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Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST) From: Hannu Savolainen Subject: Re: SDL uses obsolete OSS features I did some work on getting OSS to work better with SDL. There have been some problems with select which should be fixed now. I'm having some problems in understanding what is the purpose of the DSP_WaitAudio() routine. I added a return to the very beginning of this routine and commendted out the define for USE_BLOCKING_WRITES. At least lbreakout2 seems to work as well as earlier. The latencies are the same. An ordinary blocking write does exactly the same thing than DSP_WaitAudio does. So I would recommend using the USE_BLOCKING_WRITES approach and removing everything from the DSP_WaitAudio routine. Also enabling USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because you don't need to handle the partial writes (the do-while loop). Attached is a patch against SDL-1.2.7. After these changes SDL will use OSS as it's designed to be used (make it as simple as possible). This code should work with all OSS implementations because it uses only the very fundamental features that have been there since the jurassic times.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 12 Nov 2004 21:39:04 +0000
parents 84f930aebaeb
children 173c063d4f55
line wrap: on
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif

#ifndef _SDL_sysaudio_h
#define _SDL_sysaudio_h

#include "SDL_mutex.h"
#include "SDL_thread.h"

/* The SDL audio driver */
typedef struct SDL_AudioDevice SDL_AudioDevice;

/* Define the SDL audio driver structure */
#define _THIS	SDL_AudioDevice *_this
#ifndef _STATUS
#define _STATUS	SDL_status *status
#endif
struct SDL_AudioDevice {
	/* * * */
	/* The name of this audio driver */
	const char *name;

	/* * * */
	/* The description of this audio driver */
	const char *desc;

	/* * * */
	/* Public driver functions */
	int  (*OpenAudio)(_THIS, SDL_AudioSpec *spec);
	void (*ThreadInit)(_THIS);	/* Called by audio thread at start */
	void (*WaitAudio)(_THIS);
	void (*PlayAudio)(_THIS);
	Uint8 *(*GetAudioBuf)(_THIS);
	void (*WaitDone)(_THIS);
	void (*CloseAudio)(_THIS);

	/* * * */
	/* Lock / Unlock functions added for the Mac port */
	void (*LockAudio)(_THIS);
	void (*UnlockAudio)(_THIS);

	/* * * */
	/* Data common to all devices */

	/* The current audio specification (shared with audio thread) */
	SDL_AudioSpec spec;

	/* An audio conversion block for audio format emulation */
	SDL_AudioCVT convert;

	/* Current state flags */
	int enabled;
	int paused;
	int opened;

	/* Fake audio buffer for when the audio hardware is busy */
	Uint8 *fake_stream;

	/* A semaphore for locking the mixing buffers */
	SDL_mutex *mixer_lock;

	/* A thread to feed the audio device */
	SDL_Thread *thread;
	Uint32 threadid;

	/* * * */
	/* Data private to this driver */
	struct SDL_PrivateAudioData *hidden;

	/* * * */
	/* The function used to dispose of this structure */
	void (*free)(_THIS);
};
#undef _THIS

typedef struct AudioBootStrap {
	const char *name;
	const char *desc;
	int (*available)(void);
	SDL_AudioDevice *(*create)(int devindex);
} AudioBootStrap;

#ifdef OPENBSD_AUDIO_SUPPORT
extern AudioBootStrap OPENBSD_AUDIO_bootstrap;
#endif
#ifdef OSS_SUPPORT
extern AudioBootStrap DSP_bootstrap;
extern AudioBootStrap DMA_bootstrap;
#endif
#ifdef ALSA_SUPPORT
extern AudioBootStrap ALSA_bootstrap;
#endif
#ifdef QNXNTOAUDIO_SUPPORT
extern AudioBootStrap QNXNTOAUDIO_bootstrap;
#endif
#ifdef SUNAUDIO_SUPPORT
extern AudioBootStrap SUNAUDIO_bootstrap;
#endif
#ifdef DMEDIA_SUPPORT
extern AudioBootStrap DMEDIA_bootstrap;
#endif
#ifdef ARTSC_SUPPORT
extern AudioBootStrap ARTSC_bootstrap;
#endif
#ifdef ESD_SUPPORT
extern AudioBootStrap ESD_bootstrap;
#endif
#ifdef NAS_SUPPORT
extern AudioBootStrap NAS_bootstrap;
#endif
#ifdef ENABLE_DIRECTX
extern AudioBootStrap DSOUND_bootstrap;
#endif
#ifdef ENABLE_WINDIB
extern AudioBootStrap WAVEOUT_bootstrap;
#endif
#ifdef _AIX
extern AudioBootStrap Paud_bootstrap;
#endif
#ifdef __BEOS__
extern AudioBootStrap BAUDIO_bootstrap;
#endif
#ifdef MACOSX
extern AudioBootStrap COREAUDIO_bootstrap;
#endif
#if defined(macintosh) || TARGET_API_MAC_CARBON
extern AudioBootStrap SNDMGR_bootstrap;
#endif
#ifdef ENABLE_AHI
extern AudioBootStrap AHI_bootstrap;
#endif
#ifdef MINTAUDIO_SUPPORT
extern AudioBootStrap MINTAUDIO_GSXB_bootstrap;
extern AudioBootStrap MINTAUDIO_MCSN_bootstrap;
extern AudioBootStrap MINTAUDIO_STFA_bootstrap;
extern AudioBootStrap MINTAUDIO_XBIOS_bootstrap;
extern AudioBootStrap MINTAUDIO_DMA8_bootstrap;
#endif
#ifdef DISKAUD_SUPPORT
extern AudioBootStrap DISKAUD_bootstrap;
#endif
#ifdef ENABLE_DC
extern AudioBootStrap DCAUD_bootstrap;
#endif
#ifdef DRENDERER_SUPPORT
extern AudioBootStrap DRENDERER_bootstrap;
#endif
#ifdef MMEAUDIO_SUPPORT
extern AudioBootStrap MMEAUDIO_bootstrap;
#endif

/* This is the current audio device */
extern SDL_AudioDevice *current_audio;

#endif /* _SDL_sysaudio_h */