305 lines
9 KiB
C
305 lines
9 KiB
C
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/* libFLAC - Free Lossless Audio Codec library
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* Copyright (C) 2004,2005 Josh Coalson
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* - Neither the name of the Xiph.org Foundation nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "FLAC/assert.h"
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#include "private/float.h"
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#ifdef FLAC__INTEGER_ONLY_LIBRARY
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/* adjust for compilers that can't understand using LLU suffix for uint64_t literals */
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#ifdef _MSC_VER
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#define FLAC__U64L(x) x
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#else
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#define FLAC__U64L(x) x##LLU
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#endif
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const FLAC__fixedpoint FLAC__FP_ZERO = 0;
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const FLAC__fixedpoint FLAC__FP_ONE_HALF = 0x00008000;
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const FLAC__fixedpoint FLAC__FP_ONE = 0x00010000;
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const FLAC__fixedpoint FLAC__FP_LN2 = 45426;
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const FLAC__fixedpoint FLAC__FP_E = 178145;
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/* Lookup tables for Knuth's logarithm algorithm */
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#define LOG2_LOOKUP_PRECISION 16
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static const FLAC__uint32 log2_lookup[][LOG2_LOOKUP_PRECISION] = {
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{
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/*
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* 0 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x00000001,
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/* lg(4/3) = */ 0x00000000,
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/* lg(8/7) = */ 0x00000000,
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/* lg(16/15) = */ 0x00000000,
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/* lg(32/31) = */ 0x00000000,
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/* lg(64/63) = */ 0x00000000,
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/* lg(128/127) = */ 0x00000000,
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/* lg(256/255) = */ 0x00000000,
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/* lg(512/511) = */ 0x00000000,
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/* lg(1024/1023) = */ 0x00000000,
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/* lg(2048/2047) = */ 0x00000000,
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/* lg(4096/4095) = */ 0x00000000,
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/* lg(8192/8191) = */ 0x00000000,
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/* lg(16384/16383) = */ 0x00000000,
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/* lg(32768/32767) = */ 0x00000000
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},
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{
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/*
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* 4 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x00000010,
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/* lg(4/3) = */ 0x00000007,
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/* lg(8/7) = */ 0x00000003,
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/* lg(16/15) = */ 0x00000001,
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/* lg(32/31) = */ 0x00000001,
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/* lg(64/63) = */ 0x00000000,
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/* lg(128/127) = */ 0x00000000,
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/* lg(256/255) = */ 0x00000000,
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/* lg(512/511) = */ 0x00000000,
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/* lg(1024/1023) = */ 0x00000000,
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/* lg(2048/2047) = */ 0x00000000,
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/* lg(4096/4095) = */ 0x00000000,
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/* lg(8192/8191) = */ 0x00000000,
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/* lg(16384/16383) = */ 0x00000000,
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/* lg(32768/32767) = */ 0x00000000
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},
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{
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/*
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* 8 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x00000100,
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/* lg(4/3) = */ 0x0000006a,
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/* lg(8/7) = */ 0x00000031,
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/* lg(16/15) = */ 0x00000018,
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/* lg(32/31) = */ 0x0000000c,
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/* lg(64/63) = */ 0x00000006,
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/* lg(128/127) = */ 0x00000003,
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/* lg(256/255) = */ 0x00000001,
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/* lg(512/511) = */ 0x00000001,
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/* lg(1024/1023) = */ 0x00000000,
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/* lg(2048/2047) = */ 0x00000000,
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/* lg(4096/4095) = */ 0x00000000,
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/* lg(8192/8191) = */ 0x00000000,
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/* lg(16384/16383) = */ 0x00000000,
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/* lg(32768/32767) = */ 0x00000000
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},
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{
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/*
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* 12 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x00001000,
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/* lg(4/3) = */ 0x000006a4,
