/*

     SDL - Simple DirectMedia Layer

     Copyright (C) 1997-2006 Sam Lantinga

     This library is free software; you can redistribute it and/or

     modify it under the terms of the GNU Lesser General Public

     License as published by the Free Software Foundation; either

     version 2.1 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

     Lesser General Public License for more details.

     You should have received a copy of the GNU Lesser General Public

     License along with this library; if not, write to the Free Software

     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

     Sam Lantinga

     slouken@libsdl.org

     This file written by Ryan C. Gordon (icculus@icculus.org)

 */

 #include "SDL_config.h"

 /* Output audio to nowhere... */

 #include "SDL_rwops.h"

 #include "SDL_timer.h"

 #include "SDL_audio.h"

 #include "../SDL_audiomem.h"

 #include "../SDL_audio_c.h"

 #include "../SDL_audiodev_c.h"

 #include "SDL_dummyaudio.h"

 /* The tag name used by DUMMY audio */

 #define DUMMYAUD_DRIVER_NAME         "dummy"

 /* Audio driver functions */

 static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec);

 static void DUMMYAUD_WaitAudio(_THIS);

 static void DUMMYAUD_PlayAudio(_THIS);

 static Uint8 *DUMMYAUD_GetAudioBuf(_THIS);

 static void DUMMYAUD_CloseAudio(_THIS);

 /* Audio driver bootstrap functions */

 static int DUMMYAUD_Available(void)

 {

 	const char *envr = SDL_getenv("SDL_AUDIODRIVER");

 	if (envr && (SDL_strcmp(envr, DUMMYAUD_DRIVER_NAME) == 0)) {

 		return(1);

 	}

 	return(0);

 }

 static void DUMMYAUD_DeleteDevice(SDL_AudioDevice *device)

 {

 	SDL_free(device->hidden);

 	SDL_free(device);

 }

 static SDL_AudioDevice *DUMMYAUD_CreateDevice(int devindex)

 {

 	SDL_AudioDevice *this;

 	const char *envr;

 	/* Initialize all variables that we clean on shutdown */

 	this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice));

 	if ( this ) {

 		SDL_memset(this, 0, (sizeof *this));

 		this->hidden = (struct SDL_PrivateAudioData *)

 				SDL_malloc((sizeof *this->hidden));

 	}

 	if ( (this == NULL) || (this->hidden == NULL) ) {

 		SDL_OutOfMemory();

 		if ( this ) {

 			SDL_free(this);

 		}

 		return(0);

 	}

 	SDL_memset(this->hidden, 0, (sizeof *this->hidden));

 	/* Set the function pointers */

 	this->OpenAudio = DUMMYAUD_OpenAudio;

 	this->WaitAudio = DUMMYAUD_WaitAudio;

 	this->PlayAudio = DUMMYAUD_PlayAudio;

 	this->GetAudioBuf = DUMMYAUD_GetAudioBuf;

 	this->CloseAudio = DUMMYAUD_CloseAudio;

 	this->free = DUMMYAUD_DeleteDevice;

 	return this;

 }

 AudioBootStrap DUMMYAUD_bootstrap = {

 	DUMMYAUD_DRIVER_NAME, "SDL dummy audio driver",

 	DUMMYAUD_Available, DUMMYAUD_CreateDevice

 };

 /* This function waits until it is possible to write a full sound buffer */

 static void DUMMYAUD_WaitAudio(_THIS)

 {

 	/* Don't block on first calls to simulate initial fragment filling. */

 	if (this->hidden->initial_calls)

 		this->hidden->initial_calls--;

 	else

 		SDL_Delay(this->hidden->write_delay);

 }

 static void DUMMYAUD_PlayAudio(_THIS)

 {

 	/* no-op...this is a null driver. */

 }

 static Uint8 *DUMMYAUD_GetAudioBuf(_THIS)

 {

 	return(this->hidden->mixbuf);

 }

 static void DUMMYAUD_CloseAudio(_THIS)

 {

 	if ( this->hidden->mixbuf != NULL ) {

 		SDL_FreeAudioMem(this->hidden->mixbuf);

 		this->hidden->mixbuf = NULL;

 	}

 }

 static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec)

 {

 	float bytes_per_sec = 0.0f;

 	/* Allocate mixing buffer */

 	this->hidden->mixlen = spec->size;

 	this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);

 	if ( this->hidden->mixbuf == NULL ) {

 		return(-1);

 	}

 	SDL_memset(this->hidden->mixbuf, spec->silence, spec->size);

 	bytes_per_sec = (float) (((spec->format & 0xFF) / 8) *

 	                   spec->channels * spec->freq);

 	/*

 	 * We try to make this request more audio at the correct rate for

 	 *  a given audio spec, so timing stays fairly faithful.

 	 * Also, we have it not block at all for the first two calls, so

 	 *  it seems like we're filling two audio fragments right out of the

 	 *  gate, like other SDL drivers tend to do.

 	 */

 	this->hidden->initial_calls = 2;

 	this->hidden->write_delay =

 	               (Uint32) ((((float) spec->size) / bytes_per_sec) * 1000.0f);

 	/* We're ready to rock and roll. :-) */

 	return(0);

 }