/*
* lzms-compress.c
*
- * A compressor for the LZMS compression format.
+ * A compressor that produces output compatible with the LZMS compression format.
*/
/*
- * 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 file is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at your option) any
+ * later version.
*
- * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free
- * Software Foundation; either version 3 of the License, or (at your option)
- * any later version.
- *
- * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- * A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * This file is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*
- * You should have received a copy of the GNU General Public License
- * along with wimlib; if not, see http://www.gnu.org/licenses/.
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this file; if not, see http://www.gnu.org/licenses/.
*/
-/* This a compressor for the LZMS compression format. More details about this
- * format can be found in lzms-decompress.c. */
-
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
-#include "wimlib.h"
-#include "wimlib/assert.h"
-#include "wimlib/compressor_ops.h"
#include "wimlib/compress_common.h"
+#include "wimlib/compressor_ops.h"
+#include "wimlib/endianness.h"
#include "wimlib/error.h"
+#include "wimlib/lz_mf.h"
+#include "wimlib/lz_repsearch.h"
#include "wimlib/lzms.h"
#include "wimlib/util.h"
#include <string.h>
+#include <limits.h>
+#include <pthread.h>
+
+/* Stucture used for writing raw bits as a series of 16-bit little endian coding
+ * units. This starts at the *end* of the compressed data buffer and proceeds
+ * backwards. */
+struct lzms_output_bitstream {
+
+ /* Bits that haven't yet been written to the output buffer. */
+ u64 bitbuf;
+
+ /* Number of bits currently held in @bitbuf. */
+ unsigned bitcount;
+
+ /* Pointer to one past the next position in the compressed data buffer
+ * at which to output a 16-bit coding unit. */
+ le16 *next;
+
+ /* Pointer to the beginning of the output buffer. (The "end" when
+ * writing backwards!) */
+ le16 *begin;
+};
+
+/* Stucture used for range encoding (raw version). This starts at the
+ * *beginning* of the compressed data buffer and proceeds forward. */
+struct lzms_range_encoder_raw {
+
+ /* A 33-bit variable that holds the low boundary of the current range.
+ * The 33rd bit is needed to catch carries. */
+ u64 low;
+
+ /* Size of the current range. */
+ u32 range;
+
+ /* Next 16-bit coding unit to output. */
+ u16 cache;
+
+ /* Number of 16-bit coding units whose output has been delayed due to
+ * possible carrying. The first such coding unit is @cache; all
+ * subsequent such coding units are 0xffff. */
+ u32 cache_size;
+
+ /* Pointer to the beginning of the output buffer. */
+ le16 *begin;
+
+ /* Pointer to the position in the output buffer at which the next coding
+ * unit must be written. */
+ le16 *next;
+
+ /* Pointer just past the end of the output buffer. */
+ le16 *end;
+};
+
+/* Structure used for range encoding. This wraps around `struct
+ * lzms_range_encoder_raw' to use and maintain probability entries. */
+struct lzms_range_encoder {
+
+ /* Pointer to the raw range encoder, which has no persistent knowledge
+ * of probabilities. Multiple lzms_range_encoder's share the same
+ * lzms_range_encoder_raw. */
+ struct lzms_range_encoder_raw *rc;
+
+ /* Bits recently encoded by this range encoder. This is used as an
+ * index into @prob_entries. */
+ u32 state;
+
+ /* Bitmask for @state to prevent its value from exceeding the number of
+ * probability entries. */
+ u32 mask;
+
+ /* Probability entries being used for this range encoder. */
+ struct lzms_probability_entry prob_entries[LZMS_MAX_NUM_STATES];
+};
+
+/* Structure used for Huffman encoding. */
+struct lzms_huffman_encoder {
+
+ /* Bitstream to write Huffman-encoded symbols and verbatim bits to.
+ * Multiple lzms_huffman_encoder's share the same lzms_output_bitstream.
+ */
+ struct lzms_output_bitstream *os;
+ /* Number of symbols that have been written using this code far. Reset
+ * to 0 whenever the code is rebuilt. */
+ u32 num_syms_written;
+
+ /* When @num_syms_written reaches this number, the Huffman code must be
+ * rebuilt. */
+ u32 rebuild_freq;
+
+ /* Number of symbols in the represented Huffman code. */
+ unsigned num_syms;
+
+ /* Running totals of symbol frequencies. These are diluted slightly
+ * whenever the code is rebuilt. */
+ u32 sym_freqs[LZMS_MAX_NUM_SYMS];
+
+ /* The length, in bits, of each symbol in the Huffman code. */
+ u8 lens[LZMS_MAX_NUM_SYMS];
+
+ /* The codeword of each symbol in the Huffman code. */
+ u32 codewords[LZMS_MAX_NUM_SYMS];
+};
+
+/* Internal compression parameters */
+struct lzms_compressor_params {
+ u32 min_match_length;
+ u32 nice_match_length;
+ u32 max_search_depth;
+ u32 optim_array_length;
+};
+
+/* State of the LZMS compressor */
struct lzms_compressor {
- u8 *window;
- u32 window_size;
- u32 max_block_size;
- s32 *last_target_usages;
+ /* Internal compression parameters */
+ struct lzms_compressor_params params;
+
+ /* Data currently being compressed */
+ u8 *cur_window;
+ u32 cur_window_size;
+
+ /* Lempel-Ziv match-finder */
+ struct lz_mf *mf;
+
+ /* Temporary space to store found matches */
+ struct lz_match *matches;
+
+ /* Per-position data for near-optimal parsing */
+ struct lzms_mc_pos_data *optimum;
+ struct lzms_mc_pos_data *optimum_end;
+
+ /* Raw range encoder which outputs to the beginning of the compressed
+ * data buffer, proceeding forwards */
+ struct lzms_range_encoder_raw rc;
+
+ /* Bitstream which outputs to the end of the compressed data buffer,
+ * proceeding backwards */
+ struct lzms_output_bitstream os;
+
+ /* Range encoders */
+ struct lzms_range_encoder main_range_encoder;
+ struct lzms_range_encoder match_range_encoder;
+ struct lzms_range_encoder lz_match_range_encoder;
+ struct lzms_range_encoder lz_repeat_match_range_encoders[LZMS_NUM_RECENT_OFFSETS - 1];
+ struct lzms_range_encoder delta_match_range_encoder;
+ struct lzms_range_encoder delta_repeat_match_range_encoders[LZMS_NUM_RECENT_OFFSETS - 1];
+
+ /* Huffman encoders */
+ struct lzms_huffman_encoder literal_encoder;
+ struct lzms_huffman_encoder lz_offset_encoder;
+ struct lzms_huffman_encoder length_encoder;
+ struct lzms_huffman_encoder delta_power_encoder;
+ struct lzms_huffman_encoder delta_offset_encoder;
+
+ /* Used for preprocessing */
+ s32 last_target_usages[65536];
+
+#define LZMS_NUM_FAST_LENGTHS 256
+ /* Table: length => length slot for small lengths */
+ u8 length_slot_fast[LZMS_NUM_FAST_LENGTHS];
+
+ /* Table: length => current cost for small match lengths */
+ u32 length_cost_fast[LZMS_NUM_FAST_LENGTHS];
+
+#define LZMS_NUM_FAST_OFFSETS 32768
+ /* Table: offset => offset slot for small offsets */
+ u8 offset_slot_fast[LZMS_NUM_FAST_OFFSETS];
+};
+
+/*
+ * Match chooser position data:
+ *
+ * An array of these structures is used during the near-optimal 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 lzms_mc_pos_data {
+
+ /* The cost, in bits, of the lowest-cost path that has been found to
+ * reach this position. This can change as progressively lower cost
+ * paths are found to reach this position. */
+ u32 cost;
+#define MC_INFINITE_COST UINT32_MAX
+
+ /* The match or literal that was taken to reach this position. This can
+ * change as progressively lower cost paths are found to reach this
+ * position.
