Mercurial > sdl-ios-xcode
view include/SDL_config_win32.h @ 3069:caefe2344f65
Date: Thu, 27 Dec 2007 07:38:25 +0000
From: John Bartholomew
Subject: [SDL] SDL Semaphore implementation broken on Windows?
Hi,
Over the past couple of days, I've been battling with SDL, SDL_Mixer and SMPEG to try to find an audio hang bug. I believe I've found the problem, which I think is a race condition inside SDL's semaphore implementation (at least the Windows implementation). The semaphore code uses Windows' built in semaphore functions, but it also maintains a separate count value. This count value is updated with bare increment and decrement operations in SemPost and SemWaitTimeout - no locking primitives to protect them.
In tracking down the apparent audio bug, I found that at some point a semaphore's count value was being decremented to -1, which is clearly not a valid value for it to take.
I'm still not certain exactly what sequence of operations is occuring for this to happen, but I believe that overall it's a race condition between a thread calling SemPost (which increments the count) and the thread on the other end calling SemWait (which decrements it).
I will try to make a test case to verify this, but I'm not sure if I'll be able to (threading errors being difficult to reproduce even in the best circumstances).
However, assuming this is the cause of my problems, there is a very
simple fix:
Windows provides InterlockedIncrement() and InterlockedDecrement()
functions to perform increments and decrements which are guaranteed to be atomic. So the fix is in thread/win32/SDL_syssem.c: replace occurrences of --sem->count with InterlockedDecrement(&sem->count); and replace occurrences of ++sem->count with InterlockedIncrement(&sem->count);
This is using SDL v1.2.12, built with VC++ 2008 Express, running on a
Core 2 duo processor.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 17 Feb 2009 05:39:18 +0000 |
| parents | 77c3e67f0740 |
| children | b7a48f533966 |
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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_config_win32_h #define _SDL_config_win32_h #include "SDL_platform.h" /* This is a set of defines to configure the SDL features */ #if defined(__GNUC__) || defined(__DMC__) #define HAVE_STDINT_H 1 #elif defined(_MSC_VER) typedef signed __int8 int8_t; typedef unsigned __int8 uint8_t; typedef signed __int16 int16_t; typedef unsigned __int16 uint16_t; typedef signed __int32 int32_t; typedef unsigned __int32 uint32_t; typedef signed __int64 int64_t; typedef unsigned __int64 uint64_t; #ifndef _UINTPTR_T_DEFINED #ifdef _WIN64 typedef unsigned __int64 uintptr_t; #else typedef unsigned int uintptr_t; #endif #define _UINTPTR_T_DEFINED #endif /* Older Visual C++ headers don't have the Win64-compatible typedefs... */ #if ((_MSC_VER <= 1200) && (!defined(DWORD_PTR))) #define DWORD_PTR DWORD #endif #if ((_MSC_VER <= 1200) && (!defined(LONG_PTR))) #define LONG_PTR LONG #endif #else /* !__GNUC__ && !_MSC_VER */ typedef signed char int8_t; typedef unsigned char uint8_t; typedef signed short int16_t; typedef unsigned short uint16_t; typedef signed int int32_t; typedef unsigned int uint32_t; typedef signed long long int64_t; typedef unsigned long long uint64_t; #ifndef _SIZE_T_DEFINED_ #define _SIZE_T_DEFINED_ typedef unsigned int size_t; #endif typedef unsigned int uintptr_t; #endif /* __GNUC__ || _MSC_VER */ #define SDL_HAS_64BIT_TYPE 1 /* Enabled for SDL 1.2 (binary compatibility) */ //#define HAVE_LIBC 1 #ifdef HAVE_LIBC /* Useful headers */ #define HAVE_STDIO_H 1 #define STDC_HEADERS 1 #define HAVE_STRING_H 1 #define HAVE_CTYPE_H 1 #define HAVE_MATH_H 1 #ifndef _WIN32_WCE #define HAVE_SIGNAL_H 1 #endif /* C library functions */ #define HAVE_MALLOC 1 #define HAVE_CALLOC 1 #define HAVE_REALLOC 1 #define HAVE_FREE 1 #define HAVE_ALLOCA 1 #define HAVE_QSORT 1 #define HAVE_ABS 1 #define HAVE_MEMSET 1 #define HAVE_MEMCPY 1 #define HAVE_MEMMOVE 1 #define HAVE_MEMCMP 1 #define HAVE_STRLEN 1 #define HAVE__STRREV 1 #define HAVE__STRUPR 1 #define HAVE__STRLWR 1 #define HAVE_STRCHR 1 #define HAVE_STRRCHR 1 #define HAVE_STRSTR 1 #define HAVE_ITOA 1 #define HAVE__LTOA 1 #define HAVE__ULTOA 1 #define HAVE_STRTOL 1 #define HAVE_STRTOUL 1 #define HAVE_STRTOLL 1 #define HAVE_STRTOD 1 #define HAVE_ATOI 1 #define HAVE_ATOF 1 #define HAVE_STRCMP 1 #define HAVE_STRNCMP 1 #define HAVE__STRICMP 1 #define HAVE__STRNICMP 1 #define HAVE_SSCANF 1 #define HAVE_M_PI 1 #define HAVE_CEIL 1 #define HAVE_COPYSIGN 1 #define HAVE_COS 1 #define HAVE_COSF 1 #define HAVE_FABS 1 #define HAVE_FLOOR 1 #define HAVE_LOG 1 #define HAVE_POW 1 #define HAVE_SCALBN 1 #define HAVE_SIN 1 #define HAVE_SINF 1 #define HAVE_SQRT 1 #else #define HAVE_STDARG_H 1 #define HAVE_STDDEF_H 1 #endif /* Enable various audio drivers */ #ifndef _WIN32_WCE #define SDL_AUDIO_DRIVER_DSOUND 1 #endif #define SDL_AUDIO_DRIVER_WINWAVEOUT 1 #define SDL_AUDIO_DRIVER_DISK 1 #define SDL_AUDIO_DRIVER_DUMMY 1 /* Enable various cdrom drivers */ #ifdef _WIN32_WCE #define SDL_CDROM_DISABLED 1 #else #define SDL_CDROM_WIN32 1 #endif /* Enable various input drivers */ #ifdef _WIN32_WCE #define SDL_JOYSTICK_DISABLED 1 #define SDL_HAPTIC_DUMMY 1 #else #define SDL_JOYSTICK_DINPUT 1 #define SDL_HAPTIC_DINPUT 1 #endif /* Enable various shared object loading systems */ #define SDL_LOADSO_WIN32 1 /* Enable various threading systems */ #define SDL_THREAD_WIN32 1 /* Enable various timer systems */ #ifdef _WIN32_WCE #define SDL_TIMER_WINCE 1 #else #define SDL_TIMER_WIN32 1 #endif /* Enable various video drivers */ #define SDL_VIDEO_DRIVER_DUMMY 1 #define SDL_VIDEO_DRIVER_WIN32 1 #define SDL_VIDEO_RENDER_D3D 1 #define SDL_VIDEO_RENDER_GDI 1 /* Enable OpenGL support */ #ifndef _WIN32_WCE #define SDL_VIDEO_OPENGL 1 #define SDL_VIDEO_OPENGL_WGL 1 #define SDL_VIDEO_RENDER_OGL 1 #endif /* Enable assembly routines (Win64 doesn't have inline asm) */ #ifndef _WIN64 #define SDL_ASSEMBLY_ROUTINES 1 #endif #endif /* _SDL_config_win32_h */