X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Flzms-compress.c;h=5f5e37412db828a0c1a96d667b9e854e4b5a0959;hb=855b49ef85d274588a2848d9c69974f9b88d343a;hp=e5abf24aa6294aec736284ea8ea1036fbe4cdf4b;hpb=883833a4b3dabec325edf1ca938000f91d587c00;p=wimlib diff --git a/src/lzms-compress.c b/src/lzms-compress.c index e5abf24a..5f5e3741 100644 --- a/src/lzms-compress.c +++ b/src/lzms-compress.c @@ -1,128 +1,1582 @@ /* * lzms-compress.c * - * A compressor for the LZMS compression format. + * A compressor that produces output compatible with the LZMS compression format. */ /* - * Copyright (C) 2013 Eric Biggers + * Copyright (C) 2013, 2014 Eric Biggers * - * This file is part of wimlib, a library for working with WIM files. + * This file is free software; you can redistribute it and/or modify it under + * the terms of the GNU Lesser General Public License as published by the Free + * Software Foundation; either version 3 of the License, or (at your option) any + * later version. * - * wimlib is free software; you can redistribute it and/or modify it under the - * terms of the GNU General Public License as published by the Free - * Software Foundation; either version 3 of the License, or (at your option) - * any later version. - * - * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY - * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR - * A PARTICULAR PURPOSE. See the GNU General Public License for more + * This file is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS + * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more * details. * - * You should have received a copy of the GNU General Public License - * along with wimlib; if not, see http://www.gnu.org/licenses/. + * You should have received a copy of the GNU Lesser General Public License + * along with this file; if not, see http://www.gnu.org/licenses/. */ -/* This a compressor for the LZMS compression format. More details about this - * format can be found in lzms-decompress.c. */ - #ifdef HAVE_CONFIG_H # include "config.h" #endif -#include "wimlib.h" -#include "wimlib/assert.h" -#include "wimlib/compressor_ops.h" #include "wimlib/compress_common.h" +#include "wimlib/compressor_ops.h" +#include "wimlib/endianness.h" #include "wimlib/error.h" +#include "wimlib/lz_mf.h" +#include "wimlib/lz_repsearch.h" #include "wimlib/lzms.h" +#include "wimlib/unaligned.h" #include "wimlib/util.h" #include +#include +#include + +/* Stucture used for writing raw bits as a series of 16-bit little endian coding + * units. This starts at the *end* of the compressed data buffer and proceeds + * backwards. */ +struct lzms_output_bitstream { + + /* Bits that haven't yet been written to the output buffer. */ + u64 bitbuf; + + /* Number of bits currently held in @bitbuf. */ + unsigned bitcount; + + /* Pointer to one past the next position in the compressed data buffer + * at which to output a 16-bit coding unit. */ + le16 *next; + + /* Pointer to the beginning of the output buffer. (The "end" when + * writing backwards!) */ + le16 *begin; +}; + +/* Stucture used for range encoding (raw version). This starts at the + * *beginning* of the compressed data buffer and proceeds forward. */ +struct lzms_range_encoder_raw { + + /* A 33-bit variable that holds the low boundary of the current range. + * The 33rd bit is needed to catch carries. */ + u64 low; + + /* Size of the current range. */ + u32 range; + + /* Next 16-bit coding unit to output. */ + u16 cache; + + /* Number of 16-bit coding units whose output has been delayed due to + * possible carrying. The first such coding unit is @cache; all + * subsequent such coding units are 0xffff. */ + u32 cache_size; + + /* Pointer to the beginning of the output buffer. */ + le16 *begin; + + /* Pointer to the position in the output buffer at which the next coding + * unit must be written. */ + le16 *next; + + /* Pointer just past the end of the output buffer. */ + le16 *end; +}; + +/* Structure used for range encoding. This wraps around `struct + * lzms_range_encoder_raw' to use and maintain probability entries. */ +struct lzms_range_encoder { + + /* Pointer to the raw range encoder, which has no persistent knowledge + * of probabilities. Multiple lzms_range_encoder's share the same + * lzms_range_encoder_raw. */ + struct lzms_range_encoder_raw *rc; + + /* Bits recently encoded by this range encoder. This is used as an + * index into @prob_entries. */ + u32 state; + + /* Bitmask for @state to prevent its value from exceeding the number of + * probability entries. */ + u32 mask; + + /* Probability entries being used for this range encoder. */ + struct lzms_probability_entry prob_entries[LZMS_MAX_NUM_STATES]; +}; + +/* Structure used for Huffman encoding. */ +struct lzms_huffman_encoder { + + /* Bitstream to write Huffman-encoded symbols and verbatim bits to. + * Multiple lzms_huffman_encoder's share the same lzms_output_bitstream. + */ + struct lzms_output_bitstream *os; + /* Number of symbols that have been written using this code far. Reset + * to 0 whenever the code is rebuilt. */ + u32 num_syms_written; + + /* When @num_syms_written reaches this number, the Huffman code must be + * rebuilt. */ + u32 rebuild_freq; + + /* Number of symbols in the represented Huffman code. */ + unsigned num_syms; + + /* Running totals of symbol frequencies. These are diluted slightly + * whenever the code is rebuilt. */ + u32 sym_freqs[LZMS_MAX_NUM_SYMS]; + + /* The length, in bits, of each symbol in the Huffman code. */ + u8 lens[LZMS_MAX_NUM_SYMS]; + + /* The codeword of each symbol in the Huffman code. */ + u32 codewords[LZMS_MAX_NUM_SYMS]; +}; + +/* Internal compression parameters */ +struct lzms_compressor_params { + u32 min_match_length; + u32 nice_match_length; + u32 max_search_depth; + u32 optim_array_length; +}; + +/* State of the LZMS compressor */ struct lzms_compressor { - u8 *window; - u32 window_size; - u32 max_block_size; - s32 *last_target_usages; + /* Internal compression parameters */ + struct lzms_compressor_params params; + + /* Data currently being compressed */ + u8 *cur_window; + u32 cur_window_size; + + /* Lempel-Ziv match-finder */ + struct lz_mf *mf; + + /* Temporary space to store found matches */ + struct