*/
/*
- * 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 a compressor for the LZMS compression format. More details about this
* format can be found in lzms-decompress.c.
*
- * This is currently an unsophisticated implementation that is fast but does not
- * attain the best compression ratios allowed by the format.
+ * 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 "wimlib/compress_common.h"
#include "wimlib/endianness.h"
#include "wimlib/error.h"
-#include "wimlib/lz_hash.h"
-#include "wimlib/lz_sarray.h"
+#include "wimlib/lz.h"
+#include "wimlib/lz_bt.h"
#include "wimlib/lzms.h"
#include "wimlib/util.h"
#include <string.h>
#include <limits.h>
-
-#define LZMS_OPTIM_ARRAY_SIZE 1024
-
-struct lzms_compressor;
-struct lzms_cost_state {
- struct lzms_lz_lru_queues lru;
- u8 main_state;
- u8 match_state;
- u8 lz_match_state;
-};
-#define LZ_FORMAT_STATE struct lzms_cost_state
-#define LZ_COMPRESSOR struct lzms_compressor
-#include "wimlib/lz_optimal.h"
+#include <pthread.h>
/* Stucture used for writing raw bits to the end of the LZMS-compressed data as
* a series of 16-bit little endian coding units. */
* lzms_range_encoder_raw. */
struct lzms_range_encoder_raw *rc;
- /* Bits recently encoded by this range encoder. This are used as in
+ /* Bits recently encoded by this range encoder. This is used as an
* index into @prob_entries. */
u32 state;
struct lzms_probability_entry prob_entries[LZMS_MAX_NUM_STATES];
};
-/* Structure used for Huffman encoding, optionally encoding larger "values" as a
- * Huffman symbol specifying a slot and a slot-dependent number of extra bits.
- * */
+/* Structure used for Huffman encoding. */
struct lzms_huffman_encoder {
/* Bitstream to write Huffman-encoded symbols and verbatim bits to.
*/
struct lzms_output_bitstream *os;
- /* Pointer to the slot base table to use. */
- const u32 *slot_base_tab;
-
/* Number of symbols that have been written using this code far. Reset
* to 0 whenever the code is rebuilt. */
u32 num_syms_written;
u8 lens[LZMS_MAX_NUM_SYMS];
/* The codeword of each symbol in the Huffman code. */
- u16 codewords[LZMS_MAX_NUM_SYMS];
+ u32 codewords[LZMS_MAX_NUM_SYMS];
};
/* State of the LZMS compressor. */
struct lzms_compressor {
+ struct wimlib_lzms_compressor_params params;
+
/* Pointer to a buffer holding the preprocessed data to compress. */
u8 *window;
/* Size of the data in @buffer. */
u32 window_size;
- /* Temporary array used by lz_analyze_block(); must be at least as long
- * as the window. */
- u32 *prev_tab;
+ /* Binary tree match-finder. */
+ struct lz_bt mf;
- /* Suffix array match-finder. */
- struct lz_sarray lz_sarray;
+ /* Temporary space to store found matches. */
+ struct raw_match *matches;
- struct raw_match matches[64];
-
- /* Match-chooser. */
- struct lz_match_chooser mc;
+ /* 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. */
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_huffman_encode_symbol(struct lzms_huffman_encoder *enc, u32 sym)
{
LZMS_ASSERT(sym < enc->num_syms);
- if (enc->num_syms_written == enc->rebuild_freq) {
+ 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,
}
enc->num_syms_written = 0;
}
- lzms_output_bitstream_put_bits(enc->os,
- enc->codewords[sym],
- enc->lens[sym]);
- ++enc->num_syms_written;
- ++enc->sym_freqs[sym];
}
-/* Encode a number as a Huffman symbol specifying a slot, plus a number of
- * slot-dependent extra bits. */
static void
-lzms_encode_value(struct lzms_huffman_encoder *enc, u32 value)
+lzms_encode_length(struct lzms_huffman_encoder *enc, u32 length)
{
unsigned slot;
unsigned num_extra_bits;
u32 extra_bits;
- LZMS_ASSERT(enc->slot_base_tab != NULL);
+ slot = lzms_get_length_slot(length);
- slot = lzms_get_slot(value, enc->slot_base_tab, enc->num_syms);
+ num_extra_bits = lzms_extra_length_bits[slot];
- /* Get the number of extra bits needed to represent the range of values
- * that share the slot. */
- num_extra_bits = bsr32(enc->slot_base_tab[slot + 1] -
- enc->slot_base_tab[slot]);
+ extra_bits = length - lzms_length_slot_base[slot];
- /* Calculate the extra bits as the offset from the slot base. */
- extra_bits = value - enc->slot_base_tab[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];
- /* Output the slot (Huffman-encoded), then the extra bits (verbatim).
