| /* libFLAC - Free Lossless Audio Codec library |
| * Copyright (C) 2004-2009 Josh Coalson |
| * Copyright (C) 2011-2014 Xiph.Org Foundation |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * - Neither the name of the Xiph.org Foundation nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| # include <config.h> |
| #endif |
| |
| #include "FLAC/assert.h" |
| #include "share/compat.h" |
| #include "private/float.h" |
| |
| #ifdef FLAC__INTEGER_ONLY_LIBRARY |
| |
| const FLAC__fixedpoint FLAC__FP_ZERO = 0; |
| const FLAC__fixedpoint FLAC__FP_ONE_HALF = 0x00008000; |
| const FLAC__fixedpoint FLAC__FP_ONE = 0x00010000; |
| const FLAC__fixedpoint FLAC__FP_LN2 = 45426; |
| const FLAC__fixedpoint FLAC__FP_E = 178145; |
| |
| /* Lookup tables for Knuth's logarithm algorithm */ |
| #define LOG2_LOOKUP_PRECISION 16 |
| static const FLAC__uint32 log2_lookup[][LOG2_LOOKUP_PRECISION] = { |
| { |
| /* |
| * 0 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x00000001, |
| /* lg(4/3) = */ 0x00000000, |
| /* lg(8/7) = */ 0x00000000, |
| /* lg(16/15) = */ 0x00000000, |
| /* lg(32/31) = */ 0x00000000, |
| /* lg(64/63) = */ 0x00000000, |
| /* lg(128/127) = */ 0x00000000, |
| /* lg(256/255) = */ 0x00000000, |
| /* lg(512/511) = */ 0x00000000, |
| /* lg(1024/1023) = */ 0x00000000, |
| /* lg(2048/2047) = */ 0x00000000, |
| /* lg(4096/4095) = */ 0x00000000, |
| /* lg(8192/8191) = */ 0x00000000, |
| /* lg(16384/16383) = */ 0x00000000, |
| /* lg(32768/32767) = */ 0x00000000 |
| }, |
| { |
| /* |
| * 4 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x00000010, |
| /* lg(4/3) = */ 0x00000007, |
| /* lg(8/7) = */ 0x00000003, |
| /* lg(16/15) = */ 0x00000001, |
| /* lg(32/31) = */ 0x00000001, |
| /* lg(64/63) = */ 0x00000000, |
| /* lg(128/127) = */ 0x00000000, |
| /* lg(256/255) = */ 0x00000000, |
| /* lg(512/511) = */ 0x00000000, |
| /* lg(1024/1023) = */ 0x00000000, |
| /* lg(2048/2047) = */ 0x00000000, |
| /* lg(4096/4095) = */ 0x00000000, |
| /* lg(8192/8191) = */ 0x00000000, |
| /* lg(16384/16383) = */ 0x00000000, |
| /* lg(32768/32767) = */ 0x00000000 |
| }, |
| { |
| /* |
| * 8 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x00000100, |
| /* lg(4/3) = */ 0x0000006a, |
| /* lg(8/7) = */ 0x00000031, |
| /* lg(16/15) = */ 0x00000018, |
| /* lg(32/31) = */ 0x0000000c, |
| /* lg(64/63) = */ 0x00000006, |
| /* lg(128/127) = */ 0x00000003, |
| /* lg(256/255) = */ 0x00000001, |
| /* lg(512/511) = */ 0x00000001, |
| /* lg(1024/1023) = */ 0x00000000, |
| /* lg(2048/2047) = */ 0x00000000, |
| /* lg(4096/4095) = */ 0x00000000, |
| /* lg(8192/8191) = */ 0x00000000, |
| /* lg(16384/16383) = */ 0x00000000, |
| /* lg(32768/32767) = */ 0x00000000 |
| }, |
| { |
| /* |
| * 12 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x00001000, |
