view src/audio/SDL_audiodev.c @ 4001:6831b8723a85 SDL-1.2

Don't initialize the audio buffer passed to the application's audio callback, since they are expected to entirely fill it with data or silence. For legacy apps that might expect the buffer to already have silence and thus may not fill the buffer in the callback, there's an environment variable to expose the old behaviour. Fixes Bugzilla #416.
author Ryan C. Gordon <icculus@icculus.org>
date Thu, 05 Jul 2007 02:24:36 +0000
parents 12b6d331d82a
children 782fd950bd46 c121d94672cb a1b03ba2fcd0
line wrap: on
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/*
    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
*/
#include "SDL_config.h"

/* Get the name of the audio device we use for output */

#if SDL_AUDIO_DRIVER_BSD || SDL_AUDIO_DRIVER_OSS || SDL_AUDIO_DRIVER_SUNAUDIO

#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "SDL_stdinc.h"
#include "SDL_audiodev_c.h"

#ifndef _PATH_DEV_DSP
#if defined(__NETBSD__) || defined(__OPENBSD__)
#define _PATH_DEV_DSP  "/dev/audio"
#else
#define _PATH_DEV_DSP  "/dev/dsp"
#endif
#endif
#ifndef _PATH_DEV_DSP24
#define _PATH_DEV_DSP24	"/dev/sound/dsp"
#endif
#ifndef _PATH_DEV_AUDIO
#define _PATH_DEV_AUDIO	"/dev/audio"
#endif


int SDL_OpenAudioPath(char *path, int maxlen, int flags, int classic)
{
	const char *audiodev;
	int audio_fd;
	char audiopath[1024];

	/* Figure out what our audio device is */
	if ( ((audiodev=SDL_getenv("SDL_PATH_DSP")) == NULL) &&
	     ((audiodev=SDL_getenv("AUDIODEV")) == NULL) ) {
		if ( classic ) {
			audiodev = _PATH_DEV_AUDIO;
		} else {
			struct stat sb;

			/* Added support for /dev/sound/\* in Linux 2.4 */
			if ( ((stat("/dev/sound", &sb) == 0) && S_ISDIR(sb.st_mode)) &&
				 ((stat(_PATH_DEV_DSP24, &sb) == 0) && S_ISCHR(sb.st_mode)) ) {
				audiodev = _PATH_DEV_DSP24;
			} else {
				audiodev = _PATH_DEV_DSP;
			}
		}
	}
	audio_fd = open(audiodev, flags, 0);

	/* If the first open fails, look for other devices */
	if ( (audio_fd < 0) && (SDL_strlen(audiodev) < (sizeof(audiopath)-3)) ) {
		int exists, instance;
		struct stat sb;

		instance = 1;
		do { /* Don't use errno ENOENT - it may not be thread-safe */
			SDL_snprintf(audiopath, SDL_arraysize(audiopath),
			             "%s%d", audiodev, instance++);
			exists = 0;
			if ( stat(audiopath, &sb) == 0 ) {
				exists = 1;
				audio_fd = open(audiopath, flags, 0); 
			}
		} while ( exists && (audio_fd < 0) );
		audiodev = audiopath;
	}
	if ( path != NULL ) {
		SDL_strlcpy(path, audiodev, maxlen);
		path[maxlen-1] = '\0';
	}
	return(audio_fd);
}

#elif SDL_AUDIO_DRIVER_PAUD

/* Get the name of the audio device we use for output */

#include <sys/types.h>
#include <sys/stat.h>

#include "SDL_stdinc.h"
#include "SDL_audiodev_c.h"

#ifndef _PATH_DEV_DSP
#define _PATH_DEV_DSP	"/dev/%caud%c/%c"
#endif

char devsettings[][3] =
{
    { 'p', '0', '1' }, { 'p', '0', '2' }, { 'p', '0', '3' }, { 'p', '0', '4' },
    { 'p', '1', '1' }, { 'p', '1', '2' }, { 'p', '1', '3' }, { 'p', '1', '4' },
    { 'p', '2', '1' }, { 'p', '2', '2' }, { 'p', '2', '3' }, { 'p', '2', '4' },
    { 'p', '3', '1' }, { 'p', '3', '2' }, { 'p', '3', '3' }, { 'p', '3', '4' },
    { 'b', '0', '1' }, { 'b', '0', '2' }, { 'b', '0', '3' }, { 'b', '0', '4' },
    { 'b', '1', '1' }, { 'b', '1', '2' }, { 'b', '1', '3' }, { 'b', '1', '4' },
    { 'b', '2', '1' }, { 'b', '2', '2' }, { 'b', '2', '3' }, { 'b', '2', '4' },
    { 'b', '3', '1' }, { 'b', '3', '2' }, { 'b', '3', '3' }, { 'b', '3', '4' },
    { '\0', '\0', '\0' }
};

static int OpenUserDefinedDevice(char *path, int maxlen, int flags)
{
	const char *audiodev;
	int  audio_fd;

	/* Figure out what our audio device is */
	if ((audiodev=SDL_getenv("SDL_PATH_DSP")) == NULL) {
	    audiodev=SDL_getenv("AUDIODEV");
	}
	if ( audiodev == NULL ) {
	    return -1;
	}
	audio_fd = open(audiodev, flags, 0);
	if ( path != NULL ) {
		SDL_strlcpy(path, audiodev, maxlen);
		path[maxlen-1] = '\0';
	}
	return audio_fd;
}

int SDL_OpenAudioPath(char *path, int maxlen, int flags, int classic)
{
    struct stat sb;
    int         audio_fd;
    char        audiopath[1024];
    int         cycle;

    audio_fd = OpenUserDefinedDevice(path,maxlen,flags);
    if ( audio_fd != -1 ) {
        return audio_fd;
    }

    cycle    = 0;
    while( devsettings[cycle][0] != '\0' ) {
        SDL_snprintf( audiopath, SDL_arraysize(audiopath),
                 _PATH_DEV_DSP,
                 devsettings[cycle][0],
                 devsettings[cycle][1],
                 devsettings[cycle][2]);

	if ( stat(audiopath, &sb) == 0 ) {
	    audio_fd = open(audiopath, flags, 0);
	    if ( audio_fd > 0 ) {
		if ( path != NULL ) {
		    SDL_strlcpy( path, audiopath, maxlen );
		}
	        return audio_fd;
	    }
	}
    }
    return -1;
}

#endif /* Audio driver selection */