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/* lg(8/7) = */ 0x00000315,
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/* lg(16/15) = */ 0x0000017d,
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/* lg(32/31) = */ 0x000000bc,
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/* lg(64/63) = */ 0x0000005d,
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/* lg(128/127) = */ 0x0000002e,
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/* lg(256/255) = */ 0x00000017,
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/* lg(512/511) = */ 0x0000000c,
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/* lg(1024/1023) = */ 0x00000006,
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/* lg(2048/2047) = */ 0x00000003,
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/* lg(4096/4095) = */ 0x00000001,
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/* lg(8192/8191) = */ 0x00000001,
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/* lg(16384/16383) = */ 0x00000000,
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/* lg(32768/32767) = */ 0x00000000
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},
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{
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/*
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* 16 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x00010000,
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/* lg(4/3) = */ 0x00006a40,
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/* lg(8/7) = */ 0x00003151,
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/* lg(16/15) = */ 0x000017d6,
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/* lg(32/31) = */ 0x00000bba,
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/* lg(64/63) = */ 0x000005d1,
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/* lg(128/127) = */ 0x000002e6,
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/* lg(256/255) = */ 0x00000172,
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/* lg(512/511) = */ 0x000000b9,
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/* lg(1024/1023) = */ 0x0000005c,
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/* lg(2048/2047) = */ 0x0000002e,
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/* lg(4096/4095) = */ 0x00000017,
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/* lg(8192/8191) = */ 0x0000000c,
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/* lg(16384/16383) = */ 0x00000006,
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/* lg(32768/32767) = */ 0x00000003
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},
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{
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/*
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* 20 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x00100000,
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/* lg(4/3) = */ 0x0006a3fe,
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/* lg(8/7) = */ 0x00031513,
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/* lg(16/15) = */ 0x00017d60,
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/* lg(32/31) = */ 0x0000bb9d,
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/* lg(64/63) = */ 0x00005d10,
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/* lg(128/127) = */ 0x00002e59,
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/* lg(256/255) = */ 0x00001721,
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/* lg(512/511) = */ 0x00000b8e,
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/* lg(1024/1023) = */ 0x000005c6,
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/* lg(2048/2047) = */ 0x000002e3,
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/* lg(4096/4095) = */ 0x00000171,
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/* lg(8192/8191) = */ 0x000000b9,
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/* lg(16384/16383) = */ 0x0000005c,
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/* lg(32768/32767) = */ 0x0000002e
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},
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{
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/*
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* 24 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x01000000,
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/* lg(4/3) = */ 0x006a3fe6,
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/* lg(8/7) = */ 0x00315130,
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/* lg(16/15) = */ 0x0017d605,
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/* lg(32/31) = */ 0x000bb9ca,
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/* lg(64/63) = */ 0x0005d0fc,
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/* lg(128/127) = */ 0x0002e58f,
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/* lg(256/255) = */ 0x0001720e,
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/* lg(512/511) = */ 0x0000b8d8,
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/* lg(1024/1023) = */ 0x00005c61,
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/* lg(2048/2047) = */ 0x00002e2d,
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/* lg(4096/4095) = */ 0x00001716,
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/* lg(8192/8191) = */ 0x00000b8b,
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/* lg(16384/16383) = */ 0x000005c5,
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/* lg(32768/32767) = */ 0x000002e3
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},
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{
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/*
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* 28 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ 0x10000000,
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/* lg(4/3) = */ 0x06a3fe5c,
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/* lg(8/7) = */ 0x03151301,
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/* lg(16/15) = */ 0x017d6049,
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/* lg(32/31) = */ 0x00bb9ca6,
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/* lg(64/63) = */ 0x005d0fba,
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/* lg(128/127) = */ 0x002e58f7,
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/* lg(256/255) = */ 0x001720da,
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/* lg(512/511) = */ 0x000b8d87,
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/* lg(1024/1023) = */ 0x0005c60b,