| /* lg(4/3) = */ 0x000006a4, |
| /* lg(8/7) = */ 0x00000315, |
| /* lg(16/15) = */ 0x0000017d, |
| /* lg(32/31) = */ 0x000000bc, |
| /* lg(64/63) = */ 0x0000005d, |
| /* lg(128/127) = */ 0x0000002e, |
| /* lg(256/255) = */ 0x00000017, |
| /* lg(512/511) = */ 0x0000000c, |
| /* lg(1024/1023) = */ 0x00000006, |
| /* lg(2048/2047) = */ 0x00000003, |
| /* lg(4096/4095) = */ 0x00000001, |
| /* lg(8192/8191) = */ 0x00000001, |
| /* lg(16384/16383) = */ 0x00000000, |
| /* lg(32768/32767) = */ 0x00000000 |
| }, |
| { |
| /* |
| * 16 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x00010000, |
| /* lg(4/3) = */ 0x00006a40, |
| /* lg(8/7) = */ 0x00003151, |
| /* lg(16/15) = */ 0x000017d6, |
| /* lg(32/31) = */ 0x00000bba, |
| /* lg(64/63) = */ 0x000005d1, |
| /* lg(128/127) = */ 0x000002e6, |
| /* lg(256/255) = */ 0x00000172, |
| /* lg(512/511) = */ 0x000000b9, |
| /* lg(1024/1023) = */ 0x0000005c, |
| /* lg(2048/2047) = */ 0x0000002e, |
| /* lg(4096/4095) = */ 0x00000017, |
| /* lg(8192/8191) = */ 0x0000000c, |
| /* lg(16384/16383) = */ 0x00000006, |
| /* lg(32768/32767) = */ 0x00000003 |
| }, |
| { |
| /* |
| * 20 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x00100000, |
| /* lg(4/3) = */ 0x0006a3fe, |
| /* lg(8/7) = */ 0x00031513, |
| /* lg(16/15) = */ 0x00017d60, |
| /* lg(32/31) = */ 0x0000bb9d, |
| /* lg(64/63) = */ 0x00005d10, |
| /* lg(128/127) = */ 0x00002e59, |
| /* lg(256/255) = */ 0x00001721, |
| /* lg(512/511) = */ 0x00000b8e, |
| /* lg(1024/1023) = */ 0x000005c6, |
| /* lg(2048/2047) = */ 0x000002e3, |
| /* lg(4096/4095) = */ 0x00000171, |
| /* lg(8192/8191) = */ 0x000000b9, |
| /* lg(16384/16383) = */ 0x0000005c, |
| /* lg(32768/32767) = */ 0x0000002e |
| }, |
| { |
| /* |
| * 24 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x01000000, |
| /* lg(4/3) = */ 0x006a3fe6, |
| /* lg(8/7) = */ 0x00315130, |
| /* lg(16/15) = */ 0x0017d605, |
| /* lg(32/31) = */ 0x000bb9ca, |
| /* lg(64/63) = */ 0x0005d0fc, |
| /* lg(128/127) = */ 0x0002e58f, |
| /* lg(256/255) = */ 0x0001720e, |
| /* lg(512/511) = */ 0x0000b8d8, |
| /* lg(1024/1023) = */ 0x00005c61, |
| /* lg(2048/2047) = */ 0x00002e2d, |
| /* lg(4096/4095) = */ 0x00001716, |
| /* lg(8192/8191) = */ 0x00000b8b, |
| /* lg(16384/16383) = */ 0x000005c5, |
| /* lg(32768/32767) = */ 0x000002e3 |
| }, |
| { |
| /* |
| * 28 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ 0x10000000, |
| /* lg(4/3) = */ 0x06a3fe5c, |
| /* lg(8/7) = */ 0x03151301, |
| /* lg(16/15) = */ 0x017d6049, |
| /* lg(32/31) = */ 0x00bb9ca6, |
| /* lg(64/63) = */ 0x005d0fba, |
| /* lg(128/127) = */ 0x002e58f7, |
| /* lg(256/255) = */ 0x001720da, |
| /* lg(512/511) = */ 0x000b8d87, |
| /* lg(1024/1023) = */ 0x0005c60b, |
