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/* libFLAC - Free Lossless Audio Codec library
* Copyright (C) 2001,2002 Josh Coalson
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "private/bitmath.h"
#include "FLAC/assert.h"
/* An example of what FLAC__bitmath_ilog2() computes:
*
* ilog2( 0) = assertion failure
* ilog2( 1) = 0
* ilog2( 2) = 1
* ilog2( 3) = 1
* ilog2( 4) = 2
* ilog2( 5) = 2
* ilog2( 6) = 2
* ilog2( 7) = 2
* ilog2( 8) = 3
* ilog2( 9) = 3
* ilog2(10) = 3
* ilog2(11) = 3
* ilog2(12) = 3
* ilog2(13) = 3
* ilog2(14) = 3
* ilog2(15) = 3
* ilog2(16) = 4
* ilog2(17) = 4
* ilog2(18) = 4
*/
unsigned FLAC__bitmath_ilog2(unsigned v)
{
unsigned l = 0;
FLAC__ASSERT(v > 0);
while(v >>= 1)
l++;
return l;
}
/* An example of what FLAC__bitmath_silog2() computes:
*
* silog2(-10) = 5
* silog2(- 9) = 5
* silog2(- 8) = 4
* silog2(- 7) = 4
* silog2(- 6) = 4
* silog2(- 5) = 4
* silog2(- 4) = 3
* silog2(- 3) = 3
* silog2(- 2) = 2
* silog2(- 1) = 2
* silog2( 0) = 0
* silog2( 1) = 2
* silog2( 2) = 3
* silog2( 3) = 3
* silog2( 4) = 4
* silog2( 5) = 4
* silog2( 6) = 4
* silog2( 7) = 4
* silog2( 8) = 5
* silog2( 9) = 5
* silog2( 10) = 5
*/
unsigned FLAC__bitmath_silog2(int v)
{
while(1) {
if(v == 0) {
return 0;
}
else if(v > 0) {
unsigned l = 0;
while(v) {
l++;
v >>= 1;
}
return l+1;
}
else if(v == -1) {
return 2;
}
else {
v++;
v = -v;
}
}
}
unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v)
{
while(1) {
if(v == 0) {
return 0;
}
else if(v > 0) {
unsigned l = 0;
while(v) {
l++;
v >>= 1;
}
return l+1;
}
else if(v == -1) {
return 2;
}
else {
v++;
v = -v;
}
}
}
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