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306
dependencies/cmliblzma/liblzma/lz/lz_decoder.c vendored Normal file
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///////////////////////////////////////////////////////////////////////////////
//
/// \file lz_decoder.c
/// \brief LZ out window
///
// Authors: Igor Pavlov
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
// liblzma supports multiple LZ77-based filters. The LZ part is shared
// between these filters. The LZ code takes care of dictionary handling
// and passing the data between filters in the chain. The filter-specific
// part decodes from the input buffer to the dictionary.
#include "lz_decoder.h"
typedef struct {
/// Dictionary (history buffer)
lzma_dict dict;
/// The actual LZ-based decoder e.g. LZMA
lzma_lz_decoder lz;
/// Next filter in the chain, if any. Note that LZMA and LZMA2 are
/// only allowed as the last filter, but the long-range filter in
/// future can be in the middle of the chain.
lzma_next_coder next;
/// True if the next filter in the chain has returned LZMA_STREAM_END.
bool next_finished;
/// True if the LZ decoder (e.g. LZMA) has detected end of payload
/// marker. This may become true before next_finished becomes true.
bool this_finished;
/// Temporary buffer needed when the LZ-based filter is not the last
/// filter in the chain. The output of the next filter is first
/// decoded into buffer[], which is then used as input for the actual
/// LZ-based decoder.
struct {
size_t pos;
size_t size;
uint8_t buffer[LZMA_BUFFER_SIZE];
} temp;
} lzma_coder;
static void
lz_decoder_reset(lzma_coder *coder)
{
coder->dict.pos = 0;
coder->dict.full = 0;
coder->dict.buf[coder->dict.size - 1] = '\0';
coder->dict.need_reset = false;
return;
}
static lzma_ret
decode_buffer(lzma_coder *coder,
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size, uint8_t *restrict out,
size_t *restrict out_pos, size_t out_size)
{
while (true) {
// Wrap the dictionary if needed.
if (coder->dict.pos == coder->dict.size)
coder->dict.pos = 0;
// Store the current dictionary position. It is needed to know
// where to start copying to the out[] buffer.
const size_t dict_start = coder->dict.pos;
// Calculate how much we allow coder->lz.code() to decode.
// It must not decode past the end of the dictionary
// buffer, and we don't want it to decode more than is
// actually needed to fill the out[] buffer.
coder->dict.limit = coder->dict.pos
+ my_min(out_size - *out_pos,
coder->dict.size - coder->dict.pos);
// Call the coder->lz.code() to do the actual decoding.
const lzma_ret ret = coder->lz.code(
coder->lz.coder, &coder->dict,
in, in_pos, in_size);
// Copy the decoded data from the dictionary to the out[]
// buffer.
const size_t copy_size = coder->dict.pos - dict_start;
assert(copy_size <= out_size - *out_pos);
memcpy(out + *out_pos, coder->dict.buf + dict_start,
copy_size);
*out_pos += copy_size;
// Reset the dictionary if so requested by coder->lz.code().
if (coder->dict.need_reset) {
lz_decoder_reset(coder);
// Since we reset dictionary, we don't check if
// dictionary became full.
if (ret != LZMA_OK || *out_pos == out_size)
return ret;
} else {
// Return if everything got decoded or an error
// occurred, or if there's no more data to decode.
//
// Note that detecting if there's something to decode
// is done by looking if dictionary become full
// instead of looking if *in_pos == in_size. This
// is because it is possible that all the input was
// consumed already but some data is pending to be
// written to the dictionary.
if (ret != LZMA_OK || *out_pos == out_size
|| coder->dict.pos < coder->dict.size)
return ret;
}
}
}
static lzma_ret
lz_decode(void *coder_ptr,
const lzma_allocator *allocator lzma_attribute((__unused__)),
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size, uint8_t *restrict out,
size_t *restrict out_pos, size_t out_size,
lzma_action action)
{
lzma_coder *coder = coder_ptr;
if (coder->next.code == NULL)
return decode_buffer(coder, in, in_pos, in_size,
out, out_pos, out_size);
// We aren't the last coder in the chain, we need to decode
// our input to a temporary buffer.
while (*out_pos < out_size) {
// Fill the temporary buffer if it is empty.
if (!coder->next_finished
&& coder->temp.pos == coder->temp.size) {
coder->temp.pos = 0;
coder->temp.size = 0;
const lzma_ret ret = coder->next.code(
coder->next.coder,
allocator, in, in_pos, in_size,
coder->temp.buffer, &coder->temp.size,
LZMA_BUFFER_SIZE, action);
if (ret == LZMA_STREAM_END)
coder->next_finished = true;
else if (ret != LZMA_OK || coder->temp.size == 0)
return ret;
}
if (coder->this_finished) {
if (coder->temp.size != 0)
return LZMA_DATA_ERROR;
if (coder->next_finished)
return LZMA_STREAM_END;
return LZMA_OK;
}
const lzma_ret ret = decode_buffer(coder, coder->temp.buffer,
&coder->temp.pos, coder->temp.size,
out, out_pos, out_size);
if (ret == LZMA_STREAM_END)
coder->this_finished = true;
else if (ret != LZMA_OK)
return ret;
else if (coder->next_finished && *out_pos < out_size)
return LZMA_DATA_ERROR;
}
return LZMA_OK;
}
static void
lz_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
{
lzma_coder *coder = coder_ptr;
lzma_next_end(&coder->next, allocator);
lzma_free(coder->dict.buf, allocator);
if (coder->lz.end != NULL)
coder->lz.end(coder->lz.coder, allocator);
else
lzma_free(coder->lz.coder, allocator);
lzma_free(coder, allocator);
return;
}
extern lzma_ret
lzma_lz_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
const lzma_filter_info *filters,
lzma_ret (*lz_init)(lzma_lz_decoder *lz,
const lzma_allocator *allocator, const void *options,
lzma_lz_options *lz_options))
{
// Allocate the base structure if it isn't already allocated.
lzma_coder *coder = next->coder;
if (coder == NULL) {
coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (coder == NULL)
return LZMA_MEM_ERROR;
next->coder = coder;
next->code = &lz_decode;
next->end = &lz_decoder_end;
coder->dict.buf = NULL;
coder->dict.size = 0;
coder->lz = LZMA_LZ_DECODER_INIT;
coder->next = LZMA_NEXT_CODER_INIT;
}
// Allocate and initialize the LZ-based decoder. It will also give
// us the dictionary size.
lzma_lz_options lz_options;
return_if_error(lz_init(&coder->lz, allocator,
filters[0].options, &lz_options));
// If the dictionary size is very small, increase it to 4096 bytes.
// This is to prevent constant wrapping of the dictionary, which
// would slow things down. The downside is that since we don't check
// separately for the real dictionary size, we may happily accept
// corrupt files.
if (lz_options.dict_size < 4096)
lz_options.dict_size = 4096;
// Make dictionary size a multipe of 16. Some LZ-based decoders like
// LZMA use the lowest bits lzma_dict.pos to know the alignment of the
// data. Aligned buffer is also good when memcpying from the
// dictionary to the output buffer, since applications are
// recommended to give aligned buffers to liblzma.
//
// Avoid integer overflow.
if (lz_options.dict_size > SIZE_MAX - 15)
return LZMA_MEM_ERROR;
lz_options.dict_size = (lz_options.dict_size + 15) & ~((size_t)(15));
// Allocate and initialize the dictionary.
if (coder->dict.size != lz_options.dict_size) {
lzma_free(coder->dict.buf, allocator);
coder->dict.buf
= lzma_alloc(lz_options.dict_size, allocator);
if (coder->dict.buf == NULL)
return LZMA_MEM_ERROR;
coder->dict.size = lz_options.dict_size;
}
lz_decoder_reset(next->coder);
// Use the preset dictionary if it was given to us.
if (lz_options.preset_dict != NULL
&& lz_options.preset_dict_size > 0) {
// If the preset dictionary is bigger than the actual
// dictionary, copy only the tail.
const size_t copy_size = my_min(lz_options.preset_dict_size,
lz_options.dict_size);
const size_t offset = lz_options.preset_dict_size - copy_size;
memcpy(coder->dict.buf, lz_options.preset_dict + offset,
copy_size);
coder->dict.pos = copy_size;
coder->dict.full = copy_size;
}
// Miscellaneous initializations
coder->next_finished = false;
coder->this_finished = false;
coder->temp.pos = 0;
coder->temp.size = 0;
// Initialize the next filter in the chain, if any.
