| /* Copyright 2010 Google Inc. All Rights Reserved. |
| |
| Distributed under MIT license. |
| See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
| */ |
| |
| /* A (forgetful) hash table to the data seen by the compressor, to |
| help create backward references to previous data. */ |
| |
| #ifndef BROTLI_ENC_HASH_H_ |
| #define BROTLI_ENC_HASH_H_ |
| |
| #if !defined(STARBOARD) |
| #include <string.h> /* memcmp, memset */ |
| #endif |
| |
| #include "../common/constants.h" |
| #include "../common/dictionary.h" |
| #include "../common/platform.h" |
| #include <brotli/types.h> |
| #include "./fast_log.h" |
| #include "./find_match_length.h" |
| #include "./memory.h" |
| #include "./quality.h" |
| #include "./static_dict.h" |
| |
| #if defined(__cplusplus) || defined(c_plusplus) |
| extern "C" { |
| #endif |
| |
| /* Pointer to hasher data. |
| * |
| * Excluding initialization and destruction, hasher can be passed as |
| * HasherHandle by value. |
| * |
| * Typically hasher data consists of 3 sections: |
| * * HasherCommon structure |
| * * private structured hasher data, depending on hasher type |
| * * private dynamic hasher data, depending on hasher type and parameters |
| */ |
| typedef uint8_t* HasherHandle; |
| |
| typedef struct { |
| BrotliHasherParams params; |
| |
| /* False if hasher needs to be "prepared" before use. */ |
| BROTLI_BOOL is_prepared_; |
| |
| size_t dict_num_lookups; |
| size_t dict_num_matches; |
| } HasherCommon; |
| |
| static BROTLI_INLINE HasherCommon* GetHasherCommon(HasherHandle handle) { |
| return (HasherCommon*)handle; |
| } |
| |
| #define score_t size_t |
| |
| static const uint32_t kCutoffTransformsCount = 10; |
| /* 0, 12, 27, 23, 42, 63, 56, 48, 59, 64 */ |
| /* 0+0, 4+8, 8+19, 12+11, 16+26, 20+43, 24+32, 28+20, 32+27, 36+28 */ |
| static const uint64_t kCutoffTransforms = |
| BROTLI_MAKE_UINT64_T(0x071B520A, 0xDA2D3200); |
| |
| typedef struct HasherSearchResult { |
| size_t len; |
| size_t distance; |
| score_t score; |
| int len_code_delta; /* == len_code - len */ |
| } HasherSearchResult; |
| |
| /* kHashMul32 multiplier has these properties: |
| * The multiplier must be odd. Otherwise we may lose the highest bit. |
| * No long streaks of ones or zeros. |
| * There is no effort to ensure that it is a prime, the oddity is enough |
| for this use. |
| * The number has been tuned heuristically against compression benchmarks. */ |
| static const uint32_t kHashMul32 = 0x1e35a7bd; |
| static const uint64_t kHashMul64 = BROTLI_MAKE_UINT64_T(0x1e35a7bd, 0x1e35a7bd); |
| static const uint64_t kHashMul64Long = |
| BROTLI_MAKE_UINT64_T(0x1fe35a7bU, 0xd3579bd3U); |
| |
| static BROTLI_INLINE uint32_t Hash14(const uint8_t* data) { |
| uint32_t h = BROTLI_UNALIGNED_LOAD32LE(data) * kHashMul32; |
| /* The higher bits contain more mixture from the multiplication, |
| so we take our results from there. */ |
| return h >> (32 - 14); |
| } |
| |
| static BROTLI_INLINE void PrepareDistanceCache( |
| int* BROTLI_RESTRICT distance_cache, const int num_distances) { |
| if (num_distances > 4) { |
| int last_distance = distance_cache[0]; |
| distance_cache[4] = last_distance - 1; |
| distance_cache[5] = last_distance + 1; |
| distance_cache[6] = last_distance - 2; |
| distance_cache[7] = last_distance + 2; |
| distance_cache[8] = last_distance - 3; |
| distance_cache[9] = last_distance + 3; |
| if (num_distances > 10) { |
| int next_last_distance = distance_cache[1]; |
| distance_cache[10] = next_last_distance - 1; |
| distance_cache[11] = next_last_distance + 1; |
| distance_cache[12] = next_last_distance - 2; |