- */
lzms_huffman_encode_symbol(enc, slot);
lzms_output_bitstream_put_bits(enc->os, extra_bits, num_extra_bits);
}
{
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);
- LZMS_DEBUG("Position %u: Encoding LZ match {length=%u, offset=%u}",
- ctx->cur_window_pos, length, offset);
-
/* Main bit: 1 = a match, not a literal. */
lzms_range_encode_bit(&ctx->main_range_encoder, 1);
- /* Match bit: 0 = a LZ match, not a delta match. */
+ /* 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. */
if (recent_offset_idx == LZMS_NUM_RECENT_OFFSETS) {
/* Explicit offset. */
- /* LZ match bit: 0 = explicit offset, not a repeat 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_value(&ctx->lz_offset_encoder, offset);
+ lzms_encode_offset(&ctx->lz_offset_encoder, offset);
} else {
int i;
- /* Repeat offset. */
+ /* Recent offset. */
- /* LZ match bit: 1 = repeat offset, not an explicit 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
}
/* Encode the match length. */
- lzms_encode_value(&ctx->length_encoder, 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. */
lzms_end_encode_item(ctx, length);
}
-static void
-lzms_record_literal(u8 literal, void *_ctx)
-{
- struct lzms_compressor *ctx = _ctx;
+#define LZMS_COST_SHIFT 5
- lzms_encode_literal(ctx, literal);
-}
+/*#define LZMS_RC_COSTS_USE_FLOATING_POINT*/
-static void
-lzms_record_match(unsigned length, unsigned offset, void *_ctx)
-{
- struct lzms_compressor *ctx = _ctx;
+static u32
+lzms_rc_costs[LZMS_PROBABILITY_MAX + 1];
- lzms_encode_lz_match(ctx, length, offset);
-}
+#ifdef LZMS_RC_COSTS_USE_FLOATING_POINT
+# include <math.h>
+#endif
static void
-lzms_fast_encode(struct lzms_compressor *ctx)
+lzms_do_init_rc_costs(void)
{
- static const struct lz_params lzms_lz_params = {
- .min_match = 3,
- .max_match = UINT_MAX,
- .max_offset = UINT_MAX,
- .nice_match = 64,
- .good_match = 32,
- .max_chain_len = 64,
- .max_lazy_match = 258,
- .too_far = 4096,
- };
-
- lz_analyze_block(ctx->window,
- ctx->window_size,
- lzms_record_match,
- lzms_record_literal,
- ctx,
- &lzms_lz_params,
- ctx->prev_tab);
-
+ /* 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
+ }
}
-/* Fast heuristic cost evaluation to use in the inner loop of the match-finder.