+ *
+ * This variable is divided into two bitfields.
+ *
+ * Literals:
+ * Low bits are 1, high bits are the literal.
+ *
+ * Explicit offset matches:
+ * Low bits are the match length, high bits are the offset plus 2.
+ *
+ * Repeat offset matches:
+ * Low bits are the match length, high bits are the queue index.
+ */
+ u64 mc_item_data;
+#define MC_OFFSET_SHIFT 32
+#define MC_LEN_MASK (((u64)1 << MC_OFFSET_SHIFT) - 1)
+
+ /* The LZMS adaptive state that exists at this position. This is filled
+ * in lazily, only after the minimum-cost path to this position is
+ * found.
+ *
+ * Note: the way we handle this adaptive state in the "minimum-cost"
+ * parse is actually only an approximation. It's possible for the
+ * globally optimal, minimum cost path to contain a prefix, ending at a
+ * position, where that path prefix is *not* the minimum cost path to
+ * that position. This can happen if such a path prefix results in a
+ * different adaptive state which results in lower costs later. We do
+ * not solve this problem; we only consider the lowest cost to reach
+ * each position, which seems to be an acceptable approximation.
+ *
+ * Note: this adaptive state also does not include the probability
+ * entries or current Huffman codewords. Those aren't maintained
+ * per-position and are only updated occassionally. */
+ 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;
};
static void
-lzms_preprocess_data(u8 *data, s32 size, s32 *last_target_usages)
+lzms_init_fast_slots(struct lzms_compressor *c)
{
- for (s32 i = 0; i < size - 11; i++) {
+ /* Create table mapping small lengths to length slots. */
+ for (unsigned slot = 0, i = 0; i < LZMS_NUM_FAST_LENGTHS; i++) {
+ while (i >= lzms_length_slot_base[slot + 1])
+ slot++;
+ c->length_slot_fast[i] = slot;
+ }
+
+ /* Create table mapping small offsets to offset slots. */
+ for (unsigned slot = 0, i = 0; i < LZMS_NUM_FAST_OFFSETS; i++) {
+ while (i >= lzms_offset_slot_base[slot + 1])
+ slot++;
+ c->offset_slot_fast[i] = slot;
}
}
-static size_t
-lzms_compress(const void *uncompressed_data, size_t uncompressed_size,
- void *compressed_data, size_t compressed_size_avail, void *_ctx)
+static inline unsigned
+lzms_get_length_slot_fast(const struct lzms_compressor *c, u32 length)
{
- struct lzms_compressor *ctx = _ctx;
+ if (likely(length < LZMS_NUM_FAST_LENGTHS))
+ return c->length_slot_fast[length];
+ else
+ return lzms_get_length_slot(length);
+}
- if (uncompressed_size > ctx->max_block_size) {
- LZMS_DEBUG("Can't compress %su bytes: LZMS context "
- "only supports %u bytes",
- uncompressed_size, ctx->max_block_size);
- return 0;
+static inline unsigned
+lzms_get_offset_slot_fast(const struct lzms_compressor *c, u32 offset)
+{
+ if (offset < LZMS_NUM_FAST_OFFSETS)
+ return c->offset_slot_fast[offset];
+ else
+ return lzms_get_offset_slot(offset);
+}
+
+/* Initialize the output bitstream @os to write backwards to the specified
+ * compressed data buffer @out that is @out_limit 16-bit integers long. */
+static void
+lzms_output_bitstream_init(struct lzms_output_bitstream *os,
+ le16 *out, size_t out_limit)
+{
+ os->bitbuf = 0;
+ os->bitcount = 0;
+ os->next = out + out_limit;
+ os->begin = out;
+}
+
+/*
+ * Write some bits, contained in the low @num_bits bits of @bits (ordered from
+ * high-order to low-order), to the output bitstream @os.
+ *
+ * @max_num_bits is a compile-time constant that specifies the maximum number of
+ * bits that can ever be written at this call site.
+ */
+static inline void
+lzms_output_bitstream_put_varbits(struct lzms_output_bitstream *os,
+ u32 bits, unsigned num_bits,
+ unsigned max_num_bits)
+{
+ LZMS_ASSERT(num_bits <= 48);
+
+ /* Add the bits to the bit buffer variable. */
+ os->bitcount += num_bits;
+ os->bitbuf = (os->bitbuf << num_bits) | bits;
+
+ /* Check whether any coding units need to be written. */
+ while (os->bitcount >= 16) {
+
+ os->bitcount -= 16;
+
+ /* Write a coding unit, unless it would underflow the buffer. */
+ if (os->next != os->begin)
+ *--os->next = cpu_to_le16(os->bitbuf >> os->bitcount);
+
+ /* Optimization for call sites that never write more than 16
+ * bits at once. */
+ if (max_num_bits <= 16)
+ break;
}
+}
- memcpy(ctx->window, uncompressed_data, uncompressed_size);
- ctx->window_size = uncompressed_size;
+/* Flush the output bitstream, ensuring that all bits written to it have been
+ * written to memory. Returns %true if all bits have been output successfully,
+ * or %false if an overrun occurred. */
+static bool
+lzms_output_bitstream_flush(struct lzms_output_bitstream *os)
+{
+ if (os->next == os->begin)
+ return false;
- lzms_preprocess_data(ctx->window, ctx->window_size,
- ctx->last_target_usages);
+ if (os->bitcount != 0)
+ *--os->next = cpu_to_le16(os->bitbuf << (16 - os->bitcount));
- return 0;
+ return true;
+}
+
+/* Initialize the range encoder @rc to write forwards to the specified
+ * compressed data buffer @out that is @out_limit 16-bit integers long. */
+static void
+lzms_range_encoder_raw_init(struct lzms_range_encoder_raw *rc,
+ le16 *out, size_t out_limit)
+{
+ rc->low = 0;
+ rc->range = 0xffffffff;
+ rc->cache = 0;
+ rc->cache_size = 1;
+ rc->begin = out;
+ rc->next = out - 1;
+ rc->end = out + out_limit;
+}
+
+/*
+ * Attempt to flush bits from the range encoder.
+ *
+ * Note: this is based on the public domain code for LZMA written by Igor
+ * Pavlov. The only differences in this function are that in LZMS the bits must
+ * be output in 16-bit coding units instead of 8-bit coding units, and that in
+ * LZMS the first coding unit is not ignored by the decompressor, so the encoder
+ * cannot output a dummy value to that position.
+ *
+ * The basic idea is that we're writing bits from @rc->low to the output.
+ * However, due to carrying, the writing of coding units with value 0xffff, as
+ * well as one prior coding unit, must be delayed until it is determined whether
+ * a carry is needed.
