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1 /* Copyright 2013 Google Inc. All Rights Reserved. | |
2 | |
3 Licensed under the Apache License, Version 2.0 (the "License"); | |
4 you may not use this file except in compliance with the License. | |
5 You may obtain a copy of the License at | |
6 | |
7 http://www.apache.org/licenses/LICENSE-2.0 | |
8 | |
9 Unless required by applicable law or agreed to in writing, software | |
10 distributed under the License is distributed on an "AS IS" BASIS, | |
11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
12 See the License for the specific language governing permissions and | |
13 limitations under the License. | |
14 | |
15 Lookup tables to map prefix codes to value ranges. This is used during | |
16 decoding of the block lengths, literal insertion lengths and copy lengths. | |
17 */ | |
18 | |
19 #ifndef BROTLI_DEC_PREFIX_H_ | |
20 #define BROTLI_DEC_PREFIX_H_ | |
21 | |
22 /* Represents the range of values belonging to a prefix code: */ | |
23 /* [offset, offset + 2^nbits) */ | |
24 struct PrefixCodeRange { | |
25 int offset; | |
26 int nbits; | |
27 }; | |
28 | |
29 static const struct PrefixCodeRange kBlockLengthPrefixCode[] = { | |
30 { 1, 2}, { 5, 2}, { 9, 2}, { 13, 2}, | |
31 { 17, 3}, { 25, 3}, { 33, 3}, { 41, 3}, | |
32 { 49, 4}, { 65, 4}, { 81, 4}, { 97, 4}, | |
33 { 113, 5}, { 145, 5}, { 177, 5}, { 209, 5}, | |
34 { 241, 6}, { 305, 6}, { 369, 7}, { 497, 8}, | |
35 { 753, 9}, { 1265, 10}, {2289, 11}, {4337, 12}, | |
36 {8433, 13}, {16625, 24} | |
37 }; | |
38 | |
39 static const struct PrefixCodeRange kInsertLengthPrefixCode[] = { | |
40 { 0, 0}, { 1, 0}, { 2, 0}, { 3, 0}, | |
41 { 4, 0}, { 5, 0}, { 6, 1}, { 8, 1}, | |
42 { 10, 2}, { 14, 2}, { 18, 3}, { 26, 3}, | |
43 { 34, 4}, { 50, 4}, { 66, 5}, { 98, 5}, | |
44 { 130, 6}, { 194, 7}, { 322, 8}, { 578, 9}, | |
45 {1090, 10}, {2114, 12}, {6210, 14}, {22594, 24}, | |
46 }; | |
47 | |
48 static const struct PrefixCodeRange kCopyLengthPrefixCode[] = { | |
49 { 2, 0}, { 3, 0}, { 4, 0}, { 5, 0}, | |
50 { 6, 0}, { 7, 0}, { 8, 0}, { 9, 0}, | |
51 { 10, 1}, { 12, 1}, { 14, 2}, { 18, 2}, | |
52 { 22, 3}, { 30, 3}, { 38, 4}, { 54, 4}, | |
53 { 70, 5}, { 102, 5}, { 134, 6}, { 198, 7}, | |
54 {326, 8}, { 582, 9}, {1094, 10}, {2118, 24}, | |
55 }; | |
56 | |
57 static const int kInsertRangeLut[9] = { | |
58 0, 0, 8, 8, 0, 16, 8, 16, 16, | |
59 }; | |
60 | |
61 static const int kCopyRangeLut[9] = { | |
62 0, 8, 0, 8, 16, 0, 16, 8, 16, | |
63 }; | |
64 | |
65 #endif /* BROTLI_DEC_PREFIX_H_ */ | |
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