, offset, &ctx->costs,
+ &ctx->optimum[len].queue);
+ if (len == matchptr->len)
+ matchptr++;
+ }
+ end_pos = longest_len;
+
+ if (longest_rep_len >= LZX_MIN_MATCH_LEN) {
+ struct lzx_lru_queue queue;
+ u32 cost;
+
+ while (end_pos < longest_rep_len)
+ ctx->optimum[++end_pos].cost = MC_INFINITE_COST;
+
+ queue = ctx->queue;
+ cost = lzx_match_cost(longest_rep_len, longest_rep_offset,
+ &ctx->costs, &queue);
+ if (cost <= ctx->optimum[longest_rep_len].cost) {
+ ctx->optimum[longest_rep_len].queue = queue;
+ ctx->optimum[longest_rep_len].prev.link = 0;
+ ctx->optimum[longest_rep_len].prev.match_offset = longest_rep_offset;
+ ctx->optimum[longest_rep_len].cost = cost;
+ }
+ }
+
+ /* Step forward, calculating the estimated minimum cost to reach each
+ * position. The algorithm may find multiple paths to reach each
+ * position; only the lowest-cost path is saved.
+ *
+ * The progress of the parse is tracked in the @ctx->optimum array, which
+ * for each position contains the minimum cost to reach that position,
+ * the index of the start of the match/literal taken to reach that
+ * position through the minimum-cost path, the offset of the match taken
+ * (not relevant for literals), and the adaptive state that will exist
+ * at that position after the minimum-cost path is taken. The @cur_pos
+ * variable stores the position at which the algorithm is currently
+ * considering coding choices, and the @end_pos variable stores the
+ * greatest position at which the costs of coding choices have been
+ * saved. (Actually, the algorithm guarantees that all positions up to
+ * and including @end_pos are reachable by at least one path.)
+ *
+ * The loop terminates when any one of the following conditions occurs:
+ *
+ * 1. A match with length greater than or equal to @nice_match_length is
+ * found. When this occurs, the algorithm chooses this match
+ * unconditionally, and consequently the near-optimal match/literal
+ * sequence up to and including that match is fully determined and it
+ * can begin returning the match/literal list.
+ *
+ * 2. @cur_pos reaches a position not overlapped by a preceding match.
+ * In such cases, the near-optimal match/literal sequence up to
+ * @cur_pos is fully determined and it can begin returning the
+ * match/literal list.
+ *
+ * 3. Failing either of the above in a degenerate case, the loop
+ * terminates when space in the @ctx->optimum array is exhausted.
+ * This terminates the algorithm and forces it to start returning
+ * matches/literals even though they may not be globally optimal.
+ *
+ * Upon loop termination, a nonempty list of matches/literals will have
+ * been produced and stored in the @optimum array. These
+ * matches/literals are linked in reverse order, so the last thing this
+ * function does is reverse this list and return the first
+ * match/literal, leaving the rest to be returned immediately by
+ * subsequent calls to this function.