return lzma_next_filter_init(&coder->next, allocator, filters + 1);
}
extern uint64_t
lzma_lz_decoder_memusage(size_t dictionary_size)
{
return sizeof(lzma_coder) + (uint64_t)(dictionary_size);
}
extern void
lzma_lz_decoder_uncompressed(void *coder_ptr, lzma_vli uncompressed_size)
{
lzma_coder *coder = coder_ptr;
coder->lz.set_uncompressed(coder->lz.coder, uncompressed_size);
}

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dependencies/cmliblzma/liblzma/lz/lz_decoder.h vendored Normal file
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///////////////////////////////////////////////////////////////////////////////
//
/// \file lz_decoder.h
/// \brief LZ out window
///
// Authors: Igor Pavlov
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef LZMA_LZ_DECODER_H
#define LZMA_LZ_DECODER_H
#include "common.h"
typedef struct {
/// Pointer to the dictionary buffer. It can be an allocated buffer
/// internal to liblzma, or it can a be a buffer given by the
/// application when in single-call mode (not implemented yet).
uint8_t *buf;
/// Write position in dictionary. The next byte will be written to
/// buf[pos].
size_t pos;
/// Indicates how full the dictionary is. This is used by
/// dict_is_distance_valid() to detect corrupt files that would
/// read beyond the beginning of the dictionary.
size_t full;
/// Write limit
size_t limit;
/// Size of the dictionary
size_t size;
/// True when dictionary should be reset before decoding more data.
bool need_reset;
} lzma_dict;
typedef struct {
size_t dict_size;
const uint8_t *preset_dict;
size_t preset_dict_size;
} lzma_lz_options;
typedef struct {
/// Data specific to the LZ-based decoder
void *coder;
/// Function to decode from in[] to *dict
lzma_ret (*code)(void *coder,
lzma_dict *restrict dict, const uint8_t *restrict in,
size_t *restrict in_pos, size_t in_size);
void (*reset)(void *coder, const void *options);
/// Set the uncompressed size
void (*set_uncompressed)(void *coder, lzma_vli uncompressed_size);
/// Free allocated resources
void (*end)(void *coder, const lzma_allocator *allocator);
} lzma_lz_decoder;
#define LZMA_LZ_DECODER_INIT \
(lzma_lz_decoder){ \
.coder = NULL, \
.code = NULL, \
.reset = NULL, \
.set_uncompressed = NULL, \
.end = NULL, \
}
extern lzma_ret lzma_lz_decoder_init(lzma_next_coder *next,
const lzma_allocator *allocator,
const lzma_filter_info *filters,
lzma_ret (*lz_init)(lzma_lz_decoder *lz,
const lzma_allocator *allocator, const void *options,
lzma_lz_options *lz_options));
extern uint64_t lzma_lz_decoder_memusage(size_t dictionary_size);
extern void lzma_lz_decoder_uncompressed(
void *coder, lzma_vli uncompressed_size);
//////////////////////
// Inline functions //
//////////////////////
/// Get a byte from the history buffer.
static inline uint8_t
dict_get(const lzma_dict *const dict, const uint32_t distance)
{
return dict->buf[dict->pos - distance - 1
+ (distance < dict->pos ? 0 : dict->size)];
}
/// Test if dictionary is empty.
static inline bool
dict_is_empty(const lzma_dict *const dict)
{
return dict->full == 0;
}
/// Validate the match distance
static inline bool
dict_is_distance_valid(const lzma_dict *const dict, const size_t distance)
{
return dict->full > distance;
}
/// Repeat *len bytes at distance.
static inline bool
dict_repeat(lzma_dict *dict, uint32_t distance, uint32_t *len)
{
// Don't write past the end of the dictionary.
const size_t dict_avail = dict->limit - dict->pos;
uint32_t left = my_min(dict_avail, *len);
*len -= left;
// Repeat a block of data from the history. Because memcpy() is faster
// than copying byte by byte in a loop, the copying process gets split
// into three cases.
if (distance < left) {
// Source and target areas overlap, thus we can't use
// memcpy() nor even memmove() safely.
do {
dict->buf[dict->pos] = dict_get(dict, distance);
++dict->pos;
} while (--left > 0);
} else if (distance < dict->pos) {
// The easiest and fastest case
memcpy(dict->buf + dict->pos,
dict->buf + dict->pos - distance - 1,
left);
dict->pos += left;
} else {
// The bigger the dictionary, the more rare this
// case occurs. We need to "wrap" the dict, thus
// we might need two memcpy() to copy all the data.
assert(dict->full == dict->size);
const uint32_t copy_pos
= dict->pos - distance - 1 + dict->size;
uint32_t copy_size = dict->size - copy_pos;
if (copy_size < left) {
memmove(dict->buf + dict->pos, dict->buf + copy_pos,
copy_size);
dict->pos += copy_size;
copy_size = left - copy_size;
memcpy(dict->buf + dict->pos, dict->buf, copy_size);
dict->pos += copy_size;
} else {
memmove(dict->buf + dict->pos, dict->buf + copy_pos,
left);
dict->pos += left;
}
}
// Update how full the dictionary is.
if (dict->full < dict->pos)
dict->full = dict->pos;
return unlikely(*len != 0);
}
/// Puts one byte into the dictionary. Returns true if the dictionary was
/// already full and the byte couldn't be added.
static inline bool
dict_put(lzma_dict *dict, uint8_t byte)
{
if (unlikely(dict->pos == dict->limit))
return true;
dict->buf[dict->pos++] = byte;
if (dict->pos > dict->full)
dict->full = dict->pos;
return false;
}
/// Copies arbitrary amount of data into the dictionary.
static inline void
dict_write(lzma_dict *restrict dict, const uint8_t *restrict in,
size_t *restrict in_pos, size_t in_size,
size_t *restrict left)
{
// NOTE: If we are being given more data than the size of the
// dictionary, it could be possible to optimize the LZ decoder
// so that not everything needs to go through the dictionary.
// This shouldn't be very common thing in practice though, and
// the slowdown of one extra memcpy() isn't bad compared to how
// much time it would have taken if the data were compressed.
if (in_size - *in_pos > *left)
in_size = *in_pos + *left;
*left -= lzma_bufcpy(in, in_pos, in_size,
dict->buf, &dict->pos, dict->limit);
if (dict->pos > dict->full)
dict->full = dict->pos;
return;
}
static inline void
dict_reset(lzma_dict *dict)
{
dict->need_reset = true;
return;
}
#endif

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dependencies/cmliblzma/liblzma/lz/lz_encoder.c vendored Normal file
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///////////////////////////////////////////////////////////////////////////////
//
/// \file lz_encoder.c
/// \brief LZ in window
///
// Authors: Igor Pavlov
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "lz_encoder.h"
#include "lz_encoder_hash.h"
// See lz_encoder_hash.h. This is a bit hackish but avoids making
// endianness a conditional in makefiles.
#if defined(WORDS_BIGENDIAN) && !defined(HAVE_SMALL)
# include "lz_encoder_hash_table.h"
#endif
#include "memcmplen.h"
typedef struct {
/// LZ-based encoder e.g. LZMA
lzma_lz_encoder lz;
/// History buffer and match finder
lzma_mf mf;
/// Next coder in the chain
lzma_next_coder next;
} lzma_coder;
/// \brief Moves the data in the input window to free space for new data
///
/// mf->buffer is a sliding input window, which keeps mf->keep_size_before
/// bytes of input history available all the time. Now and then we need to
/// "slide" the buffer to make space for the new data to the end of the
/// buffer. At the same time, data older than keep_size_before is dropped.
///
static void
move_window(lzma_mf *mf)
{
// Align the move to a multiple of 16 bytes. Some LZ-based encoders
// like LZMA use the lowest bits of mf->read_pos to know the
// alignment of the uncompressed data. We also get better speed
// for memmove() with aligned buffers.
assert(mf->read_pos > mf->keep_size_before);
const uint32_t move_offset
= (mf->read_pos - mf->keep_size_before) & ~UINT32_C(15);
assert(mf->write_pos > move_offset);
const size_t move_size = mf->write_pos - move_offset;
assert(move_offset + move_size <= mf->size);
memmove(mf->buffer, mf->buffer + move_offset, move_size);
mf->offset += move_offset;
mf->read_pos -= move_offset;
mf->read_limit -= move_offset;
mf->write_pos -= move_offset;
return;
}
/// \brief Tries to fill the input window (mf->buffer)
///
/// If we are the last encoder in the chain, our input data is in in[].
