110 lines
2.8 KiB
C
110 lines
2.8 KiB
C
|
/* libFLAC - Free Lossless Audio Codec library
|
||
|
|
* Copyright (C) 2001-2009 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 "include/private/bitmath.h"
|
||
|
|
|
||
|
|
/* 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;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|