+++ /dev/null
-/*
- * lzms-decompress.c
- */
-
-/*
- * Copyright (C) 2013, 2014 Eric Biggers
- *
- * 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.
- *
- * 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 Lesser General Public License
- * along with this file; if not, see http://www.gnu.org/licenses/.
- */
-
-/*
- * This is a decompressor for the LZMS compression format used by Microsoft.
- * This format is not documented, but it is one of the formats supported by the
- * compression API available in Windows 8, and as of Windows 8 it is one of the
- * formats that can be used in WIM files.
- *
- * This decompressor only implements "raw" decompression, which decompresses a
- * single LZMS-compressed block. This behavior is the same as that of
- * Decompress() in the Windows 8 compression API when using a compression handle
- * created with CreateDecompressor() with the Algorithm parameter specified as
- * COMPRESS_ALGORITHM_LZMS | COMPRESS_RAW. Presumably, non-raw LZMS data is a
- * container format from which the locations and sizes (both compressed and
- * uncompressed) of the constituent blocks can be determined.
- *
- * An LZMS-compressed block must be read in 16-bit little endian units from both
- * directions. One logical bitstream starts at the front of the block and
- * proceeds forwards. Another logical bitstream starts at the end of the block
- * and proceeds backwards. Bits read from the forwards bitstream constitute
- * binary range-encoded data, whereas bits read from the backwards bitstream
- * constitute Huffman-encoded symbols or verbatim bits. For both bitstreams,
- * the ordering of the bits within the 16-bit coding units is such that the
- * first bit is the high-order bit and the last bit is the low-order bit.
- *
- * From these two logical bitstreams, an LZMS decompressor can reconstitute the
- * series of items that make up the LZMS data representation. Each such item
- * may be a literal byte or a match. Matches may be either traditional LZ77
- * matches or "delta" matches, either of which can have its offset encoded
- * explicitly or encoded via a reference to a recently used (repeat) offset.
- *
- * A traditional LZ match consists of a length and offset; it asserts that the
- * sequence of bytes beginning at the current position and extending for the
- * length is exactly equal to the equal-length sequence of bytes at the offset
- * back in the data buffer. On the other hand, a delta match consists of a
- * length, raw offset, and power. It asserts that the sequence of bytes
- * beginning at the current position and extending for the length is equal to
- * the bytewise sum of the two equal-length sequences of bytes (2**power) and
- * (raw_offset * 2**power) bytes before the current position, minus bytewise the
- * sequence of bytes beginning at (2**power + raw_offset * 2**power) bytes
- * before the current position. Although not generally as useful as traditional
- * LZ matches, delta matches can be helpful on some types of data. Both LZ and
- * delta matches may overlap with the current position; in fact, the minimum
- * offset is 1, regardless of match length.
- *
- * For LZ matches, up to 3 repeat offsets are allowed, similar to some other
- * LZ-based formats such as LZX and LZMA. They must updated in an LRU fashion,
- * except for a quirk: inserting anything to the front of the queue must be
- * delayed by one LZMS item. The reason for this is presumably that there is
- * almost no reason to code the same match offset twice in a row, since you
- * might as well have coded a longer match at that offset. For this same
- * reason, it also is a requirement that when an offset in the queue is used,
- * that offset is removed from the queue immediately (and made pending for
- * front-insertion after the following decoded item), and everything to the
- * right is shifted left one queue slot. This creates a need for an "overflow"
- * fourth entry in the queue, even though it is only possible to decode
- * references to the first 3 entries at any given time. The queue must be
- * initialized to the offsets {1, 2, 3, 4}.
- *
- * Repeat delta matches are handled similarly, but for them there are two queues
- * updated in lock-step: one for powers and one for raw offsets. The power
- * queue must be initialized to {0, 0, 0, 0}, and the raw offset queue must be
- * initialized to {1, 2, 3, 4}.
- *
- * Bits from the binary range decoder must be used to disambiguate item types.
- * The range decoder must hold two state variables: the range, which must
- * initially be set to 0xffffffff, and the current code, which must initially be
- * set to the first 32 bits read from the forwards bitstream. The range must be
- * maintained above 0xffff; when it falls below 0xffff, both the range and code
- * must be left-shifted by 16 bits and the low 16 bits of the code must be
- * filled in with the next 16 bits from the forwards bitstream.
- *
- * To decode each bit, the binary range decoder requires a probability that is
- * logically a real number between 0 and 1. Multiplying this probability by the
- * current range and taking the floor gives the bound between the 0-bit region of
- * the range and the 1-bit region of the range. However, in LZMS, probabilities
- * are restricted to values of n/64 where n is an integer is between 1 and 63
- * inclusively, so the implementation may use integer operations instead.
- * Following calculation of the bound, if the current code is in the 0-bit
- * region, the new range becomes the current code and the decoded bit is 0;
- * otherwise, the bound must be subtracted from both the range and the code, and
- * the decoded bit is 1. More information about range coding can be found at
- * https://en.wikipedia.org/wiki/Range_encoding. Furthermore, note that the
- * LZMA format also uses range coding and has public domain code available for
- * it.