| /* lg(2048/2047) = */ 0x0002e2d7, |
| /* lg(4096/4095) = */ 0x00017160, |
| /* lg(8192/8191) = */ 0x0000b8ad, |
| /* lg(16384/16383) = */ 0x00005c56, |
| /* lg(32768/32767) = */ 0x00002e2b |
| } |
| }; |
| |
| #if 0 |
| static const FLAC__uint64 log2_lookup_wide[] = { |
| { |
| /* |
| * 32 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ FLAC__U64L(0x100000000), |
| /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c6), |
| /* lg(8/7) = */ FLAC__U64L(0x31513015), |
| /* lg(16/15) = */ FLAC__U64L(0x17d60497), |
| /* lg(32/31) = */ FLAC__U64L(0x0bb9ca65), |
| /* lg(64/63) = */ FLAC__U64L(0x05d0fba2), |
| /* lg(128/127) = */ FLAC__U64L(0x02e58f74), |
| /* lg(256/255) = */ FLAC__U64L(0x01720d9c), |
| /* lg(512/511) = */ FLAC__U64L(0x00b8d875), |
| /* lg(1024/1023) = */ FLAC__U64L(0x005c60aa), |
| /* lg(2048/2047) = */ FLAC__U64L(0x002e2d72), |
| /* lg(4096/4095) = */ FLAC__U64L(0x00171600), |
| /* lg(8192/8191) = */ FLAC__U64L(0x000b8ad2), |
| /* lg(16384/16383) = */ FLAC__U64L(0x0005c55d), |
| /* lg(32768/32767) = */ FLAC__U64L(0x0002e2ac) |
| }, |
| { |
| /* |
| * 48 fraction bits |
| */ |
| /* undefined */ 0x00000000, |
| /* lg(2/1) = */ FLAC__U64L(0x1000000000000), |
| /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c60429), |
| /* lg(8/7) = */ FLAC__U64L(0x315130157f7a), |
| /* lg(16/15) = */ FLAC__U64L(0x17d60496cfbb), |
| /* lg(32/31) = */ FLAC__U64L(0xbb9ca64ecac), |
| /* lg(64/63) = */ FLAC__U64L(0x5d0fba187cd), |
| /* lg(128/127) = */ FLAC__U64L(0x2e58f7441ee), |
| /* lg(256/255) = */ FLAC__U64L(0x1720d9c06a8), |
| /* lg(512/511) = */ FLAC__U64L(0xb8d8752173), |
| /* lg(1024/1023) = */ FLAC__U64L(0x5c60aa252e), |
| /* lg(2048/2047) = */ FLAC__U64L(0x2e2d71b0d8), |
| /* lg(4096/4095) = */ FLAC__U64L(0x1716001719), |
| /* lg(8192/8191) = */ FLAC__U64L(0xb8ad1de1b), |
| /* lg(16384/16383) = */ FLAC__U64L(0x5c55d640d), |
| /* lg(32768/32767) = */ FLAC__U64L(0x2e2abcf52) |
| } |
| }; |
| #endif |
| |
| FLAC__uint32 FLAC__fixedpoint_log2(FLAC__uint32 x, unsigned fracbits, unsigned precision) |
| { |
| const FLAC__uint32 ONE = (1u << fracbits); |
| const FLAC__uint32 *table = log2_lookup[fracbits >> 2]; |
| |
| FLAC__ASSERT(fracbits < 32); |
| FLAC__ASSERT((fracbits & 0x3) == 0); |
| |
| if(x < ONE) |
| return 0; |
| |
| if(precision > LOG2_LOOKUP_PRECISION) |
| precision = LOG2_LOOKUP_PRECISION; |
| |
| /* Knuth's algorithm for computing logarithms, optimized for base-2 with lookup tables */ |
| { |
| FLAC__uint32 y = 0; |
| FLAC__uint32 z = x >> 1, k = 1; |
| while (x > ONE && k < precision) { |
| if (x - z >= ONE) { |
| x -= z; |
| z = x >> k; |
| y += table[k]; |
| } |
| else { |
| z >>= 1; |
| k++; |
| } |
| } |
| return y; |
| } |
| } |
| |
| #endif /* defined FLAC__INTEGER_ONLY_LIBRARY */ |