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) */
24struct PrefixCodeRange {
25  int offset;
26  int nbits;
27};
28
29static 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
39static 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
48static 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
57static const int kInsertRangeLut[9] = {
58  0, 0, 8, 8, 0, 16, 8, 16, 16,
59};
60
61static const int kCopyRangeLut[9] = {
62  0, 8, 0, 8, 16, 0, 16, 8, 16,
63};
64
65#endif  /* BROTLI_DEC_PREFIX_H_ */
66