audio/rate_template.h

   1 /*
   2  * QEMU Mixing engine
   3  *
   4  * Copyright (c) 2004-2005 Vassili Karpov (malc)
   5  * Copyright (c) 1998 Fabrice Bellard
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 /*
  27  * Processed signed long samples from ibuf to obuf.
  28  * Return number of samples processed.
  29  */
  30 void NAME (void *opaque, struct st_sample *ibuf, struct st_sample *obuf,
  31            size_t *isamp, size_t *osamp)
  32 {
  33     struct rate *rate = opaque;
  34     struct st_sample *istart, *iend;
  35     struct st_sample *ostart, *oend;
  36     struct st_sample ilast, icur, out;
  37 #ifdef FLOAT_MIXENG
  38     mixeng_real t;
  39 #else
  40     int64_t t;
  41 #endif
  42
  43     istart = ibuf;
  44     iend = ibuf + *isamp;
  45
  46     ostart = obuf;
  47     oend = obuf + *osamp;
  48
  49     if (rate->opos_inc == (1ULL + UINT_MAX)) {
  50         int i, n = *isamp > *osamp ? *osamp : *isamp;
  51         for (i = 0; i < n; i++) {
  52             OP (obuf[i].l, ibuf[i].l);
  53             OP (obuf[i].r, ibuf[i].r);
  54         }
  55         *isamp = n;
  56         *osamp = n;
  57         return;
  58     }
  59
  60     /* without input samples, there's nothing to do */
  61     if (ibuf >= iend) {
  62         *osamp = 0;
  63         return;
  64     }
  65
  66     ilast = rate->ilast;
  67
  68     while (true) {
  69
  70         /* read as many input samples so that ipos > opos */
  71         while (rate->ipos <= (rate->opos >> 32)) {
  72             ilast = *ibuf++;
  73             rate->ipos++;
  74
  75             /* See if we finished the input buffer yet */
  76             if (ibuf >= iend) {
  77                 goto the_end;
  78             }
  79         }
  80
  81         /* make sure that the next output sample can be written */
  82         if (obuf >= oend) {
  83             break;
  84         }
  85
  86         icur = *ibuf;
  87
  88         /* wrap ipos and opos around long before they overflow */
  89         if (rate->ipos >= 0x10001) {
  90             rate->ipos = 1;
  91             rate->opos &= 0xffffffff;
  92         }
  93
  94         /* interpolate */
  95 #ifdef FLOAT_MIXENG
  96 #ifdef RECIPROCAL
  97         t = (rate->opos & UINT_MAX) * (1.f / UINT_MAX);
  98 #else
  99         t = (rate->opos & UINT_MAX) / (mixeng_real) UINT_MAX;
 100 #endif
 101         out.l = (ilast.l * (1.0 - t)) + icur.l * t;
 102         out.r = (ilast.r * (1.0 - t)) + icur.r * t;
 103 #else
 104         t = rate->opos & 0xffffffff;
 105         out.l = (ilast.l * ((int64_t) UINT_MAX - t) + icur.l * t) >> 32;
 106         out.r = (ilast.r * ((int64_t) UINT_MAX - t) + icur.r * t) >> 32;
 107 #endif
 108
 109         /* output sample & increment position */
 110         OP (obuf->l, out.l);
 111         OP (obuf->r, out.r);
 112         obuf += 1;
 113         rate->opos += rate->opos_inc;
 114     }
 115
 116 the_end:
 117     *isamp = ibuf - istart;
 118     *osamp = obuf - ostart;
 119     rate->ilast = ilast;
 120 }
 121
 122 #undef NAME
 123 #undef OP