+ */
+ cur_pos = 0;
+ for (;;) {
+ u32 cost;
+
+ /* Advance to next position. */
+ cur_pos++;
+
+ /* Check termination conditions (2) and (3) noted above. */
+ if (cur_pos == end_pos || cur_pos == LZX_OPTIM_ARRAY_SIZE)
+ return lzx_match_chooser_reverse_list(ctx, cur_pos);
+
+ /* Search for matches at recent offsets. */
+ longest_rep_len = LZX_MIN_MATCH_LEN - 1;
+ unsigned limit = min(LZX_MAX_MATCH_LEN,
+ ctx->match_window_end - ctx->match_window_pos);
+ for (int i = 0; i < LZX_NUM_RECENT_OFFSETS; i++) {
+ u32 offset = ctx->optimum[cur_pos].queue.R[i];
+ const u8 *strptr = &ctx->window[ctx->match_window_pos];
+ const u8 *matchptr = strptr - offset;
+ unsigned len = 0;
+ while (len < limit && strptr[len] == matchptr[len])
+ len++;
+ if (len > longest_rep_len) {
+ longest_rep_len = len;
+ longest_rep_offset = offset;
+ }
+ }
+
+ /* If we found a long match at a recent offset, choose it
+ * immediately. */
+ if (longest_rep_len >= ctx->params.alg_params.slow.nice_match_length) {
+ /* Build the list of matches to return and get
+ * the first one. */
+ match = lzx_match_chooser_reverse_list(ctx, cur_pos);
+
+ /* Append the long match to the end of the list. */
+ ctx->optimum[cur_pos].next.match_offset = longest_rep_offset;
+ ctx->optimum[cur_pos].next.link = cur_pos + longest_rep_len;
+ ctx->optimum_end_idx = cur_pos + longest_rep_len;
+
+ /* Skip over the remaining bytes of the long match. */
+ lzx_skip_bytes(ctx, longest_rep_len);
+
+ /* Return first match in the list. */
+ return match;
+ }
+
+ /* Search other matches. */
+ num_matches = lzx_get_matches(ctx, &matches);
+
+ /* If there's a long match, take it. */
+ if (num_matches) {
+ longest_len = matches[num_matches - 1].len;
+ if (longest_len >= ctx->params.alg_params.slow.nice_match_length) {
+ /* Build the list of matches to return and get
+ * the first one. */
+ match = lzx_match_chooser_reverse_list(ctx, cur_pos);
+
+ /* Append the long match to the end of the list. */
+ ctx->optimum[cur_pos].next.match_offset =
+ matches[num_matches - 1].offset;
+ ctx->optimum[cur_pos].next.link = cur_pos + longest_len;
+ ctx->optimum_end_idx = cur_pos + longest_len;
+
+ /* Skip over the remaining bytes of the long match. */
+ lzx_skip_bytes(ctx, longest_len - 1);
+
+ /* Return first match in the list. */
+ return match;
+ }
+ } else {
+ longest_len = 1;
+ }
+
+ while (end_pos < cur_pos + longest_len)
+ ctx->optimum[++end_pos].cost = MC_INFINITE_COST;
+
+ /* Consider coding a literal. */
+ cost = ctx->optimum[cur_pos].cost +
+ lzx_literal_cost(ctx->window[ctx->match_window_pos - 1],
+ &ctx->costs);
+ if (cost < ctx->optimum[cur_pos + 1].cost) {
+ ctx->optimum[cur_pos + 1].queue = ctx->optimum[cur_pos].queue;
+ ctx->optimum[cur_pos + 1].cost = cost;
+ ctx->optimum[cur_pos + 1].prev.link = cur_pos;
+ }
+
+ /* Consider coding a match. */
+ matchptr = matches;
+ for (unsigned len = 2; len <= longest_len; len++) {
+ u32 offset;
+ struct lzx_lru_queue queue;
+
+ offset = matchptr->offset;
+ queue = ctx->optimum[cur_pos].queue;
+
+ cost = ctx->optimum[cur_pos].cost +
+ lzx_match_cost(len, offset, &ctx->costs, &queue);
+ if (cost < ctx->optimum[cur_pos + len].cost) {
+ ctx->optimum[cur_pos + len].queue = queue;
+ ctx->optimum[cur_pos + len].prev.link = cur_pos;