/// Otherwise we call the next filter in the chain to process in[] and
/// write its output to mf->buffer.
///
/// This function must not be called once it has returned LZMA_STREAM_END.
///
static lzma_ret
fill_window(lzma_coder *coder, const lzma_allocator *allocator,
const uint8_t *in, size_t *in_pos, size_t in_size,
lzma_action action)
{
assert(coder->mf.read_pos <= coder->mf.write_pos);
// Move the sliding window if needed.
if (coder->mf.read_pos >= coder->mf.size - coder->mf.keep_size_after)
move_window(&coder->mf);
// Maybe this is ugly, but lzma_mf uses uint32_t for most things
// (which I find cleanest), but we need size_t here when filling
// the history window.
size_t write_pos = coder->mf.write_pos;
lzma_ret ret;
if (coder->next.code == NULL) {
// Not using a filter, simply memcpy() as much as possible.
lzma_bufcpy(in, in_pos, in_size, coder->mf.buffer,
&write_pos, coder->mf.size);
ret = action != LZMA_RUN && *in_pos == in_size
? LZMA_STREAM_END : LZMA_OK;
} else {
ret = coder->next.code(coder->next.coder, allocator,
in, in_pos, in_size,
coder->mf.buffer, &write_pos,
coder->mf.size, action);
}
coder->mf.write_pos = write_pos;
// Silence Valgrind. lzma_memcmplen() can read extra bytes
// and Valgrind will give warnings if those bytes are uninitialized
// because Valgrind cannot see that the values of the uninitialized
// bytes are eventually ignored.
memzero(coder->mf.buffer + write_pos, LZMA_MEMCMPLEN_EXTRA);
// If end of stream has been reached or flushing completed, we allow
// the encoder to process all the input (that is, read_pos is allowed
// to reach write_pos). Otherwise we keep keep_size_after bytes
// available as prebuffer.
if (ret == LZMA_STREAM_END) {
assert(*in_pos == in_size);
ret = LZMA_OK;
coder->mf.action = action;
coder->mf.read_limit = coder->mf.write_pos;
} else if (coder->mf.write_pos > coder->mf.keep_size_after) {
// This needs to be done conditionally, because if we got
// only little new input, there may be too little input
// to do any encoding yet.
coder->mf.read_limit = coder->mf.write_pos
- coder->mf.keep_size_after;
}
// Restart the match finder after finished LZMA_SYNC_FLUSH.
if (coder->mf.pending > 0
&& coder->mf.read_pos < coder->mf.read_limit) {
// Match finder may update coder->pending and expects it to
// start from zero, so use a temporary variable.
const uint32_t pending = coder->mf.pending;
coder->mf.pending = 0;
// Rewind read_pos so that the match finder can hash
// the pending bytes.
assert(coder->mf.read_pos >= pending);
coder->mf.read_pos -= pending;
// Call the skip function directly instead of using
// mf_skip(), since we don't want to touch mf->read_ahead.
coder->mf.skip(&coder->mf, pending);
}
return ret;
}
static lzma_ret
lz_encode(void *coder_ptr, const lzma_allocator *allocator,
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size,
uint8_t *restrict out, size_t *restrict out_pos,
size_t out_size, lzma_action action)
{
lzma_coder *coder = coder_ptr;
while (*out_pos < out_size
&& (*in_pos < in_size || action != LZMA_RUN)) {
// Read more data to coder->mf.buffer if needed.
if (coder->mf.action == LZMA_RUN && coder->mf.read_pos
>= coder->mf.read_limit)
return_if_error(fill_window(coder, allocator,
in, in_pos, in_size, action));
// Encode
const lzma_ret ret = coder->lz.code(coder->lz.coder,
&coder->mf, out, out_pos, out_size);
if (ret != LZMA_OK) {
// Setting this to LZMA_RUN for cases when we are
// flushing. It doesn't matter when finishing or if
// an error occurred.
coder->mf.action = LZMA_RUN;
return ret;
}
}
return LZMA_OK;
}
static bool
lz_encoder_prepare(lzma_mf *mf, const lzma_allocator *allocator,
const lzma_lz_options *lz_options)
{
// For now, the dictionary size is limited to 1.5 GiB. This may grow
// in the future if needed, but it needs a little more work than just
// changing this check.
if (lz_options->dict_size < LZMA_DICT_SIZE_MIN
|| lz_options->dict_size
> (UINT32_C(1) << 30) + (UINT32_C(1) << 29)
|| lz_options->nice_len > lz_options->match_len_max)
return true;
mf->keep_size_before = lz_options->before_size + lz_options->dict_size;
mf->keep_size_after = lz_options->after_size
+ lz_options->match_len_max;
// To avoid constant memmove()s, allocate some extra space. Since
// memmove()s become more expensive when the size of the buffer
// increases, we reserve more space when a large dictionary is
// used to make the memmove() calls rarer.
//
// This works with dictionaries up to about 3 GiB. If bigger
// dictionary is wanted, some extra work is needed:
// - Several variables in lzma_mf have to be changed from uint32_t
// to size_t.
// - Memory usage calculation needs something too, e.g. use uint64_t
// for mf->size.
uint32_t reserve = lz_options->dict_size / 2;
if (reserve > (UINT32_C(1) << 30))
reserve /= 2;
reserve += (lz_options->before_size + lz_options->match_len_max
+ lz_options->after_size) / 2 + (UINT32_C(1) << 19);
const uint32_t old_size = mf->size;
mf->size = mf->keep_size_before + reserve + mf->keep_size_after;
// Deallocate the old history buffer if it exists but has different
// size than what is needed now.
if (mf->buffer != NULL && old_size != mf->size) {
lzma_free(mf->buffer, allocator);
mf->buffer = NULL;
}
// Match finder options
mf->match_len_max = lz_options->match_len_max;
mf->nice_len = lz_options->nice_len;
// cyclic_size has to stay smaller than 2 Gi. Note that this doesn't
// mean limiting dictionary size to less than 2 GiB. With a match
// finder that uses multibyte resolution (hashes start at e.g. every
// fourth byte), cyclic_size would stay below 2 Gi even when
// dictionary size is greater than 2 GiB.
//
// It would be possible to allow cyclic_size >= 2 Gi, but then we
// would need to be careful to use 64-bit types in various places
// (size_t could do since we would need bigger than 32-bit address
// space anyway). It would also require either zeroing a multigigabyte
// buffer at initialization (waste of time and RAM) or allow
// normalization in lz_encoder_mf.c to access uninitialized
// memory to keep the code simpler. The current way is simple and
// still allows pretty big dictionaries, so I don't expect these
// limits to change.
mf->cyclic_size = lz_options->dict_size + 1;
// Validate the match finder ID and setup the function pointers.
switch (lz_options->match_finder) {
#ifdef HAVE_MF_HC3
case LZMA_MF_HC3:
mf->find = &lzma_mf_hc3_find;
mf->skip = &lzma_mf_hc3_skip;
break;
#endif
#ifdef HAVE_MF_HC4
case LZMA_MF_HC4:
mf->find = &lzma_mf_hc4_find;
mf->skip = &lzma_mf_hc4_skip;
break;
#endif
#ifdef HAVE_MF_BT2
case LZMA_MF_BT2:
mf->find = &lzma_mf_bt2_find;
mf->skip = &lzma_mf_bt2_skip;
break;
#endif
#ifdef HAVE_MF_BT3
case LZMA_MF_BT3:
mf->find = &lzma_mf_bt3_find;
mf->skip = &lzma_mf_bt3_skip;
break;
#endif
#ifdef HAVE_MF_BT4
case LZMA_MF_BT4:
mf->find = &lzma_mf_bt4_find;
mf->skip = &lzma_mf_bt4_skip;
break;
#endif
default:
return true;
}
// Calculate the sizes of mf->hash and mf->son and check that
// nice_len is big enough for the selected match finder.
const uint32_t hash_bytes = lz_options->match_finder & 0x0F;
if (hash_bytes > mf->nice_len)
return true;
const bool is_bt = (lz_options->match_finder & 0x10) != 0;
uint32_t hs;
if (hash_bytes == 2) {
hs = 0xFFFF;
} else {
// Round dictionary size up to the next 2^n - 1 so it can
// be used as a hash mask.