- * Unlike lzms_get_match_cost(), which does a true cost evaluation, this simply
- * prioritize matches based on their offset. */
-static input_idx_t
-lzms_match_cost_fast(input_idx_t length, input_idx_t offset, const void *_lru)
+static void
+lzms_init_rc_costs(void)
{
- const struct lzms_lz_lru_queues *lru = _lru;
-
- for (input_idx_t i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++)
- if (offset == lru->recent_offsets[i])
- return i;
+ static pthread_once_t once = PTHREAD_ONCE_INIT;
- return offset;
+ 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;
- u32 cost;
-
- prob = enc->prob_entries[*cur_state & enc->mask].num_recent_zero_bits;
- if (prob == 0)
- prob = 1;
- else if (prob == LZMS_PROBABILITY_MAX)
- prob = LZMS_PROBABILITY_MAX - 1;
-
- if (bit == 0)
- prob = LZMS_PROBABILITY_MAX - prob;
+ u32 prob_zero;
+ u32 prob_correct;
- cost = prob * 2; /* TODO */
+ prob_zero = enc->prob_entries[*cur_state & enc->mask].num_recent_zero_bits;
*cur_state = (*cur_state << 1) | bit;
- return cost;
-}
+ if (bit == 0)
+ prob_correct = prob_zero;
+ else
+ prob_correct = LZMS_PROBABILITY_MAX - prob_zero;
-#define LZMS_COST_SCALE 64
+ 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_SCALE;
+ return enc->lens[sym] << LZMS_COST_SHIFT;
}
static u32
-lzms_value_cost(const struct lzms_huffman_encoder *enc, u32 value)
+lzms_offset_cost(const struct lzms_huffman_encoder *enc, u32 offset)
{
u32 slot;
u32 num_extra_bits;
u32 cost = 0;
- slot = lzms_get_slot(value, enc->slot_base_tab, enc->num_syms);
+ slot = lzms_get_position_slot(offset);
cost += lzms_huffman_symbol_cost(enc, slot);
- num_extra_bits = bsr32(enc->slot_base_tab[slot + 1] -
- enc->slot_base_tab[slot]);
+ num_extra_bits = lzms_extra_position_bits[slot];
- cost += num_extra_bits * LZMS_COST_SCALE;
+ cost += num_extra_bits << LZMS_COST_SHIFT;
return cost;
}
static u32
-lzms_get_matches(struct lzms_compressor *ctx,
- const struct lzms_cost_state *cost_state,
- struct raw_match **matches_ret)
+lzms_length_cost(const struct lzms_huffman_encoder *enc, u32 length)
{
- u32 num_matches;
- struct raw_match *matches = ctx->matches;
-
- num_matches = lz_sarray_get_matches(&ctx->lz_sarray,
- matches,
- lzms_match_cost_fast,
- &cost_state->lru);
-
-#ifdef ENABLE_LZMS_DEBUG
- u32 curpos = lz_sarray_get_pos(&ctx->lz_sarray) - 1;
- LZMS_ASSERT(curpos >= 0);
- for (u32 i = 0; i < num_matches; i++) {
- LZMS_ASSERT(matches[i].len <= ctx->window_size - curpos);
- LZMS_ASSERT(matches[i].offset > 0);
- LZMS_ASSERT(matches[i].offset <= curpos);
- LZMS_ASSERT(!memcmp(&ctx->window[curpos],
- &ctx->window[curpos - matches[i].offset],
- matches[i].len));
- if (i > 0)
- LZMS_ASSERT(matches[i - 1].len > matches[i].len);
+ u32 slot;
+ u32 num_extra_bits;
+ u32 cost = 0;
- }
-#endif
+ slot = lzms_get_length_slot(length);
- *matches_ret = matches;
- return num_matches;
+ 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 raw_match **matches_ret)
