/*
* lzms-compress.c
- *
- * A compressor for the LZMS compression format.
*/
/*
*/
/* This a compressor for the LZMS compression format. More details about this
- * format can be found in lzms-decompress.c. */
+ * format can be found in lzms-decompress.c.
+ *
+ * This is currently an unsophisticated implementation that is fast but does not
+ * attain the best compression ratios allowed by the format.
+ */
#ifdef HAVE_CONFIG_H
# include "config.h"
#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 <string.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 are used as in
+ * index into @prob_entries. */
+ u32 state;
+
+ /* Bitmask for @state to prevent its value from exceeding the number of
+ * probability entries. */
+ u32 mask;
+
+ /* Probability entries being used for this range encoder. */
+ struct lzms_probability_entry prob_entries[LZMS_MAX_NUM_STATES];
+};
+
+/* Structure used for Huffman encoding, optionally encoding larger "values" as a
+ * Huffman symbol specifying a slot and a slot-dependent number of extra bits.
+ * */
+struct lzms_huffman_encoder {
+
+ /* Bitstream to write Huffman-encoded symbols and verbatim bits to.
+ * Multiple lzms_huffman_encoder's share the same lzms_output_bitstream.
+ */
+ struct lzms_output_bitstream *os;
+
+ /* Pointer to the slot base table to use. */
+ const u32 *slot_base_tab;
+
+ /* Number of symbols that have been written using this code far. Reset
+ * to 0 whenever the code is rebuilt. */
+ u32 num_syms_written;
+
+ /* When @num_syms_written reaches this number, the Huffman code must be
+ * rebuilt. */
+ u32 rebuild_freq;
+
+ /* Number of symbols in the represented Huffman code. */
+ unsigned num_syms;
+
+ /* Running totals of symbol frequencies. These are diluted slightly
+ * whenever the code is rebuilt. */
+ u32 sym_freqs[LZMS_MAX_NUM_SYMS];
+
+ /* The length, in bits, of each symbol in the Huffman code. */
+ u8 lens[LZMS_MAX_NUM_SYMS];
+
+ /* The codeword of each symbol in the Huffman code. */
+ u16 codewords[LZMS_MAX_NUM_SYMS];
+};
+
+/* State of the LZMS compressor. */
struct lzms_compressor {
+ /* Pointer to a buffer holding the preprocessed data to compress. */
u8 *window;
+
+ /* Current position in @buffer. */
+ u32 cur_window_pos;
+
+ /* Size of the data in @buffer. */
u32 window_size;
+
+ /* 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) queue of LZ match offsets. */
+ u64 recent_lz_offsets[LZMS_NUM_RECENT_OFFSETS + 1];
+
+ /* LRU (least-recently-used) queue of delta match powers. */
+ u32 recent_delta_powers[LZMS_NUM_RECENT_OFFSETS + 1];
+
+ /* LRU (least-recently-used) queue of delta match offsets. */
+ u32 recent_delta_offsets[LZMS_NUM_RECENT_OFFSETS + 1];
+
+ /* These variables are used to delay updates to the LRU queues by one
+ * decoded item. */
+ u32 prev_lz_offset;
+ u32 prev_delta_power;
+ u32 prev_delta_offset;
+ u32 upcoming_lz_offset;
+ u32 upcoming_delta_power;
+ u32 upcoming_delta_offset;
+
+ /* Used for preprocessing. */
+ s32 last_target_usages[65536];
};
+struct lzms_match {
+ u32 length;
+ u32 offset;
+};
+
+/* Initialize the output bitstream @os to write forwards to the specified
+ * compressed data buffer @out that is @out_limit 16-bit integers long. */
+static void
+lzms_output_bitstream_init(struct lzms_output_bitstream *os,
+ le16 *out, size_t out_limit)
+{
+ os->bitbuf = 0;
+ os->num_free_bits = 16;
+ os->out = out + out_limit;
+ os->num_le16_remaining = out_limit;
+ os->overrun = false;
+}
+
+/* Write @num_bits bits, contained in the low @num_bits bits of @bits (ordered
