audio.c

   1 /*
   2    Cantaveria - action adventure platform game
   3    Copyright (C) 2009  Evan Rinehart
   4
   5    This program is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU General Public License
   7    as published by the Free Software Foundation; either version 2
   8    of the License, or (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to
  17
  18    The Free Software Foundation, Inc.
  19    51 Franklin Street, Fifth Floor
  20    Boston, MA  02110-1301, USA
  21 */
  22
  23 #include <stdlib.h>
  24
  25 #include <SDL/SDL.h>
  26
  27 #include <synth.h>
  28 #include <audio.h>
  29 #include <util.h>
  30
  31 float* lout;
  32 float* rout;
  33
  34 void audio_callback(void *userdata, Uint8 *stream, int bytes){
  35         int i, j;
  36         Sint16* out = (Sint16*)stream;
  37         int buflen = bytes / 2;        /* Sint16 = 2 bytes */
  38         int samples = buflen / 2;      /* 2 channels */
  39
  40         synth_generate(lout, rout, samples);
  41
  42         for(i=0, j=0; i<samples; i++){
  43                 out[j] = (Sint16)(lout[i]*32767); j++;
  44                 out[j] = (Sint16)(rout[i]*32767); j++;
  45         }
  46
  47 }
  48 void audio_init(){
  49         SDL_AudioSpec want;
  50         SDL_AudioSpec got;
  51
  52
  53         want.freq = SAMPLE_RATE;
  54         want.format = AUDIO_S16;
  55         want.channels = 2;
  56         want.samples = BUFFER_SIZE;
  57         want.callback = audio_callback;
  58
  59
  60         if(SDL_OpenAudio(&want, &got)<0){
  61                 report_error("sdl: cannot open audio (%s)\n", SDL_GetError());
  62                 exit(-1);
  63         }
  64
  65         printf("audio:\n");
  66         printf(" sample rate = %d\n", got.freq);
  67         printf(" channels = %d\n", got.channels);
  68         printf(" samples = %d\n", got.samples);
  69         printf(" format = %d\n", got.format);
  70
  71         if(got.format != AUDIO_S16){
  72                 printf("    WARNING: audio format not AUDIO_S16 :(\n");
  73                 return;
  74         }
  75
  76         lout = xmalloc(got.samples*sizeof(float));
  77         rout = xmalloc(got.samples*sizeof(float));
  78
  79         printf(" sound on\n");
  80         SDL_PauseAudio(0);
  81
  82 }
  83
  84 void audio_quit(){
  85         SDL_CloseAudio();
  86         free(lout);
  87         free(rout);
  88 }
  89
  90