/* compile: gcc -L/usr/lib `sdl-config --cflags --libs` sound.c -o sound */

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <SDL.h>
#include <SDL_audio.h>

typedef struct {
   SDL_AudioSpec   spec;
   Uint8          *sound;      /* ptr to wave data */
   Uint32          soundlen;   /* length of wave data */
   int             soundpos;   /* current play position */
} WAVE_T;


static int volume = SDL_MIX_MAXVOLUME;
static int done = 0;
static int spid;
static WAVE_T wave;

void play (void *unused, Uint8 *stream, int len) 

{
  Uint8 *waveptr;
  int waveleft;

  /* set up the pointers */
  waveptr  = wave.sound + wave.soundpos;
  waveleft = wave.soundlen - wave.soundpos;

  /* play sound */
  while (waveleft <= len) {
    SDL_MixAudio (stream, waveptr, waveleft, volume);
    stream += waveleft;
    len -= waveleft;
    waveptr = wave.sound;
    waveleft = wave.soundlen;
    wave.soundpos = 0;
  }

  SDL_MixAudio(stream, waveptr, len, volume);
  wave.soundpos += len;
}


void quit (int sig) 

{
  done = 1;
}


void play_sound_clip (char *fn) 

{
  char name [32];

  /* load the SDL library */
  if (SDL_Init (SDL_INIT_AUDIO) < 0 ) {
    fprintf (stderr, "Couldn't initialize SDL: %s\n", SDL_GetError ());
    exit (1);
  }

  atexit (SDL_Quit);

  /* load the wave file into memory */
  if (SDL_LoadWAV (fn, &wave.spec, &wave.sound, &wave.soundlen) == NULL) {
    fprintf (stderr, "Couldn't load %s: %s\n", fn, SDL_GetError ());
    exit (1);
  }

  wave.spec.callback = play;

  while (!done) {
    printf("Playing sound with volume = %d\n", volume);

    /* initialize play () variables */
    if (SDL_OpenAudio (&wave.spec, NULL) < 0) {
      fprintf (stderr, "Couldn't open audio: %s\n", SDL_GetError ());
      SDL_FreeWAV (wave.sound);
      exit (2);
    }

    /* enable audio to play */
    SDL_PauseAudio (0);

    /* let the audio run */
    printf ("Using audio driver: %s\n", SDL_AudioDriverName (name, 32));
    while (!done && (SDL_GetAudioStatus () == SDL_AUDIO_PLAYING))
      SDL_Delay (1000);
  }
}


void close_sound () 

{
  printf ("closing down audio\n");
  SDL_CloseAudio ();
  SDL_FreeWAV (wave.sound);
  kill (spid, SIGKILL);
}


void main ()

{
  switch (spid = fork ()) {
    case -1: printf ("OOPS - Sound failed, no fork!\n");
             exit(1);

    case  0: play_sound_clip ("nature.wav");

    default: /* calling process -- return and keep processing */
             sleep (10);
             close_sound ();
  }
}