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| 1 /* libFLAC - Free Lossless Audio Codec library |
| 2 * Copyright (C) 2004,2005,2006,2007 Josh Coalson |
| 3 * |
| 4 * Redistribution and use in source and binary forms, with or without |
| 5 * modification, are permitted provided that the following conditions |
| 6 * are met: |
| 7 * |
| 8 * - Redistributions of source code must retain the above copyright |
| 9 * notice, this list of conditions and the following disclaimer. |
| 10 * |
| 11 * - Redistributions in binary form must reproduce the above copyright |
| 12 * notice, this list of conditions and the following disclaimer in the |
| 13 * documentation and/or other materials provided with the distribution. |
| 14 * |
| 15 * - Neither the name of the Xiph.org Foundation nor the names of its |
| 16 * contributors may be used to endorse or promote products derived from |
| 17 * this software without specific prior written permission. |
| 18 * |
| 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR |
| 23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| 26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| 28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| 29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 30 */ |
| 31 |
| 32 #if HAVE_CONFIG_H |
| 33 # include <config.h> |
| 34 #endif |
| 35 |
| 36 #include "FLAC/assert.h" |
| 37 |
| 38 #include "private/float.h" |
| 39 |
| 40 #ifdef FLAC__INTEGER_ONLY_LIBRARY |
| 41 |
| 42 /* adjust for compilers that can't understand using LLU suffix for uint64_t lite
rals */ |
| 43 #ifdef _MSC_VER |
| 44 #define FLAC__U64L(x) x |
| 45 #else |
| 46 #define FLAC__U64L(x) x##LLU |
| 47 #endif |
| 48 |
| 49 const FLAC__fixedpoint FLAC__FP_ZERO = 0; |
| 50 const FLAC__fixedpoint FLAC__FP_ONE_HALF = 0x00008000; |
| 51 const FLAC__fixedpoint FLAC__FP_ONE = 0x00010000; |
| 52 const FLAC__fixedpoint FLAC__FP_LN2 = 45426; |
| 53 const FLAC__fixedpoint FLAC__FP_E = 178145; |
| 54 |
| 55 /* Lookup tables for Knuth's logarithm algorithm */ |
| 56 #define LOG2_LOOKUP_PRECISION 16 |
| 57 static const FLAC__uint32 log2_lookup[][LOG2_LOOKUP_PRECISION] = { |
| 58 { |
| 59 /* |
| 60 * 0 fraction bits |
| 61 */ |
| 62 /* undefined */ 0x00000000, |
| 63 /* lg(2/1) = */ 0x00000001, |
| 64 /* lg(4/3) = */ 0x00000000, |
| 65 /* lg(8/7) = */ 0x00000000, |
| 66 /* lg(16/15) = */ 0x00000000, |
| 67 /* lg(32/31) = */ 0x00000000, |
| 68 /* lg(64/63) = */ 0x00000000, |
| 69 /* lg(128/127) = */ 0x00000000, |
| 70 /* lg(256/255) = */ 0x00000000, |
| 71 /* lg(512/511) = */ 0x00000000, |
| 72 /* lg(1024/1023) = */ 0x00000000, |
| 73 /* lg(2048/2047) = */ 0x00000000, |
| 74 /* lg(4096/4095) = */ 0x00000000, |
