Mercurial > sdl-ios-xcode
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 */