1 /* Copyright 2013 Google Inc. All Rights Reserved. 2 3 Distributed under MIT license. 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT 5 */ 6 7 /* Function to find backward reference copies. */ 8 9 #include "./backward_references.h" 10 11 #include "../common/constants.h" 12 #include "../common/dictionary.h" 13 #include <brotli/types.h> 14 #include "./command.h" 15 #include "./dictionary_hash.h" 16 #include "./memory.h" 17 #include "./port.h" 18 #include "./quality.h" 19 20 #if defined(__cplusplus) || defined(c_plusplus) 21 extern "C" { 22 #endif 23 24 static BROTLI_INLINE size_t ComputeDistanceCode(size_t distance, 25 size_t max_distance, 26 const int* dist_cache) { 27 if (distance <= max_distance) { 28 size_t distance_plus_3 = distance + 3; 29 size_t offset0 = distance_plus_3 - (size_t)dist_cache[0]; 30 size_t offset1 = distance_plus_3 - (size_t)dist_cache[1]; 31 if (distance == (size_t)dist_cache[0]) { 32 return 0; 33 } else if (distance == (size_t)dist_cache[1]) { 34 return 1; 35 } else if (offset0 < 7) { 36 return (0x9750468 >> (4 * offset0)) & 0xF; 37 } else if (offset1 < 7) { 38 return (0xFDB1ACE >> (4 * offset1)) & 0xF; 39 } else if (distance == (size_t)dist_cache[2]) { 40 return 2; 41 } else if (distance == (size_t)dist_cache[3]) { 42 return 3; 43 } 44 } 45 return distance + BROTLI_NUM_DISTANCE_SHORT_CODES - 1; 46 } 47 48 #define EXPAND_CAT(a, b) CAT(a, b) 49 #define CAT(a, b) a ## b 50 #define FN(X) EXPAND_CAT(X, HASHER()) 51 #define EXPORT_FN(X) EXPAND_CAT(X, EXPAND_CAT(PREFIX(), HASHER())) 52 #define PREFIX() N 53 54 #define HASHER() H2 55 /* NOLINTNEXTLINE(build/include) */ 56 #include "./backward_references_inc.h" 57 #undef HASHER 58 59 #define HASHER() H3 60 /* NOLINTNEXTLINE(build/include) */ 61 #include "./backward_references_inc.h" 62 #undef HASHER 63 64 #define HASHER() H4 65 /* NOLINTNEXTLINE(build/include) */ 66 #include "./backward_references_inc.h" 67 #undef HASHER 68 69 #define HASHER() H5 70 /* NOLINTNEXTLINE(build/include) */ 71 #include "./backward_references_inc.h" 72 #undef HASHER 73 74 #define HASHER() H6 75 /* NOLINTNEXTLINE(build/include) */ 76 #include "./backward_references_inc.h" 77 #undef HASHER 78 79 #define HASHER() H40 80 /* NOLINTNEXTLINE(build/include) */ 81 #include "./backward_references_inc.h" 82 #undef HASHER 83 84 #define HASHER() H41 85 /* NOLINTNEXTLINE(build/include) */ 86 #include "./backward_references_inc.h" 87 #undef HASHER 88 89 #define HASHER() H42 90 /* NOLINTNEXTLINE(build/include) */ 91 #include "./backward_references_inc.h" 92 #undef HASHER 93 94 #define HASHER() H54 95 /* NOLINTNEXTLINE(build/include) */ 96 #include "./backward_references_inc.h" 97 #undef HASHER 98 99 #undef PREFIX 100 #undef EXPORT_FN 101 #undef FN 102 #undef CAT 103 #undef EXPAND_CAT 104 105 void BrotliCreateBackwardReferences(const BrotliDictionary* dictionary, 106 size_t num_bytes, 107 size_t position, 108 const uint8_t* ringbuffer, 109 size_t ringbuffer_mask, 110 const BrotliEncoderParams* params, 111 HasherHandle hasher, 112 int* dist_cache, 113 size_t* last_insert_len, 114 Command* commands, 115 size_t* num_commands, 116 size_t* num_literals) { 117 switch (params->hasher.type) { 118 #define CASE_(N) \ 119 case N: \ 120 CreateBackwardReferencesNH ## N(dictionary, \ 121 kStaticDictionaryHash, num_bytes, position, ringbuffer, \ 122 ringbuffer_mask, params, hasher, dist_cache, \ 123 last_insert_len, commands, num_commands, num_literals); \ 124 return; 125 FOR_GENERIC_HASHERS(CASE_) 126 #undef CASE_ 127 default: 128 break; 129 } 130 } 131 132 #if defined(__cplusplus) || defined(c_plusplus) 133 } /* extern "C" */ 134 #endif 135
