1 /********************************************************************

     2  *                                                                  *

     3  * THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE.   *

     4  *                                                                  *

     5  * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *

     6  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *

     7  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *

     8  *                                                                  *

     9  * THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002    *

    10  * BY THE Xiph.Org FOUNDATION http://www.xiph.org/                  *

    11  *                                                                  *

    12  ********************************************************************

    13 

    14  function: window functions

    15 

    16  ********************************************************************/

    17 

    18 #include <stdlib.h>

    19 #include <math.h>

    20 #include "misc.h"

    21 #include "window.h"

    22 #include "window_lookup.h"

    23 

    24 const void *_vorbis_window(int type, int left){

    25 

    26   switch(type){

    27   case 0:

    28 

    29     switch(left){

    30     case 32:

    31       return vwin64;

    32     case 64:

    33       return vwin128;

    34     case 128:

    35       return vwin256;

    36     case 256:

    37       return vwin512;

    38     case 512:

    39       return vwin1024;

    40     case 1024:

    41       return vwin2048;

    42     case 2048:

    43       return vwin4096;

    44     case 4096:

    45       return vwin8192;

    46     default:

    47       return(0);

    48     }

    49     break;

    50   default:

    51     return(0);

    52   }

    53 }

    54 

    55 void _vorbis_apply_window(ogg_int32_t *d,const void *window_p[2],

    56 			  long *blocksizes,

    57 			  int lW,int W,int nW){

    58   

    59   LOOKUP_T *window[2]={window_p[0],window_p[1]};

    60   long n=blocksizes[W];

    61   long ln=blocksizes[lW];

    62   long rn=blocksizes[nW];

    63 

    64   long leftbegin=n/4-ln/4;

    65   long leftend=leftbegin+ln/2;

    66 

    67   long rightbegin=n/2+n/4-rn/4;

    68   long rightend=rightbegin+rn/2;

    69   

    70   int i,p;

    71 

    72   for(i=0;i<leftbegin;i++)

    73     d[i]=0;

    74 

    75   for(p=0;i<leftend;i++,p++)

    76     d[i]=MULT31(d[i],window[lW][p]);

    77 

    78   for(i=rightbegin,p=rn/2-1;i<rightend;i++,p--)

    79     d[i]=MULT31(d[i],window[nW][p]);

    80 

    81   for(;i<n;i++)

    82     d[i]=0;

    83 }