- *
- * The probability used to range-decode each bit must be taken from a table, of
- * which one instance must exist for each distinct context in which a
- * range-decoded bit is needed. At each call of the range decoder, the
- * appropriate probability must be obtained by indexing the appropriate
- * probability table with the last 4 (in the context disambiguating literals
- * from matches), 5 (in the context disambiguating LZ matches from delta
- * matches), or 6 (in all other contexts) bits recently range-decoded in that
- * context, ordered such that the most recently decoded bit is the low-order bit
- * of the index.
- *
- * Furthermore, each probability entry itself is variable, as its value must be
- * maintained as n/64 where n is the number of 0 bits in the most recently
- * decoded 64 bits with that same entry. This allows the compressed
- * representation to adapt to the input and use fewer bits to represent the most
- * likely data; note that LZMA uses a similar scheme. Initially, the most
- * recently 64 decoded bits for each probability entry are assumed to be
- * 0x0000000055555555 (high order to low order); therefore, all probabilities
- * are initially 48/64. During the course of decoding, each probability may be
- * updated to as low as 0/64 (as a result of reading many consecutive 1 bits
- * with that entry) or as high as 64/64 (as a result of reading many consecutive
- * 0 bits with that entry); however, probabilities of 0/64 and 64/64 cannot be
- * used as-is but rather must be adjusted to 1/64 and 63/64, respectively,
- * before being used for range decoding.
- *
- * Representations of the LZMS items themselves must be read from the backwards
- * bitstream. For this, there are 5 different Huffman codes used:
- *
- * - The literal code, used for decoding literal bytes. Each of the 256
- * symbols represents a literal byte. This code must be rebuilt whenever
- * 1024 symbols have been decoded with it.
- *
- * - The LZ offset code, used for decoding the offsets of standard LZ77
- * matches. Each symbol represents an offset slot, which corresponds to a
- * base value and some number of extra bits which must be read and added to
- * the base value to reconstitute the full offset. The number of symbols in
- * this code is the number of offset slots needed to represent all possible
- * offsets in the uncompressed block. This code must be rebuilt whenever
- * 1024 symbols have been decoded with it.
- *
- * - The length code, used for decoding length symbols. Each of the 54 symbols
- * represents a length slot, which corresponds to a base value and some
- * number of extra bits which must be read and added to the base value to
- * reconstitute the full length. This code must be rebuilt whenever 512
- * symbols have been decoded with it.
- *
- * - The delta offset code, used for decoding the offsets of delta matches.
- * Each symbol corresponds to an offset slot, which corresponds to a base
- * value and some number of extra bits which must be read and added to the
- * base value to reconstitute the full offset. The number of symbols in this
- * code is equal to the number of symbols in the LZ offset code. This code
- * must be rebuilt whenever 1024 symbols have been decoded with it.
- *
- * - The delta power code, used for decoding the powers of delta matches. Each
- * of the 8 symbols corresponds to a power. This code must be rebuilt
- * whenever 512 symbols have been decoded with it.
- *
- * Initially, each Huffman code must be built assuming that each symbol in that
- * code has frequency 1. Following that, each code must be rebuilt each time a
- * certain number of symbols, as noted above, has been decoded with it. The
- * symbol frequencies for a code must be halved after each rebuild of that code;
- * this makes the codes adapt to the more recent data.
- *
- * Like other compression formats such as XPRESS, LZX, and DEFLATE, the LZMS
- * format requires that all Huffman codes be constructed in canonical form.
- * This form requires that same-length codewords be lexicographically ordered
- * the same way as the corresponding symbols and that all shorter codewords
- * lexicographically precede longer codewords. Such a code can be constructed
- * directly from codeword lengths.
- *
- * Even with the canonical code restriction, the same frequencies can be used to
- * construct multiple valid Huffman codes. Therefore, the decompressor needs to
- * construct the right one. Specifically, the LZMS format requires that the
- * Huffman code be constructed as if the well-known priority queue algorithm is
- * used and frequency ties are always broken in favor of leaf nodes.
- *
- * Codewords in LZMS are guaranteed to not exceed 15 bits. The format otherwise
- * places no restrictions on codeword length. Therefore, the Huffman code
- * construction algorithm that a correct LZMS decompressor uses need not
- * implement length-limited code construction. But if it does (e.g. by virtue
- * of being shared among multiple compression algorithms), the details of how it
- * does so are unimportant, provided that the maximum codeword length parameter
- * is set to at least 15 bits.
- *
- * After all LZMS items have been decoded, the data must be postprocessed to
- * translate absolute address encoded in x86 instructions into their original
- * relative addresses.
- *
- * Details omitted above can be found in the code. Note that in the absence of
- * an official specification there is no guarantee that this decompressor
- * handles all possible cases.