hs = lz_options->dict_size - 1;
hs |= hs >> 1;
hs |= hs >> 2;
hs |= hs >> 4;
hs |= hs >> 8;
hs >>= 1;
hs |= 0xFFFF;
if (hs > (UINT32_C(1) << 24)) {
if (hash_bytes == 3)
hs = (UINT32_C(1) << 24) - 1;
else
hs >>= 1;
}
}
mf->hash_mask = hs;
++hs;
if (hash_bytes > 2)
hs += HASH_2_SIZE;
if (hash_bytes > 3)
hs += HASH_3_SIZE;
/*
No match finder uses this at the moment.
if (mf->hash_bytes > 4)
hs += HASH_4_SIZE;
*/
const uint32_t old_hash_count = mf->hash_count;
const uint32_t old_sons_count = mf->sons_count;
mf->hash_count = hs;
mf->sons_count = mf->cyclic_size;
if (is_bt)
mf->sons_count *= 2;
// Deallocate the old hash array if it exists and has different size
// than what is needed now.
if (old_hash_count != mf->hash_count
|| old_sons_count != mf->sons_count) {
lzma_free(mf->hash, allocator);
mf->hash = NULL;
lzma_free(mf->son, allocator);
mf->son = NULL;
}
// Maximum number of match finder cycles
mf->depth = lz_options->depth;
if (mf->depth == 0) {
if (is_bt)
mf->depth = 16 + mf->nice_len / 2;
else
mf->depth = 4 + mf->nice_len / 4;
}
return false;
}
static bool
lz_encoder_init(lzma_mf *mf, const lzma_allocator *allocator,
const lzma_lz_options *lz_options)
{
// Allocate the history buffer.
if (mf->buffer == NULL) {
// lzma_memcmplen() is used for the dictionary buffer
// so we need to allocate a few extra bytes to prevent
// it from reading past the end of the buffer.
mf->buffer = lzma_alloc(mf->size + LZMA_MEMCMPLEN_EXTRA,
allocator);
if (mf->buffer == NULL)
return true;
// Keep Valgrind happy with lzma_memcmplen() and initialize
// the extra bytes whose value may get read but which will
// effectively get ignored.
memzero(mf->buffer + mf->size, LZMA_MEMCMPLEN_EXTRA);
}
// Use cyclic_size as initial mf->offset. This allows
// avoiding a few branches in the match finders. The downside is
// that match finder needs to be normalized more often, which may
// hurt performance with huge dictionaries.
mf->offset = mf->cyclic_size;
mf->read_pos = 0;
mf->read_ahead = 0;
mf->read_limit = 0;
mf->write_pos = 0;
mf->pending = 0;
#if UINT32_MAX >= SIZE_MAX / 4
// Check for integer overflow. (Huge dictionaries are not
// possible on 32-bit CPU.)
if (mf->hash_count > SIZE_MAX / sizeof(uint32_t)
|| mf->sons_count > SIZE_MAX / sizeof(uint32_t))
return true;
#endif
// Allocate and initialize the hash table. Since EMPTY_HASH_VALUE
// is zero, we can use lzma_alloc_zero() or memzero() for mf->hash.
//
// We don't need to initialize mf->son, but not doing that may
// make Valgrind complain in normalization (see normalize() in
// lz_encoder_mf.c). Skipping the initialization is *very* good
// when big dictionary is used but only small amount of data gets
// actually compressed: most of the mf->son won't get actually
// allocated by the kernel, so we avoid wasting RAM and improve
// initialization speed a lot.
if (mf->hash == NULL) {
mf->hash = lzma_alloc_zero(mf->hash_count * sizeof(uint32_t),
allocator);
mf->son = lzma_alloc(mf->sons_count * sizeof(uint32_t),
allocator);
if (mf->hash == NULL || mf->son == NULL) {
lzma_free(mf->hash, allocator);
mf->hash = NULL;
lzma_free(mf->son, allocator);
mf->son = NULL;
return true;
}
} else {
/*
for (uint32_t i = 0; i < mf->hash_count; ++i)
mf->hash[i] = EMPTY_HASH_VALUE;
*/
memzero(mf->hash, mf->hash_count * sizeof(uint32_t));
}
mf->cyclic_pos = 0;
// Handle preset dictionary.
if (lz_options->preset_dict != NULL
&& lz_options->preset_dict_size > 0) {
// If the preset dictionary is bigger than the actual
// dictionary, use only the tail.
mf->write_pos = my_min(lz_options->preset_dict_size, mf->size);
memcpy(mf->buffer, lz_options->preset_dict
+ lz_options->preset_dict_size - mf->write_pos,
mf->write_pos);
mf->action = LZMA_SYNC_FLUSH;
mf->skip(mf, mf->write_pos);
}
mf->action = LZMA_RUN;
return false;
}
extern uint64_t
lzma_lz_encoder_memusage(const lzma_lz_options *lz_options)
{
// Old buffers must not exist when calling lz_encoder_prepare().
lzma_mf mf = {
.buffer = NULL,
.hash = NULL,
.son = NULL,
.hash_count = 0,
.sons_count = 0,
};
// Setup the size information into mf.
if (lz_encoder_prepare(&mf, NULL, lz_options))
return UINT64_MAX;
// Calculate the memory usage.
return ((uint64_t)(mf.hash_count) + mf.sons_count) * sizeof(uint32_t)
+ mf.size + sizeof(lzma_coder);
}
static void
lz_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
{
lzma_coder *coder = coder_ptr;
lzma_next_end(&coder->next, allocator);
lzma_free(coder->mf.son, allocator);
lzma_free(coder->mf.hash, allocator);
lzma_free(coder->mf.buffer, allocator);
if (coder->lz.end != NULL)
coder->lz.end(coder->lz.coder, allocator);
else
lzma_free(coder->lz.coder, allocator);
lzma_free(coder, allocator);
return;
}
static lzma_ret
lz_encoder_update(void *coder_ptr, const lzma_allocator *allocator,
const lzma_filter *filters_null lzma_attribute((__unused__)),
const lzma_filter *reversed_filters)
{
lzma_coder *coder = coder_ptr;
if (coder->lz.options_update == NULL)
return LZMA_PROG_ERROR;
return_if_error(coder->lz.options_update(
coder->lz.coder, reversed_filters));
return lzma_next_filter_update(
&coder->next, allocator, reversed_filters + 1);
}
extern lzma_ret
lzma_lz_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
const lzma_filter_info *filters,
lzma_ret (*lz_init)(lzma_lz_encoder *lz,
const lzma_allocator *allocator, const void *options,
lzma_lz_options *lz_options))
{
#ifdef HAVE_SMALL
// We need that the CRC32 table has been initialized.
lzma_crc32_init();
#endif
// Allocate and initialize the base data structure.
lzma_coder *coder = next->coder;
if (coder == NULL) {
coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (coder == NULL)
return LZMA_MEM_ERROR;
next->coder = coder;
next->code = &lz_encode;
next->end = &lz_encoder_end;
next->update = &lz_encoder_update;
coder->lz.coder = NULL;
coder->lz.code = NULL;
coder->lz.end = NULL;
// mf.size is initialized to silence Valgrind
// when used on optimized binaries (GCC may reorder
// code in a way that Valgrind gets unhappy).
coder->mf.buffer = NULL;
coder->mf.size = 0;
coder->mf.hash = NULL;
coder->mf.son = NULL;
coder->mf.hash_count = 0;
coder->mf.sons_count = 0;
coder->next = LZMA_NEXT_CODER_INIT;
}
// Initialize the LZ-based encoder.
lzma_lz_options lz_options;
return_if_error(lz_init(&coder->lz, allocator,
filters[0].options, &lz_options));
// Setup the size information into coder->mf and deallocate
// old buffers if they have wrong size.
if (lz_encoder_prepare(&coder->mf, allocator, &lz_options))
return LZMA_OPTIONS_ERROR;
// Allocate new buffers if needed, and do the rest of
// the initialization.
if (lz_encoder_init(&coder->mf, allocator, &lz_options))
return LZMA_MEM_ERROR;
// Initialize the next filter in the chain, if any.
return lzma_next_filter_init(&coder->next, allocator, filters + 1);
}
extern LZMA_API(lzma_bool)
lzma_mf_is_supported(lzma_match_finder mf)
{
bool ret = false;
#ifdef HAVE_MF_HC3
if (mf == LZMA_MF_HC3)
ret = true;
#endif
#ifdef HAVE_MF_HC4
if (mf == LZMA_MF_HC4)
ret = true;
#endif
#ifdef HAVE_MF_BT2
if (mf == LZMA_MF_BT2)
ret = true;
#endif
#ifdef HAVE_MF_BT3
if (mf == LZMA_MF_BT3)
ret = true;
#endif
#ifdef HAVE_MF_BT4
if (mf == LZMA_MF_BT4)
ret = true;
#endif
return ret;
}

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///////////////////////////////////////////////////////////////////////////////
//
/// \file lz_encoder.h
/// \brief LZ in window and match finder API
///
// Authors: Igor Pavlov
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef LZMA_LZ_ENCODER_H
#define LZMA_LZ_ENCODER_H
#include "common.h"
/// A table of these is used by the LZ-based encoder to hold
/// the length-distance pairs found by the match finder.
typedef struct {
uint32_t len;
uint32_t dist;
} lzma_match;
typedef struct lzma_mf_s lzma_mf;
struct lzma_mf_s {
///////////////
// In Window //
///////////////
/// Pointer to buffer with data to be compressed
uint8_t *buffer;
/// Total size of the allocated buffer (that is, including all
/// the extra space)
uint32_t size;
/// Number of bytes that must be kept available in our input history.
