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Diffstat (limited to 'brotli/dec/prefix.h')
-rw-r--r-- | brotli/dec/prefix.h | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/brotli/dec/prefix.h b/brotli/dec/prefix.h new file mode 100644 index 0000000..500bd10 --- /dev/null +++ b/brotli/dec/prefix.h @@ -0,0 +1,64 @@ +// 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_ |