Index: third_party/brotli/enc/hash_longest_match_quickly_inc.h |
diff --git a/third_party/brotli/enc/hash_longest_match_quickly_inc.h b/third_party/brotli/enc/hash_longest_match_quickly_inc.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..801ab22a1c1e1f572b63e39f7248a6a4ffa12003 |
--- /dev/null |
+++ b/third_party/brotli/enc/hash_longest_match_quickly_inc.h |
@@ -0,0 +1,230 @@ |
+/* 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, BUCKET_BITS, BUCKET_SWEEP, USE_DICTIONARY */ |
+ |
+#define HashLongestMatchQuickly HASHER() |
+ |
+#define BUCKET_SIZE (1 << BUCKET_BITS) |
+ |
+#define HASH_MAP_SIZE (4 << BUCKET_BITS) |
+ |
+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. The HashLongestMatch and HashLongestMatchQuickly |
+ classes have separate, different implementations of hashing. */ |
+static uint32_t FN(HashBytes)(const uint8_t *data) { |
+ /* Computing a hash based on 5 bytes works much better for |
+ qualities 1 and 3, where the next hash value is likely to replace */ |
+ uint64_t h = (BROTLI_UNALIGNED_LOAD64(data) << 24) * kHashMul32; |
+ /* The higher bits contain more mixture from the multiplication, |
+ so we take our results from there. */ |
+ return (uint32_t)(h >> (64 - BUCKET_BITS)); |
+} |
+ |
+/* 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). Starting from the |
+ given index, BUCKET_SWEEP buckets are used to store values of a key. */ |
+typedef struct HashLongestMatchQuickly { |
+ uint32_t buckets_[BUCKET_SIZE + BUCKET_SWEEP]; |
+ /* True if buckets_ array needs to be initialized. */ |
+ BROTLI_BOOL is_dirty_; |
+ DictionarySearchStatictics dict_search_stats_; |
+} HashLongestMatchQuickly; |
+ |
+static void FN(Reset)(HashLongestMatchQuickly* self) { |
+ self->is_dirty_ = BROTLI_TRUE; |
+ DictionarySearchStaticticsReset(&self->dict_search_stats_); |
+} |
+ |
+static void FN(InitEmpty)(HashLongestMatchQuickly* self) { |
+ if (self->is_dirty_) { |
+ /* It is not strictly necessary to fill this buffer here, but |
+ not filling will make the results of the compression stochastic |
+ (but correct). This is because random data would cause the |
+ system to find accidentally good backward references here and there. */ |
+ memset(&self->buckets_[0], 0, sizeof(self->buckets_)); |
+ self->is_dirty_ = BROTLI_FALSE; |
+ } |
+} |
+ |
+static void FN(InitForData)(HashLongestMatchQuickly* self, const uint8_t* data, |
+ size_t num) { |
+ size_t i; |
+ for (i = 0; i < num; ++i) { |
+ const uint32_t key = FN(HashBytes)(&data[i]); |
+ memset(&self->buckets_[key], 0, BUCKET_SWEEP * sizeof(self->buckets_[0])); |
+ } |
+ if (num != 0) { |
+ self->is_dirty_ = BROTLI_FALSE; |
+ } |
+} |
+ |
+static void FN(Init)( |
+ MemoryManager* m, HashLongestMatchQuickly* self, const uint8_t* data, |
+ const BrotliEncoderParams* params, size_t position, size_t bytes, |
+ BROTLI_BOOL is_last) { |
+ /* Choose which initialization method is faster. |
+ Init() is about 100 times faster than InitForData(). */ |
+ const size_t kMaxBytesForPartialHashInit = HASH_MAP_SIZE >> 7; |
+ BROTLI_UNUSED(m); |
+ BROTLI_UNUSED(params); |
+ if (position == 0 && is_last && bytes <= kMaxBytesForPartialHashInit) { |
+ FN(InitForData)(self, data, bytes); |
+ } else { |
+ FN(InitEmpty)(self); |
+ } |
+} |
+ |
+/* Look at 5 bytes at &data[ix & mask]. |
+ Compute a hash from these, and store the value somewhere within |
+ [ix .. ix+3]. */ |
+static BROTLI_INLINE void FN(Store)(HashLongestMatchQuickly* self, |
+ const uint8_t *data, const size_t mask, const size_t ix) { |
+ const uint32_t key = FN(HashBytes)(&data[ix & mask]); |
+ /* Wiggle the value with the bucket sweep range. */ |
+ const uint32_t off = (ix >> 3) % BUCKET_SWEEP; |
+ self->buckets_[key + off] = (uint32_t)ix; |
+} |
+ |
+static BROTLI_INLINE void FN(StoreRange)(HashLongestMatchQuickly* self, |