+ */
+static void
+lzms_range_encoder_raw_shift_low(struct lzms_range_encoder_raw *rc)
+{
+ if ((u32)(rc->low) < 0xffff0000 ||
+ (u32)(rc->low >> 32) != 0)
+ {
+ /* Carry not needed (rc->low < 0xffff0000), or carry occurred
+ * ((rc->low >> 32) != 0, a.k.a. the carry bit is 1). */
+ do {
+ if (likely(rc->next >= rc->begin)) {
+ if (rc->next != rc->end)
+ *rc->next++ = cpu_to_le16(rc->cache +
+ (u16)(rc->low >> 32));
+ } else {
+ rc->next++;
+ }
+ rc->cache = 0xffff;
+ } while (--rc->cache_size != 0);
+
+ rc->cache = (rc->low >> 16) & 0xffff;
+ }
+ ++rc->cache_size;
+ rc->low = (rc->low & 0xffff) << 16;
}
static void
-lzms_free_compressor(void *_ctx)
+lzms_range_encoder_raw_normalize(struct lzms_range_encoder_raw *rc)
{
- struct lzms_compressor *ctx = _ctx;
+ if (rc->range <= 0xffff) {
+ rc->range <<= 16;
+ lzms_range_encoder_raw_shift_low(rc);
+ }
+}
+
+static bool
+lzms_range_encoder_raw_flush(struct lzms_range_encoder_raw *rc)
+{
+ for (unsigned i = 0; i < 4; i++)
+ lzms_range_encoder_raw_shift_low(rc);
+ return rc->next != rc->end;
+}
- if (ctx) {
- FREE(ctx->window);
- FREE(ctx->last_target_usages);
- FREE(ctx);
+/* Encode the next bit using the range encoder (raw version).
+ *
+ * @prob is the chance out of LZMS_PROBABILITY_MAX that the next bit is 0. */
+static inline void
+lzms_range_encoder_raw_encode_bit(struct lzms_range_encoder_raw *rc,
+ int bit, u32 prob)
+{
+ lzms_range_encoder_raw_normalize(rc);
+
+ u32 bound = (rc->range >> LZMS_PROBABILITY_BITS) * prob;
+ if (bit == 0) {
+ rc->range = bound;
+ } else {
+ rc->low += bound;
+ rc->range -= bound;
}
}
+/* Encode a bit using the specified range encoder. This wraps around
+ * lzms_range_encoder_raw_encode_bit() to handle using and updating the
+ * appropriate state and probability entry. */
+static void
+lzms_range_encode_bit(struct lzms_range_encoder *enc, int bit)
+{
+ struct lzms_probability_entry *prob_entry;
+ u32 prob;
+
+ /* Load the probability entry corresponding to the current state. */
+ prob_entry = &enc->prob_entries[enc->state];
+
+ /* Update the state based on the next bit. */
+ enc->state = ((enc->state << 1) | bit) & enc->mask;
+
+ /* Get the probability that the bit is 0. */
+ prob = lzms_get_probability(prob_entry);
+
+ /* Update the probability entry. */
+ lzms_update_probability_entry(prob_entry, bit);
+
+ /* Encode the bit. */
+ lzms_range_encoder_raw_encode_bit(enc->rc, bit, prob);
+}
+
+/* Called when an adaptive Huffman code needs to be rebuilt. */
+static void
+lzms_rebuild_huffman_code(struct lzms_huffman_encoder *enc)
+{
+ make_canonical_huffman_code(enc->num_syms,
+ LZMS_MAX_CODEWORD_LEN,
+ enc->sym_freqs,
+ enc->lens,
+ enc->codewords);
+
+ /* Dilute the frequencies. */
+ for (unsigned i = 0; i < enc->num_syms; i++) {
+ enc->sym_freqs[i] >>= 1;
+ enc->sym_freqs[i] += 1;
+ }
+ enc->num_syms_written = 0;
+}
+
+/* Encode a symbol using the specified Huffman encoder. */
+static inline void
+lzms_huffman_encode_symbol(struct lzms_huffman_encoder *enc, unsigned sym)
+{
+ lzms_output_bitstream_put_varbits(enc->os,
+ enc->codewords[sym],
+ enc->lens[sym],
+ LZMS_MAX_CODEWORD_LEN);
+ ++enc->sym_freqs[sym];
+ if (++enc->num_syms_written == enc->rebuild_freq)
+ lzms_rebuild_huffman_code(enc);
+}
+
+static void
+lzms_update_fast_length_costs(struct lzms_compressor *c);
+
+/* Encode a match length. */
+static void
+lzms_encode_length(struct lzms_compressor *c, u32 length)
+{
+ unsigned slot;
+ unsigned num_extra_bits;
+ u32 extra_bits;
+
+ slot = lzms_get_length_slot_fast(c, length);
+
+ extra_bits = length - lzms_length_slot_base[slot];
+ num_extra_bits = lzms_extra_length_bits[slot];
+
+ lzms_huffman_encode_symbol(&c->length_encoder, slot);
+ if (c->length_encoder.num_syms_written == 0)
+ lzms_update_fast_length_costs(c);
+
+ lzms_output_bitstream_put_varbits(c->length_encoder.os,
+ extra_bits, num_extra_bits, 30);
+}
+
+/* Encode an LZ match offset. */
+static void
+lzms_encode_lz_offset(struct lzms_compressor *c, u32 offset)
+{
+ unsigned slot;
+ unsigned num_extra_bits;
+ u32 extra_bits;
+
+ slot = lzms_get_offset_slot_fast(c, offset);
+
+ extra_bits = offset - lzms_offset_slot_base[slot];
+ num_extra_bits = lzms_extra_offset_bits[slot];
+
+ lzms_huffman_encode_symbol(&c->lz_offset_encoder, slot);
+ lzms_output_bitstream_put_varbits(c->lz_offset_encoder.os,
+ extra_bits, num_extra_bits, 30);
+}
+
+/* Encode a literal byte. */
+static void
+lzms_encode_literal(struct lzms_compressor *c, unsigned literal)
+{
+ /* Main bit: 0 = a literal, not a match. */
+ lzms_range_encode_bit(&c->main_range_encoder, 0);
+
+ /* Encode the literal using the current literal Huffman code. */
+ lzms_huffman_encode_symbol(&c->literal_encoder, literal);
+}
+
+/* Encode an LZ repeat offset match. */
+static void
+lzms_encode_lz_repeat_offset_match(struct lzms_compressor *c,
+ u32 length, unsigned rep_index)
+{
+ unsigned i;
+
+ /* Main bit: 1 = a match, not a literal. */
+ lzms_range_encode_bit(&c->main_range_encoder, 1);
+
+ /* Match bit: 0 = an LZ match, not a delta match. */
+ lzms_range_encode_bit(&c->match_range_encoder, 0);
+
+ /* LZ match bit: 1 = repeat offset, not an explicit offset. */
+ lzms_range_encode_bit(&c->lz_match_range_encoder, 1);
+
+ /* Encode the repeat offset index. A 1 bit is encoded for each index
+ * passed up. This sequence of 1 bits is terminated by a 0 bit, or
+ * automatically when (LZMS_NUM_RECENT_OFFSETS - 1) 1 bits have been
+ * encoded. */
+ for (i = 0; i < rep_index; i++)
+ lzms_range_encode_bit(&c->lz_repeat_match_range_encoders[i], 1);
+
+ if (i < LZMS_NUM_RECENT_OFFSETS - 1)
+ lzms_range_encode_bit(&c->lz_repeat_match_range_encoders[i], 0);
+
+ /* Encode the match length. */
+ lzms_encode_length(c, length);
+}
+
+/* Encode an LZ explicit offset match. */
+static void
+lzms_encode_lz_explicit_offset_match(struct lzms_compressor *c,
+ u32 length, u32 offset)
+{
+ /* Main bit: 1 = a match, not a literal. */
+ lzms_range_encode_bit(&c->main_range_encoder, 1);
+
+ /* Match bit: 0 = an LZ match, not a delta match. */
+ lzms_range_encode_bit(&c->match_range_encoder, 0);
+
+ /* LZ match bit: 0 = explicit offset, not a repeat offset. */
+ lzms_range_encode_bit(&c->lz_match_range_encoder, 0);
+
+ /* Encode the match offset. */
+ lzms_encode_lz_offset(c, offset);
+
+ /* Encode the match length. */
+ lzms_encode_length(c, length);
+}
+
+static void
+lzms_encode_item(struct lzms_compressor *c, u64 mc_item_data)
+{
+ u32 len = mc_item_data & MC_LEN_MASK;
+ u32 offset_data = mc_item_data >> MC_OFFSET_SHIFT;
+
+ if (len == 1)
+ lzms_encode_literal(c, offset_data);
+ else if (offset_data < LZMS_NUM_RECENT_OFFSETS)
+ lzms_encode_lz_repeat_offset_match(c, len, offset_data);
+ else
+ lzms_encode_lz_explicit_offset_match(c, len, offset_data - LZMS_OFFSET_OFFSET);
+}
+
+/* Encode a list of matches and literals chosen by the parsing algorithm. */
+static void
+lzms_encode_item_list(struct lzms_compressor *c,
+ struct lzms_mc_pos_data *cur_optimum_ptr)
+{
+ struct lzms_mc_pos_data *end_optimum_ptr;
+ u64 saved_item;
+ u64 item;
+
+ /* The list is currently in reverse order (last item to first item).