lz_match *matches; + + /* Per-position data for near-optimal parsing */ + struct lzms_mc_pos_data *optimum; + struct lzms_mc_pos_data *optimum_end; + + /* Raw range encoder which outputs to the beginning of the compressed + * data buffer, proceeding forwards */ + struct lzms_range_encoder_raw rc; + + /* Bitstream which outputs to the end of the compressed data buffer, + * proceeding backwards */ + struct lzms_output_bitstream os; + + /* Range encoders */ + struct lzms_range_encoder main_range_encoder; + struct lzms_range_encoder match_range_encoder; + struct lzms_range_encoder lz_match_range_encoder; + struct lzms_range_encoder lz_repeat_match_range_encoders[LZMS_NUM_RECENT_OFFSETS - 1]; + struct lzms_range_encoder delta_match_range_encoder; + struct lzms_range_encoder delta_repeat_match_range_encoders[LZMS_NUM_RECENT_OFFSETS - 1]; + + /* Huffman encoders */ + struct lzms_huffman_encoder literal_encoder; + struct lzms_huffman_encoder lz_offset_encoder; + struct lzms_huffman_encoder length_encoder; + struct lzms_huffman_encoder delta_power_encoder; + struct lzms_huffman_encoder delta_offset_encoder; + + /* Used for preprocessing */ + s32 last_target_usages[65536]; + +#define LZMS_NUM_FAST_LENGTHS 256 + /* Table: length => length slot for small lengths */ + u8 length_slot_fast[LZMS_NUM_FAST_LENGTHS]; + + /* Table: length => current cost for small match lengths */ + u32 length_cost_fast[LZMS_NUM_FAST_LENGTHS]; + +#define LZMS_NUM_FAST_OFFSETS 32768 + /* Table: offset => offset slot for small offsets */ + u8 offset_slot_fast[LZMS_NUM_FAST_OFFSETS]; +}; + +struct lzms_lz_lru_queue { + u32 recent_offsets[LZMS_NUM_RECENT_OFFSETS + 1]; + u32 prev_offset; + u32 upcoming_offset; +}; + +static void +lzms_init_lz_lru_queue(struct lzms_lz_lru_queue *queue) +{ + for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS + 1; i++) + queue->recent_offsets[i] = i + 1; + + queue->prev_offset = 0; + queue->upcoming_offset = 0; +} + +static void +lzms_update_lz_lru_queue(struct lzms_lz_lru_queue *queue) +{ + if (queue->prev_offset != 0) { + for (int i = LZMS_NUM_RECENT_OFFSETS - 1; i >= 0; i--) + queue->recent_offsets[i + 1] = queue->recent_offsets[i]; + queue->recent_offsets[0] = queue->prev_offset; + } + queue->prev_offset = queue->upcoming_offset; +} + +/* + * Match chooser position data: + * + * An array of these structures is used during the near-optimal match-choosing + * algorithm. They correspond to consecutive positions in the window and are + * used to keep track of the cost to reach each position, and the match/literal + * choices that need to be chosen to reach that position. + */ +struct lzms_mc_pos_data { + + /* The cost, in bits, of the lowest-cost path that has been found to + * reach this position. This can change as progressively lower cost + * paths are found to reach this position. */ + u32 cost; +#define MC_INFINITE_COST UINT32_MAX + + /* The match or literal that was taken to reach this position. This can + * change as progressively lower cost paths are found to reach this + * position. + * + * This variable is divided into two bitfields. + * + * Literals: + * Low bits are 1, high bits are the literal. + * + * Explicit offset matches: + * Low bits are the match length, high bits are the offset plus 2. + * + * Repeat offset matches: + * Low bits are the match length, high bits are the queue index. + */ + u64 mc_item_data; +#define MC_OFFSET_SHIFT 32 +#define MC_LEN_MASK (((u64)1 << MC_OFFSET_SHIFT) - 1) + + /* The LZMS adaptive state that exists at this position. This is filled + * in lazily, only after the minimum-cost path to this position is + * found. + * + * Note: the way we handle this adaptive state in the "minimum-cost" + * parse is actually only an approximation. It's possible for the + * globally optimal, minimum cost path to contain a prefix, ending at a + * position, where that path prefix is *not* the minimum cost path to + * that position. This can happen if such a path prefix results in a + * different adaptive state which results in lower costs later. We do + * not solve this problem; we only consider the lowest cost to reach + * each position, which seems to be an acceptable approximation. + * + * Note: this adaptive state also does not include the probability + * entries or current Huffman codewords. Those aren't maintained + * per-position and are only updated occassionally. */ + struct lzms_adaptive_state { + struct lzms_lz_lru_queue lru; + u8 main_state; + u8 match_state; + u8 lz_match_state; + u8 lz_repeat_match_state[LZMS_NUM_RECENT_OFFSETS - 1]; + } state; }; static void -lzms_preprocess_data(u8 *data, s32 size, s32 *last_target_usages) +lzms_init_fast_slots(struct lzms_compressor *c) { - for (s32 i = 0; i < size - 11; i++) { + /* Create table mapping small lengths to length slots. */ + for (unsigned slot = 0, i = 0; i < LZMS_NUM_FAST_LENGTHS; i++) { + while (i >= lzms_length_slot_base[slot + 1]) + slot++; + c->length_slot_fast[i] = slot; + } + + /* Create table mapping small offsets to offset slots. */ + for (unsigned slot = 0, i = 0; i < LZMS_NUM_FAST_OFFSETS; i++) { + while (i >= lzms_offset_slot_base[slot + 1]) + slot++; + c->offset_slot_fast[i] = slot; } } -static size_t -lzms_compress(const void *uncompressed_data, size_t uncompressed_size, - void *compressed_data, size_t compressed_size_avail, void *_ctx) +static inline unsigned +lzms_get_length_slot_fast(const struct lzms_compressor *c, u32 length) { - struct lzms_compressor *ctx = _ctx; + if (likely(length < LZMS_NUM_FAST_LENGTHS)) + return c->length_slot_fast[length]; + else + return lzms_get_length_slot(length); +} - if (uncompressed_size > ctx->max_block_size) { - LZMS_DEBUG("Can't compress %su bytes: LZMS context " - "only supports %u bytes", - uncompressed_size, ctx->max_block_size); - return 0; +static inline unsigned +lzms_get_offset_slot_fast(const struct lzms_compressor *c, u32 offset) +{ + if (offset < LZMS_NUM_FAST_OFFSETS) + return c->offset_slot_fast[offset]; + else + return lzms_get_offset_slot(offset); +} + +/* Initialize the output bitstream @os to write backwards to the specified + * compressed data buffer @out that is @out_limit 16-bit integers long. */ +static void +lzms_output_bitstream_init(struct