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/********************************************************************
* *
* THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. *
* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
* *
* THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2002 *
* by the XIPHOPHORUS Company http://www.xiph.org/ *
* *
********************************************************************
function: window functions
last mod: $Id: window.c,v 1.17 2002/03/23 03:17:34 xiphmont Exp $
********************************************************************/
#include <stdlib.h>
#include <math.h>
#include "os.h"
#include "misc.h"
float *_vorbis_window(int type, int left){
float *ret=_ogg_calloc(left,sizeof(*ret));
int i;
switch(type){
case 0:
/* The 'vorbis window' (window 0) is sin(sin(x)*sin(x)*2pi) */
{
for(i=0;i<left;i++){
float x=(i+.5f)/left*M_PI/2.;
x=sin(x);
x*=x;
x*=M_PI/2.f;
x=sin(x);
ret[i]=x;
}
}
break;
default:
_ogg_free(ret);
return(NULL);
}
return(ret);
}
void _vorbis_apply_window(float *d,float *window[2],long *blocksizes,
int lW,int W,int nW){
lW=(W?lW:0);
nW=(W?nW:0);
{
long n=blocksizes[W];
long ln=blocksizes[lW];
long rn=blocksizes[nW];
long leftbegin=n/4-ln/4;
long leftend=leftbegin+ln/2;
long rightbegin=n/2+n/4-rn/4;
long rightend=rightbegin+rn/2;
int i,p;
for(i=0;i<leftbegin;i++)
d[i]=0.f;
for(p=0;i<leftend;i++,p++)
d[i]*=window[lW][p];
for(i=rightbegin,p=rn/2-1;i<rightend;i++,p--)
d[i]*=window[nW][p];
for(;i<n;i++)
d[i]=0.f;
}
}
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