postfish/window.c

   1 /*
   2  *
   3  *  postfish
   4  *
   5  *      Copyright (C) 2002-2005 Monty and Xiph.Org
   6  *
   7  *  Postfish is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2, or (at your option)
  10  *  any later version.
  11  *
  12  *  Postfish is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with Postfish; see the file COPYING.  If not, write to the
  19  *  Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  20  *
  21  *
  22  */
  23
  24 #include "postfish.h"
  25 #include "window.h"
  26
  27 static pthread_mutex_t window_mutex=PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
  28 static float ***window_func=0; /* sin(), sin()^2, sin(sin()^2),sin(sin^2)^2
  29
  30                                   1,2,4,8,16,32,64,128,256,512,1024,
  31                                   2048,4096,8192,16384,32768,65536 */
  32
  33 /* type is one of 0==sin(x),
  34                   1==sin(x)^2,
  35                   2==sin(sin(x)^2),
  36                   3==sin(sin(x)^2)^2 */
  37 /* returns quarter-cycle (left half) n+1 samples of a window from 0. to 1. */
  38 static int ilog(long x){
  39   int ret=-1;
  40
  41   while(x>0){
  42     x>>=1;
  43     ret++;
  44   }
  45   return ret;
  46 }
  47
  48 float *window_get(int type,int n){
  49   int bits=ilog(n),i;
  50   if((1<<bits)!=n)return 0;
  51
  52   if(bits<0)return 0;
  53   if(bits>=17)return 0;
  54
  55   if(type<0)return 0;
  56   if(type>3)return 0;
  57
  58   pthread_mutex_lock(&window_mutex);
  59   if(!window_func)
  60     window_func=calloc(4,sizeof(*window_func));
  61
  62   if(!window_func[type])
  63     window_func[type]=calloc(17,sizeof(**window_func));
  64
  65   if(!window_func[type][bits]){
  66     window_func[type][bits]=malloc((n+1)*sizeof(***window_func));
  67     for(i=0;i<n+1;i++)window_func[type][bits][i]=sin(M_PIl*.5*i/n);
  68     if(type>0)
  69       for(i=0;i<n+1;i++)window_func[type][bits][i]*=
  70                            window_func[type][bits][i];
  71     if(type>1)
  72       for(i=0;i<n+1;i++)window_func[type][bits][i]=
  73                            sin(window_func[type][bits][i]*M_PIl*.5);
  74     if(type>2)
  75       for(i=0;i<n+1;i++)window_func[type][bits][i]*=
  76                            window_func[type][bits][i];
  77   }
  78
  79   pthread_mutex_unlock(&window_mutex);
  80   return window_func[type][bits];
  81 }
  82
  83 void window_apply(float *data, float *window, float scale, int halfn){
  84   float *data2=data+halfn*2;
  85   int i;
  86
  87   *(data++) *= window[0]*scale;
  88   for(i=1;i<halfn;i++){
  89     float val=window[i]*scale;
  90     *(data++) *= val;
  91     *(--data2)*= val;
  92   }
  93   *(data++) *= window[i]*scale;
  94 }