lzms_output_bitstream *os, + le16 *out, size_t out_limit) +{ + os->bitbuf = 0; + os->bitcount = 0; + os->next = out + out_limit; + os->begin = out; +} + +/* + * Write some bits, contained in the low @num_bits bits of @bits (ordered from + * high-order to low-order), to the output bitstream @os. + * + * @max_num_bits is a compile-time constant that specifies the maximum number of + * bits that can ever be written at this call site. + */ +static inline void +lzms_output_bitstream_put_varbits(struct lzms_output_bitstream *os, + u32 bits, unsigned num_bits, + unsigned max_num_bits) +{ + LZMS_ASSERT(num_bits <= 48); + + /* Add the bits to the bit buffer variable. */ + os->bitcount += num_bits; + os->bitbuf = (os->bitbuf << num_bits) | bits; + + /* Check whether any coding units need to be written. */ + while (os->bitcount >= 16) { + + os->bitcount -= 16; + + /* Write a coding unit, unless it would underflow the buffer. */ + if (os->next != os->begin) + put_unaligned_u16_le(os->bitbuf >> os->bitcount, --os->next); + + /* Optimization for call sites that never write more than 16 + * bits at once. */ + if (max_num_bits <= 16) + break; } +} - memcpy(ctx->window, uncompressed_data, uncompressed_size); - ctx->window_size = uncompressed_size; +/* Flush the output bitstream, ensuring that all bits written to it have been + * written to memory. Returns %true if all bits have been output successfully, + * or %false if an overrun occurred. */ +static bool +lzms_output_bitstream_flush(struct lzms_output_bitstream *os) +{ + if (os->next == os->begin) + return false; - lzms_preprocess_data(ctx->window, ctx->window_size, - ctx->last_target_usages); + if (os->bitcount != 0) + put_unaligned_u16_le(os->bitbuf << (16 - os->bitcount), --os->next); - return 0; + return true; +} + +/* Initialize the range encoder @rc to write forwards to the specified + * compressed data buffer @out that is @out_limit 16-bit integers long. */ +static void +lzms_range_encoder_raw_init(struct lzms_range_encoder_raw *rc, + le16 *out, size_t out_limit) +{ + rc->low = 0; + rc->range = 0xffffffff; + rc->cache = 0; + rc->cache_size = 1; + rc->begin = out; + rc->next = out - 1; + rc->end = out + out_limit; +} + +/* + * Attempt to flush bits from the range encoder. + * + * Note: this is based on the public domain code for LZMA written by Igor + * Pavlov. The only differences in this function are that in LZMS the bits must + * be output in 16-bit coding units instead of 8-bit coding units, and that in + * LZMS the first coding unit is not ignored by the decompressor, so the encoder + * cannot output a dummy value to that position. + * + * The basic idea is that we're writing bits from @rc->low to the output. + * However, due to carrying, the writing of coding units with value 0xffff, as + * well as one prior coding unit, must be delayed until it is determined whether + * a carry is needed. + */ +static void +lzms_range_encoder_raw_shift_low(struct lzms_range_encoder_raw *rc) +{ + if ((u32)(rc->low) < 0xffff0000 || + (u32)(rc->low >> 32) != 0) + { + /* Carry not needed (rc->low < 0xffff0000), or carry occurred + * ((rc->low >> 32) != 0, a.k.a. the carry bit is 1). */ + do { + if (likely(rc->next >= rc->begin)) { + if (rc->next != rc->end) { + put_unaligned_u16_le(rc->cache + + (u16)(rc->low >> 32), + rc->next++); + } + } else { + rc->next++; + } + rc->cache = 0xffff; + } while (--rc->cache_size != 0); + + rc->cache = (rc->low >> 16) & 0xffff; + } + ++rc->cache_size; + rc->low = (rc->low & 0xffff) << 16; +} + +static void +lzms_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->next != rc->end; +} + +/* Encode the next bit using the range encoder (raw version). + * + * @prob is the chance out of LZMS_PROBABILITY_MAX that the next bit is 0. */ +static inline void +lzms_range_encoder_raw_encode_bit(struct lzms_range_encoder_raw *rc, + int bit, u32 prob) +{ + lzms_range_encoder_raw_normalize(rc); + + u32 bound = (rc->range >> LZMS_PROBABILITY_BITS) * prob; + if (bit == 0) { + rc->range = bound; + } else { + rc->low += bound; + rc->range -= bound; + } +} + +/* Encode a bit using the specified range encoder. This wraps around + * lzms_range_encoder_raw_encode_bit() to handle using and updating the + * appropriate state and probability entry. */ +static void +lzms_range_encode_bit(struct lzms_range_encoder *enc, int bit) +{ + struct lzms_probability_entry *prob_entry; + u32 prob; + + /* Load the probability entry corresponding to the current state. */ + prob_entry = &enc->prob_entries[enc->state]; + + /* Update the state based on the next bit. */ + enc->state = ((enc->state << 1) | bit) & enc->mask; + + /* Get the probability that the bit is 0. */ + prob = lzms_get_probability(prob_entry); + + /* Update the probability entry. */ + lzms_update_probability_entry(prob_entry, bit); + + /* Encode the bit. */ + lzms_range_encoder_raw_encode_bit(enc->rc, bit, prob); +} + +/* Called when an adaptive Huffman code needs to be rebuilt. */ +static void +lzms_rebuild_huffman_code(struct lzms_huffman_encoder *enc) +{ + make_canonical_huffman_code(enc->num_syms, + LZMS_MAX_CODEWORD_LEN, + enc->sym_freqs, + enc->lens, + enc->codewords); + + /* Dilute the frequencies. */ + for (unsigned i = 0; i < enc->num_syms; i++) { + enc->sym_freqs[i] >>= 1; + enc->sym_freqs[i] += 1; + } + enc->num_syms_written = 0; +} + +/* Encode a symbol using the specified Huffman encoder. */ +static inline void +lzms_huffman_encode_symbol(struct lzms_huffman_encoder *enc, unsigned sym) +{ + lzms_output_bitstream_put_varbits(enc->os, + enc->codewords[sym], + enc->lens[sym], + LZMS_MAX_CODEWORD_LEN); + ++enc->sym_freqs[sym]; + if (++enc->num_syms_written == enc->rebuild_freq) + lzms_rebuild_huffman_code(enc); +} + +static void +lzms_update_fast_length_costs(struct lzms_compressor *c); + +/* Encode a match length. */ +static void +lzms_encode_length(struct lzms_compressor *c, u32 length) +{ + unsigned slot; + unsigned num_extra_bits; + u32 extra_bits; + + slot = lzms_get_length_slot_fast(c, length); + + extra_bits = length - lzms_length_slot_base[slot]; + num_extra_bits = lzms_extra_length_bits[slot]; + + lzms_huffman_encode_symbol(&c->length_encoder, slot); + if (c->length_encoder.num_syms_written == 0) + lzms_update_fast_length_costs(c); + + lzms_output_bitstream_put_varbits(c->length_encoder.os, + extra_bits, num_extra_bits, 30); +} + +/* Encode an LZ match offset. */ +static void +lzms_encode_lz_offset(struct lzms_compressor *c, u32 offset) +{ + unsigned slot; + unsigned num_extra_bits; + u32 extra_bits; + + slot = lzms_get_offset_slot_fast(c, offset); + + extra_bits = offset - lzms_offset_slot_base[slot]; + num_extra_bits = lzms_extra_offset_bits[slot]; + + lzms_huffman_encode_symbol(&c->lz_offset_encoder, slot); + lzms_output_bitstream_put_varbits(c->lz_offset_encoder.os, + extra_bits, num_extra_bits, 30); +} + +/* Encode a literal byte. */ +static void +lzms_encode_literal(struct lzms_compressor *c, unsigned literal) +{ + /* Main bit: 0 = a literal, not a match. */ + lzms_range_encode_bit(&c->main_range_encoder, 0); + + /* Encode the literal using the current literal Huffman code. */ + lzms_huffman_encode_symbol(&c->literal_encoder, literal); +} + +/* Encode an LZ repeat offset match. */ +static void +lzms_encode_lz_repeat_offset_match(struct lzms_compressor *c, + u32 length, unsigned rep_index) +{ + unsigned i; + + /* Main bit: 1 = a match, not a literal. */ + lzms_range_encode_bit(&c->main_range_encoder, 1); + + /* Match bit: 0 = an LZ match, not a delta match. */ + lzms_range_encode_bit(&c->match_range_encoder, 0); + + /* LZ match bit: 1 = repeat offset, not an explicit offset. */ + lzms_range_encode_bit(&c->lz_match_range_encoder, 1); + + /* Encode the repeat offset index. A 1 bit is encoded for each index + * passed up. This sequence of 1 bits is terminated by a 0 bit, or + * automatically when (LZMS_NUM_RECENT_OFFSETS - 1) 1 bits have been + * encoded. */ + for (i = 0; i < rep_index; i++) + lzms_range_encode_bit(&c->lz_repeat_match_range_encoders[i], 1); + + if (i < LZMS_NUM_RECENT_OFFSETS - 1) + lzms_range_encode_bit(&c->lz_repeat_match_range_encoders[i], 0); + + /* Encode the match length. */ + lzms_encode_length(c, length); +} + +/* Encode an LZ explicit offset match. */ +static void +lzms_encode_lz_explicit_offset_match(struct lzms_compressor *c, + u32 length, u32 offset) +{ + /* Main bit: 1 = a match, not a literal. */ + lzms_range_encode_bit(&c->main_range_encoder, 1); + + /* Match bit: 0 = an LZ match, not a delta match. */ + lzms_range_encode_bit(&c->match_range_encoder, 0); + + /* LZ match bit: 0 = explicit offset, not a repeat offset. */ + lzms_range_encode_bit(&c->lz_match_range_encoder, 0); + + /* Encode the match offset. */ + lzms_encode_lz_offset(c, offset); + + /* Encode the match length. */ + lzms_encode_length(c, length); +} + +static void +lzms_encode_item(struct lzms_compressor *c, u64 mc_item_data) +{ + u32 len = mc_item_data & MC_LEN_MASK; + u32 offset_data = mc_item_data >> MC_OFFSET_SHIFT; + + if (len == 1) + lzms_encode_literal(c, offset_data); + else if (offset_data < LZMS_NUM_RECENT_OFFSETS) + lzms_encode_lz_repeat_offset_match(c, len, offset_data); + else + lzms_encode_lz_explicit_offset_match(c, len, offset_data - LZMS_OFFSET_OFFSET); +} + +/* Encode a list of matches and literals chosen by the parsing algorithm. */ +static void +lzms_encode_item_list(struct lzms_compressor *c, + struct lzms_mc_pos_data *cur_optimum_ptr) +{ + struct lzms_mc_pos_data *end_optimum_ptr; + u64 saved_item; + u64 item; + + /* The list is currently in reverse order (last item to first item). + * Reverse it. */ + end_optimum_ptr = cur_optimum_ptr; + saved_item = cur_optimum_ptr->mc_item_data; + do { + item = saved_item; + cur_optimum_ptr -= item & MC_LEN_MASK; + saved_item = cur_optimum_ptr->mc_item_data; + cur_optimum_ptr->mc_item_data = item; + } while (cur_optimum_ptr != c->optimum); + + /* Walk the list of items from beginning to end, encoding each item. */ + do { + lzms_encode_item(c, cur_optimum_ptr->mc_item_data); + cur_optimum_ptr += (cur_optimum_ptr->mc_item_data) & MC_LEN_MASK; + } while (cur_optimum_ptr != end_optimum_ptr); } +/* Each bit costs 1 << LZMS_COST_SHIFT units. */ +#define LZMS_COST_SHIFT 6 + +/*#define LZMS_RC_COSTS_USE_FLOATING_POINT*/ + +static u32 +lzms_rc_costs[LZMS_PROBABILITY_MAX + 1]; + +#ifdef LZMS_RC_COSTS_USE_FLOATING_POINT +# include +#endif + static void -lzms_free_compressor(void *_ctx) +lzms_do_init_rc_costs(void) { - struct lzms_compressor *ctx = _ctx; + /* 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; - if (ctx) { - FREE(ctx->window); - FREE(ctx->last_target_usages); - FREE(ctx); + #ifdef LZMS_RC_COSTS_USE_FLOATING_POINT + lzms_rc_costs[i] = log2((double)LZMS_PROBABILITY_MAX / prob) * + (1 << LZMS_COST_SHIFT); + #else + u32 w = prob; + u32 bit_count = 0; + for (u32 j = 0; j < LZMS_COST_SHIFT; j++) { + w *= w; + bit_count <<= 1; + while (w >= ((u32)1 << 16)) { + w >>= 1; + ++bit_count; + } + } + lzms_rc_costs[i] = (LZMS_PROBABILITY_BITS << LZMS_COST_SHIFT) - + (15 + bit_count); + #endif } } +static void +lzms_init_rc_costs(void) +{ + static pthread_once_t once = PTHREAD_ONCE_INIT; + + pthread_once(&once, lzms_do_init_rc_costs); +} + +/* Return the cost to range-encode the specified bit from the specified state.*/ +static inline u32 +lzms_rc_bit_cost(const struct lzms_range_encoder *enc, u8 cur_state, int bit) +{ + u32 prob_zero; + u32 prob_correct; + + prob_zero = enc->prob_entries[cur_state].num_recent_zero_bits; + + if (bit == 0) + prob_correct = prob_zero; + else + prob_correct = LZMS_PROBABILITY_MAX - prob_zero; + + return lzms_rc_costs[prob_correct]; +} + +/* Return the cost to Huffman-encode the specified symbol. */ +static inline u32 +lzms_huffman_symbol_cost(const struct lzms_huffman_encoder *enc, unsigned sym) +{ + return (u32)enc->lens[sym] << LZMS_COST_SHIFT; +} + +/* Return the cost to encode the specified literal byte. */ +static inline u32 +lzms_literal_cost(const struct lzms_compressor *c, unsigned literal, + const struct lzms_adaptive_state *state) +{ + return lzms_rc_bit_cost(&c->main_range_encoder, state->main_state, 0) + + lzms_huffman_symbol_cost(&c->literal_encoder, literal); +} + +/* Update the table that directly provides the costs for small lengths. */ +static void +lzms_update_fast_length_costs(struct lzms_compressor *c) +{ + u32 len; + int slot = -1; + u32 cost = 0; + + for (len = 1; len < LZMS_NUM_FAST_LENGTHS; len++) { + + while (len >= lzms_length_slot_base[slot + 1]) { + slot++; + cost = (u32)(c->length_encoder.lens[slot] + + lzms_extra_length_bits[slot]) << LZMS_COST_SHIFT; + } + + c->length_cost_fast[len] = cost; + } +} + +/* Return the cost to encode the specified match length, which must be less than + * LZMS_NUM_FAST_LENGTHS. */ +static inline u32 +lzms_fast_length_cost(const struct lzms_compressor *c, u32 length) +{ + LZMS_ASSERT(length < LZMS_NUM_FAST_LENGTHS); + return c->length_cost_fast[length]; +} + +/* Return the cost to encode the specified LZ match offset. */ +static inline u32 +lzms_lz_offset_cost(const struct lzms_compressor *c, u32 offset) +{ + unsigned slot = lzms_get_offset_slot_fast(c, offset); + + return (u32)(c->lz_offset_encoder.lens[slot] + + lzms_extra_offset_bits[slot]) << LZMS_COST_SHIFT; +} + +/* + * Consider coding the match at repeat offset index @rep_idx. Consider each + * length from the minimum (2) to the full match length (@rep_len). + */ +static inline void +lzms_consider_lz_repeat_offset_match(const struct lzms_compressor *c, + struct lzms_mc_pos_data *cur_optimum_ptr, + u32 rep_len, unsigned rep_idx) +{ + u32 len; + u32 base_cost; + u32 cost; + unsigned i; + + base_cost = cur_optimum_ptr->cost; + + base_cost += lzms_rc_bit_cost(&c->main_range_encoder, + cur_optimum_ptr->state.main_state, 1); + + base_cost += lzms_rc_bit_cost(&c->match_range_encoder, + cur_optimum_ptr->state.match_state, 0); + + base_cost += lzms_rc_bit_cost(&c->lz_match_range_encoder, + cur_optimum_ptr->state.lz_match_state, 1); + + for (i = 0; i < rep_idx; i++) + base_cost += lzms_rc_bit_cost(&c->lz_repeat_match_range_encoders[i], + cur_optimum_ptr->state.lz_repeat_match_state[i], 1); + + if (i < LZMS_NUM_RECENT_OFFSETS - 1) + base_cost += lzms_rc_bit_cost(&c->lz_repeat_match_range_encoders[i], + cur_optimum_ptr->state.lz_repeat_match_state[i], 0); + + len = 2; + do { + cost = base_cost + lzms_fast_length_cost(c, len); + if (cost < (cur_optimum_ptr + len)->cost) { + (cur_optimum_ptr + len)->mc_item_data = + ((u64)rep_idx << MC_OFFSET_SHIFT) | len; + (cur_optimum_ptr + len)->cost = cost; + } + } while (++len <= rep_len); +} + +/* + * Consider coding each match in @matches as an explicit offset match. + * + * @matches must be sorted by strictly increasing length and strictly increasing + * offset. This is guaranteed by the match-finder. + * + * We consider each length from the minimum (2) to the longest + * (matches[num_matches - 1].len). For each length, we consider only the + * smallest offset for which that length is available. Although this is not + * guaranteed to be optimal due to the possibility of a larger offset costing + * less than a smaller offset to code, this is a very useful heuristic. + */ +static inline void +lzms_consider_lz_explicit_offset_matches(const struct lzms_compressor *c, + struct lzms_mc_pos_data *cur_optimum_ptr, + const struct lz_match matches[], + u32 num_matches) +{ + u32 len; + u32 i; + u32 base_cost; + u32 position_cost; + u32 cost; + + base_cost = cur_optimum_ptr->cost; + + base_cost += lzms_rc_bit_cost(&c->main_range_encoder, + cur_optimum_ptr->state.main_state, 1); + + base_cost += lzms_rc_bit_cost(&c->match_range_encoder, + cur_optimum_ptr->state.match_state, 0); + + base_cost += lzms_rc_bit_cost(&c->lz_match_range_encoder, + cur_optimum_ptr->state.lz_match_state, 0); + len = 2; + i = 0; + do { + position_cost = base_cost + lzms_lz_offset_cost(c, matches[i].offset); + do { + cost = position_cost + lzms_fast_length_cost(c, len); + if (cost < (cur_optimum_ptr + len)->cost) { + (cur_optimum_ptr + len)->mc_item_data = + ((u64)(matches[i].offset + LZMS_OFFSET_OFFSET) + << MC_OFFSET_SHIFT) | len; + (cur_optimum_ptr + len)->cost = cost; + } + } while (++len <= matches[i].len); + } while (++i != num_matches); +} + +static void +lzms_init_adaptive_state(struct lzms_adaptive_state *state) +{ + unsigned i; + + lzms_init_lz_lru_queue(&state->lru); + state->main_state = 0; + state->match_state = 0; + state->lz_match_state = 0; + for (i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++) + state->lz_repeat_match_state[i] = 0; +} + +static inline void +lzms_update_main_state(struct lzms_adaptive_state *state, int is_match) +{ + state->main_state = ((state->main_state << 1) | is_match) % LZMS_NUM_MAIN_STATES; +} + +static inline void +lzms_update_match_state(struct lzms_adaptive_state *state, int is_delta) +{ + state->match_state = ((state->match_state << 1) | is_delta) % LZMS_NUM_MATCH_STATES; +} + +static inline void +lzms_update_lz_match_state(struct lzms_adaptive_state *state, int is_repeat_offset) +{ + state->lz_match_state = ((state->lz_match_state << 1) | is_repeat_offset) % LZMS_NUM_LZ_MATCH_STATES; +} + +static inline void +lzms_update_lz_repeat_match_state(struct lzms_adaptive_state *state, int rep_idx) +{ + int i; + + for (i = 0; i < rep_idx; i++) + state->lz_repeat_match_state[i] = + ((state->lz_repeat_match_state[i] << 1) | 1) % + LZMS_NUM_LZ_REPEAT_MATCH_STATES; + + if (i < LZMS_NUM_RECENT_OFFSETS - 1) + state->lz_repeat_match_state[i] = + ((state->lz_repeat_match_state[i] << 1) | 0) % + LZMS_NUM_LZ_REPEAT_MATCH_STATES; +} + +/* + * The main near-optimal parsing routine. + * + * Briefly, the algorithm does an approximate minimum-cost path search to find a + * "near-optimal" sequence of matches and literals to output, based on the + * current cost model. The algorithm steps forward, position by position (byte + * by byte), and updates the minimum cost path to reach each later position that + * can be reached using a match or literal from the current position. This is + * essentially Dijkstra's algorithm in disguise: the graph nodes are positions, + * the graph edges are possible matches/literals to code, and the cost of each + * edge is the estimated number of bits that will be required to output the + * corresponding match or literal. But one difference is that we actually + * compute the lowest-cost path in pieces, where each piece is terminated when + * there are no choices to be made. + * + * Notes: + * + * - This does not output any delta matches. + * + * - The costs of literals and matches are estimated using the range encoder + * states