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SDL_diskaudio.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2006 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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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
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Lesser General Public License for more details.
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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
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Sam Lantinga
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slouken@libsdl.org
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This file written by Ryan C. Gordon (icculus@icculus.org)
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#include "SDL_config.h"
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/* Output raw audio data to a file. */
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#if HAVE_STDIO_H
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#include <stdio.h>
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#include "SDL_rwops.h"
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#include "SDL_timer.h"
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#include "SDL_audio.h"
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#include "../SDL_audiomem.h"
#include "../SDL_audio_c.h"
#include "../SDL_audiodev_c.h"
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#include "SDL_diskaudio.h"
/* The tag name used by DISK audio */
#define DISKAUD_DRIVER_NAME "disk"
/* environment variables and defaults. */
#define DISKENVR_OUTFILE "SDL_DISKAUDIOFILE"
#define DISKDEFAULT_OUTFILE "sdlaudio.raw"
#define DISKENVR_WRITEDELAY "SDL_DISKAUDIODELAY"
#define DISKDEFAULT_WRITEDELAY 150
/* Audio driver functions */
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static int DISKAUD_OpenAudio(_THIS, const char *devname, int iscapture);
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static void DISKAUD_WaitAudio(_THIS);
static void DISKAUD_PlayAudio(_THIS);
static Uint8 *DISKAUD_GetAudioBuf(_THIS);
static void DISKAUD_CloseAudio(_THIS);
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static const char *
DISKAUD_GetOutputFilename(void)
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const char *envr = SDL_getenv(DISKENVR_OUTFILE);
return ((envr != NULL) ? envr : DISKDEFAULT_OUTFILE);
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}
/* Audio driver bootstrap functions */
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static int
DISKAUD_Available(void)
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/* !!! FIXME: check this at a higher level... */
/* only ever use this driver if explicitly requested. */
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const char *envr = SDL_getenv("SDL_AUDIODRIVER");
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if (envr && (SDL_strcasecmp(envr, DISKAUD_DRIVER_NAME) == 0)) {
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return (1);
}
return (0);
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static int
DISKAUD_Init(SDL_AudioDriverImpl *impl)
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/* Initialize all variables that we clean on shutdown */
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SDL_memset(impl, '\0', sizeof (SDL_AudioDriverImpl));
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/* Set the function pointers */
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impl->OpenAudio = DISKAUD_OpenAudio;
impl->WaitAudio = DISKAUD_WaitAudio;
impl->PlayAudio = DISKAUD_PlayAudio;
impl->GetAudioBuf = DISKAUD_GetAudioBuf;
impl->CloseAudio = DISKAUD_CloseAudio;
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}
AudioBootStrap DISKAUD_bootstrap = {
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DISKAUD_DRIVER_NAME, "direct-to-disk audio",
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DISKAUD_Available, DISKAUD_Init
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};
/* This function waits until it is possible to write a full sound buffer */
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static void
DISKAUD_WaitAudio(_THIS)
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SDL_Delay(this->hidden->write_delay);
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static void
DISKAUD_PlayAudio(_THIS)
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int written;
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/* Write the audio data */
written = SDL_RWwrite(this->hidden->output,
this->hidden->mixbuf, 1, this->hidden->mixlen);
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/* If we couldn't write, assume fatal error for now */
if ((Uint32) written != this->hidden->mixlen) {
this->enabled = 0;
}
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#ifdef DEBUG_AUDIO
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fprintf(stderr, "Wrote %d bytes of audio data\n", written);
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#endif
}
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static Uint8 *
DISKAUD_GetAudioBuf(_THIS)
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return (this->hidden->mixbuf);
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static void
DISKAUD_CloseAudio(_THIS)
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if (this->hidden->mixbuf != NULL) {
SDL_FreeAudioMem(this->hidden->mixbuf);
this->hidden->mixbuf = NULL;
}
if (this->hidden->output != NULL) {
SDL_RWclose(this->hidden->output);
this->hidden->output = NULL;
}
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SDL_free(this->hidden);
this->hidden = NULL;
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DISKAUD_OpenAudio(_THIS, const char *devname, int iscapture)
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const char *envr = SDL_getenv(DISKENVR_WRITEDELAY);
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const char *fname = DISKAUD_GetOutputFilename();
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/* !!! FIXME: use device name for non-default filename? */
if (devname != NULL) {
SDL_SetError("Disk audio device name must be NULL");
return 0;
}
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));
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/* Open the audio device */
this->hidden->output = SDL_RWFromFile(fname, "wb");
if (this->hidden->output == NULL) {
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DISKAUD_CloseAudio(this);
return 0;
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/* Allocate mixing buffer */
this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
if (this->hidden->mixbuf == NULL) {
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DISKAUD_CloseAudio(this);
return 0;
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SDL_memset(this->hidden->mixbuf, this->spec.silence, this->spec.size);
this->hidden->mixlen = this->spec.size;
this->hidden->write_delay =
(envr) ? SDL_atoi(envr) : DISKDEFAULT_WRITEDELAY;
#if HAVE_STDIO_H
fprintf(stderr,
"WARNING: You are using the SDL disk writer audio driver!\n"
" Writing to file [%s].\n", fname);
#endif
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/* We're ready to rock and roll. :-) */
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/* vi: set ts=4 sw=4 expandtab: */