- */
-
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
-
-#include "wimlib/compress_common.h"
-#include "wimlib/decompressor_ops.h"
-#include "wimlib/decompress_common.h"
-#include "wimlib/error.h"
-#include "wimlib/lzms.h"
-#include "wimlib/util.h"
-
-/* The TABLEBITS values can be changed; they only affect decoding speed. */
-#define LZMS_LITERAL_TABLEBITS 10
-#define LZMS_LENGTH_TABLEBITS 10
-#define LZMS_LZ_OFFSET_TABLEBITS 10
-#define LZMS_DELTA_OFFSET_TABLEBITS 10
-#define LZMS_DELTA_POWER_TABLEBITS 8
-
-struct lzms_range_decoder {
-
- /* The relevant part of the current range. Although the logical range
- * for range decoding is a very large integer, only a small portion
- * matters at any given time, and it can be normalized (shifted left)
- * whenever it gets too small. */
- u32 range;
-
- /* The current position in the range encoded by the portion of the input
- * read so far. */
- u32 code;
-
- /* Pointer to the next little-endian 16-bit integer in the compressed
- * input data (reading forwards). */
- const le16 *next;
-
- /* Pointer to the end of the compressed input data. */
- const le16 *end;
-};
-
-typedef u64 bitbuf_t;
-
-struct lzms_input_bitstream {
-
- /* Holding variable for bits that have been read from the compressed
- * data. The bit ordering is high to low. */
- bitbuf_t bitbuf;
-
- /* Number of bits currently held in @bitbuf. */
- unsigned bitsleft;
-
- /* Pointer to the one past the next little-endian 16-bit integer in the
- * compressed input data (reading backwards). */
- const le16 *next;
-
- /* Pointer to the beginning of the compressed input data. */
- const le16 *begin;
-};
-
-/* Bookkeeping information for an adaptive Huffman code */
-struct lzms_huffman_rebuild_info {
- unsigned num_syms_until_rebuild;
- unsigned rebuild_freq;
- u16 *decode_table;
- unsigned table_bits;
- u32 *freqs;
- u32 *codewords;
- u8 *lens;
- unsigned num_syms;
-};
-
-struct lzms_decompressor {
-
- /* 'last_target_usages' is in union with everything else because it is
- * only used for postprocessing. */
- union {
- struct {
-
- struct lzms_range_decoder rd;
- struct lzms_input_bitstream is;
-
- /* Match offset LRU queues */
- u32 recent_lz_offsets[LZMS_NUM_RECENT_OFFSETS + 1];
- u64 recent_delta_offsets[LZMS_NUM_RECENT_OFFSETS + 1];
- u32 pending_lz_offset;
- u64 pending_delta_offset;
- const u8 *lz_offset_still_pending;
- const u8 *delta_offset_still_pending;
-
- /* States and probabilities for range decoding */
-
- u32 main_state;
- struct lzms_probability_entry main_prob_entries[
- LZMS_NUM_MAIN_STATES];
-
- u32 match_state;
- struct lzms_probability_entry match_prob_entries[
- LZMS_NUM_MATCH_STATES];
-
- u32 lz_match_state;
- struct lzms_probability_entry lz_match_prob_entries[
- LZMS_NUM_LZ_MATCH_STATES];
-
- u32 delta_match_state;
- struct lzms_probability_entry delta_match_prob_entries[
- LZMS_NUM_DELTA_MATCH_STATES];
-
- u32 lz_repeat_match_states[LZMS_NUM_RECENT_OFFSETS - 1];
- struct lzms_probability_entry lz_repeat_match_prob_entries[
- LZMS_NUM_RECENT_OFFSETS - 1][LZMS_NUM_LZ_REPEAT_MATCH_STATES];
-
- u32 delta_repeat_match_states[LZMS_NUM_RECENT_OFFSETS - 1];
- struct lzms_probability_entry delta_repeat_match_prob_entries[
- LZMS_NUM_RECENT_OFFSETS - 1][LZMS_NUM_DELTA_REPEAT_MATCH_STATES];
-
- /* Huffman decoding */
-
- u16 literal_decode_table[(1 << LZMS_LITERAL_TABLEBITS) +
- (2 * LZMS_NUM_LITERAL_SYMS)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
- u32 literal_freqs[LZMS_NUM_LITERAL_SYMS];
- struct lzms_huffman_rebuild_info literal_rebuild_info;
-