and the semi-adaptive Huffman codes. Except for range encoding + * states, costs are assumed to be constant throughout a single run of the + * parsing algorithm, which can parse up to @optim_array_length bytes of data. + * This introduces a source of inaccuracy because the probabilities and + * Huffman codes can change over this part of the data. + */ +static void +lzms_near_optimal_parse(struct lzms_compressor *c) +{ + const u8 *window_ptr; + const u8 *window_end; + struct lzms_mc_pos_data *cur_optimum_ptr; + struct lzms_mc_pos_data *end_optimum_ptr; + u32 num_matches; + u32 longest_len; + u32 rep_max_len; + unsigned rep_max_idx; + unsigned literal; + unsigned i; + u32 cost; + u32 len; + u32 offset_data; + + window_ptr = c->cur_window; + window_end = window_ptr + c->cur_window_size; + + lzms_init_adaptive_state(&c->optimum[0].state); + +begin: + /* Start building a new list of items, which will correspond to the next + * piece of the overall minimum-cost path. */ + + cur_optimum_ptr = c->optimum; + cur_optimum_ptr->cost = 0; + end_optimum_ptr = cur_optimum_ptr; + + /* States should currently be consistent with the encoders. */ + LZMS_ASSERT(cur_optimum_ptr->state.main_state == c->main_range_encoder.state); + LZMS_ASSERT(cur_optimum_ptr->state.match_state == c->match_range_encoder.state); + LZMS_ASSERT(cur_optimum_ptr->state.lz_match_state == c->lz_match_range_encoder.state); + for (i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++) + LZMS_ASSERT(cur_optimum_ptr->state.lz_repeat_match_state[i] == + c->lz_repeat_match_range_encoders[i].state); + + if (window_ptr == window_end) + return; + + /* The following loop runs once for each per byte in the window, except + * in a couple shortcut cases. */ + for (;;) { + + /* Find explicit offset matches with the current position. */ + num_matches = lz_mf_get_matches(c->mf, c->matches); + + if (num_matches) { + /* + * Find the longest repeat offset match with the current + * position. + * + * Heuristics: + * + * - Only search for repeat offset matches if the + * match-finder already found at least one match. + * + * - Only consider the longest repeat offset match. It + * seems to be rare for the optimal parse to include a + * repeat offset match that doesn't have the longest + * length (allowing for the possibility that not all + * of that length is actually used). + */ + if (likely(window_ptr - c->cur_window >= LZMS_MAX_INIT_RECENT_OFFSET)) { + BUILD_BUG_ON(LZMS_NUM_RECENT_OFFSETS != 3); + rep_max_len = lz_repsearch3(window_ptr, + window_end - window_ptr, + cur_optimum_ptr->state.lru.recent_offsets, + &rep_max_idx); + } else { + rep_max_len = 0; + } + + if (rep_max_len) { + /* If there's a very long repeat offset match, + * choose it immediately. */ + if (rep_max_len >= c->params.nice_match_length) { + + lz_mf_skip_positions(c->mf, rep_max_len - 1); + window_ptr += rep_max_len; + + if (cur_optimum_ptr != c->optimum) + lzms_encode_item_list(c, cur_optimum_ptr); + + lzms_encode_lz_repeat_offset_match(c, rep_max_len, + rep_max_idx); + + c->optimum[0].state = cur_optimum_ptr->state; + + lzms_update_main_state(&c->optimum[0].state, 1); + lzms_update_match_state(&c->optimum[0].state, 0); + lzms_update_lz_match_state(&c->optimum[0].state, 1); + lzms_update_lz_repeat_match_state(&c->optimum[0].state, + rep_max_idx); + + c->optimum[0].state.lru.upcoming_offset = + c->optimum[0].state.lru.recent_offsets[rep_max_idx]; + + for (i = rep_max_idx; i < LZMS_NUM_RECENT_OFFSETS; i++) + c->optimum[0].state.lru.recent_offsets[i] = + c->optimum[0].state.lru.recent_offsets[i + 1]; + + lzms_update_lz_lru_queue(&c->optimum[0].state.lru); + goto begin; + } + + /* If reaching any positions for the first time, + * initialize their costs to "infinity". */ + while (end_optimum_ptr < cur_optimum_ptr + rep_max_len) + (++end_optimum_ptr)->cost = MC_INFINITE_COST; + + /* Consider coding a repeat offset match. */ + lzms_consider_lz_repeat_offset_match(c, cur_optimum_ptr, + rep_max_len, rep_max_idx); + } + + longest_len = c->matches[num_matches - 1].len; + + /* If there's a very long explicit offset match, choose + * it immediately. */ + if (longest_len >= c->params.nice_match_length) { + + lz_mf_skip_positions(c->mf, longest_len - 1); + window_ptr += longest_len; + + if (cur_optimum_ptr != c->optimum) + lzms_encode_item_list(c, cur_optimum_ptr); + + lzms_encode_lz_explicit_offset_match(c, longest_len, + c->matches[num_matches - 1].offset); + + c->optimum[0].state = cur_optimum_ptr->state; + + lzms_update_main_state(&c->optimum[0].state, 1); + lzms_update_match_state(&c->optimum[0].state, 0); + lzms_update_lz_match_state(&c->optimum[0].state, 0); + + c->optimum[0].state.lru.upcoming_offset = + c->matches[num_matches - 1].offset; + + lzms_update_lz_lru_queue(&c->optimum[0].state.lru); + goto begin; + } + + /* If reaching any positions for the first time, + * initialize their costs to "infinity". */ + while (end_optimum_ptr < cur_optimum_ptr + longest_len) + (++end_optimum_ptr)->cost = MC_INFINITE_COST; + + /* Consider coding an explicit offset match. */ + lzms_consider_lz_explicit_offset_matches(c, cur_optimum_ptr, + c->matches, num_matches); + } else { + /* No matches found. The only choice at this position + * is to code a literal. */ + + if (end_optimum_ptr == cur_optimum_ptr) + (++end_optimum_ptr)->cost = MC_INFINITE_COST; + } + + /* Consider coding a literal. + + * To avoid an extra unpredictable brench, actually checking the + * preferability of coding a literal is integrated into the + * adaptive state update code below. */ + literal = *window_ptr++; + cost = cur_optimum_ptr->cost + + lzms_literal_cost(c, literal, &cur_optimum_ptr->state); + + /* Advance to the next position. */ + cur_optimum_ptr++; + + /* The lowest-cost path to the current position is now known. + * Finalize the adaptive state that results from taking this + * lowest-cost path. */ + + if (cost < cur_optimum_ptr->cost) { + /* Literal */ + cur_optimum_ptr->cost = cost; + cur_optimum_ptr->mc_item_data = ((u64)literal << MC_OFFSET_SHIFT) | 1; + + cur_optimum_ptr->state = (cur_optimum_ptr - 1)->state; + + lzms_update_main_state(&cur_optimum_ptr->state, 0); + + cur_optimum_ptr->state.lru.upcoming_offset = 0; + } else { + /* LZ match */ + len = cur_optimum_ptr->mc_item_data & MC_LEN_MASK; + offset_data = cur_optimum_ptr->mc_item_data >> MC_OFFSET_SHIFT; + + cur_optimum_ptr->state = (cur_optimum_ptr - len)->state; + + lzms_update_main_state(&cur_optimum_ptr->state, 1); + lzms_update_match_state(&cur_optimum_ptr->state, 0); + + if (offset_data >= LZMS_NUM_RECENT_OFFSETS) { + + /* Explicit offset LZ match */ + + lzms_update_lz_match_state(&cur_optimum_ptr->state, 0); + + cur_optimum_ptr->state.lru.upcoming_offset = + offset_data - LZMS_OFFSET_OFFSET; + } else { + /* Repeat offset LZ match */ + + lzms_update_lz_match_state(&cur_optimum_ptr->state, 1); + lzms_update_lz_repeat_match_state(&cur_optimum_ptr->state, + offset_data); + + cur_optimum_ptr->state.lru.upcoming_offset = + cur_optimum_ptr->state.lru.recent_offsets[offset_data]; + + for (i = offset_data; i < LZMS_NUM_RECENT_OFFSETS; i++) + cur_optimum_ptr->state.lru.recent_offsets[i] = + cur_optimum_ptr->state.lru.recent_offsets[i + 1]; + } + } + + lzms_update_lz_lru_queue(&cur_optimum_ptr->state.lru); + + /* + * This loop will terminate when either of the following + * conditions is true: + * + * (1) cur_optimum_ptr == end_optimum_ptr + * + * There are no paths that extend beyond the current + * position. In this case, any path to a later position + * must pass through the current position, so we can go + * ahead and choose the list of items that led to this + * position. + * + * (2) cur_optimum_ptr == c->optimum_end + * + * This bounds the number of times the algorithm can step + * forward before it is guaranteed to start choosing items. + * This limits the memory usage. It also guarantees that + * the parser will not go too long without updating the + * probability tables. + * + * Note: no check for end-of-window is needed because + * end-of-window will trigger condition (1). + */ + if (cur_optimum_ptr == end_optimum_ptr || + cur_optimum_ptr == c->optimum_end) + { + c->optimum[0].state = cur_optimum_ptr->state; + break; + } + } + + /* Output the current list of items that constitute the minimum-cost + * path to the current position. */ + lzms_encode_item_list(c, cur_optimum_ptr); + goto begin; +} + +static void +lzms_init_range_encoder(struct lzms_range_encoder *enc, + struct lzms_range_encoder_raw *rc, u32 num_states) +{ + enc->rc = rc; + enc->state = 0; + LZMS_ASSERT(is_power_of_2(num_states)); + enc->mask = num_states - 1; + lzms_init_probability_entries(enc->prob_entries, num_states); +} + +static void +lzms_init_huffman_encoder(struct lzms_huffman_encoder *enc, + struct lzms_output_bitstream *os, + unsigned num_syms, + unsigned rebuild_freq) +{ + enc->os = os; + enc->num_syms_written = 0; + enc->rebuild_freq = rebuild_freq; + enc->num_syms = num_syms; + for (unsigned i = 0; i < num_syms; i++) + enc->sym_freqs[i] = 1; + + make_canonical_huffman_code(enc->num_syms, + LZMS_MAX_CODEWORD_LEN, + enc->sym_freqs, + enc->lens, + enc->codewords); +} + +/* Prepare the LZMS compressor for compressing a block of data. */ +static void +lzms_prepare_compressor(struct lzms_compressor *c, const u8 *udata, u32 ulen, + le16 *cdata, u32 clen16) +{ + unsigned num_offset_slots; + + /* Copy the uncompressed data into the @c->cur_window buffer. */ + memcpy(c->cur_window, udata, ulen); + c->cur_window_size = ulen; + + /* Initialize the raw range encoder (writing forwards). */ + lzms_range_encoder_raw_init(&c->rc, cdata, clen16); + + /* Initialize the output bitstream for Huffman symbols and verbatim bits + * (writing backwards). */ + lzms_output_bitstream_init(&c->os, cdata, clen16); + + /* Calculate the number of offset slots required. */ + num_offset_slots = lzms_get_offset_slot(ulen - 1) + 1; + + /* Initialize a Huffman encoder for each alphabet. */ + lzms_init_huffman_encoder(&c->literal_encoder, &c->os, + LZMS_NUM_LITERAL_SYMS, + LZMS_LITERAL_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&c->lz_offset_encoder, &c->os, + num_offset_slots, + LZMS_LZ_OFFSET_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&c->length_encoder, &c->os, + LZMS_NUM_LENGTH_SYMS, + LZMS_LENGTH_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&c->delta_offset_encoder, &c->os, + num_offset_slots, + LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ); + + lzms_init_huffman_encoder(&c->delta_power_encoder, &c->os, + LZMS_NUM_DELTA_POWER_SYMS, + LZMS_DELTA_POWER_CODE_REBUILD_FREQ); + + /* Initialize range encoders, all of which wrap around the same + * lzms_range_encoder_raw. */ + lzms_init_range_encoder(&c->main_range_encoder, + &c->rc, LZMS_NUM_MAIN_STATES); + + lzms_init_range_encoder(&c->match_range_encoder, + &c->rc, LZMS_NUM_MATCH_STATES); + + lzms_init_range_encoder(&c->lz_match_range_encoder, + &c->rc, LZMS_NUM_LZ_MATCH_STATES); + + for (unsigned i = 0; i < ARRAY_LEN(c->lz_repeat_match_range_encoders); i++) + lzms_init_range_encoder(&c->lz_repeat_match_range_encoders[i], + &c->rc, LZMS_NUM_LZ_REPEAT_MATCH_STATES); + + lzms_init_range_encoder(&c->delta_match_range_encoder, + &c->rc, LZMS_NUM_DELTA_MATCH_STATES); + + for (unsigned i = 0; i < ARRAY_LEN(c->delta_repeat_match_range_encoders); i++) + lzms_init_range_encoder(&c->delta_repeat_match_range_encoders[i], + &c->rc, LZMS_NUM_DELTA_REPEAT_MATCH_STATES); + + /* Set initial length costs for lengths < LZMS_NUM_FAST_LENGTHS. */ + lzms_update_fast_length_costs(c); +} + +/* Flush the output streams, prepare the final compressed data, and return its + * size in bytes. + * + * A return value of 0 indicates that the data could not be compressed to fit in + * the available space. */ +static size_t +lzms_finalize(struct lzms_compressor *c, u8 *cdata, size_t csize_avail) +{ + size_t num_forwards_bytes; + size_t num_backwards_bytes; + + /* Flush both the forwards and backwards streams, and make sure they + * didn't cross each other and start overwriting each other's data. */ + if (!lzms_output_bitstream_flush(&c->os)) + return 0; + + if (!lzms_range_encoder_raw_flush(&c->rc)) + return 0; + + if (c->rc.next > c->os.next) + return 0; + + /* Now the compressed buffer contains the data output by the forwards + * bitstream, then empty space, then data output by the backwards + * bitstream. Move the data output by the backwards bitstream to