+ * from high-order to low-order), to the output bitstream @os. */
+static void
+lzms_output_bitstream_put_bits(struct lzms_output_bitstream *os,
+ u32 bits, unsigned num_bits)
+{
+ bits &= (1U << num_bits) - 1;
+
+ while (num_bits > os->num_free_bits) {
+
+ if (unlikely(os->num_le16_remaining == 0)) {
+ os->overrun = true;
+ return;
+ }
+
+ unsigned num_fill_bits = os->num_free_bits;
+
+ os->bitbuf <<= num_fill_bits;
+ os->bitbuf |= bits >> (num_bits - num_fill_bits);
+
+ *--os->out = cpu_to_le16(os->bitbuf);
+ --os->num_le16_remaining;
+
+ os->num_free_bits = 16;
+ num_bits -= num_fill_bits;
+ bits &= (1U << num_bits) - 1;
+ }
+ os->bitbuf <<= num_bits;
+ os->bitbuf |= bits;
+ os->num_free_bits -= num_bits;
+}
+
+/* Flush the output bitstream, ensuring that all bits written to it have been
+ * written to memory. Returns %true if all bits were output successfully, or
+ * %false if an overrun occurred. */
+static bool
+lzms_output_bitstream_flush(struct lzms_output_bitstream *os)
+{
+ if (os->num_free_bits != 16)
+ lzms_output_bitstream_put_bits(os, 0, os->num_free_bits + 1);
+ return !os->overrun;
+}
+
+/* Initialize the range encoder @rc to write forwards to the specified
+ * compressed data buffer @out that is @out_limit 16-bit integers long. */
+static void
+lzms_range_encoder_raw_init(struct lzms_range_encoder_raw *rc,
+ le16 *out, size_t out_limit)
+{
+ rc->low = 0;
+ rc->range = 0xffffffff;
+ rc->cache = 0;
+ rc->cache_size = 1;
+ rc->out = out;
+ rc->num_le16_remaining = out_limit;
+ rc->first = true;
+ rc->overrun = false;
+}
+
+/*
+ * Attempt to flush bits from the range encoder.
+ *
+ * Note: this is based on the public domain code for LZMA written by Igor
+ * Pavlov. The only differences in this function are that in LZMS the bits must
+ * be output in 16-bit coding units instead of 8-bit coding units, and that in
+ * LZMS the first coding unit is not ignored by the decompressor, so the encoder
+ * cannot output a dummy value to that position.
+ *
+ * The basic idea is that we're writing bits from @rc->low to the output.
+ * However, due to carrying, the writing of coding units with value 0xffff, as
+ * well as one prior coding unit, must be delayed until it is determined whether
+ * a carry is needed.
+ */
+static void
+lzms_range_encoder_raw_shift_low(struct lzms_range_encoder_raw *rc)
+{
+ LZMS_DEBUG("low=%"PRIx64", cache=%"PRIx64", cache_size=%u",
+ rc->low, rc->cache, rc->cache_size);
+ if ((u32)(rc->low) < 0xffff0000 ||
+ (u32)(rc->low >> 32) != 0)
+ {
+ /* Carry not needed (rc->low < 0xffff0000), or carry occurred
+ * ((rc->low >> 32) != 0, a.k.a. the carry bit is 1). */
+ do {
+ if (!rc->first) {
+ if (rc->num_le16_remaining == 0) {
+ rc->overrun = true;
+ return;
+ }
+ *rc->out++ = cpu_to_le16(rc->cache +
+ (u16)(rc->low >> 32));
+ --rc->num_le16_remaining;
+ } else {
+ rc->first = false;
+ }
+
+ rc->cache = 0xffff;
+ } while (--rc->cache_size != 0);
+
+ rc->cache = (rc->low >> 16) & 0xffff;
+ }
+ ++rc->cache_size;
+ rc->low = (rc->low & 0xffff) << 16;
+}
+
+static void
+lzms_range_encoder_raw_normalize(struct lzms_range_encoder_raw *rc)
+{
+ if (rc->range <= 0xffff) {
+ rc->range <<= 16;
+ lzms_range_encoder_raw_shift_low(rc);
+ }
+}
+
+static bool
+lzms_range_encoder_raw_flush(struct lzms_range_encoder_raw *rc)
+{
+ for (unsigned i = 0; i < 4; i++)
+ lzms_range_encoder_raw_shift_low(rc);
+ return !rc->overrun;
+}
+
+/* Encode the next bit using the range encoder (raw version).
