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-rw-r--r--modules/brotli/enc/hash_longest_match64_inc.h267
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diff --git a/modules/brotli/enc/hash_longest_match64_inc.h b/modules/brotli/enc/hash_longest_match64_inc.h
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+/* 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 BrotliEncoderDictionary* dictionary,
+ 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, const size_t max_distance,
+ 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,
+ handle, &data[cur_ix_masked], max_length, max_backward + gap,
+ max_distance, out, BROTLI_FALSE);
+ }
+}
+
+#undef HashLongestMatch