/// That is, once keep_size_before bytes have been processed,
/// buffer[read_pos - keep_size_before] is the oldest byte that
/// must be available for reading.
uint32_t keep_size_before;
/// Number of bytes that must be kept in buffer after read_pos.
/// That is, read_pos <= write_pos - keep_size_after as long as
/// action is LZMA_RUN; when action != LZMA_RUN, read_pos is allowed
/// to reach write_pos so that the last bytes get encoded too.
uint32_t keep_size_after;
/// Match finders store locations of matches using 32-bit integers.
/// To avoid adjusting several megabytes of integers every time the
/// input window is moved with move_window, we only adjust the
/// offset of the buffer. Thus, buffer[value_in_hash_table - offset]
/// is the byte pointed by value_in_hash_table.
uint32_t offset;
/// buffer[read_pos] is the next byte to run through the match
/// finder. This is incremented in the match finder once the byte
/// has been processed.
uint32_t read_pos;
/// Number of bytes that have been ran through the match finder, but
/// which haven't been encoded by the LZ-based encoder yet.
uint32_t read_ahead;
/// As long as read_pos is less than read_limit, there is enough
/// input available in buffer for at least one encoding loop.
///
/// Because of the stateful API, read_limit may and will get greater
/// than read_pos quite often. This is taken into account when
/// calculating the value for keep_size_after.
uint32_t read_limit;
/// buffer[write_pos] is the first byte that doesn't contain valid
/// uncompressed data; that is, the next input byte will be copied
/// to buffer[write_pos].
uint32_t write_pos;
/// Number of bytes not hashed before read_pos. This is needed to
/// restart the match finder after LZMA_SYNC_FLUSH.
uint32_t pending;
//////////////////
// Match Finder //
//////////////////
/// Find matches. Returns the number of distance-length pairs written
/// to the matches array. This is called only via lzma_mf_find().
uint32_t (*find)(lzma_mf *mf, lzma_match *matches);
/// Skips num bytes. This is like find() but doesn't make the
/// distance-length pairs available, thus being a little faster.
/// This is called only via mf_skip().
void (*skip)(lzma_mf *mf, uint32_t num);
uint32_t *hash;
uint32_t *son;
uint32_t cyclic_pos;
uint32_t cyclic_size; // Must be dictionary size + 1.
uint32_t hash_mask;
/// Maximum number of loops in the match finder
uint32_t depth;
/// Maximum length of a match that the match finder will try to find.
uint32_t nice_len;
/// Maximum length of a match supported by the LZ-based encoder.
/// If the longest match found by the match finder is nice_len,
/// mf_find() tries to expand it up to match_len_max bytes.
uint32_t match_len_max;
/// When running out of input, binary tree match finders need to know
/// if it is due to flushing or finishing. The action is used also
/// by the LZ-based encoders themselves.
lzma_action action;
/// Number of elements in hash[]
uint32_t hash_count;
/// Number of elements in son[]
uint32_t sons_count;
};
typedef struct {
/// Extra amount of data to keep available before the "actual"
/// dictionary.
size_t before_size;
/// Size of the history buffer
size_t dict_size;
/// Extra amount of data to keep available after the "actual"
/// dictionary.
size_t after_size;
/// Maximum length of a match that the LZ-based encoder can accept.
/// This is used to extend matches of length nice_len to the
/// maximum possible length.
size_t match_len_max;
/// Match finder will search matches up to this length.
/// This must be less than or equal to match_len_max.
size_t nice_len;
/// Type of the match finder to use
lzma_match_finder match_finder;
/// Maximum search depth
uint32_t depth;
/// TODO: Comment
const uint8_t *preset_dict;
uint32_t preset_dict_size;
} lzma_lz_options;
// The total usable buffer space at any moment outside the match finder:
// before_size + dict_size + after_size + match_len_max
//
// In reality, there's some extra space allocated to prevent the number of
// memmove() calls reasonable. The bigger the dict_size is, the bigger
// this extra buffer will be since with bigger dictionaries memmove() would
// also take longer.
//
// A single encoder loop in the LZ-based encoder may call the match finder
// (mf_find() or mf_skip()) at most after_size times. In other words,
// a single encoder loop may increment lzma_mf.read_pos at most after_size
// times. Since matches are looked up to
// lzma_mf.buffer[lzma_mf.read_pos + match_len_max - 1], the total
// amount of extra buffer needed after dict_size becomes
// after_size + match_len_max.
//
// before_size has two uses. The first one is to keep literals available
// in cases when the LZ-based encoder has made some read ahead.
// TODO: Maybe this could be changed by making the LZ-based encoders to
// store the actual literals as they do with length-distance pairs.
//
// Algorithms such as LZMA2 first try to compress a chunk, and then check
// if the encoded result is smaller than the uncompressed one. If the chunk
// was uncompressible, it is better to store it in uncompressed form in
// the output stream. To do this, the whole uncompressed chunk has to be
// still available in the history buffer. before_size achieves that.
typedef struct {
/// Data specific to the LZ-based encoder
void *coder;
/// Function to encode from *dict to out[]
lzma_ret (*code)(void *coder,
lzma_mf *restrict mf, uint8_t *restrict out,
size_t *restrict out_pos, size_t out_size);
/// Free allocated resources
void (*end)(void *coder, const lzma_allocator *allocator);
/// Update the options in the middle of the encoding.
lzma_ret (*options_update)(void *coder, const lzma_filter *filter);
} lzma_lz_encoder;
// Basic steps:
// 1. Input gets copied into the dictionary.
// 2. Data in dictionary gets run through the match finder byte by byte.
// 3. The literals and matches are encoded using e.g. LZMA.
//
// The bytes that have been ran through the match finder, but not encoded yet,
// are called `read ahead'.
/// Get pointer to the first byte not ran through the match finder
static inline const uint8_t *
mf_ptr(const lzma_mf *mf)
{
return mf->buffer + mf->read_pos;
}
/// Get the number of bytes that haven't been ran through the match finder yet.
static inline uint32_t
mf_avail(const lzma_mf *mf)
{
return mf->write_pos - mf->read_pos;
}
/// Get the number of bytes that haven't been encoded yet (some of these
/// bytes may have been ran through the match finder though).
static inline uint32_t
mf_unencoded(const lzma_mf *mf)
{
return mf->write_pos - mf->read_pos + mf->read_ahead;
}
/// Calculate the absolute offset from the beginning of the most recent
/// dictionary reset. Only the lowest four bits are important, so there's no
/// problem that we don't know the 64-bit size of the data encoded so far.
///
/// NOTE: When moving the input window, we need to do it so that the lowest
/// bits of dict->read_pos are not modified to keep this macro working
/// as intended.
static inline uint32_t
mf_position(const lzma_mf *mf)
{
return mf->read_pos - mf->read_ahead;
}
/// Since everything else begins with mf_, use it also for lzma_mf_find().
#define mf_find lzma_mf_find
/// Skip the given number of bytes. This is used when a good match was found.