be + * adjacent to the data output by the forward bitstream, and calculate + * the compressed size that this results in. */ + num_forwards_bytes = (u8*)c->rc.next - (u8*)cdata; + num_backwards_bytes = ((u8*)cdata + csize_avail) - (u8*)c->os.next; + + memmove(cdata + num_forwards_bytes, c->os.next, num_backwards_bytes); + + return num_forwards_bytes + num_backwards_bytes; +} + +/* Set internal compression parameters for the specified compression level and + * maximum window size. */ +static void +lzms_build_params(unsigned int compression_level, + struct lzms_compressor_params *params) +{ + /* Allow length 2 matches if the compression level is sufficiently high. + */ + if (compression_level >= 45) + params->min_match_length = 2; + else + params->min_match_length = 3; + + /* Scale nice_match_length and max_search_depth with the compression + * level. But to allow an optimization on length cost calculations, + * don't allow nice_match_length to exceed LZMS_NUM_FAST_LENGTH. */ + params->nice_match_length = ((u64)compression_level * 32) / 50; + if (params->nice_match_length < params->min_match_length) + params->nice_match_length = params->min_match_length; + if (params->nice_match_length > LZMS_NUM_FAST_LENGTHS) + params->nice_match_length = LZMS_NUM_FAST_LENGTHS; + params->max_search_depth = compression_level; + + params->optim_array_length = 1024; +} + +/* Given the internal compression parameters and maximum window size, build the + * Lempel-Ziv match-finder parameters. */ +static void +lzms_build_mf_params(const struct lzms_compressor_params *lzms_params, + u32 max_window_size, struct lz_mf_params *mf_params) +{ + memset(mf_params, 0, sizeof(*mf_params)); + + /* Choose an appropriate match-finding algorithm. */ + if (max_window_size <= 2097152) + mf_params->algorithm = LZ_MF_BINARY_TREES; + else if (max_window_size <= 33554432) + mf_params->algorithm = LZ_MF_LCP_INTERVAL_TREE; + else + mf_params->algorithm = LZ_MF_LINKED_SUFFIX_ARRAY; + + mf_params->max_window_size = max_window_size; + mf_params->min_match_len = lzms_params->min_match_length; + mf_params->max_search_depth = lzms_params->max_search_depth; + mf_params->nice_match_len = lzms_params->nice_match_length; +} + +static void +lzms_free_compressor(void *_c); + +static u64 +lzms_get_needed_memory(size_t max_block_size, unsigned int compression_level) +{ + struct lzms_compressor_params params; + struct lz_mf_params mf_params; + u64 size = 0; + + if (max_block_size >= INT32_MAX) + return 0; + + lzms_build_params(compression_level, ¶ms); + lzms_build_mf_params(¶ms, max_block_size, &mf_params); + + size += sizeof(struct lzms_compressor); + + /* cur_window */ + size += max_block_size; + + /* mf */ + size += lz_mf_get_needed_memory(mf_params.algorithm, max_block_size); + + /* matches */ + size += min(params.max_search_depth, params.nice_match_length) * + sizeof(struct lz_match); + + /* optimum */ + size += (params.optim_array_length + params.nice_match_length) * + sizeof(struct lzms_mc_pos_data); + + return size; +} + static int -lzms_create_compressor(size_t max_block_size, - const struct wimlib_compressor_params_header *params, +lzms_create_compressor(size_t max_block_size, unsigned int compression_level, void **ctx_ret) { - struct lzms_compressor *ctx; + struct lzms_compressor *c; + struct lzms_compressor_params params; + struct lz_mf_params mf_params; - if (max_block_size == 0 || max_block_size > 1U << 26) { - LZMS_DEBUG("Invalid max_block_size (%u)", max_block_size); + if (max_block_size >= INT32_MAX) + return WIMLIB_ERR_INVALID_PARAM; + + 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) + c = CALLOC(1, sizeof(struct lzms_compressor)); + if (!c) goto oom; - ctx->window = MALLOC(max_block_size); - if (ctx->window == NULL) + c->params = params; + + c->cur_window = MALLOC(max_block_size); + if (!c->cur_window) + goto oom; + + c->mf = lz_mf_alloc(&mf_params); + if (!c->mf) goto oom; - ctx->max_block_size = max_block_size; - ctx->last_target_usages = MALLOC(65536 * sizeof(ctx->last_target_usages[0])); - if (ctx->last_target_usages == NULL) + c->matches = MALLOC(min(params.max_search_depth, + params.nice_match_length) * + sizeof(struct lz_match)); + if (!c->matches) goto oom; - *ctx_ret = ctx; + c->optimum = MALLOC((params.optim_array_length + + params.nice_match_length) * + sizeof(struct lzms_mc_pos_data)); + if (!c->optimum) + goto oom; + c->optimum_end = &c->optimum[params.optim_array_length]; + + lzms_init_rc_costs(); + + lzms_init_fast_slots(c); + + *ctx_ret = c; return 0; oom: - lzms_free_compressor(ctx); + lzms_free_compressor(c); return WIMLIB_ERR_NOMEM; } +static size_t +lzms_compress(const void *uncompressed_data, size_t uncompressed_size, + void *compressed_data, size_t compressed_size_avail, void *_c) +{ + struct lzms_compressor *c = _c; + + /* Don't bother compressing extremely small inputs. */ + if (uncompressed_size < 4) + return 0; + + /* Cap the available compressed size to a 32-bit integer and round it + * down to the nearest multiple of 2. */ + if (compressed_size_avail > UINT32_MAX) + compressed_size_avail = UINT32_MAX; + if (compressed_size_avail & 1) + compressed_size_avail--; + + /* Initialize the compressor structures. */ + lzms_prepare_compressor(c, uncompressed_data, uncompressed_size, + compressed_data, compressed_size_avail / 2); + + /* Preprocess the uncompressed data. */ + lzms_x86_filter(c->cur_window, c->cur_window_size, + c->last_target_usages, false); + + /* Load the window into the match-finder. */ + lz_mf_load_window(c->mf, c->cur_window, c->cur_window_size); + + /* Compute and encode a literal/match sequence that decompresses to the + * preprocessed data. */ + lzms_near_optimal_parse(c); + + /* Return the compressed data size or 0. */ + return lzms_finalize(c, compressed_data, compressed_size_avail); +} + +static void +lzms_free_compressor(void *_c) +{ + struct lzms_compressor *c = _c; + + if (c) { + FREE(c->cur_window); + lz_mf_free(c->mf); + FREE(c->matches); + FREE(c->optimum); + FREE(c); + } +} + const struct compressor_ops lzms_compressor_ops = { + .get_needed_memory = lzms_get_needed_memory, .create_compressor = lzms_create_compressor, .compress = lzms_compress, .free_compressor = lzms_free_compressor,