+ * Reverse it. */
+ end_optimum_ptr = cur_optimum_ptr;
+ saved_item = cur_optimum_ptr->mc_item_data;
+ do {
+ item = saved_item;
+ cur_optimum_ptr -= item & MC_LEN_MASK;
+ saved_item = cur_optimum_ptr->mc_item_data;
+ cur_optimum_ptr->mc_item_data = item;
+ } while (cur_optimum_ptr != c->optimum);
+
+ /* Walk the list of items from beginning to end, encoding each item. */
+ do {
+ lzms_encode_item(c, cur_optimum_ptr->mc_item_data);
+ cur_optimum_ptr += (cur_optimum_ptr->mc_item_data) & MC_LEN_MASK;
+ } while (cur_optimum_ptr != end_optimum_ptr);
+}
+
+/* Each bit costs 1 << LZMS_COST_SHIFT units. */
+#define LZMS_COST_SHIFT 6
+
+/*#define LZMS_RC_COSTS_USE_FLOATING_POINT*/
+
+static u32
+lzms_rc_costs[LZMS_PROBABILITY_MAX + 1];
+
+#ifdef LZMS_RC_COSTS_USE_FLOATING_POINT
+# include <math.h>
+#endif
+
+static void
+lzms_do_init_rc_costs(void)
+{
+ /* Fill in a table that maps range coding probabilities needed to code a
+ * bit X (0 or 1) to the number of bits (scaled by a constant factor, to
+ * handle fractional costs) needed to code that bit X.
+ *
+ * Consider the range of the range decoder. To eliminate exactly half
+ * the range (logical probability of 0.5), we need exactly 1 bit. For
+ * lower probabilities we need more bits and for higher probabilities we
+ * need fewer bits. In general, a logical probability of N will
+ * eliminate the proportion 1 - N of the range; this information takes
+ * log2(1 / N) bits to encode.
+ *
+ * The below loop is simply calculating this number of bits for each
+ * possible probability allowed by the LZMS compression format, but
+ * without using real numbers. To handle fractional probabilities, each
+ * cost is multiplied by (1 << LZMS_COST_SHIFT). These techniques are
+ * based on those used by LZMA.
+ *
+ * Note that in LZMS, a probability x really means x / 64, and 0 / 64 is
+ * really interpreted as 1 / 64 and 64 / 64 is really interpreted as
+ * 63 / 64.
+ */
+ for (u32 i = 0; i <= LZMS_PROBABILITY_MAX; i++) {
+ u32 prob = i;
+
+ if (prob == 0)
+ prob = 1;
+ else if (prob == LZMS_PROBABILITY_MAX)
+ prob = LZMS_PROBABILITY_MAX - 1;
+
+ #ifdef LZMS_RC_COSTS_USE_FLOATING_POINT
+ lzms_rc_costs[i] = log2((double)LZMS_PROBABILITY_MAX / prob) *
+ (1 << LZMS_COST_SHIFT);
+ #else
+ u32 w = prob;
+ u32 bit_count = 0;
+ for (u32 j = 0; j < LZMS_COST_SHIFT; j++) {
+ w *= w;
+ bit_count <<= 1;
+ while (w >= ((u32)1 << 16)) {
+ w >>= 1;
+ ++bit_count;
+ }
+ }
+ lzms_rc_costs[i] = (LZMS_PROBABILITY_BITS << LZMS_COST_SHIFT) -
+ (15 + bit_count);
+ #endif
+ }
+}
+
+static void
+lzms_init_rc_costs(void)
+{
+ static pthread_once_t once = PTHREAD_ONCE_INIT;
+
+ pthread_once(&once, lzms_do_init_rc_costs);
+}
+
+/* Return the cost to range-encode the specified bit from the specified state.*/
+static inline u32
+lzms_rc_bit_cost(const struct lzms_range_encoder *enc, u8 cur_state, int bit)
+{
+ u32 prob_zero;
+ u32 prob_correct;
+
+ prob_zero = enc->prob_entries[cur_state].num_recent_zero_bits;
+
+ if (bit == 0)
+ prob_correct = prob_zero;
+ else
+ prob_correct = LZMS_PROBABILITY_MAX - prob_zero;
+
+ return lzms_rc_costs[prob_correct];
+}
+
+/* Return the cost to Huffman-encode the specified symbol. */
+static inline u32
+lzms_huffman_symbol_cost(const struct lzms_huffman_encoder *enc, unsigned sym)
+{
+ return (u32)enc->lens[sym] << LZMS_COST_SHIFT;
+}
+
+/* Return the cost to encode the specified literal byte. */
+static inline u32
+lzms_literal_cost(const struct lzms_compressor *c, unsigned literal,
+ const struct lzms_adaptive_state *state)
+{
+ return lzms_rc_bit_cost(&c->main_range_encoder, state->main_state, 0) +
+ lzms_huffman_symbol_cost(&c->literal_encoder, literal);
+}
+
+/* Update the table that directly provides the costs for small lengths. */
+static void
+lzms_update_fast_length_costs(struct lzms_compressor *c)
+{
+ u32 len;
+ int slot = -1;
+ u32 cost = 0;
+
+ for (len = 1; len < LZMS_NUM_FAST_LENGTHS; len++) {
+
+ while (len >= lzms_length_slot_base[slot + 1]) {
+ slot++;
+ cost = (u32)(c->length_encoder.lens[slot] +
+ lzms_extra_length_bits[slot]) << LZMS_COST_SHIFT;
+ }
+
+ c->length_cost_fast[len] = cost;
+ }
+}
+
+/* Return the cost to encode the specified match length, which must be less than
+ * LZMS_NUM_FAST_LENGTHS. */
+static inline u32
+lzms_fast_length_cost(const struct lzms_compressor *c, u32 length)
+{
+ LZMS_ASSERT(length < LZMS_NUM_FAST_LENGTHS);
+ return c->length_cost_fast[length];
+}
+
+/* Return the cost to encode the specified LZ match offset. */
+static inline u32
+lzms_lz_offset_cost(const struct lzms_compressor *c, u32 offset)
+{
+ unsigned slot = lzms_get_offset_slot_fast(c, offset);
+
+ return (u32)(c->lz_offset_encoder.lens[slot] +
+ lzms_extra_offset_bits[slot]) << LZMS_COST_SHIFT;
+}
+
+/*
+ * Consider coding the match at repeat offset index @rep_idx. Consider each
+ * length from the minimum (2) to the full match length (@rep_len).