/// For example, if mf_find() finds a match of 200 bytes long, the first byte
/// of that match was already consumed by mf_find(), and the rest 199 bytes
/// have to be skipped with mf_skip(mf, 199).
static inline void
mf_skip(lzma_mf *mf, uint32_t amount)
{
if (amount != 0) {
mf->skip(mf, amount);
mf->read_ahead += amount;
}
}
/// Copies at most *left number of bytes from the history buffer
/// to out[]. This is needed by LZMA2 to encode uncompressed chunks.
static inline void
mf_read(lzma_mf *mf, uint8_t *out, size_t *out_pos, size_t out_size,
size_t *left)
{
const size_t out_avail = out_size - *out_pos;
const size_t copy_size = my_min(out_avail, *left);
assert(mf->read_ahead == 0);
assert(mf->read_pos >= *left);
memcpy(out + *out_pos, mf->buffer + mf->read_pos - *left,
copy_size);
*out_pos += copy_size;
*left -= copy_size;
return;
}
extern lzma_ret lzma_lz_encoder_init(
lzma_next_coder *next, const lzma_allocator *allocator,
const lzma_filter_info *filters,
lzma_ret (*lz_init)(lzma_lz_encoder *lz,
const lzma_allocator *allocator, const void *options,
lzma_lz_options *lz_options));
extern uint64_t lzma_lz_encoder_memusage(const lzma_lz_options *lz_options);
// These are only for LZ encoder's internal use.
extern uint32_t lzma_mf_find(
lzma_mf *mf, uint32_t *count, lzma_match *matches);
extern uint32_t lzma_mf_hc3_find(lzma_mf *dict, lzma_match *matches);
extern void lzma_mf_hc3_skip(lzma_mf *dict, uint32_t amount);
extern uint32_t lzma_mf_hc4_find(lzma_mf *dict, lzma_match *matches);
extern void lzma_mf_hc4_skip(lzma_mf *dict, uint32_t amount);
extern uint32_t lzma_mf_bt2_find(lzma_mf *dict, lzma_match *matches);
extern void lzma_mf_bt2_skip(lzma_mf *dict, uint32_t amount);
extern uint32_t lzma_mf_bt3_find(lzma_mf *dict, lzma_match *matches);
extern void lzma_mf_bt3_skip(lzma_mf *dict, uint32_t amount);
extern uint32_t lzma_mf_bt4_find(lzma_mf *dict, lzma_match *matches);
extern void lzma_mf_bt4_skip(lzma_mf *dict, uint32_t amount);
#endif

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///////////////////////////////////////////////////////////////////////////////
//
/// \file lz_encoder_hash.h
/// \brief Hash macros for match finders
//
// Author: Igor Pavlov
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef LZMA_LZ_ENCODER_HASH_H
#define LZMA_LZ_ENCODER_HASH_H
#if defined(WORDS_BIGENDIAN) && !defined(HAVE_SMALL)
// This is to make liblzma produce the same output on big endian
// systems that it does on little endian systems. lz_encoder.c
// takes care of including the actual table.
extern const uint32_t lzma_lz_hash_table[256];
# define hash_table lzma_lz_hash_table
#else
# include "check.h"
# define hash_table lzma_crc32_table[0]
#endif
#define HASH_2_SIZE (UINT32_C(1) << 10)
#define HASH_3_SIZE (UINT32_C(1) << 16)
#define HASH_4_SIZE (UINT32_C(1) << 20)
#define HASH_2_MASK (HASH_2_SIZE - 1)
#define HASH_3_MASK (HASH_3_SIZE - 1)
#define HASH_4_MASK (HASH_4_SIZE - 1)
#define FIX_3_HASH_SIZE (HASH_2_SIZE)
#define FIX_4_HASH_SIZE (HASH_2_SIZE + HASH_3_SIZE)
#define FIX_5_HASH_SIZE (HASH_2_SIZE + HASH_3_SIZE + HASH_4_SIZE)
// Endianness doesn't matter in hash_2_calc() (no effect on the output).
#ifdef TUKLIB_FAST_UNALIGNED_ACCESS
# define hash_2_calc() \
const uint32_t hash_value = *(const uint16_t *)(cur)
#else
# define hash_2_calc() \
const uint32_t hash_value \
= (uint32_t)(cur[0]) | ((uint32_t)(cur[1]) << 8)
#endif
#define hash_3_calc() \
const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
const uint32_t hash_2_value = temp & HASH_2_MASK; \
const uint32_t hash_value \
= (temp ^ ((uint32_t)(cur[2]) << 8)) & mf->hash_mask
#define hash_4_calc() \
const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
const uint32_t hash_2_value = temp & HASH_2_MASK; \
const uint32_t hash_3_value \
= (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
const uint32_t hash_value = (temp ^ ((uint32_t)(cur[2]) << 8) \
^ (hash_table[cur[3]] << 5)) & mf->hash_mask
// The following are not currently used.
#define hash_5_calc() \
const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
const uint32_t hash_2_value = temp & HASH_2_MASK; \
const uint32_t hash_3_value \
= (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
uint32_t hash_4_value = (temp ^ ((uint32_t)(cur[2]) << 8) ^ \
^ hash_table[cur[3]] << 5); \
const uint32_t hash_value \
= (hash_4_value ^ (hash_table[cur[4]] << 3)) \
& mf->hash_mask; \
hash_4_value &= HASH_4_MASK
/*
#define hash_zip_calc() \
const uint32_t hash_value \
= (((uint32_t)(cur[0]) | ((uint32_t)(cur[1]) << 8)) \
^ hash_table[cur[2]]) & 0xFFFF
*/
#define hash_zip_calc() \
const uint32_t hash_value \
= (((uint32_t)(cur[2]) | ((uint32_t)(cur[0]) << 8)) \
^ hash_table[cur[1]]) & 0xFFFF
#define mt_hash_2_calc() \
const uint32_t hash_2_value \
= (hash_table[cur[0]] ^ cur[1]) & HASH_2_MASK
#define mt_hash_3_calc() \
const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
const uint32_t hash_2_value = temp & HASH_2_MASK; \
const uint32_t hash_3_value \
= (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK
#define mt_hash_4_calc() \
const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
const uint32_t hash_2_value = temp & HASH_2_MASK; \
const uint32_t hash_3_value \
= (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
const uint32_t hash_4_value = (temp ^ ((uint32_t)(cur[2]) << 8) ^ \
(hash_table[cur[3]] << 5)) & HASH_4_MASK
#endif

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/* This file has been automatically generated by crc32_tablegen.c. */
const uint32_t lzma_lz_hash_table[256] = {
0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,
0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940,
0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,
0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A,
0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818,
0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086,
0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4,
0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE,
0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252,
0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60,
0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04,
0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A,
0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E,
0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0,
0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6,
0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
};

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///////////////////////////////////////////////////////////////////////////////
//
/// \file lz_encoder_mf.c
/// \brief Match finders
///
// Authors: Igor Pavlov
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "lz_encoder.h"
#include "lz_encoder_hash.h"
#include "memcmplen.h"
/// \brief Find matches starting from the current byte
///
/// \return The length of the longest match found
extern uint32_t
lzma_mf_find(lzma_mf *mf, uint32_t *count_ptr, lzma_match *matches)
{
// Call the match finder. It returns the number of length-distance
// pairs found.
// FIXME: Minimum count is zero, what _exactly_ is the maximum?
const uint32_t count = mf->find(mf, matches);
// Length of the longest match; assume that no matches were found
// and thus the maximum length is zero.
uint32_t len_best = 0;
if (count > 0) {
#ifndef NDEBUG
// Validate the matches.
for (uint32_t i = 0; i < count; ++i) {
assert(matches[i].len <= mf->nice_len);
assert(matches[i].dist < mf->read_pos);
assert(memcmp(mf_ptr(mf) - 1,
mf_ptr(mf) - matches[i].dist - 2,
matches[i].len) == 0);
}
#endif
// The last used element in the array contains
// the longest match.
len_best = matches[count - 1].len;
// If a match of maximum search length was found, try to
// extend the match to maximum possible length.
if (len_best == mf->nice_len) {
// The limit for the match length is either the
// maximum match length supported by the LZ-based
// encoder or the number of bytes left in the
// dictionary, whichever is smaller.
uint32_t limit = mf_avail(mf) + 1;
if (limit > mf->match_len_max)
limit = mf->match_len_max;
// Pointer to the byte we just ran through
// the match finder.
const uint8_t *p1 = mf_ptr(mf) - 1;
// Pointer to the beginning of the match. We need -1
// here because the match distances are zero based.
const uint8_t *p2 = p1 - matches[count - 1].dist - 1;
len_best = lzma_memcmplen(p1, p2, len_best, limit);
}
}
*count_ptr = count;
// Finally update the read position to indicate that match finder was
// run for this dictionary offset.
++mf->read_ahead;
return len_best;
}
/// Hash value to indicate unused element in the hash. Since we start the
/// positions from dict_size + 1, zero is always too far to qualify
/// as usable match position.
#define EMPTY_HASH_VALUE 0
/// Normalization must be done when lzma_mf.offset + lzma_mf.read_pos
/// reaches MUST_NORMALIZE_POS.
