mirror of
https://github.com/classilla/tenfourfox.git
synced 2024-11-03 19:05:35 +00:00
267 lines
10 KiB
C
Executable File
267 lines
10 KiB
C
Executable File
/* NOLINT(build/header_guard) */
|
|
/* Copyright 2010 Google Inc. All Rights Reserved.
|
|
|
|
Distributed under MIT license.
|
|
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
|
|
*/
|
|
|
|
/* template parameters: FN */
|
|
|
|
/* A (forgetful) hash table to the data seen by the compressor, to
|
|
help create backward references to previous data.
|
|
|
|
This is a hash map of fixed size (bucket_size_) to a ring buffer of
|
|
fixed size (block_size_). The ring buffer contains the last block_size_
|
|
index positions of the given hash key in the compressed data. */
|
|
|
|
#define HashLongestMatch HASHER()
|
|
|
|
static BROTLI_INLINE size_t FN(HashTypeLength)(void) { return 8; }
|
|
static BROTLI_INLINE size_t FN(StoreLookahead)(void) { return 8; }
|
|
|
|
/* HashBytes is the function that chooses the bucket to place the address in. */
|
|
static BROTLI_INLINE uint32_t FN(HashBytes)(const uint8_t *data,
|
|
const uint64_t mask,
|
|
const int shift) {
|
|
const uint64_t h = (BROTLI_UNALIGNED_LOAD64LE(data) & mask) * kHashMul64Long;
|
|
/* The higher bits contain more mixture from the multiplication,
|
|
so we take our results from there. */
|
|
return (uint32_t)(h >> shift);
|
|
}
|
|
|
|
typedef struct HashLongestMatch {
|
|
/* Number of hash buckets. */
|
|
size_t bucket_size_;
|
|
/* Only block_size_ newest backward references are kept,
|
|
and the older are forgotten. */
|
|
size_t block_size_;
|
|
/* Left-shift for computing hash bucket index from hash value. */
|
|
int hash_shift_;
|
|
/* Mask for selecting the next 4-8 bytes of input */
|
|
uint64_t hash_mask_;
|
|
/* Mask for accessing entries in a block (in a ring-buffer manner). */
|
|
uint32_t block_mask_;
|
|
|
|
/* --- Dynamic size members --- */
|
|
|
|
/* Number of entries in a particular bucket. */
|
|
/* uint16_t num[bucket_size]; */
|
|
|
|
/* Buckets containing block_size_ of backward references. */
|
|
/* uint32_t* buckets[bucket_size * block_size]; */
|
|
} HashLongestMatch;
|
|
|
|
static BROTLI_INLINE HashLongestMatch* FN(Self)(HasherHandle handle) {
|
|
return (HashLongestMatch*)&(GetHasherCommon(handle)[1]);
|
|
}
|
|
|
|
static BROTLI_INLINE uint16_t* FN(Num)(HashLongestMatch* self) {
|
|
return (uint16_t*)(&self[1]);
|
|
}
|
|
|
|
static BROTLI_INLINE uint32_t* FN(Buckets)(HashLongestMatch* self) {
|
|
return (uint32_t*)(&FN(Num)(self)[self->bucket_size_]);
|
|
}
|
|
|
|
static void FN(Initialize)(
|
|
HasherHandle handle, const BrotliEncoderParams* params) {
|
|
HasherCommon* common = GetHasherCommon(handle);
|
|
HashLongestMatch* self = FN(Self)(handle);
|
|
BROTLI_UNUSED(params);
|
|
self->hash_shift_ = 64 - common->params.bucket_bits;
|
|
self->hash_mask_ = (~((uint64_t)0U)) >> (64 - 8 * common->params.hash_len);
|
|
self->bucket_size_ = (size_t)1 << common->params.bucket_bits;
|
|
self->block_size_ = (size_t)1 << common->params.block_bits;
|
|
self->block_mask_ = (uint32_t)(self->block_size_ - 1);
|
|
}
|
|
|
|
static void FN(Prepare)(HasherHandle handle, BROTLI_BOOL one_shot,
|
|
size_t input_size, const uint8_t* data) {
|
|
HashLongestMatch* self = FN(Self)(handle);
|
|
uint16_t* num = FN(Num)(self);
|
|
/* Partial preparation is 100 times slower (per socket). */
|
|
size_t partial_prepare_threshold = self->bucket_size_ >> 6;
|
|
if (one_shot && input_size <= partial_prepare_threshold) {
|
|
size_t i;
|
|
for (i = 0; i < input_size; ++i) {
|
|
const uint32_t key = FN(HashBytes)(&data[i], self->hash_mask_,
|
|
self->hash_shift_);
|
|
num[key] = 0;
|
|
}
|
|
} else {
|
|
memset(num, 0, self->bucket_size_ * sizeof(num[0]));
|
|
}
|
|
}
|
|
|
|
static BROTLI_INLINE size_t FN(HashMemAllocInBytes)(
|
|
const BrotliEncoderParams* params, BROTLI_BOOL one_shot,
|
|
size_t input_size) {
|
|
size_t bucket_size = (size_t)1 << params->hasher.bucket_bits;
|
|
size_t block_size = (size_t)1 << params->hasher.block_bits;
|
|
BROTLI_UNUSED(one_shot);
|
|
BROTLI_UNUSED(input_size);
|
|
return sizeof(HashLongestMatch) + bucket_size * (2 + 4 * block_size);
|
|
}
|
|
|
|
/* Look at 4 bytes at &data[ix & mask].
