src/divide.c

   1 /* libSoX effect: divide   Copyright (c) 2009 robs@users.sourceforge.net
   2  *
   3  * This library is free software; you can redistribute it and/or modify it
   4  * under the terms of the GNU Lesser General Public License as published by
   5  * the Free Software Foundation; either version 2.1 of the License, or (at
   6  * your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  16  */
  17
  18 /* This is W.I.P. hence marked SOX_EFF_ALPHA for now.
  19  * Needs better handling of when the divisor approaches or is zero; some
  20  * sort of interpolation of the output values perhaps.
  21  */
  22
  23 #include "sox_i.h"
  24 #include <string.h>
  25
  26 typedef struct {
  27   sox_sample_t * last;
  28 } priv_t;
  29
  30 static int start(sox_effect_t * effp)
  31 {
  32   priv_t * p = (priv_t *)effp->priv;
  33   p->last = lsx_calloc(effp->in_signal.channels, sizeof(*p->last));
  34   return SOX_SUCCESS;
  35 }
  36
  37 static int flow(sox_effect_t * effp, const sox_sample_t * ibuf,
  38     sox_sample_t * obuf, size_t * isamp, size_t * osamp)
  39 {
  40   priv_t * p = (priv_t *)effp->priv;
  41   size_t i, len =  min(*isamp, *osamp) / effp->in_signal.channels;
  42   *osamp = *isamp = len * effp->in_signal.channels;
  43
  44   while (len--) {
  45     double divisor = *obuf++ = *ibuf++;
  46     if (divisor) {
  47       double out, mult = 1. / SOX_SAMPLE_TO_FLOAT_64BIT(divisor,);
  48       for (i = 1; i < effp->in_signal.channels; ++i) {
  49         out = *ibuf++ * mult;
  50         p->last[i] = *obuf++ = SOX_ROUND_CLIP_COUNT(out, effp->clips);
  51       }
  52     }
  53     else for (i = 1; i < effp->in_signal.channels; ++i, ++ibuf)
  54       *obuf++ = p->last[i];
  55   }
  56   return SOX_SUCCESS;
  57 }
  58
  59 static int stop(sox_effect_t * effp)
  60 {
  61   priv_t * p = (priv_t *)effp->priv;
  62   free(p->last);
  63   return SOX_SUCCESS;
  64 }
  65
  66 sox_effect_handler_t const * lsx_divide_effect_fn(void)
  67 {
  68   static sox_effect_handler_t handler = {
  69     "divide", NULL, SOX_EFF_MCHAN | SOX_EFF_GAIN | SOX_EFF_ALPHA,
  70     NULL, start, flow, NULL, stop, NULL, sizeof(priv_t)
  71   };
  72   return &handler;
  73 }