+ */
+static inline void
+lzms_consider_lz_repeat_offset_match(const struct lzms_compressor *c,
+ struct lzms_mc_pos_data *cur_optimum_ptr,
+ u32 rep_len, unsigned rep_idx)
+{
+ u32 len;
+ u32 base_cost;
+ u32 cost;
+ unsigned i;
+
+ base_cost = cur_optimum_ptr->cost;
+
+ base_cost += lzms_rc_bit_cost(&c->main_range_encoder,
+ cur_optimum_ptr->state.main_state, 1);
+
+ base_cost += lzms_rc_bit_cost(&c->match_range_encoder,
+ cur_optimum_ptr->state.match_state, 0);
+
+ base_cost += lzms_rc_bit_cost(&c->lz_match_range_encoder,
+ cur_optimum_ptr->state.lz_match_state, 1);
+
+ for (i = 0; i < rep_idx; i++)
+ base_cost += lzms_rc_bit_cost(&c->lz_repeat_match_range_encoders[i],
+ cur_optimum_ptr->state.lz_repeat_match_state[i], 1);
+
+ if (i < LZMS_NUM_RECENT_OFFSETS - 1)
+ base_cost += lzms_rc_bit_cost(&c->lz_repeat_match_range_encoders[i],
+ cur_optimum_ptr->state.lz_repeat_match_state[i], 0);
+
+ len = 2;
+ do {
+ cost = base_cost + lzms_fast_length_cost(c, len);
+ if (cost < (cur_optimum_ptr + len)->cost) {
+ (cur_optimum_ptr + len)->mc_item_data =
+ ((u64)rep_idx << MC_OFFSET_SHIFT) | len;
+ (cur_optimum_ptr + len)->cost = cost;
+ }
+ } while (++len <= rep_len);
+}
+
+/*
+ * Consider coding each match in @matches as an explicit offset match.
+ *
+ * @matches must be sorted by strictly increasing length and strictly increasing
+ * offset. This is guaranteed by the match-finder.
+ *
+ * We consider each length from the minimum (2) to the longest
+ * (matches[num_matches - 1].len). For each length, we consider only the
+ * smallest offset for which that length is available. Although this is not
+ * guaranteed to be optimal due to the possibility of a larger offset costing
+ * less than a smaller offset to code, this is a very useful heuristic.
+ */
+static inline void
+lzms_consider_lz_explicit_offset_matches(const struct lzms_compressor *c,
+ struct lzms_mc_pos_data *cur_optimum_ptr,
+ const struct lz_match matches[],
+ u32 num_matches)
+{
+ u32 len;
+ u32 i;
+ u32 base_cost;
+ u32 position_cost;
+ u32 cost;
+
+ base_cost = cur_optimum_ptr->cost;
+
+ base_cost += lzms_rc_bit_cost(&c->main_range_encoder,
+ cur_optimum_ptr->state.main_state, 1);
+
+ base_cost += lzms_rc_bit_cost(&c->match_range_encoder,
+ cur_optimum_ptr->state.match_state, 0);
+
+ base_cost += lzms_rc_bit_cost(&c->lz_match_range_encoder,
+ cur_optimum_ptr->state.lz_match_state, 0);
+ len = 2;
+ i = 0;
+ do {
+ position_cost = base_cost + lzms_lz_offset_cost(c, matches[i].offset);
+ do {
+ cost = position_cost + lzms_fast_length_cost(c, len);
+ if (cost < (cur_optimum_ptr + len)->cost) {
+ (cur_optimum_ptr + len)->mc_item_data =
+ ((u64)(matches[i].offset + LZMS_OFFSET_OFFSET)
+ << MC_OFFSET_SHIFT) | len;
+ (cur_optimum_ptr + len)->cost = cost;
+ }
+ } while (++len <= matches[i].len);
+ } while (++i != num_matches);
+}
+
+static void
+lzms_init_adaptive_state(struct lzms_adaptive_state *state)
+{
+ unsigned i;
+
+ lzms_init_lz_lru_queues(&state->lru);
+ state->main_state = 0;
+ state->match_state = 0;
+ state->lz_match_state = 0;
+ for (i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++)
+ state->lz_repeat_match_state[i] = 0;
+}
+
+static inline void
+lzms_update_main_state(struct lzms_adaptive_state *state, int is_match)
+{
+ state->main_state = ((state->main_state << 1) | is_match) % LZMS_NUM_MAIN_STATES;
+}
+
+static inline void
+lzms_update_match_state(struct lzms_adaptive_state *state, int is_delta)
+{
+ state->match_state = ((state->match_state << 1) | is_delta) % LZMS_NUM_MATCH_STATES;
+}
+
+static inline void
+lzms_update_lz_match_state(struct lzms_adaptive_state *state, int is_repeat_offset)
+{
+ state->lz_match_state = ((state->lz_match_state << 1) | is_repeat_offset) % LZMS_NUM_LZ_MATCH_STATES;
+}
+
+static inline void
+lzms_update_lz_repeat_match_state(struct lzms_adaptive_state *state, int rep_idx)
+{
+ int i;
+
+ for (i = 0; i < rep_idx; i++)
+ state->lz_repeat_match_state[i] =
+ ((state->lz_repeat_match_state[i] << 1) | 1) %
+ LZMS_NUM_LZ_REPEAT_MATCH_STATES;
+
+ if (i < LZMS_NUM_RECENT_OFFSETS - 1)
+ state->lz_repeat_match_state[i] =
+ ((state->lz_repeat_match_state[i] << 1) | 0) %
+ LZMS_NUM_LZ_REPEAT_MATCH_STATES;
+}
+
+/*
+ * The main near-optimal parsing routine.
+ *
+ * Briefly, the algorithm does an approximate minimum-cost path search to find a
+ * "near-optimal" sequence of matches and literals to output, based on the
+ * current cost model. The algorithm steps forward, position by position (byte
+ * by byte), and updates the minimum cost path to reach each later position that
+ * can be reached using a match or literal from the current position. This is
+ * essentially Dijkstra's algorithm in disguise: the graph nodes are positions,
+ * the graph edges are possible matches/literals to code, and the cost of each
+ * edge is the estimated number of bits that will be required to output the
+ * corresponding match or literal. But one difference is that we actually
+ * compute the lowest-cost path in pieces, where each piece is terminated when
+ * there are no choices to be made.
+ *
+ * Notes:
+ *
+ * - 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
+ * states, costs are assumed to be constant throughout a single run of the
+ * parsing algorithm, which can parse up to @optim_array_length bytes of data.
+ * This introduces a source of inaccuracy because the probabilities and
+ * Huffman codes can change over this part of the data.