#define MUST_NORMALIZE_POS UINT32_MAX
/// \brief Normalizes hash values
///
/// The hash arrays store positions of match candidates. The positions are
/// relative to an arbitrary offset that is not the same as the absolute
/// offset in the input stream. The relative position of the current byte
/// is lzma_mf.offset + lzma_mf.read_pos. The distances of the matches are
/// the differences of the current read position and the position found from
/// the hash.
///
/// To prevent integer overflows of the offsets stored in the hash arrays,
/// we need to "normalize" the stored values now and then. During the
/// normalization, we drop values that indicate distance greater than the
/// dictionary size, thus making space for new values.
static void
normalize(lzma_mf *mf)
{
assert(mf->read_pos + mf->offset == MUST_NORMALIZE_POS);
// In future we may not want to touch the lowest bits, because there
// may be match finders that use larger resolution than one byte.
const uint32_t subvalue
= (MUST_NORMALIZE_POS - mf->cyclic_size);
// & (~(UINT32_C(1) << 10) - 1);
for (uint32_t i = 0; i < mf->hash_count; ++i) {
// If the distance is greater than the dictionary size,
// we can simply mark the hash element as empty.
if (mf->hash[i] <= subvalue)
mf->hash[i] = EMPTY_HASH_VALUE;
else
mf->hash[i] -= subvalue;
}
for (uint32_t i = 0; i < mf->sons_count; ++i) {
// Do the same for mf->son.
//
// NOTE: There may be uninitialized elements in mf->son.
// Valgrind may complain that the "if" below depends on
// an uninitialized value. In this case it is safe to ignore
// the warning. See also the comments in lz_encoder_init()
// in lz_encoder.c.
if (mf->son[i] <= subvalue)
mf->son[i] = EMPTY_HASH_VALUE;
else
mf->son[i] -= subvalue;
}
// Update offset to match the new locations.
mf->offset -= subvalue;
return;
}
/// Mark the current byte as processed from point of view of the match finder.
static void
move_pos(lzma_mf *mf)
{
if (++mf->cyclic_pos == mf->cyclic_size)
mf->cyclic_pos = 0;
++mf->read_pos;
assert(mf->read_pos <= mf->write_pos);
if (unlikely(mf->read_pos + mf->offset == UINT32_MAX))
normalize(mf);
}
/// When flushing, we cannot run the match finder unless there is nice_len
/// bytes available in the dictionary. Instead, we skip running the match
/// finder (indicating that no match was found), and count how many bytes we
/// have ignored this way.
///
/// When new data is given after the flushing was completed, the match finder
/// is restarted by rewinding mf->read_pos backwards by mf->pending. Then
/// the missed bytes are added to the hash using the match finder's skip
/// function (with small amount of input, it may start using mf->pending
/// again if flushing).
///
/// Due to this rewinding, we don't touch cyclic_pos or test for
/// normalization. It will be done when the match finder's skip function
/// catches up after a flush.
static void
move_pending(lzma_mf *mf)
{
++mf->read_pos;
assert(mf->read_pos <= mf->write_pos);
++mf->pending;
}
/// Calculate len_limit and determine if there is enough input to run
/// the actual match finder code. Sets up "cur" and "pos". This macro
/// is used by all find functions and binary tree skip functions. Hash
/// chain skip function doesn't need len_limit so a simpler code is used
/// in them.
#define header(is_bt, len_min, ret_op) \
uint32_t len_limit = mf_avail(mf); \
if (mf->nice_len <= len_limit) { \
len_limit = mf->nice_len; \
} else if (len_limit < (len_min) \
|| (is_bt && mf->action == LZMA_SYNC_FLUSH)) { \
assert(mf->action != LZMA_RUN); \
move_pending(mf); \
ret_op; \
} \
const uint8_t *cur = mf_ptr(mf); \
const uint32_t pos = mf->read_pos + mf->offset
/// Header for find functions. "return 0" indicates that zero matches
/// were found.
#define header_find(is_bt, len_min) \
header(is_bt, len_min, return 0); \
uint32_t matches_count = 0
/// Header for a loop in a skip function. "continue" tells to skip the rest
/// of the code in the loop.
#define header_skip(is_bt, len_min) \
header(is_bt, len_min, continue)
/// Calls hc_find_func() or bt_find_func() and calculates the total number
/// of matches found. Updates the dictionary position and returns the number
/// of matches found.
#define call_find(func, len_best) \
do { \
matches_count = func(len_limit, pos, cur, cur_match, mf->depth, \
mf->son, mf->cyclic_pos, mf->cyclic_size, \
matches + matches_count, len_best) \
- matches; \
move_pos(mf); \
return matches_count; \
} while (0)
////////////////
// Hash Chain //
////////////////
#if defined(HAVE_MF_HC3) || defined(HAVE_MF_HC4)
///
///
/// \param len_limit Don't look for matches longer than len_limit.
/// \param pos lzma_mf.read_pos + lzma_mf.offset
/// \param cur Pointer to current byte (mf_ptr(mf))
/// \param cur_match Start position of the current match candidate
/// \param depth Maximum length of the hash chain
/// \param son lzma_mf.son (contains the hash chain)
/// \param cyclic_pos
/// \param cyclic_size
/// \param matches Array to hold the matches.
/// \param len_best The length of the longest match found so far.
static lzma_match *
hc_find_func(
const uint32_t len_limit,
const uint32_t pos,
const uint8_t *const cur,
uint32_t cur_match,
uint32_t depth,
uint32_t *const son,
const uint32_t cyclic_pos,
const uint32_t cyclic_size,
lzma_match *matches,
uint32_t len_best)
{
son[cyclic_pos] = cur_match;
while (true) {
const uint32_t delta = pos - cur_match;
if (depth-- == 0 || delta >= cyclic_size)
return matches;
const uint8_t *const pb = cur - delta;
cur_match = son[cyclic_pos - delta
+ (delta > cyclic_pos ? cyclic_size : 0)];
if (pb[len_best] == cur[len_best] && pb[0] == cur[0]) {
uint32_t len = lzma_memcmplen(pb, cur, 1, len_limit);
if (len_best < len) {
len_best = len;
matches->len = len;
matches->dist = delta - 1;
++matches;
if (len == len_limit)
return matches;
}
}
}
}
#define hc_find(len_best) \
call_find(hc_find_func, len_best)
#define hc_skip() \
do { \
mf->son[mf->cyclic_pos] = cur_match; \
move_pos(mf); \
} while (0)
#endif
#ifdef HAVE_MF_HC3
extern uint32_t
lzma_mf_hc3_find(lzma_mf *mf, lzma_match *matches)
{
header_find(false, 3);
hash_3_calc();
const uint32_t delta2 = pos - mf->hash[hash_2_value];
const uint32_t cur_match = mf->hash[FIX_3_HASH_SIZE + hash_value];
mf->hash[hash_2_value] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_value] = pos;
uint32_t len_best = 2;
if (delta2 < mf->cyclic_size && *(cur - delta2) == *cur) {
len_best = lzma_memcmplen(cur - delta2, cur,
len_best, len_limit);
matches[0].len = len_best;
matches[0].dist = delta2 - 1;
matches_count = 1;
if (len_best == len_limit) {
hc_skip();
return 1; // matches_count
}
}
hc_find(len_best);
}
extern void
lzma_mf_hc3_skip(lzma_mf *mf, uint32_t amount)
{
do {
if (mf_avail(mf) < 3) {
move_pending(mf);
continue;
}
const uint8_t *cur = mf_ptr(mf);
const uint32_t pos = mf->read_pos + mf->offset;
hash_3_calc();
const uint32_t cur_match
