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