| distance_cache[13] = next_last_distance + 2; |
| distance_cache[14] = next_last_distance - 3; |
| distance_cache[15] = next_last_distance + 3; |
| } |
| } |
| } |
| |
| #define BROTLI_LITERAL_BYTE_SCORE 135 |
| #define BROTLI_DISTANCE_BIT_PENALTY 30 |
| /* Score must be positive after applying maximal penalty. */ |
| #define BROTLI_SCORE_BASE (BROTLI_DISTANCE_BIT_PENALTY * 8 * sizeof(size_t)) |
| |
| /* Usually, we always choose the longest backward reference. This function |
| allows for the exception of that rule. |
| |
| If we choose a backward reference that is further away, it will |
| usually be coded with more bits. We approximate this by assuming |
| log2(distance). If the distance can be expressed in terms of the |
| last four distances, we use some heuristic constants to estimate |
| the bits cost. For the first up to four literals we use the bit |
| cost of the literals from the literal cost model, after that we |
| use the average bit cost of the cost model. |
| |
| This function is used to sometimes discard a longer backward reference |
| when it is not much longer and the bit cost for encoding it is more |
| than the saved literals. |
| |
| backward_reference_offset MUST be positive. */ |
| static BROTLI_INLINE score_t BackwardReferenceScore( |
| size_t copy_length, size_t backward_reference_offset) { |
| return BROTLI_SCORE_BASE + BROTLI_LITERAL_BYTE_SCORE * (score_t)copy_length - |
| BROTLI_DISTANCE_BIT_PENALTY * Log2FloorNonZero(backward_reference_offset); |
| } |
| |
| static BROTLI_INLINE score_t BackwardReferenceScoreUsingLastDistance( |
| size_t copy_length) { |
| return BROTLI_LITERAL_BYTE_SCORE * (score_t)copy_length + |
| BROTLI_SCORE_BASE + 15; |
| } |
| |
| static BROTLI_INLINE score_t BackwardReferencePenaltyUsingLastDistance( |
| size_t distance_short_code) { |
| return (score_t)39 + ((0x1CA10 >> (distance_short_code & 0xE)) & 0xE); |
| } |
| |
| static BROTLI_INLINE BROTLI_BOOL TestStaticDictionaryItem( |
| const BrotliDictionary* dictionary, size_t item, const uint8_t* data, |
| size_t max_length, size_t max_backward, HasherSearchResult* out) { |
| size_t len; |
| size_t dist; |
| size_t offset; |
| size_t matchlen; |
| size_t backward; |
| score_t score; |
| len = item & 0x1F; |
| dist = item >> 5; |
| offset = dictionary->offsets_by_length[len] + len * dist; |
| if (len > max_length) { |
| return BROTLI_FALSE; |
| } |
| |
| matchlen = |
| FindMatchLengthWithLimit(data, &dictionary->data[offset], len); |
| if (matchlen + kCutoffTransformsCount <= len || matchlen == 0) { |
| return BROTLI_FALSE; |
| } |
| { |
| size_t cut = len - matchlen; |
| size_t transform_id = |
| (cut << 2) + (size_t)((kCutoffTransforms >> (cut * 6)) & 0x3F); |
| backward = max_backward + dist + 1 + |
| (transform_id << dictionary->size_bits_by_length[len]); |
| } |
| if (backward >= BROTLI_MAX_DISTANCE) { |
| return BROTLI_FALSE; |
| } |
| score = BackwardReferenceScore(matchlen, backward); |
| if (score < out->score) { |
| return BROTLI_FALSE; |
| } |
| out->len = matchlen; |
| out->len_code_delta = (int)len - (int)matchlen; |
| out->distance = backward; |
| out->score = score; |
| return BROTLI_TRUE; |
| } |
| |
| static BROTLI_INLINE void SearchInStaticDictionary( |
| const BrotliDictionary* dictionary, const uint16_t* dictionary_hash, |
| HasherHandle handle, const uint8_t* data, size_t max_length, |
| size_t max_backward, HasherSearchResult* out, BROTLI_BOOL shallow) { |
| size_t key; |
| size_t i; |
| HasherCommon* self = GetHasherCommon(handle); |
| if (self->dict_num_matches < (self->dict_num_lookups >> 7)) { |
| return; |
| } |
| key = Hash14(data) << 1; |
