/*
* 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.
*
*/
/* 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"
#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.h"
+#include "wimlib/lz_bt.h"
#include "wimlib/lzms.h"
#include "wimlib/util.h"
#include <string.h>
+#include <limits.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. */
+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];
+};
+
+/* 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;
+
+ /* Current position in @buffer. */
+ u32 cur_window_pos;
+
+ /* Size of the data in @buffer. */
u32 window_size;
+
+ /* Binary tree match-finder. */
+ struct lz_bt mf;
+
+ /* Temporary space to store found matches. */
+ struct raw_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;
+ /* 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_preprocess_data(u8 *data, s32 size, s32 *last_target_usages)
+lzms_output_bitstream_init(struct lzms_output_bitstream *os,
+ le16 *out, size_t out_limit)
{
- for (s32 i = 0; i < size - 11; i++) {
+ 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 <math.h>
+#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_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 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, u32 n)
+{
+ lz_bt_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(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,
+ &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];
+ }
+
+ cost += lzms_length_cost(&ctx->length_encoder, length);
+
+ 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)
+{
+ 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_encode(struct lzms_compressor *ctx)
+{
+ struct raw_match match;
+
+ /* Load window into the binary tree match-finder. */
+ lz_bt_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) {
+ match = lzms_get_near_optimal_match(ctx);
+ if (match.len <= 1)
+ lzms_encode_literal(ctx, ctx->window[ctx->cur_window_pos]);
+ else
+ lzms_encode_lz_match(ctx, match.len, match.offset);
+ }
+}
+
+static void
+lzms_init_range_encoder(struct lzms_range_encoder *enc,
+ struct lzms_range_encoder_raw *rc, u32 num_states)
+{
+ enc->rc = rc;
+ enc->state = 0;
+ enc->mask = num_states - 1;
+ for (u32 i = 0; i < num_states; i++) {
+ enc->prob_entries[i].num_recent_zero_bits = LZMS_INITIAL_PROBABILITY;
+ enc->prob_entries[i].recent_bits = LZMS_INITIAL_RECENT_BITS;
+ }
+}
+
+static void
+lzms_init_huffman_encoder(struct lzms_huffman_encoder *enc,
+ struct lzms_output_bitstream *os,
+ 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_finalize(struct lzms_compressor *ctx, u8 *cdata, size_t csize_avail)
+{
+ size_t num_forwards_bytes;
+ size_t num_backwards_bytes;
+ size_t compressed_size;
+
+ /* Flush both the forwards and backwards streams, and make sure they
+ * didn't cross each other and start overwriting each other's data. */
+ if (!lzms_output_bitstream_flush(&ctx->os)) {
+ LZMS_DEBUG("Backwards bitstream overrun.");
+ return 0;
+ }
+
+ if (!lzms_range_encoder_raw_flush(&ctx->rc)) {
+ LZMS_DEBUG("Forwards bitstream overrun.");
+ return 0;
+ }
+
+ if (ctx->rc.out > ctx->os.out) {
+ LZMS_DEBUG("Two bitstreams crossed.");
+ return 0;
+ }
+
+ /* Now the compressed buffer contains the data output by the forwards
+ * bitstream, then empty space, then data output by the backwards
+ * bitstream. Move the data output by the 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;
+
+ 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 size_t
void *compressed_data, size_t compressed_size_avail, void *_ctx)
{
struct lzms_compressor *ctx = _ctx;
+ size_t compressed_size;
+
+ LZMS_DEBUG("uncompressed_size=%zu, compressed_size_avail=%zu",
+ uncompressed_size, compressed_size_avail);
+ /* Make sure the uncompressed size is compatible with this compressor.
+ */
if (uncompressed_size > ctx->max_block_size) {
- LZMS_DEBUG("Can't compress %su bytes: LZMS context "
+ LZMS_DEBUG("Can't compress %zu bytes: LZMS context "
"only supports %u bytes",
uncompressed_size, ctx->max_block_size);
return 0;
}
- memcpy(ctx->window, uncompressed_data, uncompressed_size);
- ctx->window_size = uncompressed_size;
+ /* Don't bother compressing extremely small inputs. */
+ if (uncompressed_size < 4) {
+ LZMS_DEBUG("Input too small to bother compressing.");
+ return 0;
+ }
- lzms_preprocess_data(ctx->window, ctx->window_size,
- ctx->last_target_usages);
+ /* 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--;
- return 0;
+ /* 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);
+
+#if defined(ENABLE_VERIFY_COMPRESSION) || defined(ENABLE_LZMS_DEBUG)
+ /* Verify that we really get the same thing back when decompressing. */
+ {
+ struct wimlib_decompressor *decompressor;
+
+ LZMS_DEBUG("Verifying LZMS compression.");
+
+ if (0 == wimlib_create_decompressor(WIMLIB_COMPRESSION_TYPE_LZMS,
+ ctx->max_block_size,
+ NULL,
+ &decompressor))
+ {
+ int ret;
+ ret = wimlib_decompress(compressed_data,
+ compressed_size,
+ ctx->window,
+ uncompressed_size,
+ decompressor);
+ wimlib_free_decompressor(decompressor);
+
+ if (ret) {
+ ERROR("Failed to decompress data we "
+ "compressed using LZMS algorithm");
+ wimlib_assert(0);
+ return 0;
+ }
+ if (memcmp(uncompressed_data, ctx->window,
+ uncompressed_size))
+ {
+ ERROR("Data we compressed using LZMS algorithm "
+ "didn't decompress to original");
+ wimlib_assert(0);
+ return 0;
+ }
+ } else {
+ WARNING("Failed to create decompressor for "
+ "data verification!");
+ }
+ }
+#endif /* ENABLE_LZMS_DEBUG || ENABLE_VERIFY_COMPRESSION */
+
+ return compressed_size;
}
static void
if (ctx) {
FREE(ctx->window);
- FREE(ctx->last_target_usages);
+ 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 > 1U << 26) {
+ if (max_block_size == 0 || max_block_size >= INT32_MAX) {
LZMS_DEBUG("Invalid max_block_size (%u)", max_block_size);
return WIMLIB_ERR_INVALID_PARAM;
}
ctx->window = MALLOC(max_block_size);
if (ctx->window == NULL)
goto oom;
- ctx->max_block_size = max_block_size;
- ctx->last_target_usages = MALLOC(65536 * sizeof(ctx->last_target_usages[0]));
- if (ctx->last_target_usages == NULL)
+ ctx->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_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;
+
+ 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