| 75 /* lg(8192/8191) = */ 0x00000000, |
| 76 /* lg(16384/16383) = */ 0x00000000, |
| 77 /* lg(32768/32767) = */ 0x00000000 |
| 78 }, |
| 79 { |
| 80 /* |
| 81 * 4 fraction bits |
| 82 */ |
| 83 /* undefined */ 0x00000000, |
| 84 /* lg(2/1) = */ 0x00000010, |
| 85 /* lg(4/3) = */ 0x00000007, |
| 86 /* lg(8/7) = */ 0x00000003, |
| 87 /* lg(16/15) = */ 0x00000001, |
| 88 /* lg(32/31) = */ 0x00000001, |
| 89 /* lg(64/63) = */ 0x00000000, |
| 90 /* lg(128/127) = */ 0x00000000, |
| 91 /* lg(256/255) = */ 0x00000000, |
| 92 /* lg(512/511) = */ 0x00000000, |
| 93 /* lg(1024/1023) = */ 0x00000000, |
| 94 /* lg(2048/2047) = */ 0x00000000, |
| 95 /* lg(4096/4095) = */ 0x00000000, |
| 96 /* lg(8192/8191) = */ 0x00000000, |
| 97 /* lg(16384/16383) = */ 0x00000000, |
| 98 /* lg(32768/32767) = */ 0x00000000 |
| 99 }, |
| 100 { |
| 101 /* |
| 102 * 8 fraction bits |
| 103 */ |
| 104 /* undefined */ 0x00000000, |
| 105 /* lg(2/1) = */ 0x00000100, |
| 106 /* lg(4/3) = */ 0x0000006a, |
| 107 /* lg(8/7) = */ 0x00000031, |
| 108 /* lg(16/15) = */ 0x00000018, |
| 109 /* lg(32/31) = */ 0x0000000c, |
| 110 /* lg(64/63) = */ 0x00000006, |
| 111 /* lg(128/127) = */ 0x00000003, |
| 112 /* lg(256/255) = */ 0x00000001, |
| 113 /* lg(512/511) = */ 0x00000001, |
| 114 /* lg(1024/1023) = */ 0x00000000, |
| 115 /* lg(2048/2047) = */ 0x00000000, |
| 116 /* lg(4096/4095) = */ 0x00000000, |
| 117 /* lg(8192/8191) = */ 0x00000000, |
| 118 /* lg(16384/16383) = */ 0x00000000, |
| 119 /* lg(32768/32767) = */ 0x00000000 |
| 120 }, |
| 121 { |
| 122 /* |
| 123 * 12 fraction bits |
| 124 */ |
| 125 /* undefined */ 0x00000000, |
| 126 /* lg(2/1) = */ 0x00001000, |
| 127 /* lg(4/3) = */ 0x000006a4, |
| 128 /* lg(8/7) = */ 0x00000315, |
| 129 /* lg(16/15) = */ 0x0000017d, |
| 130 /* lg(32/31) = */ 0x000000bc, |
| 131 /* lg(64/63) = */ 0x0000005d, |
| 132 /* lg(128/127) = */ 0x0000002e, |
| 133 /* lg(256/255) = */ 0x00000017, |
| 134 /* lg(512/511) = */ 0x0000000c, |
| 135 /* lg(1024/1023) = */ 0x00000006, |
| 136 /* lg(2048/2047) = */ 0x00000003, |
| 137 /* lg(4096/4095) = */ 0x00000001, |
| 138 /* lg(8192/8191) = */ 0x00000001, |
| 139 /* lg(16384/16383) = */ 0x00000000, |
| 140 /* lg(32768/32767) = */ 0x00000000 |
| 141 }, |
| 142 { |
| 143 /* |
| 144 * 16 fraction bits |
| 145 */ |
| 146 /* undefined */ 0x00000000, |
| 147 /* lg(2/1) = */ 0x00010000, |
| 148 /* lg(4/3) = */ 0x00006a40, |
| 149 /* lg(8/7) = */ 0x00003151, |
| 150 /* lg(16/15) = */ 0x000017d6, |
| 151 /* lg(32/31) = */ 0x00000bba, |
| 152 /* lg(64/63) = */ 0x000005d1, |
| 153 /* lg(128/127) = */ 0x000002e6, |
| 154 /* lg(256/255) = */ 0x00000172, |
| 155 /* lg(512/511) = */ 0x000000b9, |