+{
+ *matches_ret = ctx->matches;
+ return lz_bt_get_matches(&ctx->mf, ctx->matches);
}
static void
-lzms_skip_bytes(struct lzms_compressor *ctx, input_idx_t n)
+lzms_skip_bytes(struct lzms_compressor *ctx, u32 n)
{
- while (n--)
- lz_sarray_skip_position(&ctx->lz_sarray);
+ lz_bt_skip_positions(&ctx->mf, n);
}
static u32
-lzms_get_prev_literal_cost(struct lzms_compressor *ctx,
- struct lzms_cost_state *cost_state)
+lzms_get_literal_cost(struct lzms_compressor *ctx,
+ struct lzms_adaptive_state *state, u8 literal)
{
- u8 literal = ctx->window[lz_sarray_get_pos(&ctx->lz_sarray) - 1];
u32 cost = 0;
- cost_state->lru.upcoming_offset = 0;
- lzms_update_lz_lru_queues(&cost_state->lru);
+ state->lru.upcoming_offset = 0;
+ lzms_update_lz_lru_queues(&state->lru);
cost += lzms_rc_bit_cost(&ctx->main_range_encoder,
- &cost_state->main_state, 0);
+ &state->main_state, 0);
+
cost += lzms_huffman_symbol_cost(&ctx->literal_encoder, literal);
return cost;
}
static u32
-lzms_get_match_cost(struct lzms_compressor *ctx,
- struct lzms_cost_state *cost_state,
- input_idx_t length, input_idx_t offset)
+lzms_get_lz_match_cost(struct lzms_compressor *ctx,
+ struct lzms_adaptive_state *state,
+ u32 length, u32 offset)
{
u32 cost = 0;
int recent_offset_idx;
cost += lzms_rc_bit_cost(&ctx->main_range_encoder,
- &cost_state->main_state, 1);
+ &state->main_state, 1);
cost += lzms_rc_bit_cost(&ctx->match_range_encoder,
- &cost_state->match_state, 0);
+ &state->match_state, 0);
for (recent_offset_idx = 0;
recent_offset_idx < LZMS_NUM_RECENT_OFFSETS;
recent_offset_idx++)
- if (offset == cost_state->lru.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,
- &cost_state->lz_match_state, 0);
+ &state->lz_match_state, 0);
- cost += lzms_value_cost(&ctx->lz_offset_encoder, offset);
+ cost += lzms_offset_cost(&ctx->lz_offset_encoder, offset);
} else {
int i;
- /* Repeat offset. */
+ /* Recent offset. */
cost += lzms_rc_bit_cost(&ctx->lz_match_range_encoder,
- &cost_state->lz_match_state, 1);
+ &state->lz_match_state, 1);
for (i = 0; i < recent_offset_idx; i++)
- cost++; /* TODO */
+ 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++; /* TODO */
+ 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++)
- cost_state->lru.recent_offsets[i] = cost_state->lru.recent_offsets[i + 1];
+ state->lru.recent_offsets[i] = state->lru.recent_offsets[i + 1];
}
- cost += lzms_value_cost(&ctx->length_encoder, length);
+ cost += lzms_length_cost(&ctx->length_encoder, length);
- cost_state->lru.upcoming_offset = offset;
- lzms_update_lz_lru_queues(&cost_state->lru);
+ state->lru.upcoming_offset = offset;
+ lzms_update_lz_lru_queues(&state->lru);
return cost;
}
+static struct raw_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 raw_match)
+ { .len = ctx->optimum_cur_idx,
+ .offset = ctx->optimum[0].next.match_offset,
+ };
+}
+
+/* This is similar to lzx_get_near_optimal_match() in lzx-compress.c.
