X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Flzms-compress.c;h=5a2e3ed5a1e0453041e2c93568bd74b8c3b0a48a;hb=027518fa61bd9232ff7fa7ecd270546d920c912f;hp=3c34b52c807f32ac61006bf35464569f58c80e86;hpb=dabaf1184dfd9581804da2a14fa3617ef61a3e06;p=wimlib diff --git a/src/lzms-compress.c b/src/lzms-compress.c index 3c34b52c..5a2e3ed5 100644 --- a/src/lzms-compress.c +++ b/src/lzms-compress.c @@ -1,7 +1,5 @@ /* * lzms-compress.c - * - * A compressor for the LZMS compression format. */ /* @@ -24,7 +22,11 @@ */ /* This a compressor for the LZMS compression format. More details about this - * format can be found in lzms-decompress.c. */ + * format can be found in lzms-decompress.c. + * + * This is currently an unsophisticated implementation that is fast but does not + * attain the best compression ratios allowed by the format. + */ #ifdef HAVE_CONFIG_H # include "config.h" @@ -32,42 +34,901 @@ #include "wimlib.h" #include "wimlib/assert.h" +#include "wimlib/compiler.h" #include "wimlib/compressor_ops.h" #include "wimlib/compress_common.h" #include "wimlib/endianness.h" #include "wimlib/error.h" +#include "wimlib/lz_hash.h" +#include "wimlib/lz_sarray.h" #include "wimlib/lzms.h" #include "wimlib/util.h" #include +#include + +/* 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 { + /* Buffer variable containing zero or more bits that have been logically + * written to the bitstream but not yet written to memory. This must be + * at least as large as the coding unit size. */ + u16 bitbuf; + + /* Number of bits in @bitbuf that are valid. */ + unsigned num_free_bits; + + /* Pointer to one past the next position in the compressed data buffer + * at which to output a 16-bit coding unit. */ + le16 *out; + + /* Maximum number of 16-bit coding units that can still be output to + * the compressed data buffer. */ + size_t num_le16_remaining; + + /* Set to %true if not all coding units could be output due to + * insufficient space. */ + bool overrun; +}; + +/* Stucture used for range encoding (raw version). */ +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 next position in the compressed data buffer at which + * to output a 16-bit coding unit. */ + le16 *out; + + /* Maximum number of 16-bit coding units that can still be output to + * the compressed data buffer. */ + size_t num_le16_remaining; + + /* %true when the very first coding unit has not yet been output. */ + bool first; + + /* Set to %true if not all coding units could be output due to + * insufficient space. */ + bool overrun; +}; + +/* 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 are used as in + * 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, optionally encoding larger "values" as a + * Huffman symbol specifying a slot and a slot-dependent number of extra bits. + * */ +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; + + /* Pointer to the slot base table to use. */ + const u32 *slot_base_tab; + + /* 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. */ + u16 codewords[LZMS_MAX_NUM_SYMS]; +}; +/* State of the LZMS compressor. */ struct lzms_compressor { + /* Pointer to a buffer holding the preprocessed data to compress. */ u8 *window; + + /* Current position in @buffer. */ + u32 cur_window_pos; + + /* Size of the data in @buffer. */ u32 window_size; + + /* Temporary array used by lz_analyze_block(); must be at least as long + * as the window. */ + u32 *prev_tab; + + /* Suffix array match-finder. */ + struct lz_sarray lz_sarray; + + /* Maximum block size this compressor instantiation allows. This is the + * allocated size of @window. */ u32 max_block_size; - s32 *last_target_usages; + + /* 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; + + /* LRU (least-recently-used) queues