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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/context.h"
13 #include "../common/dictionary.h"
14 #include "../common/platform.h"
15 #include <brotli/types.h>
16 #include "./command.h"
17 #include "./dictionary_hash.h"
18 #include "./memory.h"
19 #include "./quality.h"
20 
21 #if defined(__cplusplus) || defined(c_plusplus)
22 extern "C" {
23 #endif
24 
ComputeDistanceCode(size_t distance,size_t max_distance,const int * dist_cache)25 static BROTLI_INLINE size_t ComputeDistanceCode(size_t distance,
26                                                 size_t max_distance,
27                                                 const int* dist_cache) {
28   if (distance <= max_distance) {
29     size_t distance_plus_3 = distance + 3;
30     size_t offset0 = distance_plus_3 - (size_t)dist_cache[0];
31     size_t offset1 = distance_plus_3 - (size_t)dist_cache[1];
32     if (distance == (size_t)dist_cache[0]) {
33       return 0;
34     } else if (distance == (size_t)dist_cache[1]) {
35       return 1;
36     } else if (offset0 < 7) {
37       return (0x9750468 >> (4 * offset0)) & 0xF;
38     } else if (offset1 < 7) {
39       return (0xFDB1ACE >> (4 * offset1)) & 0xF;
40     } else if (distance == (size_t)dist_cache[2]) {
41       return 2;
42     } else if (distance == (size_t)dist_cache[3]) {
43       return 3;
44     }
45   }
46   return distance + BROTLI_NUM_DISTANCE_SHORT_CODES - 1;
47 }
48 
49 #define EXPAND_CAT(a, b) CAT(a, b)
50 #define CAT(a, b) a ## b
51 #define FN(X) EXPAND_CAT(X, HASHER())
52 #define EXPORT_FN(X) EXPAND_CAT(X, EXPAND_CAT(PREFIX(), HASHER()))
53 
54 #define PREFIX() N
55 
56 #define HASHER() H2
57 /* NOLINTNEXTLINE(build/include) */
58 #include "./backward_references_inc.h"
59 #undef HASHER
60 
61 #define HASHER() H3
62 /* NOLINTNEXTLINE(build/include) */
63 #include "./backward_references_inc.h"
64 #undef HASHER
65 
66 #define HASHER() H4
67 /* NOLINTNEXTLINE(build/include) */
68 #include "./backward_references_inc.h"
69 #undef HASHER
70 
71 #define HASHER() H5
72 /* NOLINTNEXTLINE(build/include) */
73 #include "./backward_references_inc.h"
74 #undef HASHER
75 
76 #define HASHER() H6
77 /* NOLINTNEXTLINE(build/include) */
78 #include "./backward_references_inc.h"
79 #undef HASHER
80 
81 #define HASHER() H40
82 /* NOLINTNEXTLINE(build/include) */
83 #include "./backward_references_inc.h"
84 #undef HASHER
85 
86 #define HASHER() H41
87 /* NOLINTNEXTLINE(build/include) */
88 #include "./backward_references_inc.h"
89 #undef HASHER
90 
91 #define HASHER() H42
92 /* NOLINTNEXTLINE(build/include) */
93 #include "./backward_references_inc.h"
94 #undef HASHER
95 
96 #define HASHER() H54
97 /* NOLINTNEXTLINE(build/include) */
98 #include "./backward_references_inc.h"
99 #undef HASHER
100 
101 #define HASHER() H35
102 /* NOLINTNEXTLINE(build/include) */
103 #include "./backward_references_inc.h"
104 #undef HASHER
105 
106 #define HASHER() H55
107 /* NOLINTNEXTLINE(build/include) */
108 #include "./backward_references_inc.h"
109 #undef HASHER
110 
111 #define HASHER() H65
112 /* NOLINTNEXTLINE(build/include) */
113 #include "./backward_references_inc.h"
114 #undef HASHER
115 
116 #undef PREFIX
117 
118 #undef EXPORT_FN
119 #undef FN
120 #undef CAT
121 #undef EXPAND_CAT
122 
BrotliCreateBackwardReferences(size_t num_bytes,size_t position,const uint8_t * ringbuffer,size_t ringbuffer_mask,ContextLut literal_context_lut,const BrotliEncoderParams * params,Hasher * hasher,int * dist_cache,size_t * last_insert_len,Command * commands,size_t * num_commands,size_t * num_literals)123 void BrotliCreateBackwardReferences(size_t num_bytes,
124     size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
125     ContextLut literal_context_lut, const BrotliEncoderParams* params,
126     Hasher* hasher, int* dist_cache, size_t* last_insert_len,
127     Command* commands, size_t* num_commands, size_t* num_literals) {
128   switch (params->hasher.type) {
129 #define CASE_(N)                                                  \
130     case N:                                                       \
131       CreateBackwardReferencesNH ## N(num_bytes,                  \
132           position, ringbuffer, ringbuffer_mask,                  \
133           literal_context_lut, params, hasher, dist_cache,        \
134           last_insert_len, commands, num_commands, num_literals); \
135       return;
136     FOR_GENERIC_HASHERS(CASE_)
137 #undef CASE_
138     default:
139       break;
140   }
141 }
142 
143 #if defined(__cplusplus) || defined(c_plusplus)
144 }  /* extern "C" */
145 #endif
146