/*

    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;

	/* 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);

}