+ */
+static void
+lzms_near_optimal_parse(struct lzms_compressor *c)
+{
+ const u8 *window_ptr;
+ const u8 *window_end;
+ struct lzms_mc_pos_data *cur_optimum_ptr;
+ struct lzms_mc_pos_data *end_optimum_ptr;
+ u32 num_matches;
+ u32 longest_len;
+ u32 rep_max_len;
+ unsigned rep_max_idx;
+ unsigned literal;
+ unsigned i;
+ u32 cost;
+ u32 len;
+ u32 offset_data;
+
+ window_ptr = c->cur_window;
+ window_end = window_ptr + c->cur_window_size;
+
+ lzms_init_adaptive_state(&c->optimum[0].state);
+
+begin:
+ /* Start building a new list of items, which will correspond to the next
+ * piece of the overall minimum-cost path. */
+
+ cur_optimum_ptr = c->optimum;
+ cur_optimum_ptr->cost = 0;
+ end_optimum_ptr = cur_optimum_ptr;
+
+ /* States should currently be consistent with the encoders. */
+ LZMS_ASSERT(cur_optimum_ptr->state.main_state == c->main_range_encoder.state);
+ LZMS_ASSERT(cur_optimum_ptr->state.match_state == c->match_range_encoder.state);
+ LZMS_ASSERT(cur_optimum_ptr->state.lz_match_state == c->lz_match_range_encoder.state);
+ for (i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++)
+ LZMS_ASSERT(cur_optimum_ptr->state.lz_repeat_match_state[i] ==
+ c->lz_repeat_match_range_encoders[i].state);
+
+ if (window_ptr == window_end)
+ return;
+
+ /* The following loop runs once for each per byte in the window, except
+ * in a couple shortcut cases. */
+ for (;;) {
+
+ /* Find explicit offset matches with the current position. */
+ num_matches = lz_mf_get_matches(c->mf, c->matches);
+
+ if (num_matches) {
+ /*
+ * Find the longest repeat offset match with the current
+ * position.
+ *
+ * Heuristics:
+ *
+ * - Only search for repeat offset matches if the
+ * match-finder already found at least one match.
+ *
+ * - Only consider the longest repeat offset match. It
+ * seems to be rare for the optimal parse to include a
+ * repeat offset match that doesn't have the longest
+ * length (allowing for the possibility that not all
+ * of that length is actually used).
+ */
+ if (likely(window_ptr - c->cur_window >= LZMS_MAX_INIT_RECENT_OFFSET)) {
+ BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3);
+ rep_max_len = lz_repsearch3(window_ptr,
+ window_end - window_ptr,
+ cur_optimum_ptr->state.lru.recent_offsets,
+ &rep_max_idx);
+ } else {
+ rep_max_len = 0;
+ }
+
+ if (rep_max_len) {
+ /* If there's a very long repeat offset match,
+ * choose it immediately. */
+ if (rep_max_len >= c->params.nice_match_length) {
+
+ lz_mf_skip_positions(c->mf, rep_max_len - 1);
+ window_ptr += rep_max_len;
+
+ if (cur_optimum_ptr != c->optimum)
+ lzms_encode_item_list(c, cur_optimum_ptr);
+
+ lzms_encode_lz_repeat_offset_match(c, rep_max_len,
+ rep_max_idx);
+
+ c->optimum[0].state = cur_optimum_ptr->state;
+
+ lzms_update_main_state(&c->optimum[0].state, 1);
+ lzms_update_match_state(&c->optimum[0].state, 0);
+ lzms_update_lz_match_state(&c->optimum[0].state, 1);
+ lzms_update_lz_repeat_match_state(&c->optimum[0].state,
+ rep_max_idx);
+
+ c->optimum[0].state.lru.upcoming_offset =
+ c->optimum[0].state.lru.recent_offsets[rep_max_idx];
+
+ for (i = rep_max_idx; i < LZMS_NUM_RECENT_OFFSETS; i++)
+ c->optimum[0].state.lru.recent_offsets[i] =
+ c->optimum[0].state.lru.recent_offsets[i + 1];
+
+ lzms_update_lz_lru_queue(&c->optimum[0].state.lru);
+ goto begin;
+ }
+
+ /* If reaching any positions for the first time,
+ * initialize their costs to "infinity". */
+ while (end_optimum_ptr < cur_optimum_ptr + rep_max_len)
+ (++end_optimum_ptr)->cost = MC_INFINITE_COST;
+
+ /* Consider coding a repeat offset match. */
+ lzms_consider_lz_repeat_offset_match(c, cur_optimum_ptr,
+ rep_max_len, rep_max_idx);
+ }
+
+ longest_len = c->matches[num_matches - 1].len;
+
+ /* If there's a very long explicit offset match, choose
+ * it immediately. */
+ if (longest_len >= c->params.nice_match_length) {
+
+ lz_mf_skip_positions(c->mf, longest_len - 1);
+ window_ptr += longest_len;
+
+ if (cur_optimum_ptr != c->optimum)
+ lzms_encode_item_list(c, cur_optimum_ptr);
+
+ lzms_encode_lz_explicit_offset_match(c, longest_len,
+ c->matches[num_matches - 1].offset);
+
+ c->optimum[0].state = cur_optimum_ptr->state;
+
+ lzms_update_main_state(&c->optimum[0].state, 1);
+ lzms_update_match_state(&c->optimum[0].state, 0);
+ lzms_update_lz_match_state(&c->optimum[0].state, 0);
+
+ c->optimum[0].state.lru.upcoming_offset =
+ c->matches[num_matches - 1].offset;
+
+ lzms_update_lz_lru_queue(&c->optimum[0].state.lru);
+ goto begin;
+ }
+
+ /* If reaching any positions for the first time,
+ * initialize their costs to "infinity". */
+ while (end_optimum_ptr < cur_optimum_ptr + longest_len)
+ (++end_optimum_ptr)->cost = MC_INFINITE_COST;
+
+ /* Consider coding an explicit offset match. */
+ lzms_consider_lz_explicit_offset_matches(c, cur_optimum_ptr,
+ c->matches, num_matches);
+ } else {
+ /* No matches found. The only choice at this position
+ * is to code a literal. */
+
+ if (end_optimum_ptr == cur_optimum_ptr)
+ (++end_optimum_ptr)->cost = MC_INFINITE_COST;
+ }
+
+ /* Consider coding a literal.
+
+ * To avoid an extra unpredictable brench, actually checking the
+ * preferability of coding a literal is integrated into the
+ * adaptive state update code below. */
+ literal = *window_ptr++;
+ cost = cur_optimum_ptr->cost +
+ lzms_literal_cost(c, literal, &cur_optimum_ptr->state);
+
+ /* Advance to the next position. */
+ cur_optimum_ptr++;
+
+ /* The lowest-cost path to the current position is now known.
+ * Finalize the adaptive state that results from taking this
+ * lowest-cost path. */
+
+ if (cost < cur_optimum_ptr->cost) {
+ /* Literal */
+ cur_optimum_ptr->cost = cost;
+ cur_optimum_ptr->mc_item_data = ((u64)literal << MC_OFFSET_SHIFT) | 1;
+
+ cur_optimum_ptr->state = (cur_optimum_ptr - 1)->state;
+
+ lzms_update_main_state(&cur_optimum_ptr->state, 0);
+
+ cur_optimum_ptr->state.lru.upcoming_offset = 0;
+ } else {
+ /* LZ match */
+ len = cur_optimum_ptr->mc_item_data & MC_LEN_MASK;
+ offset_data = cur_optimum_ptr->mc_item_data >> MC_OFFSET_SHIFT;
+
+ cur_optimum_ptr->state = (cur_optimum_ptr - len)->state;
+
+ lzms_update_main_state(&cur_optimum_ptr->state, 1);
+ lzms_update_match_state(&cur_optimum_ptr->state, 0);
+
+ if (offset_data >= LZMS_NUM_RECENT_OFFSETS) {
+
+ /* Explicit offset LZ match */
+
+ lzms_update_lz_match_state(&cur_optimum_ptr->state, 0);
+
+ cur_optimum_ptr->state.lru.upcoming_offset =
+ offset_data - LZMS_OFFSET_OFFSET;
+ } else {
+ /* Repeat offset LZ match */
+
+ lzms_update_lz_match_state(&cur_optimum_ptr->state, 1);
+ lzms_update_lz_repeat_match_state(&cur_optimum_ptr->state,
+ offset_data);
+
+ cur_optimum_ptr->state.lru.upcoming_offset =
+ cur_optimum_ptr->state.lru.recent_offsets[offset_data];
+
+ for (i = offset_data; i < LZMS_NUM_RECENT_OFFSETS; i++)
+ cur_optimum_ptr->state.lru.recent_offsets[i] =
+ cur_optimum_ptr->state.lru.recent_offsets[i + 1];
+ }
+ }
+
+ lzms_update_lz_lru_queue(&cur_optimum_ptr->state.lru);
+
+ /*
+ * This loop will terminate when either of the following
+ * conditions is true:
+ *
+ * (1) cur_optimum_ptr == end_optimum_ptr
+ *
+ * There are no paths that extend beyond the current
+ * position. In this case, any path to a later position
+ * must pass through the current position, so we can go
+ * ahead and choose the list of items that led to this
+ * position.