+ *
+ * @prob is the chance out of LZMS_PROBABILITY_MAX that the next bit is 0. */
+static void
+lzms_range_encoder_raw_encode_bit(struct lzms_range_encoder_raw *rc, int bit,
+ u32 prob)
+{
+ lzms_range_encoder_raw_normalize(rc);
+
+ u32 bound = (rc->range >> LZMS_PROBABILITY_BITS) * prob;
+ if (bit == 0) {
+ rc->range = bound;
+ } else {
+ rc->low += bound;
+ rc->range -= bound;
+ }
+}
+
+/* Encode a bit using the specified range encoder. This wraps around
+ * lzms_range_encoder_raw_encode_bit() to handle using and updating the
+ * appropriate probability table. */
+static void
+lzms_range_encode_bit(struct lzms_range_encoder *enc, int bit)
+{
+ struct lzms_probability_entry *prob_entry;
+ u32 prob;
+
+ /* Load the probability entry corresponding to the current state. */
+ prob_entry = &enc->prob_entries[enc->state];
+
+ /* Treat the number of zero bits in the most recently encoded
+ * LZMS_PROBABILITY_MAX bits with this probability entry as the chance,
+ * out of LZMS_PROBABILITY_MAX, that the next bit will be a 0. However,
+ * don't allow 0% or 100% probabilities. */
+ prob = prob_entry->num_recent_zero_bits;
+ if (prob == 0)
+ prob = 1;
+ else if (prob == LZMS_PROBABILITY_MAX)
+ prob = LZMS_PROBABILITY_MAX - 1;
+
+ /* Encode the next bit. */
+ lzms_range_encoder_raw_encode_bit(enc->rc, bit, prob);
+
+ /* Update the state based on the newly encoded bit. */
+ enc->state = ((enc->state << 1) | bit) & enc->mask;
+
+ /* Update the recent bits, including the cached count of 0's. */
+ BUILD_BUG_ON(LZMS_PROBABILITY_MAX > sizeof(prob_entry->recent_bits) * 8);
+ if (bit == 0) {
+ if (prob_entry->recent_bits & (1ULL << (LZMS_PROBABILITY_MAX - 1))) {
+ /* Replacing 1 bit with 0 bit; increment the zero count.
+ */
+ prob_entry->num_recent_zero_bits++;
+ }
+ } else {
+ if (!(prob_entry->recent_bits & (1ULL << (LZMS_PROBABILITY_MAX - 1)))) {
+ /* Replacing 0 bit with 1 bit; decrement the zero count.
+ */
+ prob_entry->num_recent_zero_bits--;
+ }
+ }
+ prob_entry->recent_bits = (prob_entry->recent_bits << 1) | bit;
+}
+
+/* Encode a symbol using the specified Huffman encoder. */
+static void
+lzms_huffman_encode_symbol(struct lzms_huffman_encoder *enc, u32 sym)
+{
+ LZMS_ASSERT(sym < enc->num_syms);
+ if (enc->num_syms_written == enc->rebuild_freq) {
+ /* Adaptive code needs to be rebuilt. */
+ LZMS_DEBUG("Rebuilding code (num_syms=%u)", enc->num_syms);
+ make_canonical_huffman_code(enc->num_syms,
+ LZMS_MAX_CODEWORD_LEN,
+ enc->sym_freqs,
+ enc->lens,
+ enc->codewords);
+
+ /* Dilute the frequencies. */
+ for (unsigned i = 0; i < enc->num_syms; i++) {
+ enc->sym_freqs[i] >>= 1;
+ enc->sym_freqs[i] += 1;
+ }
+ enc->num_syms_written = 0;
+ }
+ lzms_output_bitstream_put_bits(enc->os,
+ enc->codewords[sym],
+ enc->lens[sym]);
+ ++enc->num_syms_written;
+ ++enc->sym_freqs[sym];
+}
+
+/* Encode a number as a Huffman symbol specifying a slot, plus a number of
+ * slot-dependent extra bits. */
+static void
+lzms_encode_value(struct lzms_huffman_encoder *enc, u32 value)
+{
+ unsigned slot;
+ unsigned num_extra_bits;
+ u32 extra_bits;
+
+ LZMS_ASSERT(enc->slot_base_tab != NULL);
+
+ slot = lzms_get_slot(value, enc->slot_base_tab, enc->num_syms);
+
+ /* Get the number of extra bits needed to represent the range of values
+ * that share the slot. */
+ num_extra_bits = bsr32(enc->slot_base_tab[slot + 1] -
+ enc->slot_base_tab[slot]);
+
+ /* Calculate the extra bits as the offset from the slot base. */
+ extra_bits = value - enc->slot_base_tab[slot];
+
+ /* Output the slot (Huffman-encoded), then the extra bits (verbatim).
