Mercurial > sdl-ios-xcode
view src/atomic/SDL_spinlock.c @ 5003:3a95a2b93eb3
Updated the atomic API for better use cases
author | Sam Lantinga <slouken@libsdl.org> |
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date | Sat, 15 Jan 2011 12:41:59 -0800 |
parents | |
children | 0c72ae7b7cb2 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2010 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 */ #include "SDL_stdinc.h" #include "SDL_atomic.h" #include "SDL_timer.h" #if defined(__WIN32__) #define WIN32_LEAN_AND_MEAN #include <windows.h> #elif defined(__MACOSX__) #include <libkern/OSAtomic.h> #endif /* This function is where all the magic happens... */ SDL_bool SDL_AtomicTryLock(SDL_SpinLock *lock) { #if defined(__WIN32__) return (InterlockedExchange(lock, 1) == 0); #elif defined(__MACOSX__) return OSAtomicCompareAndSwap32Barrier(0, 1, lock); #elif defined(__GNUC__) #if defined(__arm__) #ifdef __ARM_ARCH_5__ int result; __asm__ __volatile__ ( "swp %0, %1, [%2]\n" : "=&r,&r" (result) : "r,0" (1), "r,r" (lock) : "memory"); return (result == 0); #else int result; __asm__ __volatile__ ( "ldrex %0, [%2]\nteq %0, #0\nstrexeq %0, %1, [%2]" : "=&r" (result) : "r" (1), "r" (lock) : "cc", "memory"); return (result == 0); #endif #else return (__sync_lock_test_and_set(lock, 1) == 0); #endif #else /* Need CPU instructions for spinlock here! */ __need_spinlock_implementation__ #endif } void SDL_AtomicLock(SDL_SpinLock *lock) { /* FIXME: Should we have an eventual timeout? */ while (!SDL_AtomicTryLock(lock)) { SDL_Delay(0); } } void SDL_AtomicUnlock(SDL_SpinLock *lock) { #if defined(__WIN32__) *lock = 0; #elif defined(__MACOSX__) *lock = 0; #elif defined(__GNUC__) && !defined(__arm__) __sync_lock_release(lock); #else /* Assuming memory barrier in lock and integral assignment operation */ *lock = 0; #endif } /* vi: set ts=4 sw=4 expandtab: */