source: roaraudio/libroardsp/fader.c @ 3003:9d0935291fca

//fader.c:

/*
 *      Copyright (C) Philipp 'ph3-der-loewe' Schafft - 2009
 *
 *  This file is part of libroardsp a part of RoarAudio,
 *  a cross-platform sound system for both, home and professional use.
 *  See README for details.
 *
 *  This file is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 3
 *  as published by the Free Software Foundation.
 *
 *  libroardsp 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this software; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include "libroardsp.h"

#define _CHECK_BASIC()   if ( state == NULL ) return -1
#define _CHECK_CALCPCM() _CHECK_BASIC(); if ( frames == 0 ) return 0; if ( data == NULL ) return -1;

int roar_fader_init         (struct roar_fader_state * state, float * poly, int coeff) {
 _CHECK_BASIC();

 if ( poly == NULL )
  return -1;

 if ( coeff < 2 )
  return -1;

 if ( coeff > ROAR_FADER_MAX_COEFF )
  return -1;

 memset(state, 0, sizeof(struct roar_fader_state));

 state->rate  = -1;
 state->coeff = coeff;

 state->start = -1;
 state->stop  = -1;

 memcpy(state->poly, poly, sizeof(float)*coeff);

 return 0;
}

int roar_fader_set_rate     (struct roar_fader_state * state, int rate) {
 _CHECK_BASIC();

 state->rate = rate;

 return 0;
}

int roar_fader_set_startstop(struct roar_fader_state * state, ssize_t start, ssize_t stop) {
 _CHECK_BASIC();

 if ( start >= 0 )
  state->start = start;

 if ( stop  >= 0 )
  state->stop  = stop;

 return 0;
}

int roar_fader_calcpcm_i16n(struct roar_fader_state * state, int16_t * data, size_t frames, int channels) {
 _CHECK_CALCPCM();

 switch (channels) {
  case 1: return roar_fader_calcpcm_i161(state, data, frames);
 }

 return -1;
}

int roar_fader_calcpcm_i161(struct roar_fader_state * state, int16_t * data, size_t frames) {
 size_t start, stop, cur;
 int i, i_s, i_e;
 float t_cur, t_step;
 float g_cur;

 _CHECK_BASIC();

 if ( state->start == -1 ) {
  start = state->pcmoffset;
 } else {
  start = state->start;
 }

 if ( state->stop == -1 ) {
  stop = state->pcmoffset + frames;
 } else {
  stop = state->stop;
 }

 cur = state->pcmoffset;

 i_s = 0;
 i_e = frames;

 if ( start > cur )
  i_s = start - cur;

 if ( stop < (cur + frames) )
  i_e = stop  - cur;

 t_step = (float)(state->coeff - 1)/(float)(stop - start);

 if ( start < cur ) {
  t_cur = (cur - start)*t_step;
 } else {
  t_cur = 0;
 }

 ROAR_DBG("roar_fader_calcpcm_i161(*): i_s->i_e: %i->%i", i_s, i_e);

 for (i = i_s; i < i_e; i++, cur++) {
  t_cur  += t_step;
  g_cur   = roar_math_cvpoly(state->poly, t_cur, state->coeff);
//  ROAR_DBG("roar_fader_calcpcm_i161(*): i=%i, g_cur=%f", i, g_cur);
  data[i] = (float)data[i] * g_cur;
 }

 state->pcmoffset = cur;

 return -1;
}

//ll