- u16 length_decode_table[(1 << LZMS_LENGTH_TABLEBITS) +
- (2 * LZMS_NUM_LENGTH_SYMS)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
- u32 length_freqs[LZMS_NUM_LENGTH_SYMS];
- struct lzms_huffman_rebuild_info length_rebuild_info;
-
- u16 lz_offset_decode_table[(1 << LZMS_LZ_OFFSET_TABLEBITS) +
- ( 2 * LZMS_MAX_NUM_OFFSET_SYMS)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
- u32 lz_offset_freqs[LZMS_MAX_NUM_OFFSET_SYMS];
- struct lzms_huffman_rebuild_info lz_offset_rebuild_info;
-
- u16 delta_offset_decode_table[(1 << LZMS_DELTA_OFFSET_TABLEBITS) +
- (2 * LZMS_MAX_NUM_OFFSET_SYMS)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
- u32 delta_offset_freqs[LZMS_MAX_NUM_OFFSET_SYMS];
- struct lzms_huffman_rebuild_info delta_offset_rebuild_info;
-
- u16 delta_power_decode_table[(1 << LZMS_DELTA_POWER_TABLEBITS) +
- (2 * LZMS_NUM_DELTA_POWER_SYMS)]
- _aligned_attribute(DECODE_TABLE_ALIGNMENT);
- u32 delta_power_freqs[LZMS_NUM_DELTA_POWER_SYMS];
- struct lzms_huffman_rebuild_info delta_power_rebuild_info;
-
- u32 codewords[LZMS_MAX_NUM_SYMS];
- u8 lens[LZMS_MAX_NUM_SYMS];
-
- }; // struct
-
- s32 last_target_usages[65536];
-
- }; // union
-};
-
-/* Initialize the input bitstream @is to read backwards from the compressed data
- * buffer @in that is @count 16-bit integers long. */
-static void
-lzms_input_bitstream_init(struct lzms_input_bitstream *is,
- const le16 *in, size_t count)
-{
- is->bitbuf = 0;
- is->bitsleft = 0;
- is->next = in + count;
- is->begin = in;
-}
-
-/* Ensure that at least @num_bits bits are in the bitbuffer variable.
- * @num_bits cannot be more than 32. */
-static inline void
-lzms_ensure_bits(struct lzms_input_bitstream *is, unsigned num_bits)
-{
- if (is->bitsleft >= num_bits)
- return;
-
- if (likely(is->next != is->begin))
- is->bitbuf |= (bitbuf_t)le16_to_cpu(*--is->next)
- << (sizeof(is->bitbuf) * 8 - is->bitsleft - 16);
- is->bitsleft += 16;
-
- if (likely(is->next != is->begin))
- is->bitbuf |= (bitbuf_t)le16_to_cpu(*--is->next)
- << (sizeof(is->bitbuf) * 8 - is->bitsleft - 16);
- is->bitsleft += 16;
-}
-
-/* Get @num_bits bits from the bitbuffer variable. */
-static inline bitbuf_t
-lzms_peek_bits(struct lzms_input_bitstream *is, unsigned num_bits)
-{
- if (unlikely(num_bits == 0))
- return 0;
- return is->bitbuf >> (sizeof(is->bitbuf) * 8 - num_bits);
-}
-
-/* Remove @num_bits bits from the bitbuffer variable. */
-static inline void
-lzms_remove_bits(struct lzms_input_bitstream *is, unsigned num_bits)
-{
- is->bitbuf <<= num_bits;
- is->bitsleft -= num_bits;
-}
-
-/* Remove and return @num_bits bits from the bitbuffer variable. */
-static inline bitbuf_t
-lzms_pop_bits(struct lzms_input_bitstream *is, unsigned num_bits)
-{
- bitbuf_t bits = lzms_peek_bits(is, num_bits);
- lzms_remove_bits(is, num_bits);
- return bits;
-}
-
-/* Read @num_bits bits from the input bitstream. */
-static inline bitbuf_t
-lzms_read_bits(struct lzms_input_bitstream *is, unsigned num_bits)
-{
- lzms_ensure_bits(is, num_bits);
- return lzms_pop_bits(is, num_bits);
-}
-
-/* Initialize the range decoder @rd to read forwards from the compressed data
- * buffer @in that is @count 16-bit integers long. */
-static void
-lzms_range_decoder_init(struct lzms_range_decoder *rd,
- const le16 *in, size_t count)
-{
- rd->range = 0xffffffff;
- rd->code = ((u32)le16_to_cpu(in[0]) << 16) | le16_to_cpu(in[1]);
- rd->next = in + 2;
- rd->end = in + count;
-}
-
-/* Decode and return the next bit from the range decoder.
- *
- * @prob is the chance out of LZMS_PROBABILITY_MAX that the next bit is 0.