+ *
+ * (2) cur_optimum_ptr == c->optimum_end
+ *
+ * This bounds the number of times the algorithm can step
+ * forward before it is guaranteed to start choosing items.
+ * This limits the memory usage. It also guarantees that
+ * the parser will not go too long without updating the
+ * probability tables.
+ *
+ * Note: no check for end-of-window is needed because
+ * end-of-window will trigger condition (1).
+ */
+ if (cur_optimum_ptr == end_optimum_ptr ||
+ cur_optimum_ptr == c->optimum_end)
+ {
+ c->optimum[0].state = cur_optimum_ptr->state;
+ break;
+ }
+ }
+
+ /* Output the current list of items that constitute the minimum-cost
+ * path to the current position. */
+ lzms_encode_item_list(c, cur_optimum_ptr);
+ goto begin;
+}
+
+static void
+lzms_init_range_encoder(struct lzms_range_encoder *enc,
+ struct lzms_range_encoder_raw *rc, u32 num_states)
+{
+ enc->rc = rc;
+ enc->state = 0;
+ LZMS_ASSERT(is_power_of_2(num_states));
+ enc->mask = num_states - 1;
+ for (u32 i = 0; i < num_states; i++) {
+ enc->prob_entries[i].num_recent_zero_bits = LZMS_INITIAL_PROBABILITY;
+ enc->prob_entries[i].recent_bits = LZMS_INITIAL_RECENT_BITS;
+ }
+}
+
+static void
+lzms_init_huffman_encoder(struct lzms_huffman_encoder *enc,
+ struct lzms_output_bitstream *os,
+ unsigned num_syms,
+ unsigned rebuild_freq)
+{
+ enc->os = os;
+ enc->num_syms_written = 0;
+ enc->rebuild_freq = rebuild_freq;
+ enc->num_syms = num_syms;
+ for (unsigned i = 0; i < num_syms; i++)
+ enc->sym_freqs[i] = 1;
+
+ make_canonical_huffman_code(enc->num_syms,
+ LZMS_MAX_CODEWORD_LEN,
+ enc->sym_freqs,
+ enc->lens,
+ enc->codewords);
+}
+
+/* Prepare the LZMS compressor for compressing a block of data. */
+static void
+lzms_prepare_compressor(struct lzms_compressor *c, const u8 *udata, u32 ulen,
+ le16 *cdata, u32 clen16)
+{
+ unsigned num_offset_slots;
+
+ /* Copy the uncompressed data into the @c->cur_window buffer. */
+ memcpy(c->cur_window, udata, ulen);
+ c->cur_window_size = ulen;
+
+ /* Initialize the raw range encoder (writing forwards). */
+ lzms_range_encoder_raw_init(&c->rc, cdata, clen16);
+
+ /* Initialize the output bitstream for Huffman symbols and verbatim bits
+ * (writing backwards). */
+ lzms_output_bitstream_init(&c->os, cdata, clen16);
+
+ /* Calculate the number of offset slots required. */
+ num_offset_slots = lzms_get_offset_slot(ulen - 1) + 1;
+
+ /* Initialize a Huffman encoder for each alphabet. */
+ lzms_init_huffman_encoder(&c->literal_encoder, &c->os,
+ LZMS_NUM_LITERAL_SYMS,
+ LZMS_LITERAL_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&c->lz_offset_encoder, &c->os,
+ num_offset_slots,
+ LZMS_LZ_OFFSET_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&c->length_encoder, &c->os,
+ LZMS_NUM_LEN_SYMS,
+ LZMS_LENGTH_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&c->delta_offset_encoder, &c->os,
+ num_offset_slots,
+ LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&c->delta_power_encoder, &c->os,
+ LZMS_NUM_DELTA_POWER_SYMS,
+ LZMS_DELTA_POWER_CODE_REBUILD_FREQ);
+
+ /* Initialize range encoders, all of which wrap around the same
+ * lzms_range_encoder_raw. */
+ lzms_init_range_encoder(&c->main_range_encoder,
+ &c->rc, LZMS_NUM_MAIN_STATES);
+
+ lzms_init_range_encoder(&c->match_range_encoder,
+ &c->rc, LZMS_NUM_MATCH_STATES);
+
+ lzms_init_range_encoder(&c->lz_match_range_encoder,
+ &c->rc, LZMS_NUM_LZ_MATCH_STATES);
+
+ for (unsigned i = 0; i < ARRAY_LEN(c->lz_repeat_match_range_encoders); i++)
+ lzms_init_range_encoder(&c->lz_repeat_match_range_encoders[i],
+ &c->rc, LZMS_NUM_LZ_REPEAT_MATCH_STATES);
+
+ lzms_init_range_encoder(&c->delta_match_range_encoder,
+ &c->rc, LZMS_NUM_DELTA_MATCH_STATES);
+
+ for (unsigned i = 0; i < ARRAY_LEN(c->delta_repeat_match_range_encoders); i++)
+ lzms_init_range_encoder(&c->delta_repeat_match_range_encoders[i],
+ &c->rc, LZMS_NUM_DELTA_REPEAT_MATCH_STATES);
+
+ /* Set initial length costs for lengths < LZMS_NUM_FAST_LENGTHS. */
+ lzms_update_fast_length_costs(c);
+}
+
+/* Flush the output streams, prepare the final compressed data, and return its
+ * size in bytes.
+ *
+ * A return value of 0 indicates that the data could not be compressed to fit in
+ * the available space. */
+static size_t
+lzms_finalize(struct lzms_compressor *c, u8 *cdata, size_t csize_avail)
+{
+ size_t num_forwards_bytes;
+ size_t num_backwards_bytes;
+
+ /* Flush both the forwards and backwards streams, and make sure they
+ * didn't cross each other and start overwriting each other's data. */
+ if (!lzms_output_bitstream_flush(&c->os))
+ return 0;
+
+ if (!lzms_range_encoder_raw_flush(&c->rc))
+ return 0;
+
+ if (c->rc.next > c->os.next)
+ return 0;
+
+ /* Now the compressed buffer contains the data output by the forwards
+ * bitstream, then empty space, then data output by the backwards
+ * bitstream. Move the data output by the backwards bitstream to be
+ * adjacent to the data output by the forward bitstream, and calculate
+ * the compressed size that this results in. */
+ num_forwards_bytes = (u8*)c->rc.next - (u8*)cdata;
+ num_backwards_bytes = ((u8*)cdata + csize_avail) - (u8*)c->os.next;
+
+ memmove(cdata + num_forwards_bytes, c->os.next, num_backwards_bytes);
+
+ return num_forwards_bytes + num_backwards_bytes;
+}
+
+/* Set internal compression parameters for the specified compression level and
+ * maximum window size. */
+static void
+lzms_build_params(unsigned int compression_level,
+ struct lzms_compressor_params *params)
+{
+ /* Allow length 2 matches if the compression level is sufficiently high.