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/* lg(2048/2047) = */ 0x0002e2d7,
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/* lg(4096/4095) = */ 0x00017160,
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/* lg(8192/8191) = */ 0x0000b8ad,
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/* lg(16384/16383) = */ 0x00005c56,
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/* lg(32768/32767) = */ 0x00002e2b
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}
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};
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#if 0
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static const FLAC__uint64 log2_lookup_wide[] = {
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{
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/*
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* 32 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ FLAC__U64L(0x100000000),
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/* lg(4/3) = */ FLAC__U64L(0x6a3fe5c6),
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/* lg(8/7) = */ FLAC__U64L(0x31513015),
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/* lg(16/15) = */ FLAC__U64L(0x17d60497),
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/* lg(32/31) = */ FLAC__U64L(0x0bb9ca65),
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/* lg(64/63) = */ FLAC__U64L(0x05d0fba2),
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/* lg(128/127) = */ FLAC__U64L(0x02e58f74),
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/* lg(256/255) = */ FLAC__U64L(0x01720d9c),
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/* lg(512/511) = */ FLAC__U64L(0x00b8d875),
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/* lg(1024/1023) = */ FLAC__U64L(0x005c60aa),
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/* lg(2048/2047) = */ FLAC__U64L(0x002e2d72),
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/* lg(4096/4095) = */ FLAC__U64L(0x00171600),
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/* lg(8192/8191) = */ FLAC__U64L(0x000b8ad2),
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/* lg(16384/16383) = */ FLAC__U64L(0x0005c55d),
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/* lg(32768/32767) = */ FLAC__U64L(0x0002e2ac)
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},
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{
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/*
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* 48 fraction bits
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*/
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/* undefined */ 0x00000000,
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/* lg(2/1) = */ FLAC__U64L(0x1000000000000),
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/* lg(4/3) = */ FLAC__U64L(0x6a3fe5c60429),
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/* lg(8/7) = */ FLAC__U64L(0x315130157f7a),
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/* lg(16/15) = */ FLAC__U64L(0x17d60496cfbb),
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/* lg(32/31) = */ FLAC__U64L(0xbb9ca64ecac),
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/* lg(64/63) = */ FLAC__U64L(0x5d0fba187cd),
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/* lg(128/127) = */ FLAC__U64L(0x2e58f7441ee),
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/* lg(256/255) = */ FLAC__U64L(0x1720d9c06a8),
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/* lg(512/511) = */ FLAC__U64L(0xb8d8752173),
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/* lg(1024/1023) = */ FLAC__U64L(0x5c60aa252e),
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/* lg(2048/2047) = */ FLAC__U64L(0x2e2d71b0d8),
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/* lg(4096/4095) = */ FLAC__U64L(0x1716001719),
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/* lg(8192/8191) = */ FLAC__U64L(0xb8ad1de1b),
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/* lg(16384/16383) = */ FLAC__U64L(0x5c55d640d),
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/* lg(32768/32767) = */ FLAC__U64L(0x2e2abcf52)
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}
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};
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#endif
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FLAC__uint32 FLAC__fixedpoint_log2(FLAC__uint32 x, unsigned fracbits, unsigned precision)
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{
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const FLAC__uint32 ONE = (1u << fracbits);
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const FLAC__uint32 *table = log2_lookup[fracbits >> 2];
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FLAC__ASSERT(fracbits < 32);
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FLAC__ASSERT((fracbits & 0x3) == 0);
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if(x < ONE)
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return 0;
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if(precision > LOG2_LOOKUP_PRECISION)
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precision = LOG2_LOOKUP_PRECISION;
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/* Knuth's algorithm for computing logarithms, optimized for base-2 with lookup tables */
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{
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FLAC__uint32 y = 0;
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FLAC__uint32 z = x >> 1, k = 1;
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while (x > ONE && k < precision) {
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if (x - z >= ONE) {
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x -= z;
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z = x >> k;
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y += table[k];
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}
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else {
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z >>= 1;
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k++;
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}
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}
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return y;
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}
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}
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#endif /* defined FLAC__INTEGER_ONLY_LIBRARY */
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