X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Flzms-compress.c;h=21c82ea87bf9f93e2005406018960f73bb6488f6;hb=de6e24d17eac26d9da7e20eef7a49b1f5334e578;hp=3c34b52c807f32ac61006bf35464569f58c80e86;hpb=dabaf1184dfd9581804da2a14fa3617ef61a3e06;p=wimlib diff --git a/src/lzms-compress.c b/src/lzms-compress.c index 3c34b52c..21c82ea8 100644 --- a/src/lzms-compress.c +++ b/src/lzms-compress.c @@ -1,11 +1,9 @@ /* * lzms-compress.c - * - * A compressor for 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. * @@ -24,89 +22,1383 @@ */ /* 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. + * + * Also see lzx-compress.c for general information about match-finding and + * match-choosing that also applies to this LZMS compressor. + * + * NOTE: this compressor currently does not code any delta matches. + */ #ifdef HAVE_CONFIG_H # include "config.h" #endif -#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_mf.h" #include "wimlib/lzms.h" #include "wimlib/util.h" #include +#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 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]; +}; + +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 { + /* 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; + + /* Lempel-Ziv match-finder. */ + struct lz_mf *mf; + + /* Temporary space to store found matches. */ + struct lz_match *matches; + + /* Match-chooser data. */ + struct lzms_mc_pos_data *optimum; + unsigned optimum_cur_idx; + unsigned optimum_end_idx; + + /* Maximum block size this compressor instantiation allows. This is the + * allocated size of @window. */ u32 max_block_size; - s32 *last_target_usages; + + /* Compression parameters. */ + struct lzms_compressor_params params; + + /* 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]; }; +struct lzms_mc_pos_data { + u32 cost; +#define MC_INFINITE_COST ((u32)~0UL) + union { + struct { + u32 link; + u32 match_offset; + } prev; + struct { + u32 link; + u32 match_offset; + } next; + }; + struct lzms_adaptive_state { + struct lzms_lz_lru_queues lru; + u8 main_state; + u8 match_state; + u8 lz_match_state; + u8 lz_repeat_match_state[LZMS_NUM_RECENT_OFFSETS - 1]; + } state; +}; + +/* Initialize the output bitstream @os to write forwards to the specified + * compressed data buffer @out that is @out_limit 16-bit integers long. */ +static void +lzms_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); + lzms_output_bitstream_put_bits(enc->os, + enc->codewords[sym], + enc->lens[sym]); + ++enc->sym_freqs[sym]; + 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; + } +} + +static void +lzms_encode_length(struct lzms_huffman_encoder *enc, u32 length) +{ + unsigned slot; + unsigned num_extra_bits; + u32 extra_bits; + + slot = lzms_get_length_slot(length); + + num_extra_bits = lzms_extra_length_bits[slot]; + + extra_bits = length - lzms_length_slot_base[slot]; + + lzms_huffman_encode_symbol(enc, slot); + lzms_output_bitstream_put_bits(enc->os, extra_bits, num_extra_bits); +} + +static void +lzms_encode_offset(struct lzms_huffman_encoder *enc, u32 offset) +{ + unsigned slot; + unsigned num_extra_bits; + u32 extra_bits; + + slot = lzms_get_position_slot(offset); + + num_extra_bits = lzms_extra_position_bits[slot]; + + extra_bits = offset - lzms_position_slot_base[slot]; + + 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_DEBUG("Position %u: Encoding LZ match {length=%u, offset=%u}", + ctx->cur_window_pos, length, offset); + + LZMS_ASSERT(length <= ctx->window_size - ctx->cur_window_pos); + LZMS_ASSERT(offset <= ctx->cur_window_pos); + LZMS_ASSERT(!memcmp(&ctx->window[ctx->cur_window_pos], + &ctx->window[ctx->cur_window_pos - offset], + length)); + + lzms_begin_encode_item(ctx); + + /* Main bit: 1 = a match, not a literal. */ + lzms_range_encode_bit(&ctx->main_range_encoder, 1); + + /* Match bit: 0 = an 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 recent offset. */ + lzms_range_encode_bit(&ctx->lz_match_range_encoder, 0); + + /* Encode the match offset. */ + lzms_encode_offset(&ctx->lz_offset_encoder, offset); + } else { + int i; + + /* Recent offset. */ + + /* LZ match bit: 1 = recent 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_length(&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); +} + +#define LZMS_COST_SHIFT 5 + +/*#define LZMS_RC_COSTS_USE_FLOATING_POINT*/ + +static u32 +lzms_rc_costs[LZMS_PROBABILITY_MAX + 1]; + +#ifdef LZMS_RC_COSTS_USE_FLOATING_POINT +# include +#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 >= (1U << 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 when in the specified + * state. + * + * @enc The range encoder to use. + * @cur_state Current state, which indicates the probability entry to choose. + * Updated by this function. + * @bit The bit to encode (0 or 1). + */ +static 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 & enc->mask].num_recent_zero_bits; + + *cur_state = (*cur_state << 1) | bit; + + if (bit == 0) + prob_correct = prob_zero; + else + prob_correct = LZMS_PROBABILITY_MAX - prob_zero; + + return lzms_rc_costs[prob_correct]; +} + +static u32 +lzms_huffman_symbol_cost(const struct lzms_huffman_encoder *enc, u32 sym) +{ + return enc->lens[sym] << LZMS_COST_SHIFT; +} + +static u32 +lzms_offset_cost(const struct lzms_huffman_encoder *enc, u32 offset) +{ + u32 slot; + u32 num_extra_bits; + u32 cost = 0; + + slot = lzms_get_position_slot(offset); + + cost += lzms_huffman_symbol_cost(enc, slot); + + num_extra_bits = lzms_extra_position_bits[slot]; + + cost += num_extra_bits << LZMS_COST_SHIFT; + + return cost; +} + +static u32 +lzms_get_length_cost(const struct lzms_huffman_encoder *enc, u32 length) +{ + u32 slot; + u32 num_extra_bits; + u32 cost = 0; + + slot = lzms_get_length_slot(length); + + cost += lzms_huffman_symbol_cost(enc, slot); + + num_extra_bits = lzms_extra_length_bits[slot]; + + cost += num_extra_bits << LZMS_COST_SHIFT; + + return cost; +} + +static u32 +lzms_get_matches(struct lzms_compressor *ctx, struct lz_match **matches_ret) +{ + *matches_ret = ctx->matches; + return lz_mf_get_matches(ctx->mf, ctx->matches); +} + +static void +lzms_skip_bytes(struct lzms_compressor *ctx, u32 n) +{ + lz_mf_skip_positions(ctx->mf, n); +} + +static u32 +lzms_get_literal_cost(struct lzms_compressor *ctx, + struct lzms_adaptive_state *state, u8 literal) +{ + u32 cost = 0; + + state->lru.upcoming_offset = 0; + lzms_update_lz_lru_queues(&state->lru); + + cost += lzms_rc_bit_cost(&ctx->main_range_encoder, + &state->main_state, 0); + + cost += lzms_huffman_symbol_cost(&ctx->literal_encoder, literal); + + return cost; +} + +static u32 +lzms_get_lz_match_cost_nolen(struct lzms_compressor *ctx, + struct lzms_adaptive_state *state, u32 offset) +{ + u32 cost = 0; + int recent_offset_idx; + + cost += lzms_rc_bit_cost(&ctx->main_range_encoder, + &state->main_state, 1); + cost += lzms_rc_bit_cost(&ctx->match_range_encoder, + &state->match_state, 0); + + for (recent_offset_idx = 0; + recent_offset_idx < LZMS_NUM_RECENT_OFFSETS; + recent_offset_idx++) + if (offset == state->lru.recent_offsets[recent_offset_idx]) + break; + + if (recent_offset_idx == LZMS_NUM_RECENT_OFFSETS) { + /* Explicit offset. */ + cost += lzms_rc_bit_cost(&ctx->lz_match_range_encoder, + &state->lz_match_state, 0); + + cost += lzms_offset_cost(&ctx->lz_offset_encoder, offset); + } else { + int i; + + /* Recent offset. */ + cost += lzms_rc_bit_cost(&ctx->lz_match_range_encoder, + &state->lz_match_state, 1); + + for (i = 0; i < recent_offset_idx; i++) + cost += lzms_rc_bit_cost(&ctx->lz_repeat_match_range_encoders[i], + &state->lz_repeat_match_state[i], 0); + + if (i < LZMS_NUM_RECENT_OFFSETS - 1) + cost += lzms_rc_bit_cost(&ctx->lz_repeat_match_range_encoders[i], + &state->lz_repeat_match_state[i], 1); + + + /* Initial update of the LZ match offset LRU queue. */ + for (; i < LZMS_NUM_RECENT_OFFSETS; i++) + state->lru.recent_offsets[i] = state->lru.recent_offsets[i + 1]; + } + + + state->lru.upcoming_offset = offset; + lzms_update_lz_lru_queues(&state->lru); + + return cost; +} + +static u32 +lzms_get_lz_match_cost(struct lzms_compressor *ctx, + struct lzms_adaptive_state *state, + u32 length, u32 offset) +{ + return lzms_get_lz_match_cost_nolen(ctx, state, offset) + + lzms_get_length_cost(&ctx->length_encoder, length); +} + +static struct lz_match +lzms_match_chooser_reverse_list(struct lzms_compressor *ctx, unsigned cur_pos) +{ + unsigned prev_link, saved_prev_link; + unsigned prev_match_offset, saved_prev_match_offset; + + ctx->optimum_end_idx = cur_pos; + + saved_prev_link = ctx->optimum[cur_pos].prev.link; + saved_prev_match_offset = ctx->optimum[cur_pos].prev.match_offset; + + do { + prev_link = saved_prev_link; + prev_match_offset = saved_prev_match_offset; + + saved_prev_link = ctx->optimum[prev_link].prev.link; + saved_prev_match_offset = ctx->optimum[prev_link].prev.match_offset; + + ctx->optimum[prev_link].next.link = cur_pos; + ctx->optimum[prev_link].next.match_offset = prev_match_offset; + + cur_pos = prev_link; + } while (cur_pos != 0); + + ctx->optimum_cur_idx = ctx->optimum[0].next.link; + + return (struct lz_match) + { .len = ctx->optimum_cur_idx, + .offset = ctx->optimum[0].next.match_offset, + }; +} + +/* This is similar to lzx_choose_near_optimal_item() in lzx-compress.c. + * Read that one if you want to understand it. */ +static struct lz_match +lzms_get_near_optimal_item(struct lzms_compressor *ctx) +{ + u32 num_matches; + struct lz_match *matches; + struct lz_match match; + u32 longest_len; + u32 longest_rep_len; + u32 longest_rep_offset; + unsigned cur_pos; + unsigned end_pos; + struct lzms_adaptive_state initial_state; + + if (ctx->optimum_cur_idx != ctx->optimum_end_idx) { + match.len = ctx->optimum[ctx->optimum_cur_idx].next.link - + ctx->optimum_cur_idx; + match.offset = ctx->optimum[ctx->optimum_cur_idx].next.match_offset; + + ctx->optimum_cur_idx = ctx->optimum[ctx->optimum_cur_idx].next.link; + return match; + } + + ctx->optimum_cur_idx = 0; + ctx->optimum_end_idx = 0; + + longest_rep_len = ctx->params.min_match_length - 1; + if (lz_mf_get_position(ctx->mf) >= LZMS_MAX_INIT_RECENT_OFFSET) { + u32 limit = lz_mf_get_bytes_remaining(ctx->mf); + for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++) { + u32 offset = ctx->lru.lz.recent_offsets[i]; + const u8 *strptr = lz_mf_get_window_ptr(ctx->mf); + const u8 *matchptr = strptr - offset; + u32 len = 0; + while (len < limit && strptr[len] == matchptr[len]) + len++; + if (len > longest_rep_len) { + longest_rep_len = len; + longest_rep_offset = offset; + } + } + } + + if (longest_rep_len >= ctx->params.nice_match_length) { + lzms_skip_bytes(ctx, longest_rep_len); + return (struct lz_match) { + .len = longest_rep_len, + .offset = longest_rep_offset, + }; + } + + num_matches = lzms_get_matches(ctx, &matches); + + if (num_matches) { + longest_len = matches[num_matches - 1].len; + if (longest_len >= ctx->params.nice_match_length) { + lzms_skip_bytes(ctx, longest_len - 1); + return matches[num_matches - 1]; + } + } else { + longest_len = 1; + } + + initial_state.lru = ctx->lru.lz; + initial_state.main_state = ctx->main_range_encoder.state; + initial_state.match_state = ctx->match_range_encoder.state; + initial_state.lz_match_state = ctx->lz_match_range_encoder.state; + for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++) + initial_state.lz_repeat_match_state[i] = ctx->lz_repeat_match_range_encoders[i].state; + + ctx->optimum[1].state = initial_state; + ctx->optimum[1].cost = lzms_get_literal_cost(ctx, + &ctx->optimum[1].state, + *(lz_mf_get_window_ptr(ctx->mf) - 1)); + ctx->optimum[1].prev.link = 0; + + for (u32 i = 0, len = 2; i < num_matches; i++) { + u32 offset = matches[i].offset; + struct lzms_adaptive_state state; + u32 position_cost; + + state = initial_state; + position_cost = 0; + position_cost += lzms_get_lz_match_cost_nolen(ctx, &state, offset); + + do { + u32 cost; + + cost = position_cost; + cost += lzms_get_length_cost(&ctx->length_encoder, len); + + ctx->optimum[len].state = state; + ctx->optimum[len].prev.link = 0; + ctx->optimum[len].prev.match_offset = offset; + ctx->optimum[len].cost = cost; + } while (++len <= matches[i].len); + } + end_pos = longest_len; + + if (longest_rep_len >= ctx->params.min_match_length) { + struct lzms_adaptive_state state; + u32 cost; + + while (end_pos < longest_rep_len) + ctx->optimum[++end_pos].cost = MC_INFINITE_COST; + + state = initial_state; + cost = lzms_get_lz_match_cost(ctx, + &state, + longest_rep_len, + longest_rep_offset); + if (cost <= ctx->optimum[longest_rep_len].cost) { + ctx->optimum[longest_rep_len].state = state; + ctx->optimum[longest_rep_len].prev.link = 0; + ctx->optimum[longest_rep_len].prev.match_offset = longest_rep_offset; + ctx->optimum[longest_rep_len].cost = cost; + } + } + + cur_pos = 0; + for (;;) { + u32 cost; + struct lzms_adaptive_state state; + + cur_pos++; + + if (cur_pos == end_pos || cur_pos == ctx->params.optim_array_length) + return lzms_match_chooser_reverse_list(ctx, cur_pos); + + longest_rep_len = ctx->params.min_match_length - 1; + if (lz_mf_get_position(ctx->mf) >= LZMS_MAX_INIT_RECENT_OFFSET) { + u32 limit = lz_mf_get_bytes_remaining(ctx->mf); + for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++) { + u32 offset = ctx->optimum[cur_pos].state.lru.recent_offsets[i]; + const u8 *strptr = lz_mf_get_window_ptr(ctx->mf); + const u8 *matchptr = strptr - offset; + u32 len = 0; + while (len < limit && strptr[len] == matchptr[len]) + len++; + if (len > longest_rep_len) { + longest_rep_len = len; + longest_rep_offset = offset; + } + } + } + + if (longest_rep_len >= ctx->params.nice_match_length) { + match = lzms_match_chooser_reverse_list(ctx, cur_pos); + + ctx->optimum[cur_pos].next.match_offset = longest_rep_offset; + ctx->optimum[cur_pos].next.link = cur_pos + longest_rep_len; + ctx->optimum_end_idx = cur_pos + longest_rep_len; + + lzms_skip_bytes(ctx, longest_rep_len); + + return match; + } + + num_matches = lzms_get_matches(ctx, &matches); + + if (num_matches) { + longest_len = matches[num_matches - 1].len; + if (longest_len >= ctx->params.nice_match_length) { + match = lzms_match_chooser_reverse_list(ctx, cur_pos); + + ctx->optimum[cur_pos].next.match_offset = + matches[num_matches - 1].offset; + ctx->optimum[cur_pos].next.link = cur_pos + longest_len; + ctx->optimum_end_idx = cur_pos + longest_len; + + lzms_skip_bytes(ctx, longest_len - 1); + + return match; + } + } else { + longest_len = 1; + } + + while (end_pos < cur_pos + longest_len) + ctx->optimum[++end_pos].cost = MC_INFINITE_COST; + + state = ctx->optimum[cur_pos].state; + cost = ctx->optimum[cur_pos].cost + + lzms_get_literal_cost(ctx, + &state, + *(lz_mf_get_window_ptr(ctx->mf) - 1)); + if (cost < ctx->optimum[cur_pos + 1].cost) { + ctx->optimum[cur_pos + 1].state = state; + ctx->optimum[cur_pos + 1].cost = cost; + ctx->optimum[cur_pos + 1].prev.link = cur_pos; + } + + for (u32 i = 0, len = 2; i < num_matches; i++) { + u32 offset = matches[i].offset; + struct lzms_adaptive_state state; + u32 position_cost; + + state = ctx->optimum[cur_pos].state; + position_cost = ctx->optimum[cur_pos].cost; + position_cost += lzms_get_lz_match_cost_nolen(ctx, &state, offset); + + do { + u32 cost; + + cost = position_cost; + cost += lzms_get_length_cost(&ctx->length_encoder, len); + + if (cost < ctx->optimum[cur_pos + len].cost) { + ctx->optimum[cur_pos + len].state = state; + ctx->optimum[cur_pos + len].prev.link = cur_pos; + ctx->optimum[cur_pos + len].prev.match_offset = offset; + ctx->optimum[cur_pos + len].cost = cost; + } + } while (++len <= matches[i].len); + } + + if (longest_rep_len >= ctx->params.min_match_length) { + + while (end_pos < cur_pos + longest_rep_len) + ctx->optimum[++end_pos].cost = MC_INFINITE_COST; + + state = ctx->optimum[cur_pos].state; + + cost = ctx->optimum[cur_pos].cost + + lzms_get_lz_match_cost(ctx, + &state, + longest_rep_len, + longest_rep_offset); + if (cost <= ctx->optimum[cur_pos + longest_rep_len].cost) { + ctx->optimum[cur_pos + longest_rep_len].state = + state; + ctx->optimum[cur_pos + longest_rep_len].prev.link = + cur_pos; + ctx->optimum[cur_pos + longest_rep_len].prev.match_offset = + longest_rep_offset; + ctx->optimum[cur_pos + longest_rep_len].cost = + cost; + } + } + } +} + +/* + * The main loop for the LZMS compressor. + * + * 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_encode(struct lzms_compressor *ctx) +{ + struct lz_match item; + + /* Load window into the match-finder. */ + lz_mf_load_window(ctx->mf, ctx->window, ctx->window_size); + + /* Reset the match-chooser. */ + ctx->optimum_cur_idx = 0; + ctx->optimum_end_idx = 0; + + while (ctx->cur_window_pos != ctx->window_size) { + item = lzms_get_near_optimal_item(ctx); + if (item.len <= 1) + lzms_encode_literal(ctx, ctx->window[ctx->cur_window_pos]); + else + lzms_encode_lz_match(ctx, item.len, item.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, + 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); +} + +/* 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); + 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); + + /* 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, + LZMS_NUM_LITERAL_SYMS, + LZMS_LITERAL_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->lz_offset_encoder, &ctx->os, + num_position_slots, + LZMS_LZ_OFFSET_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->length_encoder, &ctx->os, + LZMS_NUM_LEN_SYMS, + LZMS_LENGTH_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->delta_offset_encoder, &ctx->os, + num_position_slots, + LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&ctx->delta_power_encoder, &ctx->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(&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_compress(const void *uncompressed_data, size_t uncompressed_size, - void *compressed_data, size_t compressed_size_avail, void *_ctx) +lzms_finalize(struct lzms_compressor *ctx, u8 *cdata, size_t csize_avail) { - struct lzms_compressor *ctx = _ctx; + 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 (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); + if (!lzms_range_encoder_raw_flush(&ctx->rc)) { + LZMS_DEBUG("Forwards bitstream overrun."); return 