+ ctx->optimum[cur_pos + len].prev.match_offset = offset;
+ ctx->optimum[cur_pos + len].cost = cost;
+ }
+ if (len == matchptr->len)
+ matchptr++;
+ }
+
+ if (longest_rep_len >= LZX_MIN_MATCH_LEN) {
+ struct lzx_lru_queue queue;
+
+ while (end_pos < cur_pos + longest_rep_len)
+ ctx->optimum[++end_pos].cost = MC_INFINITE_COST;
+
+ queue = ctx->optimum[cur_pos].queue;
+
+ cost = ctx->optimum[cur_pos].cost +
+ lzx_match_cost(longest_rep_len, longest_rep_offset,
+ &ctx->costs, &queue);
+ if (cost <= ctx->optimum[cur_pos + longest_rep_len].cost) {
+ ctx->optimum[cur_pos + longest_rep_len].queue =
+ queue;
+ ctx->optimum[cur_pos + longest_rep_len].prev.link =
+ cur_pos;
+ ctx->optimum[cur_pos + longest_rep_len].prev.match_offset =
+ longest_rep_offset;
+ ctx->optimum[cur_pos + longest_rep_len].cost =
+ cost;
+ }
+ }
+ }
}
/* Set default symbol costs for the LZX Huffman codes. */
unsigned num_passes)
{
const struct lzx_lru_queue orig_queue = ctx->queue;
- struct lzx_freqs freqs;
-
- unsigned orig_window_pos = spec->window_pos;
- unsigned orig_cached_pos = ctx->cached_matches_pos;
unsigned num_passes_remaining = num_passes;
+ struct lzx_freqs freqs;
- LZX_ASSERT(ctx->match_window_pos == spec->window_pos);
+ LZX_ASSERT(num_passes >= 1);
+ LZX_ASSERT(lz_bt_get_position(&ctx->mf) == spec->window_pos);
ctx->match_window_end = spec->window_pos + spec->block_size;
- spec->chosen_matches_start_pos = spec->window_pos;
-
- LZX_ASSERT(num_passes >= 1);
+ spec->chosen_matches = &ctx->chosen_matches[spec->window_pos];
+ ctx->matches_cached = false;
/* The first optimal parsing pass is done using the cost model already
* set in ctx->costs. Each later pass is done using a cost model
* computed from the previous pass. */
do {
- --num_passes_remaining;
+ const u8 *window_ptr;
+ const u8 *window_end;
+ struct lzx_match *next_chosen_match;
- ctx->match_window_pos = orig_window_pos;
- ctx->cached_matches_pos = orig_cached_pos;
- ctx->queue = orig_queue;
- spec->num_chosen_matches = 0;
+ --num_passes_remaining;
+ ctx->match_window_pos = spec->window_pos;
+ ctx->cache_ptr = ctx->cached_matches;
memset(&freqs, 0, sizeof(freqs));
-
- const u8 *window_ptr = &ctx->window[spec->window_pos];
- const u8 *window_end = &window_ptr[spec->block_size];
- struct lzx_match *next_chosen_match =
- &ctx->chosen_matches[spec->chosen_matches_start_pos];
+ window_ptr = &ctx->window[spec->window_pos];
+ window_end = window_ptr + spec->block_size;
+ next_chosen_match = spec->chosen_matches;
while (window_ptr != window_end) {
struct raw_match raw_match;
struct lzx_match lzx_match;
- raw_match = lzx_lz_get_near_optimal_match(ctx);
+ raw_match = lzx_get_near_optimal_match(ctx);
+
+ LZX_ASSERT(!(raw_match.len == LZX_MIN_MATCH_LEN &&
+ raw_match.offset == ctx->max_window_size -
+ LZX_MIN_MATCH_LEN));
if (raw_match.len >= LZX_MIN_MATCH_LEN) {
- if (unlikely(raw_match.len == LZX_MIN_MATCH_LEN &&
- raw_match.offset == ctx->max_window_size -
- LZX_MIN_MATCH_LEN))
- {
- /* Degenerate case where the parser
- * generated the minimum match length
- * with the maximum offset. There
- * aren't actually enough position slots
- * to represent this offset, as noted in
- * the comments in
- * lzx_get_num_main_syms(), so we cannot
- * allow it. Use literals instead.