- */
-static inline int
-lzms_range_decoder_decode_bit(struct lzms_range_decoder *rd, u32 prob)
-{
- u32 bound;
-
- /* Normalize if needed. */
- if (rd->range <= 0xffff) {
- rd->range <<= 16;
- rd->code <<= 16;
- if (likely(rd->next != rd->end))
- rd->code |= le16_to_cpu(*rd->next++);
- }
-
- /* Based on the probability, calculate the bound between the 0-bit
- * region and the 1-bit region of the range. */
- bound = (rd->range >> LZMS_PROBABILITY_BITS) * prob;
-
- if (rd->code < bound) {
- /* Current code is in the 0-bit region of the range. */
- rd->range = bound;
- return 0;
- } else {
- /* Current code is in the 1-bit region of the range. */
- rd->range -= bound;
- rd->code -= bound;
- return 1;
- }
-}
-
-/* Decode and return the next bit from the range decoder. This wraps around
- * lzms_range_decoder_decode_bit() to handle using and updating the appropriate
- * state and probability entry. */
-static inline int
-lzms_range_decode_bit(struct lzms_range_decoder *rd,
- u32 *state_p, u32 num_states,
- struct lzms_probability_entry prob_entries[])
-{
- struct lzms_probability_entry *prob_entry;
- u32 prob;
- int bit;
-
- /* Load the probability entry corresponding to the current state. */
- prob_entry = &prob_entries[*state_p];
-
- /* Get the probability that the next bit is 0. */
- prob = lzms_get_probability(prob_entry);
-
- /* Decode the next bit. */
- bit = lzms_range_decoder_decode_bit(rd, prob);
-
- /* Update the state and probability entry based on the decoded bit. */
- *state_p = ((*state_p << 1) | bit) & (num_states - 1);
- lzms_update_probability_entry(prob_entry, bit);
-
- /* Return the decoded bit. */
- return bit;
-}
-
-static int
-lzms_decode_main_bit(struct lzms_decompressor *d)
-{
- return lzms_range_decode_bit(&d->rd, &d->main_state,
- LZMS_NUM_MAIN_STATES,
- d->main_prob_entries);
-}
-
-static int
-lzms_decode_match_bit(struct lzms_decompressor *d)
-{
- return lzms_range_decode_bit(&d->rd, &d->match_state,
- LZMS_NUM_MATCH_STATES,
- d->match_prob_entries);
-}
-
-static int
-lzms_decode_lz_match_bit(struct lzms_decompressor *d)
-{
- return lzms_range_decode_bit(&d->rd, &d->lz_match_state,
- LZMS_NUM_LZ_MATCH_STATES,
- d->lz_match_prob_entries);
-}
-
-static int
-lzms_decode_delta_match_bit(struct lzms_decompressor *d)
-{
- return lzms_range_decode_bit(&d->rd, &d->delta_match_state,
- LZMS_NUM_DELTA_MATCH_STATES,
- d->delta_match_prob_entries);
-}
-
-static noinline int
-lzms_decode_lz_repeat_match_bit(struct lzms_decompressor *d, int idx)
-{
- return lzms_range_decode_bit(&d->rd, &d->lz_repeat_match_states[idx],
- LZMS_NUM_LZ_REPEAT_MATCH_STATES,
- d->lz_repeat_match_prob_entries[idx]);
-}
-
-static noinline int
-lzms_decode_delta_repeat_match_bit(struct lzms_decompressor *d, int idx)
-{
- return lzms_range_decode_bit(&d->rd, &d->delta_repeat_match_states[idx],
- LZMS_NUM_DELTA_REPEAT_MATCH_STATES,
- d->delta_repeat_match_prob_entries[idx]);
-}
-
-static void
-lzms_init_huffman_rebuild_info(struct lzms_huffman_rebuild_info *info,
- unsigned rebuild_freq,
- u16 *decode_table, unsigned table_bits,
- u32 *freqs, u32 *codewords, u8 *lens,
- unsigned num_syms)
-{
- info->num_syms_until_rebuild = 1;
- info->rebuild_freq = rebuild_freq;
- info->decode_table = decode_table;
- info->table_bits = table_bits;
- info->freqs = freqs;
- info->codewords = codewords;
- info->lens = lens;
- info->num_syms = num_syms;
- lzms_init_symbol_frequencies(freqs, num_syms);
-}
-
-static noinline void
-lzms_rebuild_huffman_code(struct lzms_huffman_rebuild_info *info)
-{
- make_canonical_huffman_code(info->num_syms, LZMS_MAX_CODEWORD_LEN,
- info->freqs, info->lens, info->codewords);
- make_huffman_decode_table(info->decode_table, info->num_syms,
- info->table_bits, info->lens,
- LZMS_MAX_CODEWORD_LEN);
- for (unsigned i = 0; i < info->num_syms; i++)
- info->freqs[i] = (info->freqs[i] >> 1) + 1;
- info->num_syms_until_rebuild = info->rebuild_freq;
-}
-
-static inline unsigned
-lzms_decode_huffman_symbol(struct lzms_input_bitstream *is,
- u16 decode_table[], unsigned table_bits,
- struct lzms_huffman_rebuild_info *rebuild_info)
-{
- unsigned key_bits;
- unsigned entry;
- unsigned sym;
-
- if (unlikely(--rebuild_info->num_syms_until_rebuild == 0))
- lzms_rebuild_huffman_code(rebuild_info);
-
- lzms_ensure_bits(is, LZMS_MAX_CODEWORD_LEN);
-
- /* Index the decode table by the next table_bits bits of the input. */
- key_bits = lzms_peek_bits(is, table_bits);
- entry = decode_table[key_bits];
- if (likely(entry < 0xC000)) {
- /* Fast case: The decode table directly provided the symbol and
- * codeword length. The low 11 bits are the symbol, and the
- * high 5 bits are the codeword length. */
- lzms_remove_bits(is, entry >> 11);
- sym = entry & 0x7FF;
- } else {
- /* Slow case: The codeword for the symbol is longer than
- * table_bits, so the symbol does not have an entry directly in
- * the first (1 << table_bits) entries of the decode table.