+ */
+ lzms_huffman_encode_symbol(enc, slot);
+ lzms_output_bitstream_put_bits(enc->os, extra_bits, num_extra_bits);
+}
+
+/* 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);
+
+ /* 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);
+}
+
+/* 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);
+
+ /* Main bit: 1 = a match, not a literal. */
+ lzms_range_encode_bit(&ctx->main_range_encoder, 1);
+
+ /* Match bit: 0 = a LZ match, not a delta match. */
+ lzms_range_encode_bit(&ctx->match_range_encoder, 0);
+
+ /* Determine if the offset can be represented as a recent offset. */
+ for (recent_offset_idx = 0;
+ recent_offset_idx < LZMS_NUM_RECENT_OFFSETS;
+ recent_offset_idx++)
+ if (offset == ctx->recent_lz_offsets[recent_offset_idx])
+ break;
+
+ if (recent_offset_idx == LZMS_NUM_RECENT_OFFSETS) {
+ /* Explicit offset. */
+
+ /* LZ match bit: 0 = explicit offset, not a repeat offset. */
+ lzms_range_encode_bit(&ctx->lz_match_range_encoder, 0);
+
+ /* Encode the match offset. */
+ lzms_encode_value(&ctx->lz_offset_encoder, offset);
+ } else {
+ int i;
+
+ /* Repeat offset. */
+
+
+ /* LZ match bit: 0 = repeat offset, not an explicit offset. */
+ lzms_range_encode_bit(&ctx->lz_match_range_encoder, 1);
+
+ /* Encode the recent offset index. A 1 bit is encoded for each
+ * index passed up. This sequence of 1 bits is terminated by a
+ * 0 bit, or automatically when (LZMS_NUM_RECENT_OFFSETS - 1) 1
+ * bits have been encoded. */
+ for (i = 0; i < recent_offset_idx - 1; 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 = recent_offset_idx; i < LZMS_NUM_RECENT_OFFSETS; i++)
+ ctx->recent_lz_offsets[i] = ctx->recent_lz_offsets[i + 1];
+ }
+
+ /* Encode the match length. */
+ lzms_encode_value(&ctx->length_encoder, length);
+
+ /* Save the match offset for later insertion at the front of the LZ
+ * match offset LRU queue. */
+ ctx->upcoming_lz_offset = offset;
+}
+
+static struct lzms_match
+lzms_get_best_match(struct lzms_compressor *ctx)
+{
+ struct lzms_match match;
+
+ /* TODO */
+
+ match.length = 0;
+
+ return match;
+}
+
+static void
+lzms_init_range_encoder(struct lzms_range_encoder *enc,
+ struct lzms_range_encoder_raw *rc, u32 num_states)
+{
+ enc->rc = rc;
+ enc->state = 0;
+ enc->mask = num_states - 1;
+ for (u32 i = 0; i < num_states; i++) {
+ enc->prob_entries[i].num_recent_zero_bits = LZMS_INITIAL_PROBABILITY;
+ enc->prob_entries[i].recent_bits = LZMS_INITIAL_RECENT_BITS;
+ }
+}
+
+static void
+lzms_init_huffman_encoder(struct lzms_huffman_encoder *enc,
+ struct lzms_output_bitstream *os,
+ const u32 *slot_base_tab,
+ unsigned num_syms,
+ unsigned rebuild_freq)
+{
+ enc->os = os;
+ enc->slot_base_tab = slot_base_tab;
+ enc->num_syms_written = rebuild_freq;
+ enc->rebuild_freq = rebuild_freq;
+ enc->num_syms = num_syms;
+ for (unsigned i = 0; i < num_syms; i++)
+ enc->sym_freqs[i] = 1;
+}
+
+/* Initialize the LZMS compressor. */
+static void
+lzms_init_compressor(struct lzms_compressor *ctx, const u8 *udata, u32 ulen,
+ le16 *cdata, u32 clen16)
+{
