ref: 9eaba52cafcac7c2f3bfc72d7be1f15893196be1
dir: /external/SDL2/src/atomic/SDL_atomic.c/
/* Simple DirectMedia Layer Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org> This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution. */ #include "../SDL_internal.h" #include "SDL_atomic.h" #if defined(_MSC_VER) && (_MSC_VER >= 1500) #include <intrin.h> #define HAVE_MSC_ATOMICS 1 #endif #if defined(__MACOSX__) /* !!! FIXME: should we favor gcc atomics? */ #include <libkern/OSAtomic.h> #endif #if !defined(HAVE_GCC_ATOMICS) && defined(__SOLARIS__) #include <atomic.h> #endif /* The __atomic_load_n() intrinsic showed up in different times for different compilers. */ #if defined(HAVE_GCC_ATOMICS) # if defined(__clang__) # if __has_builtin(__atomic_load_n) /* !!! FIXME: this advertises as available in the NDK but uses an external symbol we don't have. It might be in a later NDK or we might need an extra library? --ryan. */ # if !defined(__ANDROID__) # define HAVE_ATOMIC_LOAD_N 1 # endif # endif # elif defined(__GNUC__) # if (__GNUC__ >= 5) # define HAVE_ATOMIC_LOAD_N 1 # endif # endif #endif #if defined(__WATCOMC__) && defined(__386__) SDL_COMPILE_TIME_ASSERT(intsize, 4==sizeof(int)); #define HAVE_WATCOM_ATOMICS extern _inline int _SDL_xchg_watcom(volatile int *a, int v); #pragma aux _SDL_xchg_watcom = \ "lock xchg [ecx], eax" \ parm [ecx] [eax] \ value [eax] \ modify exact [eax]; extern _inline unsigned char _SDL_cmpxchg_watcom(volatile int *a, int newval, int oldval); #pragma aux _SDL_cmpxchg_watcom = \ "lock cmpxchg [edx], ecx" \ "setz al" \ parm [edx] [ecx] [eax] \ value [al] \ modify exact [eax]; extern _inline int _SDL_xadd_watcom(volatile int *a, int v); #pragma aux _SDL_xadd_watcom = \ "lock xadd [ecx], eax" \ parm [ecx] [eax] \ value [eax] \ modify exact [eax]; #endif /* __WATCOMC__ && __386__ */ /* If any of the operations are not provided then we must emulate some of them. That means we need a nice implementation of spin locks that avoids the "one big lock" problem. We use a vector of spin locks and pick which one to use based on the address of the operand of the function. To generate the index of the lock we first shift by 3 bits to get rid on the zero bits that result from 32 and 64 bit allignment of data. We then mask off all but 5 bits and use those 5 bits as an index into the table. Picking the lock this way insures that accesses to the same data at the same time will go to the same lock. OTOH, accesses to different data have only a 1/32 chance of hitting the same lock. That should pretty much eliminate the chances of several atomic operations on different data from waiting on the same "big lock". If it isn't then the table of locks can be expanded to a new size so long as the new size is a power of two. Contributed by Bob Pendleton, bob@pendleton.com */ #if !defined(HAVE_MSC_ATOMICS) && !defined(HAVE_GCC_ATOMICS) && !defined(__MACOSX__) && !defined(__SOLARIS__) && !defined(HAVE_WATCOM_ATOMICS) #define EMULATE_CAS 1 #endif #if EMULATE_CAS static SDL_SpinLock locks[32]; static SDL_INLINE void enterLock(void *a) { uintptr_t index = ((((uintptr_t)a) >> 3) & 0x1f); SDL_AtomicLock(&locks[index]); } static SDL_INLINE void leaveLock(void *a) { uintptr_t index = ((((uintptr_t)a) >> 3) & 0x1f); SDL_AtomicUnlock(&locks[index]); } #endif SDL_bool SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval) { #ifdef HAVE_MSC_ATOMICS return (_InterlockedCompareExchange((long*)&a->value, (long)newval, (long)oldval) == (long)oldval); #elif defined(HAVE_WATCOM_ATOMICS) return (SDL_bool) _SDL_cmpxchg_watcom(&a->value, newval, oldval); #elif defined(HAVE_GCC_ATOMICS) return (SDL_bool) __sync_bool_compare_and_swap(&a->value, oldval, newval); #elif defined(__MACOSX__) /* this is deprecated in 10.12 sdk; favor gcc atomics. */ return (SDL_bool) OSAtomicCompareAndSwap32Barrier(oldval, newval, &a->value); #elif defined(__SOLARIS__) && defined(_LP64) return (SDL_bool) ((int) atomic_cas_64((volatile uint64_t*)&a->value, (uint64_t)oldval, (uint64_t)newval) == oldval); #elif