src/audio/SDL_audio.c
author Sam Lantinga <slouken@lokigames.com>
Thu, 26 Apr 2001 16:45:43 +0000
changeset 0 74212992fb08
child 21 75a95f82bc1f
permissions -rw-r--r--
Initial revision

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@devolution.com
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif

/* Allow access to a raw mixing buffer */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "SDL.h"
#include "SDL_audio.h"
#include "SDL_timer.h"
#include "SDL_error.h"
#include "SDL_audio_c.h"
#include "SDL_audiomem.h"
#include "SDL_sysaudio.h"

/* Available audio drivers */
static AudioBootStrap *bootstrap[] = {
#if defined(unix) && \
   !defined(linux) && !defined(__FreeBSD__) && !defined(__CYGWIN32__) \
   && !defined(__bsdi__)
	&AUDIO_bootstrap,
#endif
#ifdef OSS_SUPPORT
	&DSP_bootstrap,
	&DMA_bootstrap,
#endif
#ifdef ALSA_SUPPORT
	&ALSA_bootstrap,
#endif
#ifdef ARTSC_SUPPORT
	&ARTSC_bootstrap,
#endif
#ifdef ESD_SUPPORT
	&ESD_bootstrap,
#endif
#ifdef NAS_SUPPORT
	&NAS_bootstrap,
#endif
#ifdef ENABLE_DIRECTX
	&DSOUND_bootstrap,
#endif
#ifdef ENABLE_WINDIB
	&WAVEOUT_bootstrap,
#endif
#ifdef __BEOS__
	&BAUDIO_bootstrap,
#endif
#if defined(macintosh) || TARGET_API_MAC_CARBON
	&SNDMGR_bootstrap,
#endif
#ifdef _AIX
	&Paud_bootstrap,
#endif
	NULL
};
SDL_AudioDevice *current_audio = NULL;

/* Various local functions */
int SDL_AudioInit(const char *driver_name);
void SDL_AudioQuit(void);


/* The general mixing thread function */
int SDL_RunAudio(void *audiop)
{
	SDL_AudioDevice *audio = (SDL_AudioDevice *)audiop;
	Uint8 *stream;
	int    stream_len;
	void  *udata;
	void (*fill)(void *userdata,Uint8 *stream, int len);
	int    silence;

	/* Perform any thread setup */
	if ( audio->ThreadInit ) {
		audio->ThreadInit(audio);
	}
	audio->threadid = SDL_ThreadID();

	/* Set up the mixing function */
	fill  = audio->spec.callback;
	udata = audio->spec.userdata;
	if ( audio->convert.needed ) {
		if ( audio->convert.src_format == AUDIO_U8 ) {
			silence = 0x80;
		} else {
			silence = 0;
		}
		stream_len = audio->convert.len;
	} else {
		silence = audio->spec.silence;
		stream_len = audio->spec.size;
	}
	stream = audio->fake_stream;

	/* Loop, filling the audio buffers */
	while ( audio->enabled ) {

		/* Wait for new current buffer to finish playing */
		if ( stream == audio->fake_stream ) {
			SDL_Delay((audio->spec.samples*1000)/audio->spec.freq);
		} else {
			audio->WaitAudio(audio);
		}

		/* Fill the current buffer with sound */
		if ( audio->convert.needed ) {
			/* The buffer may not be allocated yet */
			if ( audio->convert.buf ) {
				stream = audio->convert.buf;
			} else {
				continue;
			}
		} else {
			stream = audio->GetAudioBuf(audio);
			if ( stream == NULL ) {
				stream = audio->fake_stream;
			}
		}
		memset(stream, silence, stream_len);

		if ( ! audio->paused ) {
			SDL_mutexP(audio->mixer_lock);
			(*fill)(udata, stream, stream_len);
			SDL_mutexV(audio->mixer_lock);
		}

		/* Convert the audio if necessary */
		if ( audio->convert.needed ) {
			SDL_ConvertAudio(&audio->convert);
			stream = audio->GetAudioBuf(audio);
			if ( stream == NULL ) {
				stream = audio->fake_stream;
			}
			memcpy(stream, audio->convert.buf,
			               audio->convert.len_cvt);
		}

		/* Ready current buffer for play and change current buffer */
		if ( stream != audio->fake_stream ) {
			audio->PlayAudio(audio);
		}
	}
	/* Wait for the audio to drain.. */
	if ( audio->WaitDone ) {
		audio->WaitDone(audio);
	}
	return(0);
}

int SDL_AudioInit(const char *driver_name)
{
	SDL_AudioDevice *audio;
	int i = 0, idx;

	/* Check to make sure we don't overwrite 'current_audio' */
	if ( current_audio != NULL ) {
		SDL_AudioQuit();
	}

	/* Select the proper audio driver */
	audio = NULL;
	idx = 0;
#ifdef unix
	if ( (driver_name == NULL) && (getenv("ESPEAKER") != NULL) ) {
		/* Ahem, we know that if ESPEAKER is set, user probably wants
		   to use ESD, but don't start it if it's not already running.
		   This probably isn't the place to do this, but... Shh! :)
		 */
		for ( i=0; bootstrap[i]; ++i ) {
			if ( strcmp(bootstrap[i]->name, "esd") == 0 ) {
				const char *esd_no_spawn;

