sys/sdl/sdl-audio.c

   1 /*
   2  * sdl-audio.c
   3  * sdl audio interface
   4  *
   5  * (C) 2001 Laguna
   6  *
   7  * Licensed under the GPLv2, or later.
   8  */
   9
  10 #include <stdlib.h>
  11 #include <stdio.h>
  12
  13 #include <SDL/SDL.h>
  14
  15 #include "rc.h"
  16 #include "pcm.h"
  17
  18
  19 struct pcm pcm;
  20
  21
  22 static int sound = 1;
  23 static int samplerate = 44100;
  24 static int stereo = 1;
  25 static volatile int audio_done;
  26
  27 rcvar_t pcm_exports[] =
  28 {
  29         RCV_BOOL("sound", &sound, "enable sound"),
  30         RCV_INT("stereo", &stereo, "enable stereo"),
  31         RCV_INT("samplerate", &samplerate, "samplerate, recommended: 32768"),
  32         RCV_END
  33 };
  34
  35
  36 static void audio_callback(void *blah, byte *stream, int len)
  37 {
  38         memcpy(stream, pcm.buf, len);
  39         audio_done = 1;
  40 }
  41
  42
  43 void pcm_init()
  44 {
  45         int i;
  46         SDL_AudioSpec as = {0}, ob;
  47
  48         if (!sound) return;
  49
  50         SDL_InitSubSystem(SDL_INIT_AUDIO);
  51         as.freq = samplerate;
  52         as.format = AUDIO_U8;
  53         as.channels = 1 + stereo;
  54         as.samples = samplerate / 60;
  55         for (i = 1; i < as.samples; i<<=1);
  56         as.samples = i;
  57         as.callback = audio_callback;
  58         as.userdata = 0;
  59         if (SDL_OpenAudio(&as, &ob) == -1) {
  60                 sound = 0;
  61                 return;
  62         }
  63
  64         pcm.hz = ob.freq;
  65         pcm.stereo = ob.channels - 1;
  66         pcm.len = ob.size;
  67         pcm.buf = malloc(pcm.len);
  68         pcm.pos = 0;
  69         memset(pcm.buf, 0, pcm.len);
  70
  71         SDL_PauseAudio(0);
  72 }
  73
  74 int pcm_submit()
  75 {
  76         if (!pcm.buf) return 0;
  77         if (pcm.pos < pcm.len) return 1;
  78         while (!audio_done)
  79                 SDL_Delay(4);
  80         audio_done = 0;
  81         pcm.pos = 0;
  82         return 1;
  83 }
  84
  85 void pcm_close()
  86 {
  87         if (sound) SDL_CloseAudio();
  88 }
  89
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