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101 lines
2.1 KiB
C
101 lines
2.1 KiB
C
/* libFLAC - Free Lossless Audio Codec library
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* Copyright (C) 2001,2002 Josh Coalson
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "private/bitmath.h"
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#include "FLAC/assert.h"
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/* An example of what FLAC__bitmath_ilog2() computes:
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*
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* ilog2( 0) = assertion failure
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* ilog2( 1) = 0
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* ilog2( 2) = 1
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* ilog2( 3) = 1
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* ilog2( 4) = 2
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* ilog2( 5) = 2
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* ilog2( 6) = 2
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* ilog2( 7) = 2
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* ilog2( 8) = 3
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* ilog2( 9) = 3
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* ilog2(10) = 3
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* ilog2(11) = 3
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* ilog2(12) = 3
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* ilog2(13) = 3
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* ilog2(14) = 3
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* ilog2(15) = 3
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* ilog2(16) = 4
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* ilog2(17) = 4
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* ilog2(18) = 4
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*/
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unsigned FLAC__bitmath_ilog2(unsigned v)
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{
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unsigned l = 0;
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FLAC__ASSERT(v > 0);
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while(v >>= 1)
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l++;
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return l;
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}
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/* An example of what FLAC__bitmath_silog2() computes:
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*
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* silog2(-10) = 5
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* silog2(- 9) = 5
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* silog2(- 8) = 4
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* silog2(- 7) = 4
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* silog2(- 6) = 4
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* silog2(- 5) = 4
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* silog2(- 4) = 3
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* silog2(- 3) = 3
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* silog2(- 2) = 2
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* silog2(- 1) = 2
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* silog2( 0) = 0
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* silog2( 1) = 2
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* silog2( 2) = 3
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* silog2( 3) = 3
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* silog2( 4) = 4
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* silog2( 5) = 4
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* silog2( 6) = 4
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* silog2( 7) = 4
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* silog2( 8) = 5
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* silog2( 9) = 5
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* silog2( 10) = 5
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*/
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unsigned FLAC__bitmath_silog2(int v)
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{
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while(1) {
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if(v == 0) {
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return 0;
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}
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else if(v > 0) {
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unsigned l = 0;
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while(v) {
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l++;
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v >>= 1;
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}
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return l+1;
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}
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else if(v == -1) {
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return 2;
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}
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else {
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v++;
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v = -v;
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}
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}
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}
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