deps/flac-1.3.2/src/libFLAC/float.c

   1 /* libFLAC - Free Lossless Audio Codec library
   2  * Copyright (C) 2004-2009  Josh Coalson
   3  * Copyright (C) 2011-2016  Xiph.Org Foundation
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * - Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *
  12  * - Redistributions in binary form must reproduce the above copyright
  13  * notice, this list of conditions and the following disclaimer in the
  14  * documentation and/or other materials provided with the distribution.
  15  *
  16  * - Neither the name of the Xiph.org Foundation nor the names of its
  17  * contributors may be used to endorse or promote products derived from
  18  * this software without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  23  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
  24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  26  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  27  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  29  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  30  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #ifdef HAVE_CONFIG_H
  34 #  include <config.h>
  35 #endif
  36
  37 #include "FLAC/assert.h"
  38 #include "share/compat.h"
  39 #include "private/float.h"
  40
  41 #ifdef FLAC__INTEGER_ONLY_LIBRARY
  42
  43 const FLAC__fixedpoint FLAC__FP_ZERO = 0;
  44 const FLAC__fixedpoint FLAC__FP_ONE_HALF = 0x00008000;
  45 const FLAC__fixedpoint FLAC__FP_ONE = 0x00010000;
  46 const FLAC__fixedpoint FLAC__FP_LN2 = 45426;
  47 const FLAC__fixedpoint FLAC__FP_E = 178145;
  48
  49 /* Lookup tables for Knuth's logarithm algorithm */
  50 #define LOG2_LOOKUP_PRECISION 16
  51 static const FLAC__uint32 log2_lookup[][LOG2_LOOKUP_PRECISION] = {
  52         {
  53                 /*
  54                  * 0 fraction bits
  55                  */
  56                 /* undefined */ 0x00000000,
  57                 /* lg(2/1) = */ 0x00000001,
  58                 /* lg(4/3) = */ 0x00000000,
  59                 /* lg(8/7) = */ 0x00000000,
  60                 /* lg(16/15) = */ 0x00000000,
  61                 /* lg(32/31) = */ 0x00000000,
  62                 /* lg(64/63) = */ 0x00000000,
  63                 /* lg(128/127) = */ 0x00000000,
  64                 /* lg(256/255) = */ 0x00000000,
  65                 /* lg(512/511) = */ 0x00000000,
  66                 /* lg(1024/1023) = */ 0x00000000,
  67                 /* lg(2048/2047) = */ 0x00000000,
  68                 /* lg(4096/4095) = */ 0x00000000,
  69                 /* lg(8192/8191) = */ 0x00000000,
  70                 /* lg(16384/16383) = */ 0x00000000,
  71                 /* lg(32768/32767) = */ 0x00000000
  72         },
  73         {
  74                 /*
  75                  * 4 fraction bits
  76                  */
  77                 /* undefined */ 0x00000000,
  78                 /* lg(2/1) = */ 0x00000010,
  79                 /* lg(4/3) = */ 0x00000007,
  80                 /* lg(8/7) = */ 0x00000003,
  81                 /* lg(16/15) = */ 0x00000001,
  82                 /* lg(32/31) = */ 0x00000001,
  83                 /* lg(64/63) = */ 0x00000000,
  84                 /* lg(128/127) = */ 0x00000000,
  85                 /* lg(256/255) = */ 0x00000000,
  86                 /* lg(512/511) = */ 0x00000000,
  87                 /* lg(1024/1023) = */ 0x00000000,
  88                 /* lg(2048/2047) = */ 0x00000000,
  89                 /* lg(4096/4095) = */ 0x00000000,
  90                 /* lg(8192/8191) = */ 0x00000000,
  91                 /* lg(16384/16383) = */ 0x00000000,
  92                 /* lg(32768/32767) = */ 0x00000000
  93         },
  94         {
  95                 /*
  96                  * 8 fraction bits
  97                  */
  98                 /* undefined */ 0x00000000,
  99                 /* lg(2/1) = */ 0x00000100,
 100                 /* lg(4/3) = */ 0x0000006a,
 101                 /* lg(8/7) = */ 0x00000031,
 102                 /* lg(16/15) = */ 0x00000018,
 103                 /* lg(32/31) = */ 0x0000000c,
 104                 /* lg(64/63) = */ 0x00000006,
 105                 /* lg(128/127) = */ 0x00000003,
 106                 /* lg(256/255) = */ 0x00000001,
 107                 /* lg(512/511) = */ 0x00000001,
 108                 /* lg(1024/1023) = */ 0x00000000,
 109                 /* lg(2048/2047) = */ 0x00000000,