+ * Read that one if you want to understand it. */
static struct raw_match
lzms_get_near_optimal_match(struct lzms_compressor *ctx)
{
- struct lzms_cost_state initial_state = {
- .lru = ctx->lru.lz,
- .main_state = ctx->main_range_encoder.state,
- .match_state = ctx->match_range_encoder.state,
- .lz_match_state = ctx->lz_match_range_encoder.state,
- };
- return lz_get_near_optimal_match(&ctx->mc,
- lzms_get_matches,
- lzms_skip_bytes,
- lzms_get_prev_literal_cost,
- lzms_get_match_cost,
- ctx,
- &initial_state);
+ u32 num_matches;
+ struct raw_match *matches;
+ struct raw_match match;
+ u32 longest_len;
+ u32 longest_rep_len;
+ u32 longest_rep_offset;
+ struct raw_match *matchptr;
+ 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_bt_get_position(&ctx->mf) >= 1) {
+ u32 limit = min(ctx->params.max_match_length,
+ lz_bt_get_remaining_size(&ctx->mf));
+ for (int i = 0; i < LZMS_NUM_RECENT_OFFSETS; i++) {
+ u32 offset = ctx->lru.lz.recent_offsets[i];
+ const u8 *strptr = lz_bt_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 raw_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_bt_get_window_ptr(&ctx->mf) - 1));
+ ctx->optimum[1].prev.link = 0;
+
+ matchptr = matches;
+ for (u32 len = 2; len <= longest_len; len++) {
+ u32 offset = matchptr->offset;
+
+ ctx->optimum[len].state = initial_state;
+ ctx->optimum[len].prev.link = 0;
+ ctx->optimum[len].prev.match_offset = offset;
+ ctx->optimum[len].cost = lzms_get_lz_match_cost(ctx,
+ &ctx->optimum[len].state,
+ len, offset);
+ if (len == matchptr->len)
+ matchptr++;
+ }
+ 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;
+ u32 limit = min(ctx->params.max_match_length,
+ lz_bt_get_remaining_size(&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_bt_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_bt_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;
+ }
+
+ matchptr = matches;
+ for (u32 len = 2; len <= longest_len; len++) {
+ u32 offset;
+
+ offset = matchptr->offset;
+ state = ctx->optimum[cur_pos].state;
+
+ cost = ctx->optimum[cur_pos].cost +
+ lzms_get_lz_match_cost(ctx, &state, len, offset);
+ 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;
+ }
+ if (len == matchptr->len)
+ matchptr++;
+ }
+
+ 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 uses near-optimal LZ parsing backed by a binary tree match-finder.
+ *
+ * - 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 (from the
+ * `struct wimlib_lzms_compressor_params') 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_slow_encode(struct lzms_compressor *ctx)
+lzms_encode(struct lzms_compressor *ctx)
{
struct raw_match match;
- /* Load window into suffix array match-finder. */
- lz_sarray_load_window(&ctx->lz_sarray, ctx->window, ctx->window_size);
+ /* Load window into the binary tree match-finder. */
+ lz_bt_load_window(&ctx->mf, ctx->window, ctx->window_size);
/* Reset the match-chooser. */
- lz_match_chooser_begin(&ctx->mc);
+ ctx->optimum_cur_idx = 0;
+ ctx->optimum_end_idx = 0;
- /* TODO */
while (ctx->cur_window_pos != ctx->window_size) {
-
match = lzms_get_near_optimal_match(ctx);
- if (match.len <= 1) {
- /* Literal */
+ if (match.len <= 1)
lzms_encode_literal(ctx, ctx->window[ctx->cur_window_pos]);
- } else {
- /* LZ match */
+ else
lzms_encode_lz_match(ctx, match.len, match.offset);
- }
}
}
static void
lzms_init_huffman_encoder(struct lzms_huffman_encoder *enc,
struct lzms_output_bitstream *os,
- const u32 *slot_base_tab,
unsigned num_syms,
