view include/SDL_thread.h @ 4216:5b99971a27b4 SDL-1.2

Fixed bug #698 Hans de Goede 2009-02-13 01:10:52 PST Since the new "glitch free" version of pulseaudio (used in Fedora 10 amongst others), the sound of SDL using apps (like a simple playmus call) has been crackling. While looking in to fixing this I noticed that the current pulseaudio code in SDL uses pa_simple. However pa_simple uses a thread to pump pulseaudio events and ipc, given that SDL already has its own thread for audio handling this is clearly suboptimal, leading to unnecessary context switching IPC, etc. Also pa_simple does not allow one to implement the WaitAudio() callback for SDL audiodrivers properly. Given that my work is mostly a rewrite (although some original pieces remain) I'm attaching the new .c and .h file, as that is easier to review then the huge diff. Let me know if you also want the diff. This new version has the following features: -no longer use an additional thread next to the SDL sound thread -do not crackle with glitch free audio -when used with a newer pulse, which does glitch free audio, the total latency is the same as with the alsa driver -proper WaitAudio() implementation, saving another mixlen worth of latency -adds a WaitDone() implementation This patch has been written in consultancy with Lennart Poetering (the pulseaudio author) and has been reviewed by him for correct use of the pa API.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 21 Sep 2009 09:27:08 +0000
parents a1b03ba2fcd0
children 4c4113c2162c
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 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
*/

#ifndef _SDL_thread_h
#define _SDL_thread_h

/* Header for the SDL thread management routines 

	These are independent of the other SDL routines.
*/

#include "SDL_stdinc.h"
#include "SDL_error.h"

/* Thread synchronization primitives */
#include "SDL_mutex.h"

#include "begin_code.h"
/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
extern "C" {
#endif

/* The SDL thread structure, defined in SDL_thread.c */
struct SDL_Thread;
typedef struct SDL_Thread SDL_Thread;

/* Create a thread */
#if ((defined(__WIN32__) && !defined(HAVE_LIBC)) || defined(__OS2__)) &&  !defined(__SYMBIAN32__)
/*
   We compile SDL into a DLL on OS/2. This means, that it's the DLL which
   creates a new thread for the calling process with the SDL_CreateThread()
   API. There is a problem with this, that only the RTL of the SDL.DLL will
   be initialized for those threads, and not the RTL of the calling application!
   To solve this, we make a little hack here.
   We'll always use the caller's _beginthread() and _endthread() APIs to
   start a new thread. This way, if it's the SDL.DLL which uses this API,
   then the RTL of SDL.DLL will be used to create the new thread, and if it's
   the application, then the RTL of the application will be used.
   So, in short:
   Always use the _beginthread() and _endthread() of the calling runtime library!
*/
#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
#ifndef _WIN32_WCE
#include <process.h> /* This has _beginthread() and _endthread() defined! */
#endif

#ifdef __OS2__
typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void *arg); 
typedef void (*pfnSDL_CurrentEndThread)(void);
#elif __GNUC__
typedef unsigned long (__cdecl *pfnSDL_CurrentBeginThread) (void *, unsigned,
        unsigned (__stdcall *func)(void *), void *arg, 
        unsigned, unsigned *threadID);
typedef void (__cdecl *pfnSDL_CurrentEndThread)(unsigned code);
#else
typedef uintptr_t (__cdecl *pfnSDL_CurrentBeginThread) (void *, unsigned,
        unsigned (__stdcall *func)(void *), void *arg, 
        unsigned, unsigned *threadID);
typedef void (__cdecl *pfnSDL_CurrentEndThread)(unsigned code);
#endif

extern DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread);

#ifdef __OS2__
#define SDL_CreateThread(fn, data) SDL_CreateThread(fn, data, _beginthread, _endthread)
#elif defined(_WIN32_WCE)
#define SDL_CreateThread(fn, data) SDL_CreateThread(fn, data, NULL, NULL)
#else
#define SDL_CreateThread(fn, data) SDL_CreateThread(fn, data, _beginthreadex, _endthreadex)
#endif
#else
extern DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data);
#endif

/* Get the 32-bit thread identifier for the current thread */
extern DECLSPEC Uint32 SDLCALL SDL_ThreadID(void);

/* Get the 32-bit thread identifier for the specified thread,
   equivalent to SDL_ThreadID() if the specified thread is NULL.
 */
extern DECLSPEC Uint32 SDLCALL SDL_GetThreadID(SDL_Thread *thread);

/* Wait for a thread to finish.
   The return code for the thread function is placed in the area
   pointed to by 'status', if 'status' is not NULL.
 */
extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread *thread, int *status);

/* Forcefully kill a thread without worrying about its state */
extern DECLSPEC void SDLCALL SDL_KillThread(SDL_Thread *thread);


/* Ends C function definitions when using C++ */
#ifdef __cplusplus
}
#endif
#include "close_code.h"

#endif /* _SDL_thread_h */