 110                 /* lg(4096/4095) = */ 0x00000000,
 111                 /* lg(8192/8191) = */ 0x00000000,
 112                 /* lg(16384/16383) = */ 0x00000000,
 113                 /* lg(32768/32767) = */ 0x00000000
 114         },
 115         {
 116                 /*
 117                  * 12 fraction bits
 118                  */
 119                 /* undefined */ 0x00000000,
 120                 /* lg(2/1) = */ 0x00001000,
 121                 /* lg(4/3) = */ 0x000006a4,
 122                 /* lg(8/7) = */ 0x00000315,
 123                 /* lg(16/15) = */ 0x0000017d,
 124                 /* lg(32/31) = */ 0x000000bc,
 125                 /* lg(64/63) = */ 0x0000005d,
 126                 /* lg(128/127) = */ 0x0000002e,
 127                 /* lg(256/255) = */ 0x00000017,
 128                 /* lg(512/511) = */ 0x0000000c,
 129                 /* lg(1024/1023) = */ 0x00000006,
 130                 /* lg(2048/2047) = */ 0x00000003,
 131                 /* lg(4096/4095) = */ 0x00000001,
 132                 /* lg(8192/8191) = */ 0x00000001,
 133                 /* lg(16384/16383) = */ 0x00000000,
 134                 /* lg(32768/32767) = */ 0x00000000
 135         },
 136         {
 137                 /*
 138                  * 16 fraction bits
 139                  */
 140                 /* undefined */ 0x00000000,
 141                 /* lg(2/1) = */ 0x00010000,
 142                 /* lg(4/3) = */ 0x00006a40,
 143                 /* lg(8/7) = */ 0x00003151,
 144                 /* lg(16/15) = */ 0x000017d6,
 145                 /* lg(32/31) = */ 0x00000bba,
 146                 /* lg(64/63) = */ 0x000005d1,
 147                 /* lg(128/127) = */ 0x000002e6,
 148                 /* lg(256/255) = */ 0x00000172,
 149                 /* lg(512/511) = */ 0x000000b9,
 150                 /* lg(1024/1023) = */ 0x0000005c,
 151                 /* lg(2048/2047) = */ 0x0000002e,
 152                 /* lg(4096/4095) = */ 0x00000017,
 153                 /* lg(8192/8191) = */ 0x0000000c,
 154                 /* lg(16384/16383) = */ 0x00000006,
 155                 /* lg(32768/32767) = */ 0x00000003
 156         },
 157         {
 158                 /*
 159                  * 20 fraction bits
 160                  */
 161                 /* undefined */ 0x00000000,
 162                 /* lg(2/1) = */ 0x00100000,
 163                 /* lg(4/3) = */ 0x0006a3fe,
 164                 /* lg(8/7) = */ 0x00031513,
 165                 /* lg(16/15) = */ 0x00017d60,
 166                 /* lg(32/31) = */ 0x0000bb9d,
 167                 /* lg(64/63) = */ 0x00005d10,
 168                 /* lg(128/127) = */ 0x00002e59,
 169                 /* lg(256/255) = */ 0x00001721,
 170                 /* lg(512/511) = */ 0x00000b8e,
 171                 /* lg(1024/1023) = */ 0x000005c6,
 172                 /* lg(2048/2047) = */ 0x000002e3,
 173                 /* lg(4096/4095) = */ 0x00000171,
 174                 /* lg(8192/8191) = */ 0x000000b9,
 175                 /* lg(16384/16383) = */ 0x0000005c,
 176                 /* lg(32768/32767) = */ 0x0000002e
 177         },
 178         {
 179                 /*
 180                  * 24 fraction bits
 181                  */
 182                 /* undefined */ 0x00000000,
 183                 /* lg(2/1) = */ 0x01000000,
 184                 /* lg(4/3) = */ 0x006a3fe6,
 185                 /* lg(8/7) = */ 0x00315130,
 186                 /* lg(16/15) = */ 0x0017d605,
 187                 /* lg(32/31) = */ 0x000bb9ca,
 188                 /* lg(64/63) = */ 0x0005d0fc,
 189                 /* lg(128/127) = */ 0x0002e58f,
 190                 /* lg(256/255) = */ 0x0001720e,
 191                 /* lg(512/511) = */ 0x0000b8d8,
 192                 /* lg(1024/1023) = */ 0x00005c61,
 193                 /* lg(2048/2047) = */ 0x00002e2d,
 194                 /* lg(4096/4095) = */ 0x00001716,
 195                 /* lg(8192/8191) = */ 0x00000b8b,
 196                 /* lg(16384/16383) = */ 0x000005c5,
 197                 /* lg(32768/32767) = */ 0x000002e3
 198         },
 199         {
 200                 /*
 201                  * 28 fraction bits
 202                  */
 203                 /* undefined */ 0x00000000,
 204                 /* lg(2/1) = */ 0x10000000,
 205                 /* lg(4/3) = */ 0x06a3fe5c,
 206                 /* lg(8/7) = */ 0x03151301,
