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    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
 116the_end:
 117    *isamp = ibuf - istart;
 118    *osamp = obuf - ostart;
 119    rate->ilast = ilast;
 120}
 121
 122#undef NAME
 123#undef OP
 124