+ */
+ if (compression_level >= 45)
+ params->min_match_length = 2;
+ else
+ params->min_match_length = 3;
+
+ /* Scale nice_match_length and max_search_depth with the compression
+ * level. But to allow an optimization on length cost calculations,
+ * don't allow nice_match_length to exceed LZMS_NUM_FAST_LENGTH. */
+ params->nice_match_length = ((u64)compression_level * 32) / 50;
+ if (params->nice_match_length < params->min_match_length)
+ params->nice_match_length = params->min_match_length;
+ if (params->nice_match_length > LZMS_NUM_FAST_LENGTHS)
+ params->nice_match_length = LZMS_NUM_FAST_LENGTHS;
+ params->max_search_depth = compression_level;
+
+ params->optim_array_length = 1024;
+}
+
+/* Given the internal compression parameters and maximum window size, build the
+ * Lempel-Ziv match-finder parameters. */
+static void
+lzms_build_mf_params(const struct lzms_compressor_params *lzms_params,
+ u32 max_window_size, struct lz_mf_params *mf_params)
+{
+ memset(mf_params, 0, sizeof(*mf_params));
+
+ /* Choose an appropriate match-finding algorithm. */
+ if (max_window_size <= 2097152)
+ mf_params->algorithm = LZ_MF_BINARY_TREES;
+ else if (max_window_size <= 33554432)
+ mf_params->algorithm = LZ_MF_LCP_INTERVAL_TREE;
+ else
+ mf_params->algorithm = LZ_MF_LINKED_SUFFIX_ARRAY;
+
+ mf_params->max_window_size = max_window_size;
+ mf_params->min_match_len = lzms_params->min_match_length;
+ mf_params->max_search_depth = lzms_params->max_search_depth;
+ mf_params->nice_match_len = lzms_params->nice_match_length;
+}
+
+static void
+lzms_free_compressor(void *_c);
+
+static u64
+lzms_get_needed_memory(size_t max_block_size, unsigned int compression_level)
+{
+ struct lzms_compressor_params params;
+ struct lz_mf_params mf_params;
+ u64 size = 0;
+
+ if (max_block_size >= INT32_MAX)
+ return 0;
+
+ lzms_build_params(compression_level, ¶ms);
+ lzms_build_mf_params(¶ms, max_block_size, &mf_params);
+
+ size += sizeof(struct lzms_compressor);
+
+ /* cur_window */
+ size += max_block_size;
+
+ /* mf */
+ size += lz_mf_get_needed_memory(mf_params.algorithm, max_block_size);
+
+ /* matches */
+ size += min(params.max_search_depth, params.nice_match_length) *
+ sizeof(struct lz_match);
+
+ /* optimum */
+ size += (params.optim_array_length + params.nice_match_length) *
+ sizeof(struct lzms_mc_pos_data);
+
+ return size;
+}
+
static int
-lzms_create_compressor(size_t max_block_size,
- const struct wimlib_compressor_params_header *params,
+lzms_create_compressor(size_t max_block_size, unsigned int compression_level,
void **ctx_ret)
{
- struct lzms_compressor *ctx;
+ struct lzms_compressor *c;
+ struct lzms_compressor_params params;
+ struct lz_mf_params mf_params;
- if (max_block_size == 0 || max_block_size > 1U << 26) {
- LZMS_DEBUG("Invalid max_block_size (%u)", max_block_size);
+ if (max_block_size >= INT32_MAX)
return WIMLIB_ERR_INVALID_PARAM;
- }
- ctx = CALLOC(1, sizeof(struct lzms_compressor));
- if (ctx == NULL)
+ lzms_build_params(compression_level, ¶ms);
+ lzms_build_mf_params(¶ms, max_block_size, &mf_params);
+ if (!lz_mf_params_valid(&mf_params))
+ return WIMLIB_ERR_INVALID_PARAM;
+
+ c = CALLOC(1, sizeof(struct lzms_compressor));
+ if (!c)
+ goto oom;
+
+ c->params = params;
+
+ c->cur_window = MALLOC(max_block_size);
+ if (!c->cur_window)
+ goto oom;
+
+ c->mf = lz_mf_alloc(&mf_params);
+ if (!c->mf)
goto oom;
- ctx->window = MALLOC(max_block_size);
- if (ctx->window == NULL)
+ c->matches = MALLOC(min(params.max_search_depth,
+ params.nice_match_length) *
+ sizeof(struct lz_match));
+ if (!c->matches)
goto oom;
- ctx->max_block_size = max_block_size;
- ctx->last_target_usages = MALLOC(65536 * sizeof(ctx->last_target_usages[0]));
- if (ctx->last_target_usages == NULL)
+ c->optimum = MALLOC((params.optim_array_length +
+ params.nice_match_length) *
+ sizeof(struct lzms_mc_pos_data));
+ if (!c->optimum)
goto oom;
+ c->optimum_end = &c->optimum[params.optim_array_length];
+
+ lzms_init_slots();
+
+ lzms_init_rc_costs();
+
+ lzms_init_fast_slots(c);
- *ctx_ret = ctx;
+ *ctx_ret = c;
return 0;
oom:
- lzms_free_compressor(ctx);
+ lzms_free_compressor(c);
return WIMLIB_ERR_NOMEM;
}
+static size_t
+lzms_compress(const void *uncompressed_data, size_t uncompressed_size,
+ void *compressed_data, size_t compressed_size_avail, void *_c)
+{
+ struct lzms_compressor *c = _c;
+
+ /* Don't bother compressing extremely small inputs. */
+ if (uncompressed_size < 4)
+ return 0;
+
+ /* Cap the available compressed size to a 32-bit integer and round it
+ * down to the nearest multiple of 2. */
+ if (compressed_size_avail > UINT32_MAX)
+ compressed_size_avail = UINT32_MAX;
+ if (compressed_size_avail & 1)
+ compressed_size_avail--;
+
+ /* Initialize the compressor structures. */
+ lzms_prepare_compressor(c, uncompressed_data, uncompressed_size,
+ compressed_data, compressed_size_avail / 2);
+
+ /* Preprocess the uncompressed data. */
+ lzms_x86_filter(c->cur_window, c->cur_window_size,
+ c->last_target_usages, false);
+
+ /* Load the window into the match-finder. */
+ lz_mf_load_window(c->mf, c->cur_window, c->cur_window_size);
+
+ /* Compute and encode a literal/match sequence that decompresses to the
+ * preprocessed data. */
+ lzms_near_optimal_parse(c);
+
+ /* Return the compressed data size or 0. */
+ return lzms_finalize(c, compressed_data, compressed_size_avail);
+}
+
+static void
+lzms_free_compressor(void *_c)
+{
+ struct lzms_compressor *c = _c;
+
+ if (c) {
+ FREE(c->cur_window);
+ lz_mf_free(c->mf);
+ FREE(c->matches);
+ FREE(c->optimum);
+ FREE(c);
+ }
+}
+
const struct compressor_ops lzms_compressor_ops = {
+ .get_needed_memory = lzms_get_needed_memory,
.create_compressor = lzms_create_compressor,
.compress = lzms_compress,
.free_compressor = lzms_free_compressor,
git://wimlib.net / wimlib / blobdiff