|
|
Compute a hash from these, and store the value of ix at that position. */
|
|
static BROTLI_INLINE void FN(Store)(HasherHandle handle, const uint8_t *data,
|
|
const size_t mask, const size_t ix) {
|
|
HashLongestMatch* self = FN(Self)(handle);
|
|
uint16_t* num = FN(Num)(self);
|
|
const uint32_t key = FN(HashBytes)(&data[ix & mask], self->hash_mask_,
|
|
self->hash_shift_);
|
|
const size_t minor_ix = num[key] & self->block_mask_;
|
|
const size_t offset =
|
|
minor_ix + (key << GetHasherCommon(handle)->params.block_bits);
|
|
FN(Buckets)(self)[offset] = (uint32_t)ix;
|
|
++num[key];
|
|
}
|
|
|
|
static BROTLI_INLINE void FN(StoreRange)(HasherHandle handle,
|
|
const uint8_t *data, const size_t mask, const size_t ix_start,
|
|
const size_t ix_end) {
|
|
size_t i;
|
|
for (i = ix_start; i < ix_end; ++i) {
|
|
FN(Store)(handle, data, mask, i);
|
|
}
|
|
}
|
|
|
|
static BROTLI_INLINE void FN(StitchToPreviousBlock)(HasherHandle handle,
|
|
size_t num_bytes, size_t position, const uint8_t* ringbuffer,
|
|
size_t ringbuffer_mask) {
|
|
if (num_bytes >= FN(HashTypeLength)() - 1 && position >= 3) {
|
|
/* Prepare the hashes for three last bytes of the last write.
|
|
These could not be calculated before, since they require knowledge
|
|
of both the previous and the current block. */
|
|
FN(Store)(handle, ringbuffer, ringbuffer_mask, position - 3);
|
|
FN(Store)(handle, ringbuffer, ringbuffer_mask, position - 2);
|
|
FN(Store)(handle, ringbuffer, ringbuffer_mask, position - 1);
|
|
}
|
|
}
|
|
|
|
static BROTLI_INLINE void FN(PrepareDistanceCache)(
|
|
HasherHandle handle, int* BROTLI_RESTRICT distance_cache) {
|
|
PrepareDistanceCache(distance_cache,
|
|
GetHasherCommon(handle)->params.num_last_distances_to_check);
|
|
}
|
|
|
|
/* Find a longest backward match of &data[cur_ix] up to the length of
|
|
max_length and stores the position cur_ix in the hash table.
|
|
|
|
REQUIRES: FN(PrepareDistanceCache) must be invoked for current distance cache
|
|
values; if this method is invoked repeatedly with the same distance
|
|
cache values, it is enough to invoke FN(PrepareDistanceCache) once.
|
|
|
|
Does not look for matches longer than max_length.
|
|
Does not look for matches further away than max_backward.
|
|
Writes the best match into |out|.