				/* Don't start ESD if it's not running */
				esd_no_spawn = getenv("ESD_NO_SPAWN");
				if ( esd_no_spawn == NULL ) {
					putenv("ESD_NO_SPAWN=1");
				}
				if ( bootstrap[i]->available() ) {
					audio = bootstrap[i]->create(0);
					break;
				}
#ifdef linux	/* No unsetenv() on most platforms */
				if ( esd_no_spawn == NULL ) {
					unsetenv("ESD_NO_SPAWN");
				}
#endif
			}
		}
	}
#endif /* unix */
	if ( audio == NULL ) {
		if ( driver_name != NULL ) {
#if 0	/* This will be replaced with a better driver selection API */
			if ( strrchr(driver_name, ':') != NULL ) {
				idx = atoi(strrchr(driver_name, ':')+1);
			}
#endif
			for ( i=0; bootstrap[i]; ++i ) {
				if (strncmp(bootstrap[i]->name, driver_name,
				            strlen(bootstrap[i]->name)) == 0) {
					if ( bootstrap[i]->available() ) {
						audio=bootstrap[i]->create(idx);
						break;
					}
				}
			}
		} else {
			for ( i=0; bootstrap[i]; ++i ) {
				if ( bootstrap[i]->available() ) {
					audio = bootstrap[i]->create(idx);
					if ( audio != NULL ) {
						break;
					}
				}
			}
		}
		if ( audio == NULL ) {
			SDL_SetError("No available audio device");
#if 0 /* Don't fail SDL_Init() if audio isn't available.
         SDL_OpenAudio() will handle it at that point.  *sigh*
       */
			return(-1);
#endif
		}
	}
	current_audio = audio;
	if ( current_audio ) {
		current_audio->name = bootstrap[i]->name;
	}
	return(0);
}

char *SDL_AudioDriverName(char *namebuf, int maxlen)
{
	if ( current_audio != NULL ) {
		strncpy(namebuf, current_audio->name, maxlen-1);
		namebuf[maxlen-1] = '\0';
		return(namebuf);
	}
	return(NULL);
}

int SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained)
{
	SDL_AudioDevice *audio;

	/* Start up the audio driver, if necessary */
	if ( ! current_audio ) {
		if ( (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) ||
		     (current_audio == NULL) ) {
			return(-1);
		}
	}
	audio = current_audio;

	/* Verify some parameters */
	if ( desired->callback == NULL ) {
		SDL_SetError("SDL_OpenAudio() passed a NULL callback");
		return(-1);
	}
	switch ( desired->channels ) {
	    case 1:	/* Mono */
	    case 2:	/* Stereo */
		break;
	    default:
		SDL_SetError("1 (mono) and 2 (stereo) channels supported");
		return(-1);
	}

#ifdef macintosh
	/* FIXME: Need to implement PPC interrupt asm for SDL_LockAudio() */
#else
	/* Create a semaphore for locking the sound buffers */
	audio->mixer_lock = SDL_CreateMutex();
	if ( audio->mixer_lock == NULL ) {
		SDL_SetError("Couldn't create mixer lock");
		SDL_CloseAudio();
		return(-1);
	}
#endif

	/* Calculate the silence and size of the audio specification */
	SDL_CalculateAudioSpec(desired);

	/* Open the audio subsystem */
	memcpy(&audio->spec, desired, sizeof(audio->spec));
	audio->convert.needed = 0;
	audio->enabled = 1;
	audio->paused  = 1;
	audio->opened = audio->OpenAudio(audio, &audio->spec)+1;
	if ( ! audio->opened ) {
		SDL_CloseAudio();
		return(-1);
	}

	/* If the audio driver changes the buffer size, accept it */
	if ( audio->spec.samples != desired->samples ) {
		desired->samples = audio->spec.samples;
		SDL_CalculateAudioSpec(desired);
	}

	/* Allocate a fake audio memory buffer */
	audio->fake_stream = SDL_AllocAudioMem(audio->spec.size);
	if ( audio->fake_stream == NULL ) {
		SDL_CloseAudio();
		SDL_OutOfMemory();
		return(-1);
	}

	/* See if we need to do any conversion */
	if ( memcmp(desired, &audio->spec, sizeof(audio->spec)) == 0 ) {
		/* Just copy over the desired audio specification */
		if ( obtained != NULL ) {
			memcpy(obtained, &audio->spec, sizeof(audio->spec));
		}
	} else {
		/* Copy over the audio specification if possible */
		if ( obtained != NULL ) {
			memcpy(obtained, &audio->spec, sizeof(audio->spec));
		} else {
			/* Build an audio conversion block */
			if ( SDL_BuildAudioCVT(&audio->convert,
				desired->format, desired->channels,
						desired->freq,
				audio->spec.format, audio->spec.channels,
						audio->spec.freq) < 0 ) {
				SDL_CloseAudio();
				return(-1);
			}
			if ( audio->convert.needed ) {
				audio->convert.len = desired->size;
				audio->convert.buf =(Uint8 *)SDL_AllocAudioMem(
				   audio->convert.len*audio->convert.len_mult);
				if ( audio->convert.buf == NULL ) {
					SDL_CloseAudio();
					SDL_OutOfMemory();
					return(-1);
				}
			}
		}
	}