unsigned rebuild_freq)
{
enc->os = os;
- enc->slot_base_tab = slot_base_tab;
- enc->num_syms_written = rebuild_freq;
+ enc->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. */
/* Copy the uncompressed data into the @ctx->window buffer. */
memcpy(ctx->window, udata, ulen);
- memset(&ctx->window[ulen], 0, 8);
ctx->cur_window_pos = 0;
ctx->window_size = ulen;
* (writing backwards). */
lzms_output_bitstream_init(&ctx->os, cdata, clen16);
- /* Initialize position and length slot bases if not done already. */
- lzms_init_slot_bases();
-
/* Calculate the number of position slots needed for this compressed
* block. */
num_position_slots = lzms_get_position_slot(ulen - 1) + 1;
/* Initialize Huffman encoders for each alphabet used in the compressed
* representation. */
lzms_init_huffman_encoder(&ctx->literal_encoder, &ctx->os,
- NULL, LZMS_NUM_LITERAL_SYMS,
+ LZMS_NUM_LITERAL_SYMS,
LZMS_LITERAL_CODE_REBUILD_FREQ);
lzms_init_huffman_encoder(&ctx->lz_offset_encoder, &ctx->os,
- lzms_position_slot_base, num_position_slots,
+ num_position_slots,
LZMS_LZ_OFFSET_CODE_REBUILD_FREQ);
lzms_init_huffman_encoder(&ctx->length_encoder, &ctx->os,
- lzms_length_slot_base, LZMS_NUM_LEN_SYMS,
+ LZMS_NUM_LEN_SYMS,
LZMS_LENGTH_CODE_REBUILD_FREQ);
lzms_init_huffman_encoder(&ctx->delta_offset_encoder, &ctx->os,
- lzms_position_slot_base, num_position_slots,
+ num_position_slots,
LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ);
lzms_init_huffman_encoder(&ctx->delta_power_encoder, &ctx->os,
- NULL, LZMS_NUM_DELTA_POWER_SYMS,
+ LZMS_NUM_DELTA_POWER_SYMS,
LZMS_DELTA_POWER_CODE_REBUILD_FREQ);
/* Initialize range encoders, all of which wrap around the same
&ctx->rc, LZMS_NUM_DELTA_REPEAT_MATCH_STATES);
/* Initialize LRU match information. */
- lzms_init_lru_queues(&ctx->lru);
+ lzms_init_lru_queues(&ctx->lru);
}
/* Flush the output streams, prepare the final compressed data, and return its
/* Now the compressed buffer contains the data output by the forwards
* bitstream, then empty space, then data output by the backwards
- * bitstream. Move the data output by the forwards bitstream to be
- * adjacent to the data output by the backwards bitstream, and calculate
+ * 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;
LZMS_DEBUG("num_forwards_bytes=%zu, num_backwards_bytes=%zu, "
"compressed_size=%zu",
num_forwards_bytes, num_backwards_bytes, compressed_size);
- LZMS_ASSERT(!(compressed_size & 1));
+ LZMS_ASSERT(compressed_size % 2 == 0);
return compressed_size;
}
}
/* Don't bother compressing extremely small inputs. */
- if (uncompressed_size < 4)
+ 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
+ /* 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;
lzms_x86_filter(ctx->window, ctx->window_size,
ctx->last_target_usages, false);
- /* Determine and output a literal/match sequence that decompresses to
- * the preprocessed data. */
- if (1)
- lzms_slow_encode(ctx);
- else
- lzms_fast_encode(ctx);
+ /* 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,
if (ctx) {
FREE(ctx->window);
- FREE(ctx->prev_tab);
- lz_sarray_destroy(&ctx->lz_sarray);
- lz_match_chooser_destroy(&ctx->mc);
+ FREE(ctx->matches);
+ lz_bt_destroy(&ctx->mf);
+ FREE(ctx->optimum);
FREE(ctx);
}
}
+static const struct wimlib_lzms_compressor_params lzms_default = {
+ .hdr = {
+ .size = sizeof(struct wimlib_lzms_compressor_params),
+ },
+ .min_match_length = 2,
+ .max_match_length = UINT32_MAX,
+ .nice_match_length = 32,
+ .max_search_depth = 50,