 207                 /* lg(16/15) = */ 0x017d6049,
 208                 /* lg(32/31) = */ 0x00bb9ca6,
 209                 /* lg(64/63) = */ 0x005d0fba,
 210                 /* lg(128/127) = */ 0x002e58f7,
 211                 /* lg(256/255) = */ 0x001720da,
 212                 /* lg(512/511) = */ 0x000b8d87,
 213                 /* lg(1024/1023) = */ 0x0005c60b,
 214                 /* lg(2048/2047) = */ 0x0002e2d7,
 215                 /* lg(4096/4095) = */ 0x00017160,
 216                 /* lg(8192/8191) = */ 0x0000b8ad,
 217                 /* lg(16384/16383) = */ 0x00005c56,
 218                 /* lg(32768/32767) = */ 0x00002e2b
 219         }
 220 };
 221
 222 #if 0
 223 static const FLAC__uint64 log2_lookup_wide[] = {
 224         {
 225                 /*
 226                  * 32 fraction bits
 227                  */
 228                 /* undefined */ 0x00000000,
 229                 /* lg(2/1) = */ FLAC__U64L(0x100000000),
 230                 /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c6),
 231                 /* lg(8/7) = */ FLAC__U64L(0x31513015),
 232                 /* lg(16/15) = */ FLAC__U64L(0x17d60497),
 233                 /* lg(32/31) = */ FLAC__U64L(0x0bb9ca65),
 234                 /* lg(64/63) = */ FLAC__U64L(0x05d0fba2),
 235                 /* lg(128/127) = */ FLAC__U64L(0x02e58f74),
 236                 /* lg(256/255) = */ FLAC__U64L(0x01720d9c),
 237                 /* lg(512/511) = */ FLAC__U64L(0x00b8d875),
 238                 /* lg(1024/1023) = */ FLAC__U64L(0x005c60aa),
 239                 /* lg(2048/2047) = */ FLAC__U64L(0x002e2d72),
 240                 /* lg(4096/4095) = */ FLAC__U64L(0x00171600),
 241                 /* lg(8192/8191) = */ FLAC__U64L(0x000b8ad2),
 242                 /* lg(16384/16383) = */ FLAC__U64L(0x0005c55d),
 243                 /* lg(32768/32767) = */ FLAC__U64L(0x0002e2ac)
 244         },
 245         {
 246                 /*
 247                  * 48 fraction bits
 248                  */
 249                 /* undefined */ 0x00000000,
 250                 /* lg(2/1) = */ FLAC__U64L(0x1000000000000),
 251                 /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c60429),
 252                 /* lg(8/7) = */ FLAC__U64L(0x315130157f7a),
 253                 /* lg(16/15) = */ FLAC__U64L(0x17d60496cfbb),
 254                 /* lg(32/31) = */ FLAC__U64L(0xbb9ca64ecac),
 255                 /* lg(64/63) = */ FLAC__U64L(0x5d0fba187cd),
 256                 /* lg(128/127) = */ FLAC__U64L(0x2e58f7441ee),
 257                 /* lg(256/255) = */ FLAC__U64L(0x1720d9c06a8),
 258                 /* lg(512/511) = */ FLAC__U64L(0xb8d8752173),
 259                 /* lg(1024/1023) = */ FLAC__U64L(0x5c60aa252e),
 260                 /* lg(2048/2047) = */ FLAC__U64L(0x2e2d71b0d8),
 261                 /* lg(4096/4095) = */ FLAC__U64L(0x1716001719),
 262                 /* lg(8192/8191) = */ FLAC__U64L(0xb8ad1de1b),
 263                 /* lg(16384/16383) = */ FLAC__U64L(0x5c55d640d),
 264                 /* lg(32768/32767) = */ FLAC__U64L(0x2e2abcf52)
 265         }
 266 };
 267 #endif
 268
 269 FLAC__uint32 FLAC__fixedpoint_log2(FLAC__uint32 x, unsigned fracbits, unsigned precision)
 270 {
 271         const FLAC__uint32 ONE = (1u << fracbits);
 272         const FLAC__uint32 *table = log2_lookup[fracbits >> 2];
 273
 274         FLAC__ASSERT(fracbits < 32);
 275         FLAC__ASSERT((fracbits & 0x3) == 0);
 276
 277         if(x < ONE)
 278                 return 0;
 279
 280         if(precision > LOG2_LOOKUP_PRECISION)
 281                 precision = LOG2_LOOKUP_PRECISION;
 282
 283         /* Knuth's algorithm for computing logarithms, optimized for base-2 with lookup tables */
 284         {
 285                 FLAC__uint32 y = 0;
 286                 FLAC__uint32 z = x >> 1, k = 1;
 287                 while (x > ONE && k < precision) {
 288                         if (x - z >= ONE) {
 289                                 x -= z;
 290                                 z = x >> k;
 291                                 y += table[k];
 292                         }
 293                         else {
 294                                 z >>= 1;
 295                                 k++;
 296                         }
 297                 }
 298                 return y;
 299         }
 300 }
 301
 302 #endif /* defined FLAC__INTEGER_ONLY_LIBRARY */