+ unsigned num_position_slots;
+
+ /* Copy the uncompressed data into the @ctx->window buffer. */
+ memcpy(ctx->window, udata, ulen);
+ ctx->cur_window_pos = 0;
+ ctx->window_size = ulen;
+
+ /* Initialize the raw range encoder (writing forwards). */
+ lzms_range_encoder_raw_init(&ctx->rc, cdata, clen16);
+
+ /* Initialize the output bitstream for Huffman symbols and verbatim bits
+ * (writing backwards). */
+ lzms_output_bitstream_init(&ctx->os, cdata, clen16);
+
+ /* Initialize position and length slot bases if not done already. */
+ lzms_init_slot_bases();
+
+ /* Calculate the number of position slots needed for this compressed
+ * block. */
+ num_position_slots = lzms_get_position_slot(ulen - 1) + 1;
+
+ LZMS_DEBUG("Using %u position slots", num_position_slots);
+
+ /* Initialize Huffman encoders for each alphabet used in the compressed
+ * representation. */
+ lzms_init_huffman_encoder(&ctx->literal_encoder, &ctx->os,
+ NULL, LZMS_NUM_LITERAL_SYMS,
+ LZMS_LITERAL_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&ctx->lz_offset_encoder, &ctx->os,
+ lzms_position_slot_base, num_position_slots,
+ LZMS_LZ_OFFSET_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&ctx->length_encoder, &ctx->os,
+ lzms_length_slot_base, LZMS_NUM_LEN_SYMS,
+ LZMS_LENGTH_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&ctx->delta_offset_encoder, &ctx->os,
+ lzms_position_slot_base, num_position_slots,
+ LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_encoder(&ctx->delta_power_encoder, &ctx->os,
+ NULL, LZMS_NUM_DELTA_POWER_SYMS,
+ LZMS_DELTA_POWER_CODE_REBUILD_FREQ);
+
+ /* Initialize range encoders, all of which wrap around the same
+ * lzms_range_encoder_raw. */
+ lzms_init_range_encoder(&ctx->main_range_encoder,
+ &ctx->rc, LZMS_NUM_MAIN_STATES);
+
+ lzms_init_range_encoder(&ctx->match_range_encoder,
+ &ctx->rc, LZMS_NUM_MATCH_STATES);
+
+ lzms_init_range_encoder(&ctx->lz_match_range_encoder,
+ &ctx->rc, LZMS_NUM_LZ_MATCH_STATES);
+
+ for (size_t i = 0; i < ARRAY_LEN(ctx->lz_repeat_match_range_encoders); i++)
+ lzms_init_range_encoder(&ctx->lz_repeat_match_range_encoders[i],
+ &ctx->rc, LZMS_NUM_LZ_REPEAT_MATCH_STATES);
+
+ lzms_init_range_encoder(&ctx->delta_match_range_encoder,
+ &ctx->rc, LZMS_NUM_DELTA_MATCH_STATES);
+
+ for (size_t i = 0; i < ARRAY_LEN(ctx->delta_repeat_match_range_encoders); i++)
+ lzms_init_range_encoder(&ctx->delta_repeat_match_range_encoders[i],
+ &ctx->rc, LZMS_NUM_DELTA_REPEAT_MATCH_STATES);
+
+ /* Initialize the LRU queue for recent match offsets. */
+ for (size_t i = 0; i < LZMS_NUM_RECENT_OFFSETS + 1; i++)
+ ctx->recent_lz_offsets[i] = i + 1;
+
+ for (size_t i = 0; i < LZMS_NUM_RECENT_OFFSETS + 1; i++) {
+ ctx->recent_delta_powers[i] = 0;
+ ctx->recent_delta_offsets[i] = i + 1;
+ }
+ ctx->prev_lz_offset = 0;
+ ctx->prev_delta_offset = 0;
+ ctx->prev_delta_power = 0;
+ ctx->upcoming_lz_offset = 0;
+ ctx->upcoming_delta_offset = 0;
+ ctx->upcoming_delta_power = 0;
+}
+
+/* Flush the output streams, prepare the final compressed data, and return its
+ * size in bytes.
