diff options
Diffstat (limited to 'Source/external/SDL2/src/atomic/SDL_spinlock.c')
| -rw-r--r-- | Source/external/SDL2/src/atomic/SDL_spinlock.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/Source/external/SDL2/src/atomic/SDL_spinlock.c b/Source/external/SDL2/src/atomic/SDL_spinlock.c new file mode 100644 index 0000000..6a7b14a --- /dev/null +++ b/Source/external/SDL2/src/atomic/SDL_spinlock.c @@ -0,0 +1,176 @@ +/* + 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" + +#if defined(__WIN32__) || defined(__WINRT__) +#include "../core/windows/SDL_windows.h" +#endif + +#include "SDL_atomic.h" +#include "SDL_mutex.h" +#include "SDL_timer.h" + +#if !defined(HAVE_GCC_ATOMICS) && defined(__SOLARIS__) +#include <atomic.h> +#endif + +#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) +#include <xmmintrin.h> +#endif + +#if defined(__WATCOMC__) && defined(__386__) +SDL_COMPILE_TIME_ASSERT(locksize, 4==sizeof(SDL_SpinLock)); +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]; +#endif /* __WATCOMC__ && __386__ */ + +/* This function is where all the magic happens... */ +SDL_bool +SDL_AtomicTryLock(SDL_SpinLock *lock) +{ +#if SDL_ATOMIC_DISABLED + /* Terrible terrible damage */ + static SDL_mutex *_spinlock_mutex; + + if (!_spinlock_mutex) { + /* Race condition on first lock... */ + _spinlock_mutex = SDL_CreateMutex(); + } + SDL_LockMutex(_spinlock_mutex); + if (*lock == 0) { + *lock = 1; + SDL_UnlockMutex(_spinlock_mutex); + return SDL_TRUE; + } else { + SDL_UnlockMutex(_spinlock_mutex); + return SDL_FALSE; + } + +#elif defined(_MSC_VER) + SDL_COMPILE_TIME_ASSERT(locksize, sizeof(*lock) == sizeof(long)); + return (InterlockedExchange((long*)lock, 1) == 0); + +#elif defined(__WATCOMC__) && defined(__386__) + return _SDL_xchg_watcom(lock, 1) == 0; + +#elif HAVE_GCC_ATOMICS || HAVE_GCC_SYNC_LOCK_TEST_AND_SET + return (__sync_lock_test_and_set(lock, 1) == 0); + +#elif defined(__GNUC__) && defined(__arm__) && \ + (defined(__ARM_ARCH_4__) || defined(__ARM_ARCH_4T__) || \ + defined(__ARM_ARCH_5__) || defined(__ARM_ARCH_5TE__) || \ + defined(__ARM_ARCH_5TEJ__)) + int result; + __asm__ __volatile__ ( + "swp %0, %1, [%2]\n" + : "=&r,&r" (result) : "r,0" (1), "r,r" (lock) : "memory"); + return (result == 0); + +#elif defined(__GNUC__) && defined(__arm__) + 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); + +#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)) + int result; + __asm__ __volatile__( + "lock ; xchgl %0, (%1)\n" + : "=r" (result) : "r" (lock), "0" (1) : "cc", "memory"); + return (result == 0); + +#elif defined(__MACOSX__) || defined(__IPHONEOS__) + /* Maybe used for PowerPC, but the Intel asm or gcc atomics are favored. */ + return OSAtomicCompareAndSwap32Barrier(0, 1, lock); + +#elif defined(__SOLARIS__) && defined(_LP64) + /* Used for Solaris with non-gcc compilers. */ + return (SDL_bool) ((int) atomic_cas_64((volatile uint64_t*)lock, 0, 1) == 0); + +#elif defined(__SOLARIS__) && !defined(_LP64) + /* Used for Solaris with non-gcc compilers. */ + return (SDL_bool) ((int) atomic_cas_32((volatile uint32_t*)lock, 0, 1) == 0); + +#else +#error Please implement for your platform. + return SDL_FALSE; +#endif +} + +/* "REP NOP" is PAUSE, coded for tools that don't know it by that name. */ +#if (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) + #define PAUSE_INSTRUCTION() __asm__ __volatile__("pause\n") /* Some assemblers can't do REP NOP, so go with PAUSE. */ +#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) + #define PAUSE_INSTRUCTION() _mm_pause() /* this is actually "rep nop" and not a SIMD instruction. No inline asm in MSVC x86-64! */ +#elif defined(__WATCOMC__) && defined(__386__) + /* watcom assembler rejects PAUSE if CPU < i686, and it refuses REP NOP as an invalid combination. Hardcode the bytes. */ + extern _inline void PAUSE_INSTRUCTION(void); + #pragma aux PAUSE_INSTRUCTION = "db 0f3h,90h" +#else + #define PAUSE_INSTRUCTION() +#endif + +void +SDL_AtomicLock(SDL_SpinLock *lock) +{ + int iterations = 0; + /* FIXME: Should we have an eventual timeout? */ + while (!SDL_AtomicTryLock(lock)) { + if (iterations < 32) { + iterations++; + PAUSE_INSTRUCTION(); + } else { + /* !!! FIXME: this doesn't definitely give up the current timeslice, it does different things on various platforms. */ + SDL_Delay(0); + } + } +} + +void +SDL_AtomicUnlock(SDL_SpinLock *lock) +{ +#if defined(_MSC_VER) + _ReadWriteBarrier(); + *lock = 0; + +#elif defined(__WATCOMC__) && defined(__386__) + SDL_CompilerBarrier (); + *lock = 0; + +#elif HAVE_GCC_ATOMICS || HAVE_GCC_SYNC_LOCK_TEST_AND_SET + __sync_lock_release(lock); + +#elif defined(__SOLARIS__) + /* Used for Solaris when not using gcc. */ + *lock = 0; + membar_producer(); + +#else + *lock = 0; +#endif +} + +/* vi: set ts=4 sw=4 expandtab: */ |