+ 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)(self, data, mask, i); |
+ } |
+} |
+ |
+static BROTLI_INLINE void FN(StitchToPreviousBlock)( |
+ HashLongestMatchQuickly* self, 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)(self, ringbuffer, ringbuffer_mask, position - 3); |
+ FN(Store)(self, ringbuffer, ringbuffer_mask, position - 2); |
+ FN(Store)(self, ringbuffer, ringbuffer_mask, position - 1); |
+ } |
+} |
+ |
+/* Find a longest backward match of &data[cur_ix & ring_buffer_mask] |
+ up to the length of max_length and stores the position cur_ix in the |
+ hash table. |
+ |
+ 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|. |
+ Returns true if match is found, otherwise false. */ |
+static BROTLI_INLINE BROTLI_BOOL FN(FindLongestMatch)( |
+ HashLongestMatchQuickly* self, 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, |
+ HasherSearchResult* BROTLI_RESTRICT out) { |
+ const size_t best_len_in = out->len; |
+ const size_t cur_ix_masked = cur_ix & ring_buffer_mask; |
+ const uint32_t key = FN(HashBytes)(&data[cur_ix_masked]); |
+ int compare_char = data[cur_ix_masked + best_len_in]; |
+ score_t best_score = out->score; |
+ size_t best_len = best_len_in; |
+ size_t cached_backward = (size_t)distance_cache[0]; |
+ size_t prev_ix = cur_ix - cached_backward; |
+ BROTLI_BOOL is_match_found = BROTLI_FALSE; |
+ out->len_x_code = 0; |
+ if (prev_ix < cur_ix) { |
+ prev_ix &= (uint32_t)ring_buffer_mask; |
+ if (compare_char == data[prev_ix + best_len]) { |
+ size_t len = FindMatchLengthWithLimit(&data[prev_ix], |
+ &data[cur_ix_masked], |
+ max_length); |
+ if (len >= 4) { |
+ best_score = BackwardReferenceScoreUsingLastDistance(len, 0); |
+ best_len = len; |
+ out->len = len; |
+ out->distance = cached_backward; |
+ out->score = best_score; |
+ compare_char = data[cur_ix_masked + best_len]; |
+ if (BUCKET_SWEEP == 1) { |
+ self->buckets_[key] = (uint32_t)cur_ix; |
+ return BROTLI_TRUE; |
+ } else { |
+ is_match_found = BROTLI_TRUE; |
+ } |
+ } |
+ } |
+ } |
+ if (BUCKET_SWEEP == 1) { |
+ size_t backward; |
+ size_t len; |
+ /* Only one to look for, don't bother to prepare for a loop. */ |
+ prev_ix = self->buckets_[key]; |
+ self->buckets_[key] = (uint32_t)cur_ix; |
+ backward = cur_ix - prev_ix; |
+ prev_ix &= (uint32_t)ring_buffer_mask; |
+ if (compare_char != data[prev_ix + best_len_in]) { |
+ return BROTLI_FALSE; |
+ } |
+ if (BROTLI_PREDICT_FALSE(backward == 0 || backward > max_backward)) { |
+ return BROTLI_FALSE; |
+ } |
+ len = FindMatchLengthWithLimit(&data[prev_ix], |
+ &data[cur_ix_masked], |
+ max_length); |
+ if (len >= 4) { |
+ out->len = len; |
+ out->distance = backward; |
+ out->score = BackwardReferenceScore(len, backward); |
+ return BROTLI_TRUE; |
+ } |
+ } else { |
+ uint32_t *bucket = self->buckets_ + key; |
+ int i; |
+ prev_ix = *bucket++; |
+ for (i = 0; i < BUCKET_SWEEP; ++i, prev_ix = *bucket++) { |
+ const size_t backward = cur_ix - prev_ix; |
+ size_t len; |
+ prev_ix &= (uint32_t)ring_buffer_mask; |
+ if (compare_char != data[prev_ix + best_len]) { |
+ continue; |
+ } |
+ if (BROTLI_PREDICT_FALSE(backward == 0 || backward > max_backward)) { |
+ continue; |
+ } |
+ len = FindMatchLengthWithLimit(&data[prev_ix], |
+ &data[cur_ix_masked], |
+ max_length); |
+ if (len >= 4) { |
+ const 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 = score; |
+ compare_char = data[cur_ix_masked + best_len]; |
+ is_match_found = BROTLI_TRUE; |
+ } |
+ } |
+ } |
+ } |
+ if (USE_DICTIONARY && !is_match_found) { |
+ is_match_found = SearchInStaticDictionary(&self->dict_search_stats_, |
+ &data[cur_ix_masked], max_length, max_backward, out, BROTLI_TRUE); |
+ } |
+ self->buckets_[key + ((cur_ix >> 3) % BUCKET_SWEEP)] = (uint32_t)cur_ix; |
+ return is_match_found; |
+} |
+ |
+#undef HASH_MAP_SIZE |
+#undef BUCKET_SIZE |
+ |
+#undef HashLongestMatchQuickly |