+ *
+ * A return value of 0 indicates that the data could not be compressed to fit in
+ * the available space. */
+static size_t
+lzms_finalize(struct lzms_compressor *ctx, u8 *cdata, size_t csize_avail)
+{
+ size_t num_forwards_bytes;
+ size_t num_backwards_bytes;
+ size_t compressed_size;
+
+ /* Flush both the forwards and backwards streams, and make sure they
+ * didn't cross each other and start overwriting each other's data. */
+ if (!lzms_output_bitstream_flush(&ctx->os)) {
+ LZMS_DEBUG("Backwards bitstream overrun.");
+ return 0;
+ }
+
+ if (!lzms_range_encoder_raw_flush(&ctx->rc)) {
+ LZMS_DEBUG("Forwards bitstream overrun.");
+ return 0;
+ }
+
+ if (ctx->rc.out > ctx->os.out) {
+ LZMS_DEBUG("Two bitstreams crossed.");
+ return 0;
+ }
+
+ /* Now the compressed buffer contains the data output by the forwards
+ * bitstream, then empty space, then data output by the backwards
+ * bitstream. Move the data output by the forwards bitstream to be
+ * adjacent to the data output by the backwards bitstream, and calculate
+ * the compressed size that this results in. */
+ num_forwards_bytes = (u8*)ctx->rc.out - (u8*)cdata;
+ num_backwards_bytes = ((u8*)cdata + csize_avail) - (u8*)ctx->os.out;
+
+ memmove(cdata + num_forwards_bytes, ctx->os.out, num_backwards_bytes);
+
+ compressed_size = num_forwards_bytes + num_backwards_bytes;
+ LZMS_DEBUG("num_forwards_bytes=%zu, num_backwards_bytes=%zu, "
+ "compressed_size=%zu",
+ num_forwards_bytes, num_backwards_bytes, compressed_size);
+ LZMS_ASSERT(!(compressed_size & 1));
+ return compressed_size;
+}
+
static size_t
lzms_compress(const void *uncompressed_data, size_t uncompressed_size,
void *compressed_data, size_t compressed_size_avail, void *_ctx)
{
struct lzms_compressor *ctx = _ctx;
+ struct lzms_match match;
+ size_t compressed_size;
+
+ LZMS_DEBUG("uncompressed_size=%zu, compressed_size_avail=%zu",
+ uncompressed_size, compressed_size_avail);
+ /* Make sure the uncompressed size is compatible with this compressor.