	/* Start the audio thread if necessary */
	switch (audio->opened) {
		case  1:
			/* Start the audio thread */
			audio->thread = SDL_CreateThread(SDL_RunAudio, audio);
			if ( audio->thread == NULL ) {
				SDL_CloseAudio();
				SDL_SetError("Couldn't create audio thread");
				return(-1);
			}
			break;

		default:
			/* The audio is now playing */
			break;
	}
	return(0);
}

SDL_audiostatus SDL_GetAudioStatus(void)
{
	SDL_AudioDevice *audio = current_audio;
	SDL_audiostatus status;

	status = SDL_AUDIO_STOPPED;
	if ( audio && audio->enabled ) {
		if ( audio->paused ) {
			status = SDL_AUDIO_PAUSED;
		} else {
			status = SDL_AUDIO_PLAYING;
		}
	}
	return(status);
}

void SDL_PauseAudio (int pause_on)
{
	SDL_AudioDevice *audio = current_audio;

	if ( audio ) {
		audio->paused = pause_on;
	}
}

void SDL_LockAudio (void)
{
	SDL_AudioDevice *audio = current_audio;

	/* Obtain a lock on the mixing buffers */
	if ( audio ) {
		if ( audio->thread && (SDL_ThreadID() == audio->threadid) ) {
			return;
		}
		SDL_mutexP(audio->mixer_lock);
	}
}

void SDL_UnlockAudio (void)
{
	SDL_AudioDevice *audio = current_audio;

	/* Release lock on the mixing buffers */
	if ( audio ) {
		if ( audio->thread && (SDL_ThreadID() == audio->threadid) ) {
			return;
		}
		SDL_mutexV(audio->mixer_lock);
	}
}

void SDL_CloseAudio (void)
{
	SDL_QuitSubSystem(SDL_INIT_AUDIO);
}

void SDL_AudioQuit(void)
{
	SDL_AudioDevice *audio = current_audio;

	if ( audio ) {
		audio->enabled = 0;
		if ( audio->thread != NULL ) {
			SDL_WaitThread(audio->thread, NULL);
		}
		if ( audio->mixer_lock != NULL ) {
			SDL_DestroyMutex(audio->mixer_lock);
		}
		if ( audio->fake_stream != NULL ) {
			SDL_FreeAudioMem(audio->fake_stream);
		}
		if ( audio->convert.needed ) {
			SDL_FreeAudioMem(audio->convert.buf);
		}
		if ( audio->opened ) {
			audio->CloseAudio(audio);
			audio->opened = 0;
		}

		/* Free the driver data */
		audio->free(audio);
		current_audio = NULL;
	}
}

#define NUM_FORMATS	6
static int format_idx;
static int format_idx_sub;
static Uint16 format_list[NUM_FORMATS][NUM_FORMATS] = {
 { AUDIO_U8, AUDIO_S8, AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U16LSB, AUDIO_U16MSB },
 { AUDIO_S8, AUDIO_U8, AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U16LSB, AUDIO_U16MSB },
 { AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U16LSB, AUDIO_U16MSB, AUDIO_U8, AUDIO_S8 },
 { AUDIO_S16MSB, AUDIO_S16LSB, AUDIO_U16MSB, AUDIO_U16LSB, AUDIO_U8, AUDIO_S8 },
 { AUDIO_U16LSB, AUDIO_U16MSB, AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_U8, AUDIO_S8 },
 { AUDIO_U16MSB, AUDIO_U16LSB, AUDIO_S16MSB, AUDIO_S16LSB, AUDIO_U8, AUDIO_S8 },
};

Uint16 SDL_FirstAudioFormat(Uint16 format)
{
	for ( format_idx=0; format_idx < NUM_FORMATS; ++format_idx ) {
		if ( format_list[format_idx][0] == format ) {
			break;
		}
	}
	format_idx_sub = 0;
	return(SDL_NextAudioFormat());
}

Uint16 SDL_NextAudioFormat(void)
{
	if ( (format_idx == NUM_FORMATS) || (format_idx_sub == NUM_FORMATS) ) {
		return(0);
	}
	return(format_list[format_idx][format_idx_sub++]);
}

void SDL_CalculateAudioSpec(SDL_AudioSpec *spec)
{
	switch (spec->format) {
		case AUDIO_U8:
			spec->silence = 0x80;
			break;
		default:
			spec->silence = 0x00;
			break;
	}
	spec->size = (spec->format&0xFF)/8;
	spec->size *= spec->channels;
	spec->size *= spec->samples;
}