0; } - memcpy(ctx->window, uncompressed_data, uncompressed_size); - ctx->window_size = uncompressed_size; + if (ctx->rc.out > ctx->os.out) { + LZMS_DEBUG("Two bitstreams crossed."); + return 0; + } - lzms_x86_filter(ctx->window, ctx->window_size, - ctx->last_target_usages, false); + /* 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*)ctx->rc.out - (u8*)cdata; + num_backwards_bytes = ((u8*)cdata + csize_avail) - (u8*)ctx->os.out; - return 0; + 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 % 2 == 0); + return compressed_size; } + static void -lzms_free_compressor(void *_ctx) +lzms_build_params(unsigned int compression_level, + struct lzms_compressor_params *lzms_params) { - struct lzms_compressor *ctx = _ctx; + lzms_params->min_match_length = (compression_level >= 50) ? 2 : 3; + lzms_params->nice_match_length = max(((u64)compression_level * 32) / 50, + lzms_params->min_match_length); + lzms_params->max_search_depth = ((u64)compression_level * 50) / 50; + lzms_params->optim_array_length = 224 + compression_level * 16; +} - if (ctx) { - FREE(ctx->window); - FREE(ctx->last_target_usages); - FREE(ctx); - } +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)); + + mf_params->algorithm = LZ_MF_DEFAULT; + 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 *_ctx); + +static u64 +lzms_get_needed_memory(size_t max_block_size, unsigned int compression_level) +{ + struct lzms_compressor_params params; + u64 size = 0; + + if (max_block_size >= INT32_MAX) + return 0; + + lzms_build_params(compression_level, ¶ms); + + size += sizeof(struct lzms_compressor); + size += max_block_size; + size += lz_mf_get_needed_memory(LZ_MF_DEFAULT, max_block_size); + size += params.max_search_depth * sizeof(struct lz_match); + 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_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; + + 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; - } ctx = CALLOC(1, sizeof(struct lzms_compressor)); - if (ctx == NULL) + if (!ctx) goto oom; + ctx->params = params; + ctx->max_block_size = max_block_size; + ctx->window = MALLOC(max_block_size); - if (ctx->window == NULL) + if (!ctx->window) 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->mf = lz_mf_alloc(&mf_params); + if (!ctx->mf) goto oom; + ctx->matches = MALLOC(params.max_search_depth * sizeof(struct lz_match)); + if (!ctx->matches) + goto oom; + + ctx->optimum = MALLOC((params.optim_array_length + + params.nice_match_length) * + sizeof(struct lzms_mc_pos_data)); + if (!ctx->optimum) + goto oom; + + /* Initialize position and length slot data if not done already. */ + lzms_init_slots(); + + /* Initialize range encoding cost table if not done already. */ + lzms_init_rc_costs(); + *ctx_ret = ctx; return 0; @@ -115,7 +1407,72 @@ oom: 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 *_ctx) +{ + struct lzms_compressor *ctx = _ctx; + size_t compressed_size; + + LZMS_DEBUG("uncompressed_size=%zu, compressed_size_avail=%zu", + uncompressed_size, compressed_size_avail); + + /* Don't bother compressing extremely small inputs. */ + if (uncompressed_size < 4) { + LZMS_DEBUG("Input too small to bother compressing."); + 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); + + /* Compute and encode a literal/match sequence that decompresses to the + * preprocessed data. */ + lzms_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); + + return compressed_size; +} + +static void +lzms_free_compressor(void *_ctx) +{ + struct lzms_compressor *ctx = _ctx; + + if (ctx) { + FREE(ctx->window); + lz_mf_free(ctx->mf); + FREE(ctx->matches); + FREE(ctx->optimum); + FREE(ctx); + } +} + 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,