+ .optim_array_length = 1024,
+};
+
+static bool
+lzms_params_valid(const struct wimlib_compressor_params_header *);
+
+static const struct wimlib_lzms_compressor_params *
+lzms_get_params(const struct wimlib_compressor_params_header *_params)
+{
+ const struct wimlib_lzms_compressor_params *params =
+ (const struct wimlib_lzms_compressor_params*)_params;
+
+ if (params == NULL)
+ params = &lzms_default;
+
+ LZMS_ASSERT(lzms_params_valid(¶ms->hdr));
+
+ return params;
+}
+
static int
lzms_create_compressor(size_t max_block_size,
- const struct wimlib_compressor_params_header *params,
+ const struct wimlib_compressor_params_header *_params,
void **ctx_ret)
{
struct lzms_compressor *ctx;
+ const struct wimlib_lzms_compressor_params *params = lzms_get_params(_params);
if (max_block_size == 0 || max_block_size >= INT32_MAX) {
LZMS_DEBUG("Invalid max_block_size (%u)", max_block_size);
if (ctx == NULL)
goto oom;
- ctx->window = MALLOC(max_block_size + 8);
+ ctx->window = MALLOC(max_block_size);
if (ctx->window == NULL)
goto oom;
- ctx->prev_tab = MALLOC(max_block_size * sizeof(ctx->prev_tab[0]));
- if (ctx->prev_tab == NULL)
+ ctx->matches = MALLOC(min(params->max_match_length -
+ params->min_match_length + 1,
+ params->max_search_depth + 2) *
+ sizeof(ctx->matches[0]));
+ if (ctx->matches == NULL)
goto oom;
- if (!lz_sarray_init(&ctx->lz_sarray,
- max_block_size,
- 2,
- max_block_size,
- 100,
- 10))
+ if (!lz_bt_init(&ctx->mf,
+ max_block_size,
+ params->min_match_length,
+ params->max_match_length,
+ params->nice_match_length,
+ params->max_search_depth))
goto oom;
- if (!lz_match_chooser_init(&ctx->mc,
- LZMS_OPTIM_ARRAY_SIZE,
- 32,
- max_block_size))
+ ctx->optimum = MALLOC((params->optim_array_length +
+ min(params->nice_match_length,
+ params->max_match_length)) *
+ sizeof(ctx->optimum[0]));
+ 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->max_block_size = max_block_size;
+ memcpy(&ctx->params, params, sizeof(*params));
*ctx_ret = ctx;
return 0;
return WIMLIB_ERR_NOMEM;
}
+static u64
+lzms_get_needed_memory(size_t max_block_size,
+ const struct wimlib_compressor_params_header *_params)
+{
+ const struct wimlib_lzms_compressor_params *params = lzms_get_params(_params);
+
+ u64 size = 0;
+
+ size += max_block_size;
+ size += sizeof(struct lzms_compressor);
+ size += lz_bt_get_needed_memory(max_block_size);
+ size += (params->optim_array_length +
+ min(params->nice_match_length,
+ params->max_match_length)) *
+ sizeof(((struct lzms_compressor *)0)->optimum[0]);
+ size += min(params->max_match_length - params->min_match_length + 1,
+ params->max_search_depth + 2) *
+ sizeof(((struct lzms_compressor*)0)->matches[0]);
+ return size;
+}
+
+static bool
+lzms_params_valid(const struct wimlib_compressor_params_header *_params)
+{
+ const struct wimlib_lzms_compressor_params *params =
+ (const struct wimlib_lzms_compressor_params*)_params;
+
+ if (params->hdr.size != sizeof(*params) ||
+ params->max_match_length < params->min_match_length ||
+ params->min_match_length < 2 ||
+ params->optim_array_length == 0 ||
+ min(params->max_match_length, params->nice_match_length) > 65536)
+ return false;
+
+ return true;
+}
+
const struct compressor_ops lzms_compressor_ops = {
+ .params_valid = lzms_params_valid,
+ .get_needed_memory = lzms_get_needed_memory,
.create_compressor = lzms_create_compressor,
.compress = lzms_compress,
.free_compressor = lzms_free_compressor,
git://wimlib.net / wimlib / blobdiff