= mf->hash[FIX_3_HASH_SIZE + hash_value];
mf->hash[hash_2_value] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_value] = pos;
hc_skip();
} while (--amount != 0);
}
#endif
#ifdef HAVE_MF_HC4
extern uint32_t
lzma_mf_hc4_find(lzma_mf *mf, lzma_match *matches)
{
header_find(false, 4);
hash_4_calc();
uint32_t delta2 = pos - mf->hash[hash_2_value];
const uint32_t delta3
= pos - mf->hash[FIX_3_HASH_SIZE + hash_3_value];
const uint32_t cur_match = mf->hash[FIX_4_HASH_SIZE + hash_value];
mf->hash[hash_2_value ] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos;
mf->hash[FIX_4_HASH_SIZE + hash_value] = pos;
uint32_t len_best = 1;
if (delta2 < mf->cyclic_size && *(cur - delta2) == *cur) {
len_best = 2;
matches[0].len = 2;
matches[0].dist = delta2 - 1;
matches_count = 1;
}
if (delta2 != delta3 && delta3 < mf->cyclic_size
&& *(cur - delta3) == *cur) {
len_best = 3;
matches[matches_count++].dist = delta3 - 1;
delta2 = delta3;
}
if (matches_count != 0) {
len_best = lzma_memcmplen(cur - delta2, cur,
len_best, len_limit);
matches[matches_count - 1].len = len_best;
if (len_best == len_limit) {
hc_skip();
return matches_count;
}
}
if (len_best < 3)
len_best = 3;
hc_find(len_best);
}
extern void
lzma_mf_hc4_skip(lzma_mf *mf, uint32_t amount)
{
do {
if (mf_avail(mf) < 4) {
move_pending(mf);
continue;
}
const uint8_t *cur = mf_ptr(mf);
const uint32_t pos = mf->read_pos + mf->offset;
hash_4_calc();
const uint32_t cur_match
= mf->hash[FIX_4_HASH_SIZE + hash_value];
mf->hash[hash_2_value] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos;
mf->hash[FIX_4_HASH_SIZE + hash_value] = pos;
hc_skip();
} while (--amount != 0);
}
#endif
/////////////////
// Binary Tree //
/////////////////
#if defined(HAVE_MF_BT2) || defined(HAVE_MF_BT3) || defined(HAVE_MF_BT4)
static lzma_match *
bt_find_func(
const uint32_t len_limit,
const uint32_t pos,
const uint8_t *const cur,
uint32_t cur_match,
uint32_t depth,
uint32_t *const son,
const uint32_t cyclic_pos,
const uint32_t cyclic_size,
lzma_match *matches,
uint32_t len_best)
{
uint32_t *ptr0 = son + (cyclic_pos << 1) + 1;
uint32_t *ptr1 = son + (cyclic_pos << 1);
uint32_t len0 = 0;
uint32_t len1 = 0;
while (true) {
const uint32_t delta = pos - cur_match;
if (depth-- == 0 || delta >= cyclic_size) {
*ptr0 = EMPTY_HASH_VALUE;
*ptr1 = EMPTY_HASH_VALUE;
return matches;
}
uint32_t *const pair = son + ((cyclic_pos - delta
+ (delta > cyclic_pos ? cyclic_size : 0))
<< 1);
const uint8_t *const pb = cur - delta;
uint32_t len = my_min(len0, len1);
if (pb[len] == cur[len]) {
len = lzma_memcmplen(pb, cur, len + 1, len_limit);
if (len_best < len) {
len_best = len;
matches->len = len;
matches->dist = delta - 1;
++matches;
if (len == len_limit) {
*ptr1 = pair[0];
*ptr0 = pair[1];
return matches;
}
}
}
if (pb[len] < cur[len]) {
*ptr1 = cur_match;
ptr1 = pair + 1;
cur_match = *ptr1;
len1 = len;
} else {
*ptr0 = cur_match;
ptr0 = pair;
cur_match = *ptr0;
len0 = len;
}
}
}
static void
bt_skip_func(
const uint32_t len_limit,
const uint32_t pos,
const uint8_t *const cur,
uint32_t cur_match,
uint32_t depth,
uint32_t *const son,
const uint32_t cyclic_pos,
const uint32_t cyclic_size)
{
uint32_t *ptr0 = son + (cyclic_pos << 1) + 1;
uint32_t *ptr1 = son + (cyclic_pos << 1);
uint32_t len0 = 0;
uint32_t len1 = 0;
while (true) {
const uint32_t delta = pos - cur_match;
if (depth-- == 0 || delta >= cyclic_size) {
*ptr0 = EMPTY_HASH_VALUE;
*ptr1 = EMPTY_HASH_VALUE;
return;
}
uint32_t *pair = son + ((cyclic_pos - delta
+ (delta > cyclic_pos ? cyclic_size : 0))
<< 1);
const uint8_t *pb = cur - delta;
uint32_t len = my_min(len0, len1);
if (pb[len] == cur[len]) {
len = lzma_memcmplen(pb, cur, len + 1, len_limit);
if (len == len_limit) {
*ptr1 = pair[0];
*ptr0 = pair[1];
return;
}
}
if (pb[len] < cur[len]) {
*ptr1 = cur_match;
ptr1 = pair + 1;
cur_match = *ptr1;
len1 = len;
} else {
*ptr0 = cur_match;
ptr0 = pair;
cur_match = *ptr0;
len0 = len;
}
}
}
#define bt_find(len_best) \
call_find(bt_find_func, len_best)
#define bt_skip() \
do { \
bt_skip_func(len_limit, pos, cur, cur_match, mf->depth, \
mf->son, mf->cyclic_pos, \
mf->cyclic_size); \
move_pos(mf); \
} while (0)
#endif
#ifdef HAVE_MF_BT2
extern uint32_t
lzma_mf_bt2_find(lzma_mf *mf, lzma_match *matches)
{
header_find(true, 2);
hash_2_calc();
const uint32_t cur_match = mf->hash[hash_value];
mf->hash[hash_value] = pos;
bt_find(1);
}
extern void
lzma_mf_bt2_skip(lzma_mf *mf, uint32_t amount)
{
do {
header_skip(true, 2);
hash_2_calc();
const uint32_t cur_match = mf->hash[hash_value];
mf->hash[hash_value] = pos;
bt_skip();
} while (--amount != 0);
}
#endif
#ifdef HAVE_MF_BT3
extern uint32_t
lzma_mf_bt3_find(lzma_mf *mf, lzma_match *matches)
{
header_find(true, 3);
hash_3_calc();
const uint32_t delta2 = pos - mf->hash[hash_2_value];
const uint32_t cur_match = mf->hash[FIX_3_HASH_SIZE + hash_value];
mf->hash[hash_2_value] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_value] = pos;
uint32_t len_best = 2;
if (delta2 < mf->cyclic_size && *(cur - delta2) == *cur) {
len_best = lzma_memcmplen(
cur, cur - delta2, len_best, len_limit);
matches[0].len = len_best;
matches[0].dist = delta2 - 1;
matches_count = 1;
if (len_best == len_limit) {
bt_skip();
return 1; // matches_count
}
}
bt_find(len_best);
}
extern void
lzma_mf_bt3_skip(lzma_mf *mf, uint32_t amount)
{
do {
header_skip(true, 3);
hash_3_calc();
const uint32_t cur_match
= mf->hash[FIX_3_HASH_SIZE + hash_value];
mf->hash[hash_2_value] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_value] = pos;
bt_skip();
} while (--amount != 0);
}
#endif
#ifdef HAVE_MF_BT4
extern uint32_t
lzma_mf_bt4_find(lzma_mf *mf, lzma_match *matches)
{
header_find(true, 4);
hash_4_calc();
uint32_t delta2 = pos - mf->hash[hash_2_value];
const uint32_t delta3
= pos - mf->hash[FIX_3_HASH_SIZE + hash_3_value];
const uint32_t cur_match = mf->hash[FIX_4_HASH_SIZE + hash_value];
mf->hash[hash_2_value] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos;
mf->hash[FIX_4_HASH_SIZE + hash_value] = pos;
uint32_t len_best = 1;
if (delta2 < mf->cyclic_size && *(cur - delta2) == *cur) {
len_best = 2;
matches[0].len = 2;
matches[0].dist = delta2 - 1;
matches_count = 1;
}
if (delta2 != delta3 && delta3 < mf->cyclic_size
&& *(cur - delta3) == *cur) {
len_best = 3;
matches[matches_count++].dist = delta3 - 1;
delta2 = delta3;
}
if (matches_count != 0) {
len_best = lzma_memcmplen(
cur, cur - delta2, len_best, len_limit);
matches[matches_count - 1].len = len_best;
if (len_best == len_limit) {
bt_skip();
return matches_count;
}
}
if (len_best < 3)
len_best = 3;
bt_find(len_best);
}
extern void
lzma_mf_bt4_skip(lzma_mf *mf, uint32_t amount)
{
do {
header_skip(true, 4);
hash_4_calc();
const uint32_t cur_match
= mf->hash[FIX_4_HASH_SIZE + hash_value];
mf->hash[hash_2_value] = pos;
mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos;
mf->hash[FIX_4_HASH_SIZE + hash_value] = pos;
bt_skip();
} while (--amount != 0);
}
#endif