- * Traverse the appropriate binary tree bit-by-bit in order to
- * decode the symbol. */
- lzms_remove_bits(is, table_bits);
- do {
- key_bits = (entry & 0x3FFF) + lzms_pop_bits(is, 1);
- } while ((entry = decode_table[key_bits]) >= 0xC000);
- sym = entry;
- }
-
- /* Tally and return the decoded symbol. */
- rebuild_info->freqs[sym]++;
- return sym;
-}
-
-static unsigned
-lzms_decode_literal(struct lzms_decompressor *d)
-{
- return lzms_decode_huffman_symbol(&d->is,
- d->literal_decode_table,
- LZMS_LITERAL_TABLEBITS,
- &d->literal_rebuild_info);
-}
-
-static u32
-lzms_decode_length(struct lzms_decompressor *d)
-{
- unsigned slot = lzms_decode_huffman_symbol(&d->is,
- d->length_decode_table,
- LZMS_LENGTH_TABLEBITS,
- &d->length_rebuild_info);
- u32 length = lzms_length_slot_base[slot];
- unsigned num_extra_bits = lzms_extra_length_bits[slot];
- /* Usually most lengths are short and have no extra bits. */
- if (num_extra_bits)
- length += lzms_read_bits(&d->is, num_extra_bits);
- return length;
-}
-
-static u32
-lzms_decode_lz_offset(struct lzms_decompressor *d)
-{
- unsigned slot = lzms_decode_huffman_symbol(&d->is,
- d->lz_offset_decode_table,
- LZMS_LZ_OFFSET_TABLEBITS,
- &d->lz_offset_rebuild_info);
- return lzms_offset_slot_base[slot] +
- lzms_read_bits(&d->is, lzms_extra_offset_bits[slot]);
-}
-
-static u32
-lzms_decode_delta_offset(struct lzms_decompressor *d)
-{
- unsigned slot = lzms_decode_huffman_symbol(&d->is,
- d->delta_offset_decode_table,
- LZMS_DELTA_OFFSET_TABLEBITS,
- &d->delta_offset_rebuild_info);
- return lzms_offset_slot_base[slot] +
- lzms_read_bits(&d->is, lzms_extra_offset_bits[slot]);
-}
-
-static unsigned
-lzms_decode_delta_power(struct lzms_decompressor *d)
-{
- return lzms_decode_huffman_symbol(&d->is,
- d->delta_power_decode_table,
- LZMS_DELTA_POWER_TABLEBITS,
- &d->delta_power_rebuild_info);
-}
-
-/* Decode the series of literals and matches from the LZMS-compressed data.
- * Return 0 if successful or -1 if the compressed data is invalid. */
-static int
-lzms_decode_items(struct lzms_decompressor * const restrict d,
- u8 * const restrict out, const size_t out_nbytes)
-{
- u8 *out_next = out;
- u8 * const out_end = out + out_nbytes;
-
- while (out_next != out_end) {
-
- if (!lzms_decode_main_bit(d)) {
-
- /* Literal */
- *out_next++ = lzms_decode_literal(d);
-
- } else if (!lzms_decode_match_bit(d)) {
-
- /* LZ match */
-
- u32 offset;
- u32 length;
-
- if (d->pending_lz_offset != 0 &&
- out_next != d->lz_offset_still_pending)
- {
- BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3);
- d->recent_lz_offsets[3] = d->recent_lz_offsets[2];
- d->recent_lz_offsets[2] = d->recent_lz_offsets[1];
- d->recent_lz_offsets[1] = d->recent_lz_offsets[0];
- d->recent_lz_offsets[0] = d->pending_lz_offset;
- d->pending_lz_offset = 0;
- }
-
- if (!lzms_decode_lz_match_bit(d)) {
- /* Explicit offset */
- offset = lzms_decode_lz_offset(d);
- } else {
- /* Repeat offset */
-
- BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3);
- if (!lzms_decode_lz_repeat_match_bit(d, 0)) {
- offset = d->recent_lz_offsets[0];
- d->recent_lz_offsets[0] = d->recent_lz_offsets[1];
- d->recent_lz_offsets[1] = d->recent_lz_offsets[2];
- d->recent_lz_offsets[2] = d->recent_lz_offsets[3];
- } else if (!lzms_decode_lz_repeat_match_bit(d, 1)) {
- offset = d->recent_lz_offsets[1];
- d->recent_lz_offsets[1] = d->recent_lz_offsets[2];
- d->recent_lz_offsets[2] = d->recent_lz_offsets[3];
- } else {
- offset = d->recent_lz_offsets[2];
- d->recent_lz_offsets[2] = d->recent_lz_offsets[3];
- }
- }
-
- if (d->pending_lz_offset != 0) {
- BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3);
- d->recent_lz_offsets[3] = d->recent_lz_offsets[2];