for match information. */ + struct lzms_lru_queues lru; + + /* Used for preprocessing. */ + s32 last_target_usages[65536]; }; +/* 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_output_bitstream_init(struct lzms_output_bitstream *os, + le16 *out, size_t out_limit) +{ + os->bitbuf = 0; + os->num_free_bits = 16; + os->out = out + out_limit; + os->num_le16_remaining = out_limit; + os->overrun = false; +} + +/* Write @num_bits bits, contained in the low @num_bits bits of @bits (ordered + * from high-order to low-order), to the output bitstream @os. */ +static void +lzms_output_bitstream_put_bits(struct lzms_output_bitstream *os, + u32 bits, unsigned num_bits) +{ + bits &= (1U << num_bits) - 1; + + while (num_bits > os->num_free_bits) { + + if (unlikely(os->num_le16_remaining == 0)) { + os->overrun = true; + return; + } + + unsigned num_fill_bits = os->num_free_bits; + + os->bitbuf <<= num_fill_bits; + os->bitbuf |= bits >> (num_bits - num_fill_bits); + + *--os->out = cpu_to_le16(os->bitbuf); + --os->num_le16_remaining; + + os->num_free_bits = 16; + num_bits -= num_fill_bits; + bits &= (1U << num_bits) - 1; + } + os->bitbuf <<= num_bits; + os->bitbuf |= bits; + os->num_free_bits -= num_bits; +} + +/* Flush the output bitstream, ensuring that all bits written to it have been + * written to memory. Returns %true if all bits were output successfully, or + * %false if an overrun occurred. */ +static bool +lzms_output_bitstream_flush(struct lzms_output_bitstream *os) +{ + if (os->num_free_bits != 16) + lzms_output_bitstream_put_bits(os, 0, os->num_free_bits + 1); + return !os->overrun; +} + +/* 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->out = out; + rc->num_le16_remaining = out_limit; + rc->first = true; + rc->overrun = false; +} + +/* + * 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) +{ + LZMS_DEBUG("low=%"PRIx64", cache=%"PRIx64", cache_size=%u", + rc->low, rc->cache, rc->cache_size); + 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 (!rc->first) { + if (rc->num_le16_remaining == 0) { + rc->overrun = true; + return; + } + *rc->out++ = cpu_to_le16(rc->cache + + (u16)(rc->low >> 32)); + --rc->num_le16_remaining; + } else { + rc->first = false; + } + + 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_range_encoder_raw_normalize(struct lzms_range_encoder_raw *rc) +{ + 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->overrun; +} + +/* 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 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 probability table. */ +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]; + + /* Treat the number of zero bits in the most recently encoded + * LZMS_PROBABILITY_MAX bits with this probability entry as the chance, + * out of LZMS_PROBABILITY_MAX, that the next bit will be a 0. However, + * don't allow 0% or 100% probabilities. */ + prob = prob_entry->num_recent_zero_bits; + if (prob == 0) + prob = 1; + else if (prob == LZMS_PROBABILITY_MAX) + prob = LZMS_PROBABILITY_MAX - 1; + + /* Encode the next bit. */ + lzms_range_encoder_raw_encode_bit(enc->rc, bit, prob); + + /* Update the state based on the newly encoded bit. */ + enc->state = ((enc->state << 1) | bit) & enc->mask; + + /* Update the recent bits, including the cached count of 0's. */ + BUILD_BUG_ON(LZMS_PROBABILITY_MAX > sizeof(prob_entry->recent_bits) * 8); + if (bit == 0) { + if (prob_entry->recent_bits & (1ULL << (LZMS_PROBABILITY_MAX - 1))) { + /* Replacing 1 bit with 0 bit; increment the zero count. + */ + prob_entry->num_recent_zero_bits++; + } + } else { + if (!