libaf/af_resample.h

   1 /*=============================================================================
   2 //
   3 //  This software has been released under the terms of the GNU Public
   4 //  license. See http://www.gnu.org/copyleft/gpl.html for details.
   5 //
   6 //  Copyright 2002 Anders Johansson ajh@atri.curtin.edu.au
   7 //
   8 //=============================================================================
   9 */
  10
  11 /* This file contains the resampling engine, the sample format is
  12    controlled by the FORMAT parameter, the filter length by the L
  13    parameter and the resampling type by UP and DN. This file should
  14    only be included by af_resample.c
  15 */
  16
  17 #undef L
  18 #undef SHIFT
  19 #undef FORMAT
  20 #undef FIR
  21 #undef ADDQUE
  22
  23 /* The lenght Lxx definition selects the length of each poly phase
  24    component. Valid definitions are L8 and L16 where the number
  25    defines the nuber of taps. This definition affects the
  26    computational complexity, the performance and the memory usage.
  27 */
  28
  29 /* The FORMAT_x parameter selects the sample format type currently
  30    float and int16 are supported. Thes two formats are selected by
  31    defining eiter FORMAT_F or FORMAT_I. The advantage of using float
  32    is that the amplitude and therefore the SNR isn't affected by the
  33    filtering, the disadvantage is that it is a lot slower.
  34 */
  35
  36 #if defined(FORMAT_I)
  37 #define SHIFT >>16
  38 #define FORMAT int16_t
  39 #else
  40 #define SHIFT
  41 #define FORMAT float
  42 #endif
  43
  44 // Short filter
  45 #if defined(L8)
  46
  47 #define L       8       // Filter length
  48 // Unrolled loop to speed up execution
  49 #define FIR(x,w,y) \
  50   (y[0])  = ( w[0]*x[0]+w[1]*x[1]+w[2]*x[2]+w[3]*x[3] \
  51             + w[4]*x[4]+w[5]*x[5]+w[6]*x[6]+w[7]*x[7] ) SHIFT
  52
  53
  54
  55 #else  /* L8/L16 */
  56
  57 #define L       16
  58 // Unrolled loop to speed up execution
  59 #define FIR(x,w,y) \
  60   y[0] = ( w[0] *x[0] +w[1] *x[1] +w[2] *x[2] +w[3] *x[3] \
  61          + w[4] *x[4] +w[5] *x[5] +w[6] *x[6] +w[7] *x[7] \
  62          + w[8] *x[8] +w[9] *x[9] +w[10]*x[10]+w[11]*x[11] \
  63          + w[12]*x[12]+w[13]*x[13]+w[14]*x[14]+w[15]*x[15] ) SHIFT
  64
  65 #endif /* L8/L16 */
  66
  67 // Macro to add data to circular que
  68 #define ADDQUE(xi,xq,in)\
  69   xq[xi]=xq[(xi)+L]=*(in);\
  70   xi=((xi)-1)&(L-1);
  71
  72 #if defined(UP)
  73
  74   uint32_t              ci    = l->nch;         // Index for channels
  75   uint32_t              nch   = l->nch;         // Number of channels
  76   uint32_t              inc   = s->up/s->dn;
  77   uint32_t              level = s->up%s->dn;
  78   uint32_t              up    = s->up;
  79   uint32_t              dn    = s->dn;
  80   uint32_t              ns    = c->len/l->bps;
  81   register FORMAT*      w     = s->w;
  82
  83   register uint32_t     wi    = 0;
  84   register uint32_t     xi    = 0;
  85
  86   // Index current channel
  87   while(ci--){
  88     // Temporary pointers
  89     register FORMAT*    x     = s->xq[ci];
  90     register FORMAT*    in    = ((FORMAT*)c->audio)+ci;
  91     register FORMAT*    out   = ((FORMAT*)l->audio)+ci;
  92     FORMAT*             end   = in+ns; // Block loop end
  93     wi = s->wi; xi = s->xi;
  94
  95     while(in < end){
  96       register uint32_t i = inc;
  97       if(wi<level) i++;
  98
  99       ADDQUE(xi,x,in);
 100       in+=nch;
 101       while(i--){
 102         // Run the FIR filter
 103         FIR((&x[xi]),(&w[wi*L]),out);
 104         len++; out+=nch;
 105         // Update wi to point at the correct polyphase component
 106         wi=(wi+dn)%up;
 107       }
 108     }
 109
 110   }
 111   // Save values that needs to be kept for next time
 112   s->wi = wi;
 113   s->xi = xi;
 114 #endif /* UP */
 115
 116 #if defined(DN) /* DN */
 117   uint32_t              ci    = l->nch;         // Index for channels
 118   uint32_t              nch   = l->nch;         // Number of channels
 119   uint32_t              inc   = s->dn/s->up;
 120   uint32_t              level = s->dn%s->up;
 121   uint32_t              up    = s->up;
 122   uint32_t              dn    = s->dn;
 123   uint32_t              ns    = c->len/l->bps;
 124   FORMAT*               w     = s->w;
 125
 126   register int32_t      i     = 0;
 127   register uint32_t     wi    = 0;
 128   register uint32_t     xi    = 0;
 129
 130   // Index current channel
 131   while(ci--){
 132     // Temporary pointers
 133     register FORMAT*    x     = s->xq[ci];
 134     register FORMAT*    in    = ((FORMAT*)c->audio)+ci;
 135     register FORMAT*    out   = ((FORMAT*)l->audio)+ci;
 136     register FORMAT*    end   = in+ns;    // Block loop end
 137     i = s->i; wi = s->wi; xi = s->xi;
 138
 139     while(in < end){
 140
 141       ADDQUE(xi,x,in);
 142       in+=nch;
 143       if((--i)<=0){
 144         // Run the FIR filter
 145         FIR((&x[xi]),(&w[wi*L]),out);
 146         len++;  out+=nch;
 147
 148         // Update wi to point at the correct polyphase component
 149         wi=(wi+dn)%up;
 150
 151         // Insert i number of new samples in queue
 152         i = inc;
 153         if(wi<level) i++;
 154       }
 155     }
 156   }
 157   // Save values that needs to be kept for next time
 158   s->wi = wi;
 159   s->xi = xi;
 160   s->i = i;
 161 #endif /* DN */