| 156 /* lg(1024/1023) = */ 0x0000005c, |
| 157 /* lg(2048/2047) = */ 0x0000002e, |
| 158 /* lg(4096/4095) = */ 0x00000017, |
| 159 /* lg(8192/8191) = */ 0x0000000c, |
| 160 /* lg(16384/16383) = */ 0x00000006, |
| 161 /* lg(32768/32767) = */ 0x00000003 |
| 162 }, |
| 163 { |
| 164 /* |
| 165 * 20 fraction bits |
| 166 */ |
| 167 /* undefined */ 0x00000000, |
| 168 /* lg(2/1) = */ 0x00100000, |
| 169 /* lg(4/3) = */ 0x0006a3fe, |
| 170 /* lg(8/7) = */ 0x00031513, |
| 171 /* lg(16/15) = */ 0x00017d60, |
| 172 /* lg(32/31) = */ 0x0000bb9d, |
| 173 /* lg(64/63) = */ 0x00005d10, |
| 174 /* lg(128/127) = */ 0x00002e59, |
| 175 /* lg(256/255) = */ 0x00001721, |
| 176 /* lg(512/511) = */ 0x00000b8e, |
| 177 /* lg(1024/1023) = */ 0x000005c6, |
| 178 /* lg(2048/2047) = */ 0x000002e3, |
| 179 /* lg(4096/4095) = */ 0x00000171, |
| 180 /* lg(8192/8191) = */ 0x000000b9, |
| 181 /* lg(16384/16383) = */ 0x0000005c, |
| 182 /* lg(32768/32767) = */ 0x0000002e |
| 183 }, |
| 184 { |
| 185 /* |
| 186 * 24 fraction bits |
| 187 */ |
| 188 /* undefined */ 0x00000000, |
| 189 /* lg(2/1) = */ 0x01000000, |
| 190 /* lg(4/3) = */ 0x006a3fe6, |
| 191 /* lg(8/7) = */ 0x00315130, |
| 192 /* lg(16/15) = */ 0x0017d605, |
| 193 /* lg(32/31) = */ 0x000bb9ca, |
| 194 /* lg(64/63) = */ 0x0005d0fc, |
| 195 /* lg(128/127) = */ 0x0002e58f, |
| 196 /* lg(256/255) = */ 0x0001720e, |
| 197 /* lg(512/511) = */ 0x0000b8d8, |
| 198 /* lg(1024/1023) = */ 0x00005c61, |
| 199 /* lg(2048/2047) = */ 0x00002e2d, |
| 200 /* lg(4096/4095) = */ 0x00001716, |
| 201 /* lg(8192/8191) = */ 0x00000b8b, |
| 202 /* lg(16384/16383) = */ 0x000005c5, |
| 203 /* lg(32768/32767) = */ 0x000002e3 |
| 204 }, |
| 205 { |
| 206 /* |
| 207 * 28 fraction bits |
| 208 */ |
| 209 /* undefined */ 0x00000000, |
| 210 /* lg(2/1) = */ 0x10000000, |
| 211 /* lg(4/3) = */ 0x06a3fe5c, |
| 212 /* lg(8/7) = */ 0x03151301, |
| 213 /* lg(16/15) = */ 0x017d6049, |
| 214 /* lg(32/31) = */ 0x00bb9ca6, |
| 215 /* lg(64/63) = */ 0x005d0fba, |
| 216 /* lg(128/127) = */ 0x002e58f7, |
| 217 /* lg(256/255) = */ 0x001720da, |
| 218 /* lg(512/511) = */ 0x000b8d87, |
| 219 /* lg(1024/1023) = */ 0x0005c60b, |
| 220 /* lg(2048/2047) = */ 0x0002e2d7, |
| 221 /* lg(4096/4095) = */ 0x00017160, |
| 222 /* lg(8192/8191) = */ 0x0000b8ad, |
| 223 /* lg(16384/16383) = */ 0x00005c56, |
| 224 /* lg(32768/32767) = */ 0x00002e2b |
| 225 } |
| 226 }; |
| 227 |
| 228 #if 0 |
| 229 static const FLAC__uint64 log2_lookup_wide[] = { |
| 230 { |
| 231 /* |
| 232 * 32 fraction bits |
| 233 */ |
| 234 /* undefined */ 0x00000000, |
| 235 /* lg(2/1) = */ FLAC__U64L(0x100000000), |
| 236 /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c6), |