+ */
if (uncompressed_size > ctx->max_block_size) {
- LZMS_DEBUG("Can't compress %su bytes: LZMS context "
+ LZMS_DEBUG("Can't compress %zu bytes: LZMS context "
"only supports %u bytes",
uncompressed_size, ctx->max_block_size);
return 0;
}
- memcpy(ctx->window, uncompressed_data, uncompressed_size);
- ctx->window_size = uncompressed_size;
+ /* Don't bother compressing extremely small inputs. */
+ if (uncompressed_size < 4)
+ return 0;
+
+ /* Cap the available compressed size to a 32-bit integer, and round it
+ * down to the nearest multiple of 2. */
+ if (compressed_size_avail > UINT32_MAX)
+ compressed_size_avail = UINT32_MAX;
+ if (compressed_size_avail & 1)
+ compressed_size_avail--;
+ /* Initialize the compressor structures. */
+ lzms_init_compressor(ctx, uncompressed_data, uncompressed_size,
+ compressed_data, compressed_size_avail / 2);
+
+ /* Preprocess the uncompressed data. */
lzms_x86_filter(ctx->window, ctx->window_size,
ctx->last_target_usages, false);
- return 0;
+ /* Determine and output a literal/match sequence that decompresses to
+ * the preprocessed data. */
+ while (ctx->cur_window_pos != ctx->window_size) {
+ match = lzms_get_best_match(ctx);
+ if (match.length == 0) {
+ /* Literal */
+ lzms_encode_literal(ctx, ctx->window[ctx->cur_window_pos]);
+ ctx->cur_window_pos++;
+ } else {
+ /* LZ match */
+ lzms_encode_lz_match(ctx, match.length, match.offset);
+ ctx->cur_window_pos += match.length;
+ }
+ }
+
+ /* 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 LZMN algorithm");
+ wimlib_assert(0);
+ return 0;
+ }
+ if (memcmp(uncompressed_data, ctx->window,
+ uncompressed_size))
+ {
+ ERROR("Data we compressed using LZMN 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);
}
}
{
struct lzms_compressor *ctx;
- if (max_block_size == 0 || max_block_size > 1U << 26) {
+ if (max_block_size == 0 || max_block_size >= INT32_MAX) {
LZMS_DEBUG("Invalid max_block_size (%u)", max_block_size);
return WIMLIB_ERR_INVALID_PARAM;
}
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)
- goto oom;
-
*ctx_ret = ctx;
return 0;
/*
* lzms-decompress.c
- *
- * A decompressor for the LZMS compression format.
*/
/*
#include "wimlib/util.h"
#include <limits.h>
-#include <pthread.h>
#define LZMS_DECODE_TABLE_BITS 10
size_t num_le16_remaining;
};
-/* Probability entry for use by the range decoder when in a specific state. */
-struct lzms_probability_entry {
-
- /* Number of zeroes in the most recent LZMS_PROBABILITY_MAX bits that
- * have been decoded using this probability entry. This is a cached
- * value because it can be computed as LZMS_PROBABILITY_MAX minus the
- * Hamming weight of the low-order LZMS_PROBABILITY_MAX bits of
- * @recent_bits. */
- u32 num_recent_zero_bits;
-
- /* The most recent LZMS_PROBABILITY_MAX bits that have been decoded
- * using this probability entry. The size of this variable, in bits,
- * must be at least LZMS_PROBABILITY_MAX. */
- u64 recent_bits;
-};
-
/* Structure used for range decoding. This wraps around `struct
* lzms_range_decoder_raw' to use and maintain probability entries. */
struct lzms_range_decoder {
u32 upcoming_delta_power;
u32 upcoming_delta_offset;
- /* Used for postprocessing */
+ /* Used for postprocessing. */
s32 last_target_usages[65536];
};
-/* A table that maps position slots to their base values. These are constants
- * computed at runtime by lzms_compute_slot_bases(). */
-static u32 lzms_position_slot_base[LZMS_MAX_NUM_OFFSET_SYMS + 1];
-
-/* A table that maps length slots to their base values. These are constants
- * computed at runtime by lzms_compute_slot_bases(). */
-static u32 lzms_length_slot_base[LZMS_NUM_LEN_SYMS + 1];
-
-static void
-lzms_decode_delta_rle_slot_bases(u32 slot_bases[],
- const u8 delta_run_lens[], size_t num_run_lens)
-{
- u32 delta = 1;
- u32 base = 0;
- size_t slot = 0;
