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