| /* |
| SDL - Simple DirectMedia Layer |
| Copyright (C) 1997-2012 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); |
| } |
| |