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1 /*
2 Copyright 2016 Google Inc. All Rights Reserved.
3
4 Licensed under the Apache License, Version 2.0 (the "License");
5 you may not use this file except in compliance with the License.
6 You may obtain a copy of the License at
7
8 http://www.apache.org/licenses/LICENSE-2.0
9
10 Unless required by applicable law or agreed to in writing, software
11 distributed under the License is distributed on an "AS IS" BASIS,
12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 See the License for the specific language governing permissions and
14 limitations under the License.
15
16 Author: lode.vandevenne@gmail.com (Lode Vandevenne)
17 Author: jyrki.alakuijala@gmail.com (Jyrki Alakuijala)
18 */
19
20 #include "symbols.h"
21
22 /* __has_builtin available in clang */
23 #ifdef __has_builtin
24 # if __has_builtin(__builtin_clz)
25 # define ZOPFLI_HAS_BUILTIN_CLZ
26 # endif
27 /* __builtin_clz available beginning with GCC 3.4 */
28 #elif __GNUC__ * 100 + __GNUC_MINOR__ >= 304
29 # define ZOPFLI_HAS_BUILTIN_CLZ
30 #endif
31
32 int ZopfliGetDistExtraBits(int dist) {
33 #ifdef ZOPFLI_HAS_BUILTIN_CLZ
34 if (dist < 5) return 0;
35 return (31 ^ __builtin_clz(dist - 1)) - 1; /* log2(dist - 1) - 1 */
36 #else
37 if (dist < 5) return 0;
38 else if (dist < 9) return 1;
39 else if (dist < 17) return 2;
40 else if (dist < 33) return 3;
41 else if (dist < 65) return 4;
42 else if (dist < 129) return 5;
43 else if (dist < 257) return 6;
44 else if (dist < 513) return 7;
45 else if (dist < 1025) return 8;
46 else if (dist < 2049) return 9;
47 else if (dist < 4097) return 10;
48 else if (dist < 8193) return 11;
49 else if (dist < 16385) return 12;
50 else return 13;
51 #endif
52 }
53
54 int ZopfliGetDistExtraBitsValue(int dist) {
55 #ifdef ZOPFLI_HAS_BUILTIN_CLZ
56 if (dist < 5) {
57 return 0;
58 } else {
59 int l = 31 ^ __builtin_clz(dist - 1); /* log2(dist - 1) */
60 return (dist - (1 + (1 << l))) & ((1 << (l - 1)) - 1);
61 }
62 #else
63 if (dist < 5) return 0;
64 else if (dist < 9) return (dist - 5) & 1;
65 else if (dist < 17) return (dist - 9) & 3;
66 else if (dist < 33) return (dist - 17) & 7;
67 else if (dist < 65) return (dist - 33) & 15;
68 else if (dist < 129) return (dist - 65) & 31;
69 else if (dist < 257) return (dist - 129) & 63;
70 else if (dist < 513) return (dist - 257) & 127;
71 else if (dist < 1025) return (dist - 513) & 255;
72 else if (dist < 2049) return (dist - 1025) & 511;
73 else if (dist < 4097) return (dist - 2049) & 1023;
74 else if (dist < 8193) return (dist - 4097) & 2047;
75 else if (dist < 16385) return (dist - 8193) & 4095;
76 else return (dist - 16385) & 8191;
77 #endif
78 }
79
80 int ZopfliGetDistSymbol(int dist) {
81 #ifdef ZOPFLI_HAS_BUILTIN_CLZ
82 if (dist < 5) {
83 return dist - 1;
84 } else {
85 int l = (31 ^ __builtin_clz(dist - 1)); /* log2(dist - 1) */
86 int r = ((dist - 1) >> (l - 1)) & 1;
87 return l * 2 + r;
88 }
89 #else
90 if (dist < 193) {
91 if (dist < 13) { /* dist 0..13. */
92 if (dist < 5) return dist - 1;
93 else if (dist < 7) return 4;
94 else if (dist < 9) return 5;
95 else return 6;
96 } else { /* dist 13..193. */
97 if (dist < 17) return 7;
98 else if (dist < 25) return 8;
99 else if (dist < 33) return 9;
100 else if (dist < 49) return 10;
101 else if (dist < 65) return 11;
102 else if (dist < 97) return 12;
103 else if (dist < 129) return 13;
104 else return 14;
105 }
106 } else {
107 if (dist < 2049) { /* dist 193..2049. */
108 if (dist < 257) return 15;
109 else if (dist < 385) return 16;
110 else if (dist < 513) return 17;
111 else if (dist < 769) return 18;
112 else if (dist < 1025) return 19;
113 else if (dist < 1537) return 20;
114 else return 21;
115 } else { /* dist 2049..32768. */
116 if (dist < 3073) return 22;
117 else if (dist < 4097) return 23;
118 else if (dist < 6145) return 24;
119 else if (dist < 8193) return 25;
120 else if (dist < 12289) return 26;
121 else if (dist < 16385) return 27;
122 else if (dist < 24577) return 28;