| 237 /* lg(8/7) = */ FLAC__U64L(0x31513015), |
| 238 /* lg(16/15) = */ FLAC__U64L(0x17d60497), |
| 239 /* lg(32/31) = */ FLAC__U64L(0x0bb9ca65), |
| 240 /* lg(64/63) = */ FLAC__U64L(0x05d0fba2), |
| 241 /* lg(128/127) = */ FLAC__U64L(0x02e58f74), |
| 242 /* lg(256/255) = */ FLAC__U64L(0x01720d9c), |
| 243 /* lg(512/511) = */ FLAC__U64L(0x00b8d875), |
| 244 /* lg(1024/1023) = */ FLAC__U64L(0x005c60aa), |
| 245 /* lg(2048/2047) = */ FLAC__U64L(0x002e2d72), |
| 246 /* lg(4096/4095) = */ FLAC__U64L(0x00171600), |
| 247 /* lg(8192/8191) = */ FLAC__U64L(0x000b8ad2), |
| 248 /* lg(16384/16383) = */ FLAC__U64L(0x0005c55d), |
| 249 /* lg(32768/32767) = */ FLAC__U64L(0x0002e2ac) |
| 250 }, |
| 251 { |
| 252 /* |
| 253 * 48 fraction bits |
| 254 */ |
| 255 /* undefined */ 0x00000000, |
| 256 /* lg(2/1) = */ FLAC__U64L(0x1000000000000), |
| 257 /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c60429), |
| 258 /* lg(8/7) = */ FLAC__U64L(0x315130157f7a), |
| 259 /* lg(16/15) = */ FLAC__U64L(0x17d60496cfbb), |
| 260 /* lg(32/31) = */ FLAC__U64L(0xbb9ca64ecac), |
| 261 /* lg(64/63) = */ FLAC__U64L(0x5d0fba187cd), |
| 262 /* lg(128/127) = */ FLAC__U64L(0x2e58f7441ee), |
| 263 /* lg(256/255) = */ FLAC__U64L(0x1720d9c06a8), |
| 264 /* lg(512/511) = */ FLAC__U64L(0xb8d8752173), |
| 265 /* lg(1024/1023) = */ FLAC__U64L(0x5c60aa252e), |
| 266 /* lg(2048/2047) = */ FLAC__U64L(0x2e2d71b0d8), |
| 267 /* lg(4096/4095) = */ FLAC__U64L(0x1716001719), |
| 268 /* lg(8192/8191) = */ FLAC__U64L(0xb8ad1de1b), |
| 269 /* lg(16384/16383) = */ FLAC__U64L(0x5c55d640d), |
| 270 /* lg(32768/32767) = */ FLAC__U64L(0x2e2abcf52) |
| 271 } |
| 272 }; |
| 273 #endif |
| 274 |
| 275 FLAC__uint32 FLAC__fixedpoint_log2(FLAC__uint32 x, unsigned fracbits, unsigned p
recision) |
| 276 { |
| 277 const FLAC__uint32 ONE = (1u << fracbits); |
| 278 const FLAC__uint32 *table = log2_lookup[fracbits >> 2]; |
| 279 |
| 280 FLAC__ASSERT(fracbits < 32); |
| 281 FLAC__ASSERT((fracbits & 0x3) == 0); |
| 282 |
| 283 if(x < ONE) |
| 284 return 0; |
| 285 |
| 286 if(precision > LOG2_LOOKUP_PRECISION) |
| 287 precision = LOG2_LOOKUP_PRECISION; |
| 288 |
| 289 /* Knuth's algorithm for computing logarithms, optimized for base-2 with
lookup tables */ |
| 290 { |
| 291 FLAC__uint32 y = 0; |
| 292 FLAC__uint32 z = x >> 1, k = 1; |
| 293 while (x > ONE && k < precision) { |
| 294 if (x - z >= ONE) { |
| 295 x -= z; |
| 296 z = x >> k; |
| 297 y += table[k]; |
| 298 } |
| 299 else { |
| 300 z >>= 1; |
| 301 k++; |
| 302 } |
| 303 } |
| 304 return y; |
| 305 } |
| 306 } |
| 307 |
| 308 #endif /* defined FLAC__INTEGER_ONLY_LIBRARY */ |
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