(prob_entry->recent_bits & (1ULL << (LZMS_PROBABILITY_MAX - 1)))) { + /* Replacing 0 bit with 1 bit; decrement the zero count. + */ + prob_entry->num_recent_zero_bits--; + } + } + prob_entry->recent_bits = (prob_entry->recent_bits << 1) | bit; +} + +/* Encode a symbol using the specified Huffman encoder. */ +static void +lzms_huffman_encode_symbol(struct lzms_huffman_encoder *enc, u32 sym) +{ + LZMS_ASSERT(sym < enc->num_syms); + if (enc->num_syms_written == enc->rebuild_freq) { + /* Adaptive code needs to be rebuilt. */ + LZMS_DEBUG("Rebuilding code (num_syms=%u)", enc->num_syms); + 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; + } + lzms_output_bitstream_put_bits(enc->os, + enc->codewords[sym], + enc->lens[sym]); + ++enc->num_syms_written; + ++enc->sym_freqs[sym]; +} + +/* Encode a number as a Huffman symbol specifying a slot, plus a number of + * slot-dependent extra bits. */ +static void +lzms_encode_value(struct lzms_huffman_encoder *enc, u32 value) +{ + unsigned slot; + unsigned num_extra_bits; + u32 extra_bits; + + LZMS_ASSERT(enc->slot_base_tab != NULL); + + slot = lzms_get_slot(value, enc->slot_base_tab, enc->num_syms); + + /* Get the number of extra bits needed to represent the range of values + * that share the slot. */ + num_extra_bits = bsr32(enc->slot_base_tab[slot + 1] - + enc->slot_base_tab[slot]); + + /* Calculate the extra bits as the offset from the slot base. */ + extra_bits = value - enc->slot_base_tab[slot]; + + /* Output the slot (Huffman-encoded), then the extra bits (verbatim). + */ + lzms_huffman_encode_symbol(enc, slot); + lzms_output_bitstream_put_bits(enc->os, extra_bits, num_extra_bits); +} + +static void +lzms_begin_encode_item(struct lzms_compressor *ctx) +{ + ctx->lru.lz.upcoming_offset = 0; + ctx->lru.delta.upcoming_offset = 0; + ctx->lru.delta.upcoming_power = 0; +} + +static void +lzms_end_encode_item(struct lzms_compressor *ctx, u32 length) +{ + LZMS_ASSERT(ctx->window_size - ctx->cur_window_pos >= length); + ctx->cur_window_pos += length; + lzms_update_lru_queues(&ctx->lru); +} + +/* Encode a literal byte. */ +static void +lzms_encode_literal(struct lzms_compressor *ctx, u8 literal) +{ + LZMS_DEBUG("Position %u: Encoding literal 0x%02x ('%c')", + ctx->cur_window_pos, literal, literal); + + lzms_begin_encode_item(ctx); + + /* Main bit: 0 = a literal, not a match. */ + lzms_range_encode_bit(&ctx->main_range_encoder, 0); + + /* Encode the literal using the current literal Huffman code. */ + lzms_huffman_encode_symbol(&ctx->literal_encoder, literal); + + lzms_end_encode_item(ctx, 1); +} + +/* Encode a (length, offset) pair (LZ match). */ +static void +lzms_encode_lz_match(struct lzms_compressor *ctx, u32 length, u32 offset) +{ + int recent_offset_idx; + + lzms_begin_encode_item(ctx); + + LZMS_DEBUG("Position %u: Encoding LZ match {length=%u, offset=%u}", + ctx->cur_window_pos, length, offset); + + /* Main bit: 1 = a match, not a literal. */ + lzms_range_encode_bit(&ctx->main_range_encoder, 1); + + /* Match bit: 0 = a LZ match, not a delta match. */ + lzms_range_encode_bit(&ctx->match_range_encoder, 0); + + /* Determine if the offset can be represented as a recent offset. */ + for (recent_offset_idx = 0; + recent_offset_idx < LZMS_NUM_RECENT_OFFSETS; + recent_offset_idx++) + if (offset == ctx->lru.lz.recent_offsets[recent_offset_idx]) + break; + + if (recent_offset_idx == LZMS_NUM_RECENT_OFFSETS) { + /* Explicit offset. */ + + /* LZ match bit: 0 = explicit offset, not a repeat offset. */ + lzms_range_encode_bit(&ctx->lz_match_range_encoder, 0); + + /* Encode the match offset. */ + lzms_encode_value(&ctx->lz_offset_encoder, offset); + } else { + int i; + + /* Repeat offset. */ + + /* LZ match bit: 1 = repeat offset, not an explicit offset. */ + lzms_range_encode_bit(&ctx->lz_match_range_encoder, 1); + + /* Encode the recent 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 < recent_offset_idx; i++) + lzms_range_encode_bit(&ctx->lz_repeat_match_range_encoders[i], 1); + + if (i < LZMS_NUM_RECENT_OFFSETS - 1) + lzms_range_encode_bit(&ctx->lz_repeat_match_range_encoders[i], 0); + + /* Initial update of the LZ match offset LRU queue. */ + for (; i < LZMS_NUM_RECENT_OFFSETS; i++) + ctx->lru.lz.recent_offsets[i] = ctx->lru.lz.recent_offsets[i + 1]; + } + + /* Encode the match length. */ + lzms_encode_value(&ctx->length_encoder, length); + + /* Save the match offset for later insertion at the front of the LZ + * match offset LRU queue. */ + ctx->lru.lz.upcoming_offset = offset; + + lzms_end_encode_item(ctx, length); +} + +static void +lzms_record_literal(u8 literal, void *_ctx) +{ + struct lzms_compressor *ctx = _ctx; + + lzms_encode_literal(ctx, literal); +} + +static void +lzms_record_match(unsigned length, unsigned offset, void *_ctx) +{ + struct lzms_compressor *ctx = _ctx; + + lzms_encode_lz_match(ctx, length, offset); +} + +static void +lzms_fast_encode(struct lzms_compressor *ctx) +{ + static const struct lz_params lzms_lz_params = { + .min_match = 3, + .max_match = UINT_MAX, + .max_offset = UINT_MAX, + .nice_match = 64, + .good_match = 32, + .max_chain_len = 64, + .max_lazy_match = 258, + .too_far = 4096, + }; + + lz_analyze_block(ctx->window, + ctx->window_size, + lzms_record_match, + lzms_record_literal, + ctx, + &lzms_lz_params, + ctx->prev_tab); + +} + +/* Fast heuristic cost evaluation to use in the inner loop of the match-finder. + * Unlike lzms_match_cost() which does a true cost evaluation, this simply + * prioritize matches based on their offset. */ +static input_idx_t +lzms_match_cost_fast(input_idx_t length, input_idx_t offset, const void *_lru) +{ + const struct lzms_lz_lru_queues *lru = _lru; + + + /* It seems well worth it to take the time to give priority to recently + * used offsets. */ + for (input_idx_t i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++) + if (offset == lru->recent_offsets[i]) + return i; + + return offset; +} + +static void +lzms_lz_skip_bytes(struct lzms_compressor *ctx, u32 n) +{ + while (n--) + lz_sarray_skip_position(&ctx->lz_sarray); +} + +static struct raw_match +lzms_get_near_optimal_match(struct lzms_compressor *ctx) +{ + struct raw_match matches[10]; + u32 num_matches; + + num_matches = lz_sarray_get_matches(&ctx->lz_sarray, + matches, + lzms_match_cost_fast, + &ctx->lru.lz); + if (num_matches == 0) + return (struct raw_match) { .len = 0 }; + +#if 0 + fprintf(stderr, "Pos %u/%u: %u matches\n", + lz_sarray_get_pos(&ctx->lz_sarray) - 1, + ctx->window_size, num_matches); + for (u32 i = 0; i < num_matches; i++) + fprintf(stderr, "\tLen %u Offset %u\n", matches[i].len, matches[i].offset); +#endif + + lzms_lz_skip_bytes(ctx, matches[0].len - 1); + return matches[0]; +} + +static void +lzms_slow_encode(struct lzms_compressor *ctx) +{ + struct raw_match match; + + /* Load window into suffix array match-finder. */ + lz_sarray_load_window(&ctx->lz_sarray, ctx->window, ctx->window_size); + + /* TODO */ + while (ctx->cur_window_pos != ctx->window_size) { + + match = lzms_get_near_optimal_match(ctx); + if (match.len == 0) { + /* Literal */ + lzms_encode_literal(ctx, ctx->window[ctx->cur_window_pos]); + } else { + /* LZ match */ + lzms_encode_lz_match(ctx, match.len, match.offset); + } + } +} + +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; + 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, + const u32 *slot_base_tab, + unsigned num_syms, + unsigned rebuild_freq) +{ + enc->os = os; + enc->slot_base_tab = slot_base_tab; + enc->num_syms_written = rebuild_freq; + enc->rebuild_freq = rebuild_freq; + enc->num_syms = num_syms; + for (unsigned i = 0; i < num_syms; i++) + enc->sym_freqs[i] = 1; +} + +/* Initialize the LZMS compressor. */ +static void +lzms_init_compressor(struct lzms_compressor *ctx, const u8 *udata, u32 ulen, + le16 *cdata, u32 clen16) +{ + unsigned num_position_slots; + + /* Copy the uncompressed data into the @ctx->window buffer. */ + memcpy(ctx->window, udata, ulen); + memset(&ctx->window[ulen], 0, 8); + ctx->cur_window_pos = 0; + ctx->window_size = ulen; + + /* Initialize the raw range encoder (writing forwards). */ + lzms_range_encoder_raw_init(&ctx->rc, cdata, clen16); + + /* Initialize the output bitstream for Huffman symbols and verbatim bits + * (writing backwards). */ + lzms_output_bitstream_init(&ctx->os, cdata, clen16); + + /* Initialize position and length slot bases if not done already. */ + lzms_init_slot_bases(); + + /* Calculate the number of position slots needed for this compressed + * block. */ + num_position_slots = lzms_get_position_slot(ulen - 1) + 1; + + LZMS_DEBUG("Using %u position slots", num_position_slots); + + /* Initialize Huffman encoders for each alphabet used in the compressed + * representation. */ + lzms_init_huffman_encoder(&ctx->literal_encoder, &ctx->os, + NULL, LZMS_NUM_LITERAL_SYMS, + LZMS_LITERAL_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->lz_offset_encoder, &ctx->os, + lzms_position_slot_base, num_position_slots, + LZMS_LZ_OFFSET_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->length_encoder, &ctx->os, + lzms_length_slot_base, LZMS_NUM_LEN_SYMS, + LZMS_LENGTH_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->delta_offset_encoder, &ctx->os, + lzms_position_slot_base, num_position_slots, + LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->delta_power_encoder, &ctx->os, + NULL, 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(&ctx->main_range_encoder, + &ctx->rc, LZMS_NUM_MAIN_STATES); + + lzms_init_range_encoder(&ctx->match_range_encoder, + &ctx->rc, LZMS_NUM_MATCH_STATES); + + lzms_init_range_encoder(&ctx->lz_match_range_encoder, + &ctx->rc, LZMS_NUM_LZ_MATCH_STATES); + + for (size_t i = 0; i < ARRAY_LEN(ctx->lz_repeat_match_range_encoders); i++) + lzms_init_range_encoder(&ctx->lz_repeat_match_range_encoders[i], + &ctx->rc, LZMS_NUM_LZ_REPEAT_MATCH_STATES); + + lzms_init_range_encoder(&ctx->delta_match_range_encoder, + &ctx->rc, LZMS_NUM_DELTA_MATCH_STATES); + + for (size_t i = 0; i < ARRAY_LEN(ctx->delta_repeat_match_range_encoders); i++) + lzms_init_range_encoder(&ctx->delta_repeat_match_range_encoders[i], + &ctx->rc, LZMS_NUM_DELTA_REPEAT_MATCH_STATES); + + /* Initialize LRU match information. */ + lzms_init_lru_queues(&ctx->lru); +} + +/* 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 *ctx, u8 *cdata, size_t csize_avail) +{ + size_t num_forwards_bytes; + size_t num_backwards_bytes; + size_t compressed_size; + + /* 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(&ctx->os)) { + LZMS_DEBUG("Backwards bitstream overrun."); + return 0; + } + + if (!lzms_range_encoder_raw_flush(&ctx->rc)) { + LZMS_DEBUG("Forwards bitstream overrun."); + return 0; + } + + if (ctx->rc.out > ctx->os.out) { + LZMS_DEBUG("Two bitstreams crossed."); + 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 forwards bitstream to be + * adjacent to the data output by the backwards bitstream, and calculate + * the compressed size that this results in. */ + num_forwards_bytes = (u8*)ctx->rc.out - (u8*)cdata; + num_backwards_bytes = ((u8*)cdata + csize_avail) - (u8*)ctx->os.out; + + memmove(cdata + num_forwards_bytes, ctx->os.out, num_backwards_bytes); + + compressed_size = num_forwards_bytes + num_backwards_bytes; + LZMS_DEBUG("num_forwards_bytes=%zu, num_backwards_bytes=%zu, " + "compressed_size=%zu", + num_forwards_bytes, num_backwards_bytes, compressed_size); + LZMS_ASSERT(!