| for (i = 0; i < (shallow ? 1u : 2u); ++i, ++key) { |
| size_t item = dictionary_hash[key]; |
| self->dict_num_lookups++; |
| if (item != 0) { |
| BROTLI_BOOL item_matches = TestStaticDictionaryItem( |
| dictionary, item, data, max_length, max_backward, out); |
| if (item_matches) { |
| self->dict_num_matches++; |
| } |
| } |
| } |
| } |
| |
| typedef struct BackwardMatch { |
| uint32_t distance; |
| uint32_t length_and_code; |
| } BackwardMatch; |
| |
| static BROTLI_INLINE void InitBackwardMatch(BackwardMatch* self, |
| size_t dist, size_t len) { |
| self->distance = (uint32_t)dist; |
| self->length_and_code = (uint32_t)(len << 5); |
| } |
| |
| static BROTLI_INLINE void InitDictionaryBackwardMatch(BackwardMatch* self, |
| size_t dist, size_t len, size_t len_code) { |
| self->distance = (uint32_t)dist; |
| self->length_and_code = |
| (uint32_t)((len << 5) | (len == len_code ? 0 : len_code)); |
| } |
| |
| static BROTLI_INLINE size_t BackwardMatchLength(const BackwardMatch* self) { |
| return self->length_and_code >> 5; |
| } |
| |
| static BROTLI_INLINE size_t BackwardMatchLengthCode(const BackwardMatch* self) { |
| size_t code = self->length_and_code & 31; |
| return code ? code : BackwardMatchLength(self); |
| } |
| |
| #define EXPAND_CAT(a, b) CAT(a, b) |
| #define CAT(a, b) a ## b |
| #define FN(X) EXPAND_CAT(X, HASHER()) |
| |
| #define HASHER() H10 |
| #define BUCKET_BITS 17 |
| #define MAX_TREE_SEARCH_DEPTH 64 |
| #define MAX_TREE_COMP_LENGTH 128 |
| #include "./hash_to_binary_tree_inc.h" /* NOLINT(build/include) */ |
| #undef MAX_TREE_SEARCH_DEPTH |
| #undef MAX_TREE_COMP_LENGTH |
| #undef BUCKET_BITS |
| #undef HASHER |
| /* MAX_NUM_MATCHES == 64 + MAX_TREE_SEARCH_DEPTH */ |
| #define MAX_NUM_MATCHES_H10 128 |
| |
| /* For BUCKET_SWEEP == 1, enabling the dictionary lookup makes compression |
| a little faster (0.5% - 1%) and it compresses 0.15% better on small text |
| and HTML inputs. */ |
| |
| #define HASHER() H2 |
| #define BUCKET_BITS 16 |
| #define BUCKET_SWEEP 1 |
| #define HASH_LEN 5 |
| #define USE_DICTIONARY 1 |
| #include "./hash_longest_match_quickly_inc.h" /* NOLINT(build/include) */ |
| #undef BUCKET_SWEEP |
| #undef USE_DICTIONARY |
| #undef HASHER |
| |
| #define HASHER() H3 |
| #define BUCKET_SWEEP 2 |
| #define USE_DICTIONARY 0 |
| #include "./hash_longest_match_quickly_inc.h" /* NOLINT(build/include) */ |
| #undef USE_DICTIONARY |
| #undef BUCKET_SWEEP |
| #undef BUCKET_BITS |
| #undef HASHER |
| |
| #define HASHER() H4 |
| #define BUCKET_BITS 17 |
| #define BUCKET_SWEEP 4 |
| #define USE_DICTIONARY 1 |
| #include "./hash_longest_match_quickly_inc.h" /* NOLINT(build/include) */ |
| #undef USE_DICTIONARY |
| #undef HASH_LEN |
| #undef BUCKET_SWEEP |
| #undef BUCKET_BITS |
| #undef HASHER |
| |
| #define HASHER() H5 |
| #include "./hash_longest_match_inc.h" /* NOLINT(build/include) */ |
| #undef HASHER |
| |
| #define HASHER() H6 |
| #include "./hash_longest_match64_inc.h" /* NOLINT(build/include) */ |
| #undef HASHER |
| |
| #define BUCKET_BITS 15 |
| |
| #define NUM_LAST_DISTANCES_TO_CHECK 4 |
| #define NUM_BANKS 1 |
| #define BANK_BITS 16 |
| #define HASHER() H40 |
| #include "./hash_forgetful_chain_inc.h" /* NOLINT(build/include) */ |
| #undef HASHER |
| #undef NUM_LAST_DISTANCES_TO_CHECK |
| |
| #define NUM_LAST_DISTANCES_TO_CHECK 10 |
| #define HASHER() H41 |
| #include "./hash_forgetful_chain_inc.h" /* NOLINT(build/include) */ |
| #undef HASHER |
| #undef NUM_LAST_DISTANCES_TO_CHECK |
| #undef NUM_BANKS |
| #undef BANK_BITS |
| |
| #define NUM_LAST_DISTANCES_TO_CHECK 16 |
| #define NUM_BANKS 512 |
| #define BANK_BITS 9 |
