/*
 *    Example program for the Allegro library, by Shawn Hargreaves.
 *
 *    This program shows how to use the audio stream functions to
 *    transfer large blocks of sample data to the sound card. In
 *    this case, the sample data is generated during runtime,
 *    and the resulting sound reminds of a car engine when you
 *    are accelerating.
 */


#include <allegro.h>


#define BUFFER_SIZE  1024


int main(void)
{
   AUDIOSTREAM *stream;
   unsigned char *p;
   int updates = 0;
   int pitch = 0;
   int val = 0;
   int i,c ;

   if (allegro_init() != 0)
      return 1;
   install_keyboard(); 
   install_timer();

   if (set_gfx_mode(GFX_AUTODETECT_WINDOWED, 320, 200, 0, 0) != 0) {
      if (set_gfx_mode(GFX_SAFE, 320, 200, 0, 0) != 0) {
	 set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
	 allegro_message("Unable to set any graphic mode\n%s\n",
			 allegro_error);
	 return 1;
      }
   }

   if (set_display_switch_mode(SWITCH_BACKGROUND) != 0) {
      set_display_switch_mode(SWITCH_BACKAMNESIA);
   }

   set_palette(desktop_palette);
   clear_to_color(screen, makecol(255, 255, 255));

   /* install a digital sound driver */
   if (install_sound(DIGI_AUTODETECT, MIDI_NONE, NULL) != 0) {
      set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
      allegro_message("Error initialising sound driver\n%s\n",
		      allegro_error);
      return 1;
   }

   /* we want a _real_ sound driver */
   if (digi_card == DIGI_NONE) {
      set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
      allegro_message("Unable to find a sound driver\n%s\n",
		      allegro_error);
      return 1;
   }
   
   /* create an audio stream */
   stream = play_audio_stream(BUFFER_SIZE, 8, FALSE, 22050, 255, 128);
   if (!stream) {
      set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
      allegro_message("Error creating audio stream!\n");
      return 1;
   }

   textprintf_centre_ex(screen, font, SCREEN_W/2, SCREEN_H/3-24,
			makecol(0, 0, 0), makecol(255, 255, 255),
			"Audio stream is now playing...");
   textprintf_centre_ex(screen, font, SCREEN_W/2, SCREEN_H/3,
			makecol(0, 0, 0), makecol(255, 255, 255),
			"Driver: %s", digi_driver->name);
   textprintf_centre_ex(screen, font, SCREEN_W/2, SCREEN_H/3+24,
			makecol(0, 0, 0), makecol(255, 255, 255),
			"Press [space] to stop/resume");

   while (TRUE) {
      if (keypressed()) {
	 c = readkey();
	 if ((c >> 8) == KEY_SPACE) {
	    voice_stop(stream->voice);
	    while (TRUE) {
	       c = readkey();
	       if ((c >> 8) == KEY_ESC)
		  goto End;
	       else if ((c >> 8) == KEY_SPACE)
		  break;
	    }
	    voice_start(stream->voice);
	 }
	 else if ((c >> 8) == KEY_ESC)
	    break;
      }
	       
      /* does the stream need any more data yet? */
      p = get_audio_stream_buffer(stream);

      if (p) {
	 /* if so, generate a bit more of our waveform... */
	 textprintf_centre_ex(screen, font, SCREEN_W/2, SCREEN_H*2/3,
			      makecol(0, 0, 0), makecol(255, 255, 255),
			      "update #%d", updates++);

	 for (i=0; i<BUFFER_SIZE; i++) {
	    /* this is just a sawtooth wave that gradually increases in 
	     * pitch. Obviously you would want to do something a bit more
	     * interesting here, for example you could fread() the next
	     * buffer of data in from a disk file...
	     */
	    p[i] = (val >> 16) & 0xFF;
	    val += pitch;
	    pitch++;
	    if (pitch > 0x40000)
	       pitch = 0x10000;
	 }

	 free_audio_stream_buffer(stream);
      }
   }

 End:
   stop_audio_stream(stream);

   return 0;
}

END_OF_MAIN()