defined(__SOLARIS__) && !defined(_LP64) return (SDL_bool) ((int) atomic_cas_32((volatile uint32_t*)&a->value, (uint32_t)oldval, (uint32_t)newval) == oldval); #elif EMULATE_CAS SDL_bool retval = SDL_FALSE; enterLock(a); if (a->value == oldval) { a->value = newval; retval = SDL_TRUE; } leaveLock(a); return retval; #else #error Please define your platform. #endif } SDL_bool SDL_AtomicCASPtr(void **a, void *oldval, void *newval) { #if defined(HAVE_MSC_ATOMICS) && (_M_IX86) return (_InterlockedCompareExchange((long*)a, (long)newval, (long)oldval) == (long)oldval); #elif defined(HAVE_MSC_ATOMICS) && (!_M_IX86) return (_InterlockedCompareExchangePointer(a, newval, oldval) == oldval); #elif defined(HAVE_WATCOM_ATOMICS) return (SDL_bool) _SDL_cmpxchg_watcom((int *)a, (long)newval, (long)oldval); #elif defined(HAVE_GCC_ATOMICS) return __sync_bool_compare_and_swap(a, oldval, newval); #elif defined(__MACOSX__) && defined(__LP64__) /* this is deprecated in 10.12 sdk; favor gcc atomics. */ return (SDL_bool) OSAtomicCompareAndSwap64Barrier((int64_t)oldval, (int64_t)newval, (int64_t*) a); #elif defined(__MACOSX__) && !defined(__LP64__) /* this is deprecated in 10.12 sdk; favor gcc atomics. */ return (SDL_bool) OSAtomicCompareAndSwap32Barrier((int32_t)oldval, (int32_t)newval, (int32_t*) a); #elif defined(__SOLARIS__) return (SDL_bool) (atomic_cas_ptr(a, oldval, newval) == oldval); #elif EMULATE_CAS SDL_bool retval = SDL_FALSE; enterLock(a); if (*a == oldval) { *a = newval; retval = SDL_TRUE; } leaveLock(a); return retval; #else #error Please define your platform. #endif } int SDL_AtomicSet(SDL_atomic_t *a, int v) { #ifdef HAVE_MSC_ATOMICS return _InterlockedExchange((long*)&a->value, v); #elif defined(HAVE_WATCOM_ATOMICS) return _SDL_xchg_watcom(&a->value, v); #elif defined(HAVE_GCC_ATOMICS) return __sync_lock_test_and_set(&a->value, v); #elif defined(__SOLARIS__) && defined(_LP64) return (int) atomic_swap_64((volatile uint64_t*)&a->value, (uint64_t)v); #elif defined(__SOLARIS__) && !defined(_LP64) return (int) atomic_swap_32((volatile uint32_t*)&a->value, (uint32_t)v); #else int value; do { value = a->value; } while (!SDL_AtomicCAS(a, value, v)); return value; #endif } void* SDL_AtomicSetPtr(void **a, void *v) { #if defined(HAVE_MSC_ATOMICS) && (_M_IX86) return (void *) _InterlockedExchange((long *)a, (long) v); #elif defined(HAVE_MSC_ATOMICS) && (!_M_IX86) return _InterlockedExchangePointer(a, v); #elif defined(HAVE_WATCOM_ATOMICS) return (void *) _SDL_xchg_watcom((int *)a, (long)v); #elif defined(HAVE_GCC_ATOMICS) return __sync_lock_test_and_set(a, v); #elif defined(__SOLARIS__) return atomic_swap_ptr(a, v); #else void *value; do { value = *a; } while (!SDL_AtomicCASPtr(a, value, v)); return value; #endif } int SDL_AtomicAdd(SDL_atomic_t *a, int v) { #ifdef HAVE_MSC_ATOMICS return _InterlockedExchangeAdd((long*)&a->value, v); #elif defined(HAVE_WATCOM_ATOMICS) return _SDL_xadd_watcom(&a->value, v); #elif defined(HAVE_GCC_ATOMICS) return __sync_fetch_and_add(&a->value, v); #elif defined(__SOLARIS__) int pv = a->value; membar_consumer(); #if defined(_LP64) atomic_add_64((volatile uint64_t*)&a->value, v); #elif !defined(_LP64) atomic_add_32((volatile uint32_t*)&a->value, v); #endif return pv; #else int value; do { value = a->value; } while (!SDL_AtomicCAS(a, value, (value + v))); return value; #endif } int SDL_AtomicGet(SDL_atomic_t *a) { #ifdef HAVE_ATOMIC_LOAD_N return __atomic_load_n(&a->value, __ATOMIC_SEQ_CST); #else int value; do { value = a->value; } while (!SDL_AtomicCAS(a, value, value)); return value; #endif } void * SDL_AtomicGetPtr(void **a) { #ifdef HAVE_ATOMIC_LOAD_N return __atomic_load_n(a, __ATOMIC_SEQ_CST); #else void *value; do { value = *a; } while (!SDL_AtomicCASPtr(a, value, value)); return value; #endif } void SDL_MemoryBarrierReleaseFunction(void) { SDL_MemoryBarrierRelease(); } void SDL_MemoryBarrierAcquireFunction(void) { SDL_MemoryBarrierAcquire(); } /* vi: set ts=4 sw=4 expandtab: */