/*

    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_OpenDevice(_THIS, const char *devname, int iscapture);

static void DUMMYAUD_WaitDevice(_THIS);

static void DUMMYAUD_PlayDevice(_THIS);

static Uint8 *DUMMYAUD_GetDeviceBuf(_THIS);

static void DUMMYAUD_CloseDevice(_THIS);

/* Audio driver bootstrap functions */

static int

DUMMYAUD_Available(void)

{

    /* !!! FIXME: check this at a higher level... */

    /* only ever use this driver if explicitly requested. */

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

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

        return (1);

    }

    return (0);

}

static int

DUMMYAUD_Init(SDL_AudioDriverImpl *impl)

{

    /* Set the function pointers */

    impl->OpenDevice = DUMMYAUD_OpenDevice;

    impl->WaitDevice = DUMMYAUD_WaitDevice;

    impl->PlayDevice = DUMMYAUD_PlayDevice;

    impl->GetDeviceBuf = DUMMYAUD_GetDeviceBuf;

    impl->CloseDevice = DUMMYAUD_CloseDevice;

    impl->OnlyHasDefaultOutputDevice = 1;

    return 1;

}

AudioBootStrap DUMMYAUD_bootstrap = {

    DUMMYAUD_DRIVER_NAME, "SDL dummy audio driver",

    DUMMYAUD_Available, DUMMYAUD_Init

};

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

static void

DUMMYAUD_WaitDevice(_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_PlayDevice(_THIS)

{

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

}

static Uint8 *

DUMMYAUD_GetDeviceBuf(_THIS)

{

    return (this->hidden->mixbuf);

}

static void

DUMMYAUD_CloseDevice(_THIS)

{

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

        SDL_FreeAudioMem(this->hidden->mixbuf);

        this->hidden->mixbuf = NULL;

    }

    SDL_free(this->hidden);

    this->hidden = NULL;

}

static int

DUMMYAUD_OpenDevice(_THIS, const char *devname, int iscapture)

{

    float bytes_per_sec = 0.0f;

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

    this->hidden = (struct SDL_PrivateAudioData *)

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

    if (this->hidden == NULL) {

        SDL_OutOfMemory();

        return 0;

    }

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

    /* Allocate mixing buffer */

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

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

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

        DUMMYAUD_CloseDevice(this);

        return 0;

    }

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

    bytes_per_sec = (float) (SDL_AUDIO_BITSIZE(this->spec.format) / 8) *

                             this->spec.channels * this->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) this->spec.size) / bytes_per_sec) * 1000.0f);

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

    return 1;

}

/* vi: set ts=4 sw=4 expandtab: */