(compressed_size & 1)); + return compressed_size; +} + static size_t lzms_compress(const void *uncompressed_data, size_t uncompressed_size, void *compressed_data, size_t compressed_size_avail, void *_ctx) { struct lzms_compressor *ctx = _ctx; + size_t compressed_size; + LZMS_DEBUG("uncompressed_size=%zu, compressed_size_avail=%zu", + uncompressed_size, compressed_size_avail); + + /* Make sure the uncompressed size is compatible with this compressor. + */ if (uncompressed_size > ctx->max_block_size) { - LZMS_DEBUG("Can't compress %su bytes: LZMS context " + LZMS_DEBUG("Can't compress %zu bytes: LZMS context " "only supports %u bytes", uncompressed_size, ctx->max_block_size); return 0; } - memcpy(ctx->window, uncompressed_data, uncompressed_size); - ctx->window_size = uncompressed_size; + /* 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_init_compressor(ctx, uncompressed_data, uncompressed_size, + compressed_data, compressed_size_avail / 2); + /* Preprocess the uncompressed data. */ lzms_x86_filter(ctx->window, ctx->window_size, ctx->last_target_usages, false); - return 0; + /* Determine and output a literal/match sequence that decompresses to + * the preprocessed data. */ + if (1) + lzms_slow_encode(ctx); + else + lzms_fast_encode(ctx); + + /* Get and return the compressed data size. */ + compressed_size = lzms_finalize(ctx, compressed_data, + compressed_size_avail); + + if (compressed_size == 0) { + LZMS_DEBUG("Data did not compress to requested size or less."); + return 0; + } + + LZMS_DEBUG("Compressed %zu => %zu bytes", + uncompressed_size, compressed_size); + +#if defined(ENABLE_VERIFY_COMPRESSION) || defined(ENABLE_LZMS_DEBUG) + /* Verify that we really get the same thing back when decompressing. */ + { + struct wimlib_decompressor *decompressor; + + LZMS_DEBUG("Verifying LZMS compression."); + + if (0 == wimlib_create_decompressor(WIMLIB_COMPRESSION_TYPE_LZMS, + ctx->max_block_size, + NULL, + &decompressor)) + { + int ret; + ret = wimlib_decompress(compressed_data, + compressed_size, + ctx->window, + uncompressed_size, + decompressor); + wimlib_free_decompressor(decompressor); + + if (ret) { + ERROR("Failed to decompress data we " + "compressed using LZMS algorithm"); + wimlib_assert(0); + return 0; + } + if (memcmp(uncompressed_data, ctx->window, + uncompressed_size)) + { + ERROR("Data we compressed using LZMS algorithm " + "didn't decompress to original"); + wimlib_assert(0); + return 0; + } + } else { + WARNING("Failed to create decompressor for " + "data verification!"); + } + } +#endif /* ENABLE_LZMS_DEBUG || ENABLE_VERIFY_COMPRESSION */ + + return compressed_size; } static void @@ -77,7 +938,8 @@ lzms_free_compressor(void *_ctx) if (ctx) { FREE(ctx->window); - FREE(ctx->last_target_usages); + FREE(ctx->prev_tab); + lz_sarray_destroy(&ctx->lz_sarray); FREE(ctx); } } @@ -89,7 +951,7 @@ lzms_create_compressor(size_t max_block_size, { struct lzms_compressor *ctx; - if (max_block_size == 0 || max_block_size > 1U << 26) { + if (max_block_size == 0 || max_block_size >= INT32_MAX) { LZMS_DEBUG("Invalid max_block_size (%u)", max_block_size); return WIMLIB_ERR_INVALID_PARAM; } @@ -98,15 +960,25 @@ lzms_create_compressor(size_t max_block_size, if (ctx == NULL) goto oom; - ctx->window = MALLOC(max_block_size); + ctx->window = MALLOC(max_block_size + 8); if (ctx->window == NULL) 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) + ctx->prev_tab = MALLOC(max_block_size * sizeof(ctx->prev_tab[0])); + if (ctx->prev_tab == NULL) + goto oom; + + if (!lz_sarray_init(&ctx->lz_sarray, + max_block_size, + 2, + max_block_size, + 100, + 10)) goto oom; + + ctx->max_block_size = max_block_size; + *ctx_ret = ctx; return 0;