- d->recent_lz_offsets[2] = d->recent_lz_offsets[1];
- d->recent_lz_offsets[1] = d->recent_lz_offsets[0];
- d->recent_lz_offsets[0] = d->pending_lz_offset;
- }
- d->pending_lz_offset = offset;
-
- length = lzms_decode_length(d);
-
- if (unlikely(length > out_end - out_next))
- return -1;
- if (unlikely(offset > out_next - out))
- return -1;
-
- lz_copy(out_next, length, offset, out_end, LZMS_MIN_MATCH_LEN);
- out_next += length;
-
- d->lz_offset_still_pending = out_next;
- } else {
- /* Delta match */
-
- u32 power;
- u32 raw_offset, offset1, offset2, offset;
- const u8 *matchptr1, *matchptr2, *matchptr;
- u32 length;
-
- if (d->pending_delta_offset != 0 &&
- out_next != d->delta_offset_still_pending)
- {
- BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3);
- d->recent_delta_offsets[3] = d->recent_delta_offsets[2];
- d->recent_delta_offsets[2] = d->recent_delta_offsets[1];
- d->recent_delta_offsets[1] = d->recent_delta_offsets[0];
- d->recent_delta_offsets[0] = d->pending_delta_offset;
- d->pending_delta_offset = 0;
- }
-
- if (!lzms_decode_delta_match_bit(d)) {
- /* Explicit offset */
- power = lzms_decode_delta_power(d);
- raw_offset = lzms_decode_delta_offset(d);
- } else {
- /* Repeat offset */
- u64 val;
-
- BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3);
- if (!lzms_decode_delta_repeat_match_bit(d, 0)) {
- val = d->recent_delta_offsets[0];
- d->recent_delta_offsets[0] = d->recent_delta_offsets[1];
- d->recent_delta_offsets[1] = d->recent_delta_offsets[2];
- d->recent_delta_offsets[2] = d->recent_delta_offsets[3];
- } else if (!lzms_decode_delta_repeat_match_bit(d, 1)) {
- val = d->recent_delta_offsets[1];
- d->recent_delta_offsets[1] = d->recent_delta_offsets[2];
- d->recent_delta_offsets[2] = d->recent_delta_offsets[3];
- } else {
- val = d->recent_delta_offsets[2];
- d->recent_delta_offsets[2] = d->recent_delta_offsets[3];
- }
- power = val >> 32;
- raw_offset = (u32)val;
- }
-
- if (d->pending_delta_offset != 0) {
- BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3);
- d->recent_delta_offsets[3] = d->recent_delta_offsets[2];
- d->recent_delta_offsets[2] = d->recent_delta_offsets[1];
- d->recent_delta_offsets[1] = d->recent_delta_offsets[0];
- d->recent_delta_offsets[0] = d->pending_delta_offset;
- d->pending_delta_offset = 0;
- }
- d->pending_delta_offset = raw_offset | ((u64)power << 32);
-
- length = lzms_decode_length(d);
-
- offset1 = (u32)1 << power;
- offset2 = raw_offset << power;
- offset = offset1 + offset2;
-
- /* raw_offset<<power overflowed? */
- if (unlikely((offset2 >> power) != raw_offset))
- return -1;
-
- /* offset1+offset2 overflowed? */
- if (unlikely(offset < offset2))
- return -1;
-
- if (unlikely(length > out_end - out_next))
- return -1;
-
- if (unlikely(offset > out_next - out))
- return -1;
-
- matchptr1 = out_next - offset1;
- matchptr2 = out_next - offset2;
- matchptr = out_next - offset;
-
- do {
- *out_next++ = *matchptr1++ + *matchptr2++ - *matchptr++;
- } while (--length);
-
- d->delta_offset_still_pending = out_next;
- }
- }
- return 0;
-}
-
-static void
-lzms_init_decompressor(struct lzms_decompressor *d, const void *in,
- size_t in_nbytes, unsigned num_offset_slots)
-{
- /* Match offset LRU queues */
- for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS + 1; i++) {
- d->recent_lz_offsets[i] = i + 1;
- d->recent_delta_offsets[i] = i + 1;
- }
- d->pending_lz_offset = 0;
- d->pending_delta_offset = 0;
-
- /* Range decoding */
-
- lzms_range_decoder_init(&d->rd, in, in_nbytes / sizeof(le16));
-
- d->main_state = 0;
- lzms_init_probability_entries(d->main_prob_entries, LZMS_NUM_MAIN_STATES);
-
- d->match_state = 0;
