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      1 /*
      2     SDL - Simple DirectMedia Layer
      3     Copyright (C) 1997-2012 Sam Lantinga
      4 
      5     This library is free software; you can redistribute it and/or
      6     modify it under the terms of the GNU Lesser General Public
      7     License as published by the Free Software Foundation; either
      8     version 2.1 of the License, or (at your option) any later version.
      9 
     10     This library is distributed in the hope that it will be useful,
     11     but WITHOUT ANY WARRANTY; without even the implied warranty of
     12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13     Lesser General Public License for more details.
     14 
     15     You should have received a copy of the GNU Lesser General Public
     16     License along with this library; if not, write to the Free Software
     17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
     18 
     19     Sam Lantinga
     20     slouken (at) libsdl.org
     21 
     22     This file written by Ryan C. Gordon (icculus (at) icculus.org)
     23 */
     24 #include "SDL_config.h"
     25 
     26 /* Output raw audio data to a file. */
     27 
     28 #if HAVE_STDIO_H
     29 #include <stdio.h>
     30 #endif
     31 
     32 #include "SDL_rwops.h"
     33 #include "SDL_timer.h"
     34 #include "SDL_audio.h"
     35 #include "../SDL_audiomem.h"
     36 #include "../SDL_audio_c.h"
     37 #include "../SDL_audiodev_c.h"
     38 #include "SDL_diskaudio.h"
     39 
     40 /* The tag name used by DISK audio */
     41 #define DISKAUD_DRIVER_NAME         "disk"
     42 
     43 /* environment variables and defaults. */
     44 #define DISKENVR_OUTFILE         "SDL_DISKAUDIOFILE"
     45 #define DISKDEFAULT_OUTFILE      "sdlaudio.raw"
     46 #define DISKENVR_WRITEDELAY      "SDL_DISKAUDIODELAY"
     47 #define DISKDEFAULT_WRITEDELAY   150
     48 
     49 /* Audio driver functions */
     50 static int DISKAUD_OpenAudio(_THIS, SDL_AudioSpec *spec);
     51 static void DISKAUD_WaitAudio(_THIS);
     52 static void DISKAUD_PlayAudio(_THIS);
     53 static Uint8 *DISKAUD_GetAudioBuf(_THIS);
     54 static void DISKAUD_CloseAudio(_THIS);
     55 
     56 static const char *DISKAUD_GetOutputFilename(void)
     57 {
     58 	const char *envr = SDL_getenv(DISKENVR_OUTFILE);
     59 	return((envr != NULL) ? envr : DISKDEFAULT_OUTFILE);
     60 }
     61 
     62 /* Audio driver bootstrap functions */
     63 static int DISKAUD_Available(void)
     64 {
     65 	const char *envr = SDL_getenv("SDL_AUDIODRIVER");
     66 	if (envr && (SDL_strcmp(envr, DISKAUD_DRIVER_NAME) == 0)) {
     67 		return(1);
     68 	}
     69 	return(0);
     70 }
     71 
     72 static void DISKAUD_DeleteDevice(SDL_AudioDevice *device)
     73 {
     74 	SDL_free(device->hidden);
     75 	SDL_free(device);
     76 }
     77 
     78 static SDL_AudioDevice *DISKAUD_CreateDevice(int devindex)
     79 {
     80 	SDL_AudioDevice *this;
     81 	const char *envr;
     82 
     83 	/* Initialize all variables that we clean on shutdown */
     84 	this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice));
     85 	if ( this ) {
     86 		SDL_memset(this, 0, (sizeof *this));
     87 		this->hidden = (struct SDL_PrivateAudioData *)
     88 				SDL_malloc((sizeof *this->hidden));
     89 	}
     90 	if ( (this == NULL) || (this->hidden == NULL) ) {
     91 		SDL_OutOfMemory();
     92 		if ( this ) {
     93 			SDL_free(this);
     94 		}
     95 		return(0);
     96 	}
     97 	SDL_memset(this->hidden, 0, (sizeof *this->hidden));
     98 
     99 	envr = SDL_getenv(DISKENVR_WRITEDELAY);
    100 	this->hidden->write_delay = (envr) ? SDL_atoi(envr) : DISKDEFAULT_WRITEDELAY;
    101 
    102 	/* Set the function pointers */
    103 	this->OpenAudio = DISKAUD_OpenAudio;
    104 	this->WaitAudio = DISKAUD_WaitAudio;
    105 	this->PlayAudio = DISKAUD_PlayAudio;
    106 	this->GetAudioBuf = DISKAUD_GetAudioBuf;
    107 	this->CloseAudio = DISKAUD_CloseAudio;
    108 
    109 	this->free = DISKAUD_DeleteDevice;
    110 
    111 	return this;
    112 }
    113 
    114 AudioBootStrap DISKAUD_bootstrap = {
    115 	DISKAUD_DRIVER_NAME, "direct-to-disk audio",
    116 	DISKAUD_Available, DISKAUD_CreateDevice
    117 };
    118 
    119 /* This function waits until it is possible to write a full sound buffer */
    120 static void DISKAUD_WaitAudio(_THIS)
    121 {
    122 	SDL_Delay(this->hidden->write_delay);
    123 }
    124 
    125 static void DISKAUD_PlayAudio(_THIS)
    126 {
    127 	int written;
    128 
    129 	/* Write the audio data */
    130 	written = SDL_RWwrite(this->hidden->output,
    131                         this->hidden->mixbuf, 1,
    132                         this->hidden->mixlen);
    133 
    134 	/* If we couldn't write, assume fatal error for now */
    135 	if ( (Uint32)written != this->hidden->mixlen ) {
    136 		this->enabled = 0;
    137 	}
    138 #ifdef DEBUG_AUDIO
    139 	fprintf(stderr, "Wrote %d bytes of audio data\n", written);
    140 #endif
    141 }
    142 
    143 static Uint8 *DISKAUD_GetAudioBuf(_THIS)
    144 {
    145 	return(this->hidden->mixbuf);
    146 }
    147 
    148 static void DISKAUD_CloseAudio(_THIS)
    149 {
    150 	if ( this->hidden->mixbuf != NULL ) {
    151 		SDL_FreeAudioMem(this->hidden->mixbuf);
    152 		this->hidden->mixbuf = NULL;
    153 	}
    154 	if ( this->hidden->output != NULL ) {
    155 		SDL_RWclose(this->hidden->output);
    156 		this->hidden->output = NULL;
    157 	}
    158 }
    159 
    160 static int DISKAUD_OpenAudio(_THIS, SDL_AudioSpec *spec)
    161 {
    162 	const char *fname = DISKAUD_GetOutputFilename();
    163 
    164 	/* Open the audio device */
    165 	this->hidden->output = SDL_RWFromFile(fname, "wb");
    166 	if ( this->hidden->output == NULL ) {
    167 		return(-1);
    168 	}
    169 
    170 #if HAVE_STDIO_H
    171 	fprintf(stderr, "WARNING: You are using the SDL disk writer"
    172                     " audio driver!\n Writing to file [%s].\n", fname);
    173 #endif
    174 
    175 	/* Allocate mixing buffer */
    176 	this->hidden->mixlen = spec->size;
    177 	this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
    178 	if ( this->hidden->mixbuf == NULL ) {
    179 		return(-1);
    180 	}
    181 	SDL_memset(this->hidden->mixbuf, spec->silence, spec->size);
    182 
    183 	/* We're ready to rock and roll. :-) */
    184 	return(0);
    185 }
    186 
    187