| #define HASHER() H42 |
| #include "./hash_forgetful_chain_inc.h" /* NOLINT(build/include) */ |
| #undef HASHER |
| #undef NUM_LAST_DISTANCES_TO_CHECK |
| #undef NUM_BANKS |
| #undef BANK_BITS |
| |
| #undef BUCKET_BITS |
| |
| #define HASHER() H54 |
| #define BUCKET_BITS 20 |
| #define BUCKET_SWEEP 4 |
| #define HASH_LEN 7 |
| #define USE_DICTIONARY 0 |
| #include "./hash_longest_match_quickly_inc.h" /* NOLINT(build/include) */ |
| #undef USE_DICTIONARY |
| #undef HASH_LEN |
| #undef BUCKET_SWEEP |
| #undef BUCKET_BITS |
| #undef HASHER |
| |
| #undef FN |
| #undef CAT |
| #undef EXPAND_CAT |
| |
| #define FOR_GENERIC_HASHERS(H) H(2) H(3) H(4) H(5) H(6) H(40) H(41) H(42) H(54) |
| #define FOR_ALL_HASHERS(H) FOR_GENERIC_HASHERS(H) H(10) |
| |
| static BROTLI_INLINE void DestroyHasher( |
| MemoryManager* m, HasherHandle* handle) { |
| if (*handle == NULL) return; |
| BROTLI_FREE(m, *handle); |
| } |
| |
| static BROTLI_INLINE void HasherReset(HasherHandle handle) { |
| if (handle == NULL) return; |
| GetHasherCommon(handle)->is_prepared_ = BROTLI_FALSE; |
| } |
| |
| static BROTLI_INLINE size_t HasherSize(const BrotliEncoderParams* params, |
| BROTLI_BOOL one_shot, const size_t input_size) { |
| size_t result = sizeof(HasherCommon); |
| switch (params->hasher.type) { |
| #define SIZE_(N) \ |
| case N: \ |
| result += HashMemAllocInBytesH ## N(params, one_shot, input_size); \ |
| break; |
| FOR_ALL_HASHERS(SIZE_) |
| #undef SIZE_ |
| default: |
| break; |
| } |
| return result; |
| } |
| |
| static BROTLI_INLINE void HasherSetup(MemoryManager* m, HasherHandle* handle, |
| BrotliEncoderParams* params, const uint8_t* data, size_t position, |
| size_t input_size, BROTLI_BOOL is_last) { |
| HasherHandle self = NULL; |
| HasherCommon* common = NULL; |
| BROTLI_BOOL one_shot = (position == 0 && is_last); |
| if (*handle == NULL) { |
| size_t alloc_size; |
| ChooseHasher(params, ¶ms->hasher); |
| alloc_size = HasherSize(params, one_shot, input_size); |
| self = BROTLI_ALLOC(m, uint8_t, alloc_size); |
| if (BROTLI_IS_OOM(m)) return; |
| *handle = self; |
| common = GetHasherCommon(self); |
| common->params = params->hasher; |
| switch (common->params.type) { |
| #define INITIALIZE_(N) \ |
| case N: \ |
| InitializeH ## N(*handle, params); \ |
| break; |
| FOR_ALL_HASHERS(INITIALIZE_); |
| #undef INITIALIZE_ |
| default: |
| break; |
| } |
| HasherReset(*handle); |
| } |
| |
| self = *handle; |
| common = GetHasherCommon(self); |
| if (!common->is_prepared_) { |
| switch (common->params.type) { |
| #define PREPARE_(N) \ |
| case N: \ |
| PrepareH ## N(self, one_shot, input_size, data); \ |
| break; |
| FOR_ALL_HASHERS(PREPARE_) |
| #undef PREPARE_ |
| default: break; |
| } |
| if (position == 0) { |
| common->dict_num_lookups = 0; |
| common->dict_num_matches = 0; |
| } |
| common->is_prepared_ = BROTLI_TRUE; |
| } |
| } |
| |
| static BROTLI_INLINE void InitOrStitchToPreviousBlock( |
| MemoryManager* m, HasherHandle* handle, const uint8_t* data, size_t mask, |
| BrotliEncoderParams* params, size_t position, size_t input_size, |
| BROTLI_BOOL is_last) { |
| HasherHandle self; |
| HasherSetup(m, handle, params, data, position, input_size, is_last); |
| if (BROTLI_IS_OOM(m)) return; |
| self = *handle; |
| switch (GetHasherCommon(self)->params.type) { |
| #define INIT_(N) \ |
| case N: \ |
| StitchToPreviousBlockH ## N(self, input_size, position, data, mask); \ |
| break; |
| FOR_ALL_HASHERS(INIT_) |
| #undef INIT_ |
| default: break; |
| } |
| } |
| |
| #if defined(__cplusplus) || defined(c_plusplus) |
| } /* extern "C" */ |
| #endif |
| |
| #endif /* BROTLI_ENC_HASH_H_ */ |