- *
- * Note that this case only occurs if
- * the match-finder can generate matches
- * to the very start of the window. The
- * suffix array match-finder can,
- * although typical hash chain and
- * binary tree match-finders use 0 as a
- * null value and therefore cannot
- * generate such matches. */
- BUILD_BUG_ON(LZX_MIN_MATCH_LEN != 2);
- lzx_match.data = lzx_tally_literal(*window_ptr++,
- &freqs);
- *next_chosen_match++ = lzx_match;
- lzx_match.data = lzx_tally_literal(*window_ptr++,
- &freqs);
- } else {
- lzx_match.data = lzx_tally_match(raw_match.len,
- raw_match.offset,
- &freqs,
- &ctx->queue);
- window_ptr += raw_match.len;
- }
+ lzx_match.data = lzx_tally_match(raw_match.len,
+ raw_match.offset,
+ &freqs,
+ &ctx->queue);
+ window_ptr += raw_match.len;
} else {
- lzx_match.data = lzx_tally_literal(*window_ptr++, &freqs);
+ lzx_match.data = lzx_tally_literal(*window_ptr,
+ &freqs);
+ window_ptr += 1;
}
*next_chosen_match++ = lzx_match;
}
- spec->num_chosen_matches = next_chosen_match -
- &ctx->chosen_matches[spec->chosen_matches_start_pos];
-
- lzx_make_huffman_codes(&freqs, &spec->codes,
- ctx->num_main_syms);
- if (num_passes_remaining)
+ spec->num_chosen_matches = next_chosen_match - spec->chosen_matches;
+ lzx_make_huffman_codes(&freqs, &spec->codes, ctx->num_main_syms);
+ if (num_passes_remaining) {
lzx_set_costs(ctx, &spec->codes.lens);
- ctx->matches_cached = true;
+ ctx->queue = orig_queue;
+ ctx->matches_cached = true;
+ }
} while (num_passes_remaining);
spec->block_type = lzx_choose_verbatim_or_aligned(&freqs, &spec->codes);
- ctx->matches_cached = false;
-}
-
-static void
-lzx_optimize_blocks(struct lzx_compressor *ctx)
-{
- lzx_lru_queue_init(&ctx->queue);
- lz_match_chooser_begin(&ctx->mc);
-
- const unsigned num_passes = ctx->params.alg_params.slow.num_optim_passes;
-
- for (unsigned i = 0; i < ctx->num_blocks; i++)
- lzx_optimize_block(ctx, &ctx->block_specs[i], num_passes);
}
/* Prepare the input window into one or more LZX blocks ready to be output. */
static void
lzx_prepare_blocks(struct lzx_compressor * ctx)
{
- /* Initialize the match-finder. */
- lz_sarray_load_window(&ctx->lz_sarray, ctx->window, ctx->window_size);
- ctx->cached_matches_pos = 0;
- ctx->matches_cached = false;
- ctx->match_window_pos = 0;
-
/* Set up a default cost model. */
lzx_set_default_costs(&ctx->costs, ctx->num_main_syms);
- /* TODO: The compression ratio could be slightly improved by performing
+ /* Set up the block specifications.
+ * TODO: The compression ratio could be slightly improved by performing
* data-dependent block splitting instead of using fixed-size blocks.
* Doing so well is a computationally hard problem, however. */
ctx->num_blocks = DIV_ROUND_UP(ctx->window_size, LZX_DIV_BLOCK_SIZE);
for (unsigned i = 0; i < ctx->num_blocks; i++) {
unsigned pos = LZX_DIV_BLOCK_SIZE * i;
ctx->block_specs[i].window_pos = pos;
- ctx->block_specs[i].block_size = min(ctx->window_size - pos, LZX_DIV_BLOCK_SIZE);
+ ctx->block_specs[i].block_size = min(ctx->window_size - pos,
+ LZX_DIV_BLOCK_SIZE);
}
+ /* Load the window into the match-finder. */
+ lz_bt_load_window(&ctx->mf, ctx->window, ctx->window_size);
+
/* Determine sequence of matches/literals to output for each block. */
- lzx_optimize_blocks(ctx);
+ lzx_lru_queue_init(&ctx->queue);
+ ctx->optimum_cur_idx = 0;
+ ctx->optimum_end_idx = 0;
+ for (unsigned i = 0; i < ctx->num_blocks; i++) {
+ lzx_optimize_block(ctx, &ctx->block_specs[i],
