/* libSoX effect: Skeleton effect used as sample for creating new effects. * * Copyright 1999-2008 Chris Bagwell And SoX Contributors * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or (at * your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser * General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this library; if not, write to the Free Software Foundation, * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA */ #include "sox_i.h" /* Private data for effect */typedef struct {  int  localdata;} priv_t; /* * Process command-line options but don't do other * initialization now: effp->in_signal & effp->out_signal are not * yet filled in. */static int getopts(sox_effect_t * effp, int argc, char UNUSED **argv){  priv_t * UNUSED p = (priv_t *)effp->priv;   if (argc != 2)    return lsx_usage(effp);   p->localdata = atoi(argv[1]);   return p->localdata > 0 ? SOX_SUCCESS : SOX_EOF;} /* * Prepare processing. * Do all initializations. */static int start(sox_effect_t * effp){  if (effp->out_signal.channels == 1) {    lsx_fail("Can't run on mono data.");    return SOX_EOF;  }   return SOX_SUCCESS;} /* * Process up to *isamp samples from ibuf and produce up to *osamp samples * in obuf.  Write back the actual numbers of samples to *isamp and *osamp. * Return SOX_SUCCESS or, if error occurs, SOX_EOF. */static int flow(sox_effect_t * effp, const sox_sample_t *ibuf, sox_sample_t *obuf,                           size_t *isamp, size_t *osamp){  size_t len, done;   switch (effp->out_signal.channels) {  case 2:    /* Length to process will be buffer length / 2 since we     * work with two samples at a time.     */    len = min(*isamp, *osamp) / 2;    for (done = 0; done < len; done++)      {        obuf[0] = ibuf[0];        obuf[1] = ibuf[1];        /* Advance buffer by 2 samples */        ibuf += 2;        obuf += 2;      }     *isamp = len * 2;    *osamp = len * 2;     break;  }   return SOX_SUCCESS;} /* * Drain out remaining samples if the effect generates any. */static int drain(sox_effect_t UNUSED * effp, sox_sample_t UNUSED *obuf, size_t *osamp){  USED(effp); USED(obuf);  *osamp = 0;  /* Return SOX_EOF when drain   * will not output any more samples.   * *osamp == 0 also indicates that.   */  return SOX_EOF;} /* * Do anything required when you stop reading samples. */static int stop(sox_effect_t UNUSED * effp){  USED(effp);  return SOX_SUCCESS;} /* * Do anything required when you kill an effect. *      (free allocated memory, etc.) */static int lsx_kill(sox_effect_t UNUSED * effp){  USED(effp);  return SOX_SUCCESS;} /* * Function returning effect descriptor. This should be the only * externally visible object. */const sox_effect_handler_t *lsx_skel_effect_fn(void);const sox_effect_handler_t *lsx_skel_effect_fn(void){  /*   * Effect descriptor.   * If no specific processing is needed for any of   * the 6 functions, then the function above can be deleted   * and NULL used in place of the its name below.   */  static sox_effect_handler_t sox_skel_effect = {    "skel", "[OPTION]", SOX_EFF_MCHAN,    getopts, start, flow, drain, stop, lsx_kill, sizeof(priv_t)  };  return &sox_skel_effect;}