SDL_atomic.h

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/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2019 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.
*/

#ifndef SDL_atomic_h_
#define SDL_atomic_h_

#include "SDL_stdinc.h"
#include "SDL_platform.h"

#include "begin_code.h"

/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
extern "C" {
#endif

/* @{ */

typedef int SDL_SpinLock;

extern DECLSPEC SDL_bool SDLCALL SDL_AtomicTryLock(SDL_SpinLock *lock);

extern DECLSPEC void SDLCALL SDL_AtomicLock(SDL_SpinLock *lock);

extern DECLSPEC void SDLCALL SDL_AtomicUnlock(SDL_SpinLock *lock);

/* @} *//* SDL AtomicLock */


#if defined(_MSC_VER) && (_MSC_VER > 1200) && !defined(__clang__)
void _ReadWriteBarrier(void);
#pragma intrinsic(_ReadWriteBarrier)
#define SDL_CompilerBarrier()   _ReadWriteBarrier()
#elif (defined(__GNUC__) && !defined(__EMSCRIPTEN__)) || (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x5120))
/* This is correct for all CPUs when using GCC or Solaris Studio 12.1+. */
#define SDL_CompilerBarrier()   __asm__ __volatile__ ("" : : : "memory")
#elif defined(__WATCOMC__)
extern _inline void SDL_CompilerBarrier (void);
#pragma aux SDL_CompilerBarrier = "" parm [] modify exact [];
#else
#define SDL_CompilerBarrier()   \
{ SDL_SpinLock _tmp = 0; SDL_AtomicLock(&_tmp); SDL_AtomicUnlock(&_tmp); }
#endif

extern DECLSPEC void SDLCALL SDL_MemoryBarrierReleaseFunction(void);
extern DECLSPEC void SDLCALL SDL_MemoryBarrierAcquireFunction(void);

#if defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("lwsync" : : : "memory")
#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("lwsync" : : : "memory")
#elif defined(__GNUC__) && defined(__aarch64__)
#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("dmb ish" : : : "memory")
#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("dmb ish" : : : "memory")
#elif defined(__GNUC__) && defined(__arm__)
#if 0 /* defined(__LINUX__) || defined(__ANDROID__) */
/* Information from:
   https://chromium.googlesource.com/chromium/chromium/+/trunk/base/atomicops_internals_arm_gcc.h#19

   The Linux kernel provides a helper function which provides the right code for a memory barrier,
   hard-coded at address 0xffff0fa0
*/
typedef void (*SDL_KernelMemoryBarrierFunc)();
#define SDL_MemoryBarrierRelease()      ((SDL_KernelMemoryBarrierFunc)0xffff0fa0)()
#define SDL_MemoryBarrierAcquire()      ((SDL_KernelMemoryBarrierFunc)0xffff0fa0)()
#elif 0 /* defined(__QNXNTO__) */
#include <sys/cpuinline.h>

#define SDL_MemoryBarrierRelease()   __cpu_membarrier()
#define SDL_MemoryBarrierAcquire()   __cpu_membarrier()
#else
#if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7EM__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) || defined(__ARM_ARCH_8A__)
#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("dmb ish" : : : "memory")
#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("dmb ish" : : : "memory")
#elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_5TE__)
#ifdef __thumb__
/* The mcr instruction isn't available in thumb mode, use real functions */
#define SDL_MEMORY_BARRIER_USES_FUNCTION
#define SDL_MemoryBarrierRelease()   SDL_MemoryBarrierReleaseFunction()
#define SDL_MemoryBarrierAcquire()   SDL_MemoryBarrierAcquireFunction()
#else
#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" : : "r"(0) : "memory")
#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" : : "r"(0) : "memory")
#endif /* __thumb__ */
#else
#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("" : : : "memory")
#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("" : : : "memory")
#endif /* __LINUX__ || __ANDROID__ */
#endif /* __GNUC__ && __arm__ */
#else
#if (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x5120))
/* This is correct for all CPUs on Solaris when using Solaris Studio 12.1+. */
#include <mbarrier.h>
#define SDL_MemoryBarrierRelease()  __machine_rel_barrier()
#define SDL_MemoryBarrierAcquire()  __machine_acq_barrier()
#else
/* This is correct for the x86 and x64 CPUs, and we'll expand this over time. */
#define SDL_MemoryBarrierRelease()  SDL_CompilerBarrier()
#define SDL_MemoryBarrierAcquire()  SDL_CompilerBarrier()
#endif
#endif

typedef struct { int value; } SDL_atomic_t;

extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval);

extern DECLSPEC int SDLCALL SDL_AtomicSet(SDL_atomic_t *a, int v);

extern DECLSPEC int SDLCALL SDL_AtomicGet(SDL_atomic_t *a);

extern DECLSPEC int SDLCALL SDL_AtomicAdd(SDL_atomic_t *a, int v);

#ifndef SDL_AtomicIncRef
#define SDL_AtomicIncRef(a)    SDL_AtomicAdd(a, 1)
#endif

#ifndef SDL_AtomicDecRef
#define SDL_AtomicDecRef(a)    (SDL_AtomicAdd(a, -1) == 1)
#endif

extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCASPtr(void **a, void *oldval, void *newval);

extern DECLSPEC void* SDLCALL SDL_AtomicSetPtr(void **a, void* v);

extern DECLSPEC void* SDLCALL SDL_AtomicGetPtr(void **a);

/* Ends C function definitions when using C++ */
#ifdef __cplusplus
}
#endif

#include "close_code.h"

#endif /* SDL_atomic_h_ */

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