+ ctx->params.alg_params.slow.num_optim_passes);
+ }
}
/*
spec->window_pos = 0;
spec->block_size = ctx->window_size;
spec->num_chosen_matches = (record_ctx.matches - ctx->chosen_matches);
- spec->chosen_matches_start_pos = 0;
+ spec->chosen_matches = ctx->chosen_matches;
lzx_make_huffman_codes(&record_ctx.freqs, &spec->codes,
ctx->num_main_syms);
ctx->num_blocks = 1;
if (ctx) {
FREE(ctx->chosen_matches);
FREE(ctx->cached_matches);
- lz_match_chooser_destroy(&ctx->mc);
- lz_sarray_destroy(&ctx->lz_sarray);
+ FREE(ctx->optimum);
+ lz_bt_destroy(&ctx->mf);
FREE(ctx->block_specs);
FREE(ctx->prev_tab);
FREE(ctx->window);
.nice_match_length = 32,
.num_optim_passes = 2,
.max_search_depth = 50,
- .max_matches_per_pos = 3,
.main_nostat_cost = 15,
.len_nostat_cost = 15,
.aligned_nostat_cost = 7,
if (!params->alg_params.slow.use_len2_matches)
min_match_len = max(min_match_len, 3);
- if (!lz_sarray_init(&ctx->lz_sarray,
- window_size,
- min_match_len,
- LZX_MAX_MATCH_LEN,
- params->alg_params.slow.max_search_depth,
- params->alg_params.slow.max_matches_per_pos))
+ if (!lz_bt_init(&ctx->mf,
+ window_size,
+ min_match_len,
+ LZX_MAX_MATCH_LEN,
+ params->alg_params.slow.nice_match_length,
+ params->alg_params.slow.max_search_depth))
goto oom;
}
if (params->algorithm == WIMLIB_LZX_ALGORITHM_SLOW) {
- if (!lz_match_chooser_init(&ctx->mc,
- LZX_OPTIM_ARRAY_SIZE,
- params->alg_params.slow.nice_match_length,
- LZX_MAX_MATCH_LEN))
+ ctx->optimum = MALLOC((LZX_OPTIM_ARRAY_SIZE +
+ min(params->alg_params.slow.nice_match_length,
+ LZX_MAX_MATCH_LEN)) *
+ sizeof(ctx->optimum[0]));
+ if (!ctx->optimum)
goto oom;
}
if (params->algorithm == WIMLIB_LZX_ALGORITHM_SLOW) {
- u32 cache_per_pos;
-
- cache_per_pos = params->alg_params.slow.max_matches_per_pos;
- if (cache_per_pos > LZX_MAX_CACHE_PER_POS)
- cache_per_pos = LZX_MAX_CACHE_PER_POS;
-
- ctx->cached_matches = MALLOC(window_size * (cache_per_pos + 1) *
- sizeof(ctx->cached_matches[0]));
+ ctx->cached_matches = MALLOC(LZX_CACHE_SIZE);
if (ctx->cached_matches == NULL)
goto oom;
+ ctx->cache_limit = ctx->cached_matches +
+ LZX_CACHE_LEN - (LZX_MAX_MATCHES_PER_POS + 1);
}
ctx->chosen_matches = MALLOC(window_size * sizeof(ctx->chosen_matches[0]));
if (params->algorithm == WIMLIB_LZX_ALGORITHM_SLOW) {
size += max_block_size * sizeof(((struct lzx_compressor*)0)->chosen_matches[0]);
- size += lz_sarray_get_needed_memory(max_block_size);
- size += lz_match_chooser_get_needed_memory(LZX_OPTIM_ARRAY_SIZE,
- params->alg_params.slow.nice_match_length,
- LZX_MAX_MATCH_LEN);
- u32 cache_per_pos;
-
- cache_per_pos = params->alg_params.slow.max_matches_per_pos;
- if (cache_per_pos > LZX_MAX_CACHE_PER_POS)
- cache_per_pos = LZX_MAX_CACHE_PER_POS;
-
- size += max_block_size * (cache_per_pos + 1) *
- sizeof(((struct lzx_compressor*)0)->cached_matches[0]);
+ size += lz_bt_get_needed_memory(max_block_size);
+ size += (LZX_OPTIM_ARRAY_SIZE +
+ min(params->alg_params.slow.nice_match_length,
+ LZX_MAX_MATCH_LEN)) *
+ sizeof(((struct lzx_compressor *)0)->optimum[0]);
+ size += LZX_CACHE_SIZE;
} else {
size += max_block_size * sizeof(((struct lzx_compressor*)0)->prev_tab[0]);
}
wim_default_pack_chunk_size(int ctype) {
switch (ctype) {
case WIMLIB_COMPRESSION_TYPE_LZMS:
- /* Note: WIMGAPI uses 1 << 26, but lower sizes are compatible.
- * */
- return 1U << 25; /* 33554432 */
+ return 1U << 26; /* 67108864 */
default:
return 1U << 15; /* 32768 */
}
git://wimlib.net / wimlib / commitdiff