LXR qemu/audio/rate

   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 */
  30void 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    ilast = rate->ilast;
  44
  45    istart = ibuf;
  46    iend = ibuf + *isamp;
  47
  48    ostart = obuf;
  49    oend = obuf + *osamp;
  50
  51    if (rate->opos_inc == (1ULL + UINT_MAX)) {
  52        int i, n = *isamp > *osamp ? *osamp : *isamp;
  53        for (i = 0; i < n; i++) {
  54            OP (obuf[i].l, ibuf[i].l);
  55            OP (obuf[i].r, ibuf[i].r);
  56        }
  57        *isamp = n;
  58        *osamp = n;
  59        return;
  60    }
  61
  62    while (obuf < oend) {
  63
  64        /* Safety catch to make sure we have input samples.  */
  65        if (ibuf >= iend) {
  66            break;
  67        }
  68
  69        /* read as many input samples so that ipos > opos */
  70
  71        while (rate->ipos <= (rate->opos >> 32)) {
  72            ilast = *ibuf++;
  73            rate->ipos++;
  74
  75            /* if ipos overflow, there is  a infinite loop */
  76            if (rate->ipos == 0xffffffff) {
  77                rate->ipos = 1;
  78                rate->opos = rate->opos & 0xffffffff;
  79            }
  80            /* See if we finished the input buffer yet */
  81            if (ibuf >= iend) {
  82                goto the_end;
  83            }
  84        }
  85
  86        icur = *ibuf;
  87
  88        /* interpolate */
  89#ifdef FLOAT_MIXENG
  90#ifdef RECIPROCAL
  91        t = (rate->opos & UINT_MAX) * (1.f / UINT_MAX);
  92#else
  93        t = (rate->opos & UINT_MAX) / (mixeng_real) UINT_MAX;
  94#endif
  95        out.l = (ilast.l * (1.0 - t)) + icur.l * t;
  96        out.r = (ilast.r * (1.0 - t)) + icur.r * t;
  97#else
  98        t = rate->opos & 0xffffffff;
  99        out.l = (ilast.l * ((int64_t) UINT_MAX - t) + icur.l * t) >> 32;
 100        out.r = (ilast.r * ((int64_t) UINT_MAX - t) + icur.r * t) >> 32;
 101#endif
 102
 103        /* output sample & increment position */
 104        OP (obuf->l, out.l);
 105        OP (obuf->r, out.r);
 106        obuf += 1;
 107        rate->opos += rate->opos_inc;
 108    }
 109
 110the_end:
 111    *isamp = ibuf - istart;
 112    *osamp = obuf - ostart;
 113    rate->ilast = ilast;
 114}
 115
 116#undef NAME
 117#undef OP
 118