Ozkan Sezer 2010-02-06 12:31:06 PST
Hi:
Here are some small fixes for compiling SDL against mingw-w64.
(see http://mingw-w64.sourceforge.net/ . Despite the name, it
supports both win32 and win64.)
src/audio/windx5/directx.h and src/video/windx5/directx.h (both
SDL-1.2 and SDL-1.3.) I get compilation errors about some union
not having a member named u1 and alike, because of other system
headers being included before this one and them already defining
DUMMYUNIONNAME and stuff. This header probably assumes that those
stuff are defined in windef.h, but mingw-w64 headers define them
in _mingw.h. Easily fixed by moving NONAMELESSUNION definition to
the top of the file.
src/thread/win32/SDL_systhread.c (both SDL-1.2 and SDL-1.3.) :
The __GNUC__ case for pfnSDL_CurrentBeginThread is 32-bit centric
because _beginthreadex returns uintptr_t, not unsigned long which
is 32 bits in win64. Changing the return type to uintptr_t fixes
it.
video/SDL_blit.h (and configure.in) (SDL-1.3-only) : MinGW-w64
uses msvcrt version of _aligned_malloc and _aligned_free and
they are defined in intrin.h (similar to VC). Adding proper
ifdefs fixes it. (Notes about macros to check: __MINGW32__ is
defined for both mingw.org and for mingw-w64 for both win32 and
win64, __MINGW64__ is only defined for _WIN64, so __MINGW64__
can't be used to detect mingw-w64: including _mingw.h and then
checking for __MINGW64_VERSION_MAJOR does the trick.)
SDL_win32video.h (SDL-1.3-only) : Tweaked the VINWER definition
and location in order to avoid multiple redefinition warnings.
Hope these are useful. Thanks.
The thread ID is an unsigned long so it can hold pthread_t so people can do naughty things with it.
I'm going to be adding additional useful thread API functions, but this should prevent crashes in people's existing code on 64-bit architectures.
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.
The current SVN trunk is missing the SDLCALL specifier at numerous locations.
It has to be added for all (possibly user provided) callbacks.
I stumbled over this while creating a makefile for the OpenWatcom compiler for
Win32.
FIXME:
Change #include <stdlib.h> to #include "SDL_stdlib.h"
Change #include <string.h> to #include "SDL_string.h"
Make sure nothing else broke because of this...
