/*

     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: */