- for (size_t i = 0; i < num_run_lens; i++) {
- u8 run_len = delta_run_lens[i];
- while (run_len--) {
- base += delta;
- slot_bases[slot++] = base;
- }
- delta <<= 1;
- }
-}
-
-/* Initialize the global position and length slot tables. */
-static void
-lzms_compute_slot_bases(void)
-{
- /* If an explicit formula that maps LZMS position and length slots to
- * slot bases exists, then it could be used here. But until one is
- * found, the following code fills in the slots using the observation
- * that the increase from one slot base to the next is an increasing
- * power of 2. Therefore, run-length encoding of the delta of adjacent
- * entries can be used. */
- static const u8 position_slot_delta_run_lens[] = {
- 9, 0, 9, 7, 10, 15, 15, 20,
- 20, 30, 33, 40, 42, 45, 60, 73,
- 80, 85, 95, 105, 6,
- };
-
- static const u8 length_slot_delta_run_lens[] = {
- 27, 4, 6, 4, 5, 2, 1, 1,
- 1, 1, 1, 0, 0, 0, 0, 0,
- 1,
- };
-
- lzms_decode_delta_rle_slot_bases(lzms_position_slot_base,
- position_slot_delta_run_lens,
- ARRAY_LEN(position_slot_delta_run_lens));
-
- lzms_position_slot_base[LZMS_MAX_NUM_OFFSET_SYMS] = 0x7fffffff;
-
- lzms_decode_delta_rle_slot_bases(lzms_length_slot_base,
- length_slot_delta_run_lens,
- ARRAY_LEN(length_slot_delta_run_lens));
-
- lzms_length_slot_base[LZMS_NUM_LEN_SYMS] = 0x400108ab;
-}
-
-/* Initialize the global position length slot tables if not done so already. */
-static void
-lzms_init_slot_bases(void)
-{
- static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
- static bool already_computed = false;
-
- if (unlikely(!already_computed)) {
- pthread_mutex_lock(&mutex);
- if (!already_computed) {
- lzms_compute_slot_bases();
- already_computed = true;
- }
- pthread_mutex_unlock(&mutex);
- }
-}
-
-/* Return the position slot for the specified offset. */
-static u32
-lzms_get_position_slot_raw(u32 offset)
-{
- u32 position_slot = 0;
- while (lzms_position_slot_base[position_slot + 1] <= offset)
- position_slot++;
- return position_slot;
-}
-
/* Initialize the input bitstream @is to read forwards from the specified
* compressed data buffer @in that is @in_limit 16-bit integers long. */
static void
/* Decode and return the next Huffman-encoded symbol from the LZMS-compressed
* block using the specified Huffman decoder. */
static u32
-lzms_decode_huffman_symbol(struct lzms_huffman_decoder *dec)
+lzms_huffman_decode_symbol(struct lzms_huffman_decoder *dec)
{
const u8 *lens = dec->lens;
const u16 *decode_table = dec->decode_table;
/* Read the slot (position slot, length slot, etc.), which is encoded as
* a Huffman symbol. */
- slot = lzms_decode_huffman_symbol(dec);
+ slot = lzms_huffman_decode_symbol(dec);
LZMS_ASSERT(dec->slot_base_tab != NULL);
bit = lzms_range_decode_bit(&ctx->delta_match_range_decoder);
if (bit == 0) {
- power = lzms_decode_huffman_symbol(&ctx->delta_power_decoder);
+ power = lzms_huffman_decode_symbol(&ctx->delta_power_decoder);
raw_offset = lzms_decode_value(&ctx->delta_offset_decoder);
} else {
int i;
static int
lzms_decode_literal(struct lzms_decompressor *ctx)
{
- u8 literal = lzms_decode_huffman_symbol(&ctx->literal_decoder);
+ u8 literal = lzms_huffman_decode_symbol(&ctx->literal_decoder);
LZMS_DEBUG("Decoded literal: 0x%02x", literal);
return lzms_copy_literal(ctx, literal);
}
/* Calculate the number of position slots needed for this compressed
* block. */
- num_position_slots = lzms_get_position_slot_raw(ulen - 1) + 1;
+ num_position_slots = lzms_get_position_slot(ulen - 1) + 1;
LZMS_DEBUG("Using %u position slots", num_position_slots);
* searched for a position of INT32_MAX or greater. */
if (uncompressed_size >= INT32_MAX) {
LZMS_DEBUG("Uncompressed length too large "
- "(got %u, expected < INT32_MAX)", ulen);
+ "(got %zu, expected < INT32_MAX)",
+ uncompressed_size);
return -1;
}
git://wimlib.net / wimlib / commitdiff