- lzms_init_probability_entries(d->match_prob_entries, LZMS_NUM_MATCH_STATES);
-
- d->lz_match_state = 0;
- lzms_init_probability_entries(d->lz_match_prob_entries, LZMS_NUM_LZ_MATCH_STATES);
-
- d->delta_match_state = 0;
- lzms_init_probability_entries(d->delta_match_prob_entries, LZMS_NUM_DELTA_MATCH_STATES);
-
- for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++) {
- d->lz_repeat_match_states[i] = 0;
- lzms_init_probability_entries(d->lz_repeat_match_prob_entries[i],
- LZMS_NUM_LZ_REPEAT_MATCH_STATES);
-
- d->delta_repeat_match_states[i] = 0;
- lzms_init_probability_entries(d->delta_repeat_match_prob_entries[i],
- LZMS_NUM_DELTA_REPEAT_MATCH_STATES);
- }
-
- /* Huffman decoding */
-
- lzms_input_bitstream_init(&d->is, in, in_nbytes / sizeof(le16));
-
- lzms_init_huffman_rebuild_info(&d->literal_rebuild_info,
- LZMS_LITERAL_CODE_REBUILD_FREQ,
- d->literal_decode_table,
- LZMS_LITERAL_TABLEBITS,
- d->literal_freqs,
- d->codewords,
- d->lens,
- LZMS_NUM_LITERAL_SYMS);
-
- lzms_init_huffman_rebuild_info(&d->length_rebuild_info,
- LZMS_LENGTH_CODE_REBUILD_FREQ,
- d->length_decode_table,
- LZMS_LENGTH_TABLEBITS,
- d->length_freqs,
- d->codewords,
- d->lens,
- LZMS_NUM_LENGTH_SYMS);
-
- lzms_init_huffman_rebuild_info(&d->lz_offset_rebuild_info,
- LZMS_LZ_OFFSET_CODE_REBUILD_FREQ,
- d->lz_offset_decode_table,
- LZMS_LZ_OFFSET_TABLEBITS,
- d->lz_offset_freqs,
- d->codewords,
- d->lens,
- num_offset_slots);
-
- lzms_init_huffman_rebuild_info(&d->delta_offset_rebuild_info,
- LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ,
- d->delta_offset_decode_table,
- LZMS_DELTA_OFFSET_TABLEBITS,
- d->delta_offset_freqs,
- d->codewords,
- d->lens,
- num_offset_slots);
-
- lzms_init_huffman_rebuild_info(&d->delta_power_rebuild_info,
- LZMS_DELTA_POWER_CODE_REBUILD_FREQ,
- d->delta_power_decode_table,
- LZMS_DELTA_POWER_TABLEBITS,
- d->delta_power_freqs,
- d->codewords,
- d->lens,
- LZMS_NUM_DELTA_POWER_SYMS);
-}
-
-static int
-lzms_create_decompressor(size_t max_bufsize, void **d_ret)
-{
- struct lzms_decompressor *d;
-
- if (max_bufsize > LZMS_MAX_BUFFER_SIZE)
- return WIMLIB_ERR_INVALID_PARAM;
-
- d = ALIGNED_MALLOC(sizeof(struct lzms_decompressor),
- DECODE_TABLE_ALIGNMENT);
- if (!d)
- return WIMLIB_ERR_NOMEM;
-
- *d_ret = d;
- return 0;
-}
-
-/* Decompress @in_nbytes bytes of LZMS-compressed data at @in and write the
- * uncompressed data, which had original size @out_nbytes, to @out. Return 0 if
- * successful or -1 if the compressed data is invalid. */
-static int
-lzms_decompress(const void *in, size_t in_nbytes, void *out, size_t out_nbytes,
- void *_d)
-{
- struct lzms_decompressor *d = _d;
-
- /*
- * Requirements on the compressed data:
- *
- * 1. LZMS-compressed data is a series of 16-bit integers, so the
- * compressed data buffer cannot take up an odd number of bytes.
- * 2. To prevent poor performance on some architectures, we require that
- * the compressed data buffer is 2-byte aligned.
- * 3. There must be at least 4 bytes of compressed data, since otherwise
- * we cannot even initialize the range decoder.
- */
- if ((in_nbytes & 1) || ((uintptr_t)in & 1) || (in_nbytes < 4))
- return -1;
-
- lzms_init_decompressor(d, in, in_nbytes,
- lzms_get_num_offset_slots(out_nbytes));
-
- if (lzms_decode_items(d, out, out_nbytes))
- return -1;
-
- lzms_x86_filter(out, out_nbytes, d->last_target_usages, true);
- return 0;
-}
-
-static void
-lzms_free_decompressor(void *_d)
-{
- struct lzms_decompressor *d = _d;
-
- ALIGNED_FREE(d);
-}
-
-const struct decompressor_ops lzms_decompressor_ops = {
- .create_decompressor = lzms_create_decompressor,
- .decompress = lzms_decompress,
- .free_decompressor = lzms_free_decompressor,
-};
git://wimlib.net / wimlib / blobdiff