window.c
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/********************************************************************
* *
* THIS FILE IS PART OF THE OggVorbis 'TREMOR' 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 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002 *
* BY THE Xiph.Org FOUNDATION http://www.xiph.org/ *
* *
********************************************************************
function: window functions
********************************************************************/
#include <stdlib.h>
#include <math.h>
#include "misc.h"
#include "window.h"
#include "window_lookup.h"
const void *_vorbis_window(int type, int left){
switch(type){
case 0:
switch(left){
case 32:
return vwin64;
case 64:
return vwin128;
case 128:
return vwin256;
case 256:
return vwin512;
case 512:
return vwin1024;
case 1024:
return vwin2048;
case 2048:
return vwin4096;
case 4096:
return vwin8192;
default:
return(0);
}
break;
default:
return(0);
}
}
void _vorbis_apply_window(ogg_int32_t *d,const void *window_p[2],
long *blocksizes,
int lW,int W,int nW){
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const LOOKUP_T *window[2];
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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;
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window[0] = (const LOOKUP_T *)window_p[0];
window[1] = (const LOOKUP_T *)window_p[1];
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for(i=0;i<leftbegin;i++)
d[i]=0;
for(p=0;i<leftend;i++,p++)
d[i]=MULT31(d[i],window[lW][p]);
for(i=rightbegin,p=rn/2-1;i<rightend;i++,p--)
d[i]=MULT31(d[i],window[nW][p]);
for(;i<n;i++)
d[i]=0;
}