|
|
|out|->score is updated only if a better match is found. */
|
|
static BROTLI_INLINE void FN(FindLongestMatch)(HasherHandle handle,
|
|
const BrotliDictionary* dictionary, const uint16_t* dictionary_hash,
|
|
const uint8_t* BROTLI_RESTRICT data, const size_t ring_buffer_mask,
|
|
const int* BROTLI_RESTRICT distance_cache, const size_t cur_ix,
|
|
const size_t max_length, const size_t max_backward, const size_t gap,
|
|
HasherSearchResult* BROTLI_RESTRICT out) {
|
|
HasherCommon* common = GetHasherCommon(handle);
|
|
HashLongestMatch* self = FN(Self)(handle);
|
|
uint16_t* num = FN(Num)(self);
|
|
uint32_t* buckets = FN(Buckets)(self);
|
|
const size_t cur_ix_masked = cur_ix & ring_buffer_mask;
|
|
/* Don't accept a short copy from far away. */
|
|
score_t min_score = out->score;
|
|
score_t best_score = out->score;
|
|
size_t best_len = out->len;
|
|
size_t i;
|
|
out->len = 0;
|
|
out->len_code_delta = 0;
|
|
/* Try last distance first. */
|
|
for (i = 0; i < (size_t)common->params.num_last_distances_to_check; ++i) {
|
|
const size_t backward = (size_t)distance_cache[i];
|
|
size_t prev_ix = (size_t)(cur_ix - backward);
|
|
if (prev_ix >= cur_ix) {
|
|
continue;
|
|
}
|
|
if (BROTLI_PREDICT_FALSE(backward > max_backward)) {
|
|
continue;
|
|
}
|
|
prev_ix &= ring_buffer_mask;
|
|
|
|
if (cur_ix_masked + best_len > ring_buffer_mask ||
|
|
prev_ix + best_len > ring_buffer_mask ||
|
|
data[cur_ix_masked + best_len] != data[prev_ix + best_len]) {
|
|
continue;
|
|
}
|
|
{
|
|
const size_t len = FindMatchLengthWithLimit(&data[prev_ix],
|
|
&data[cur_ix_masked],
|
|
max_length);
|
|
if (len >= 3 || (len == 2 && i < 2)) {
|
|
/* Comparing for >= 2 does not change the semantics, but just saves for
|
|
a few unnecessary binary logarithms in backward reference score,
|
|
since we are not interested in such short matches. */
|
|
score_t score = BackwardReferenceScoreUsingLastDistance(len);
|
|
if (best_score < score) {
|
|
if (i != 0) score -= BackwardReferencePenaltyUsingLastDistance(i);
|
|
if (best_score < score) {
|
|
best_score = score;
|
|
best_len = len;
|
|
out->len = best_len;
|
|
out->distance = backward;
|
|
out->score = best_score;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
{
|
|
const uint32_t key = FN(HashBytes)(
|
|
&data[cur_ix_masked], self->hash_mask_, self->hash_shift_);
|
|
uint32_t* BROTLI_RESTRICT bucket =
|
|
&buckets[key << common->params.block_bits];
|
|
const size_t down =
|
|
(num[key] > self->block_size_) ?
|
|
(num[key] - self->block_size_) : 0u;
|
|
for (i = num[key]; i > down;) {
|
|
size_t prev_ix = bucket[--i & self->block_mask_];
|
|
const size_t backward = cur_ix - prev_ix;
|
|
if (BROTLI_PREDICT_FALSE(backward > max_backward)) {
|
|
break;
|
|
}
|
|
prev_ix &= ring_buffer_mask;
|
|
if (cur_ix_masked + best_len > ring_buffer_mask ||
|
|
prev_ix + best_len > ring_buffer_mask ||
|
|
data[cur_ix_masked + best_len] != data[prev_ix + best_len]) {
|
|
continue;
|
|
}
|
|
{
|
|
const size_t len = FindMatchLengthWithLimit(&data[prev_ix],
|
|
&data[cur_ix_masked],
|
|
max_length);
|
|
if (len >= 4) {
|
|
/* Comparing for >= 3 does not change the semantics, but just saves
|
|
for a few unnecessary binary logarithms in backward reference
|
|
score, since we are not interested in such short matches. */
|
|
score_t score = BackwardReferenceScore(len, backward);
|
|
if (best_score < score) {
|
|
best_score = score;
|
|
best_len = len;
|
|
out->len = best_len;
|
|
out->distance = backward;
|
|
out->score = best_score;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
bucket[num[key] & self->block_mask_] = (uint32_t)cur_ix;
|
|
++num[key];
|
|
}
|
|
if (min_score == out->score) {
|
|
SearchInStaticDictionary(dictionary, dictionary_hash,
|
|
handle, &data[cur_ix_masked], max_length, max_backward + gap, out,
|
|
BROTLI_FALSE);
|
|
}
|
|
}
|
|
|
|
#undef HashLongestMatch
|