123 else return 29;
124 }
125 }
126 #endif
127 }
128
129 int ZopfliGetLengthExtraBits(int l) {
130 static const int table[259] = {
131 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1,
132 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
133 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
134 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
135 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
136 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
137 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
138 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
139 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
140 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
141 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
142 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
143 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
144 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
145 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
146 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 0
147 };
148 return table[l];
149 }
150
151 int ZopfliGetLengthExtraBitsValue(int l) {
152 static const int table[259] = {
153 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 2, 3, 0,
154 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5,
155 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6,
156 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
157 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2,
158 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
159 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
160 29, 30, 31, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
161 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 0, 1, 2, 3, 4, 5, 6,
162 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
163 27, 28, 29, 30, 31, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
164 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 0
165 };
166 return table[l];
167 }
168
169 int ZopfliGetLengthSymbol(int l) {
170 static const int table[259] = {
171 0, 0, 0, 257, 258, 259, 260, 261, 262, 263, 264,
172 265, 265, 266, 266, 267, 267, 268, 268,
173 269, 269, 269, 269, 270, 270, 270, 270,
174 271, 271, 271, 271, 272, 272, 272, 272,
175 273, 273, 273, 273, 273, 273, 273, 273,
176 274, 274, 274, 274, 274, 274, 274, 274,
177 275, 275, 275, 275, 275, 275, 275, 275,
178 276, 276, 276, 276, 276, 276, 276, 276,
179 277, 277, 277, 277, 277, 277, 277, 277,
180 277, 277, 277, 277, 277, 277, 277, 277,
181 278, 278, 278, 278, 278, 278, 278, 278,
182 278, 278, 278, 278, 278, 278, 278, 278,
183 279, 279, 279, 279, 279, 279, 279, 279,
184 279, 279, 279, 279, 279, 279, 279, 279,
185 280, 280, 280, 280, 280, 280, 280, 280,
186 280, 280, 280, 280, 280, 280, 280, 280,
187 281, 281, 281, 281, 281, 281, 281, 281,
188 281, 281, 281, 281, 281, 281, 281, 281,
189 281, 281, 281, 281, 281, 281, 281, 281,
190 281, 281, 281, 281, 281, 281, 281, 281,
191 282, 282, 282, 282, 282, 282, 282, 282,
192 282, 282, 282, 282, 282, 282, 282, 282,
193 282, 282, 282, 282, 282, 282, 282, 282,
194 282, 282, 282, 282, 282, 282, 282, 282,
195 283, 283, 283, 283, 283, 283, 283, 283,
196 283, 283, 283, 283, 283, 283, 283, 283,
197 283, 283, 283, 283, 283, 283, 283, 283,
198 283, 283, 283, 283, 283, 283, 283, 283,
199 284, 284, 284, 284, 284, 284, 284, 284,
200 284, 284, 284, 284, 284, 284, 284, 284,
201 284, 284, 284, 284, 284, 284, 284, 284,
202 284, 284, 284, 284, 284, 284, 284, 285
203 };
204 return table[l];
205 }
206
207 int ZopfliGetLengthSymbolExtraBits(int s) {
208 static const int table[29] = {
209 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
210 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0
211 };
212 return table[s - 257];
213 }
214
215 int ZopfliGetDistSymbolExtraBits(int s) {
216 static const int table[30] = {
217 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
218 9, 9, 10, 10, 11, 11, 12, 12, 13, 13
219 };
220 return table[s];
221 }