diff options
Diffstat (limited to 'dependencies/SDL/SDL_atomic.h')
| -rw-r--r-- | dependencies/SDL/SDL_atomic.h | 415 |
1 files changed, 0 insertions, 415 deletions
diff --git a/dependencies/SDL/SDL_atomic.h b/dependencies/SDL/SDL_atomic.h deleted file mode 100644 index f0c05f4..0000000 --- a/dependencies/SDL/SDL_atomic.h +++ /dev/null @@ -1,415 +0,0 @@ -/* - Simple DirectMedia Layer - Copyright (C) 1997-2022 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. -*/ - -/** - * \file SDL_atomic.h - * - * Atomic operations. - * - * IMPORTANT: - * If you are not an expert in concurrent lockless programming, you should - * only be using the atomic lock and reference counting functions in this - * file. In all other cases you should be protecting your data structures - * with full mutexes. - * - * The list of "safe" functions to use are: - * SDL_AtomicLock() - * SDL_AtomicUnlock() - * SDL_AtomicIncRef() - * SDL_AtomicDecRef() - * - * Seriously, here be dragons! - * ^^^^^^^^^^^^^^^^^^^^^^^^^^^ - * - * You can find out a little more about lockless programming and the - * subtle issues that can arise here: - * http://msdn.microsoft.com/en-us/library/ee418650%28v=vs.85%29.aspx - * - * There's also lots of good information here: - * http://www.1024cores.net/home/lock-free-algorithms - * http://preshing.com/ - * - * These operations may or may not actually be implemented using - * processor specific atomic operations. When possible they are - * implemented as true processor specific atomic operations. When that - * is not possible the are implemented using locks that *do* use the - * available atomic operations. - * - * All of the atomic operations that modify memory are full memory barriers. - */ - -#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 - -/** - * \name SDL AtomicLock - * - * The atomic locks are efficient spinlocks using CPU instructions, - * but are vulnerable to starvation and can spin forever if a thread - * holding a lock has been terminated. For this reason you should - * minimize the code executed inside an atomic lock and never do - * expensive things like API or system calls while holding them. - * - * The atomic locks are not safe to lock recursively. - * - * Porting Note: - * The spin lock functions and type are required and can not be - * emulated because they are used in the atomic emulation code. - */ -/* @{ */ - -typedef int SDL_SpinLock; - -/** - * Try to lock a spin lock by setting it to a non-zero value. - * - * ***Please note that spinlocks are dangerous if you don't know what you're - * doing. Please be careful using any sort of spinlock!*** - * - * \param lock a pointer to a lock variable - * \returns SDL_TRUE if the lock succeeded, SDL_FALSE if the lock is already - * held. - * - * \since This function is available since SDL 2.0.0. - * - * \sa SDL_AtomicLock - * \sa SDL_AtomicUnlock - */ -extern DECLSPEC SDL_bool SDLCALL SDL_AtomicTryLock(SDL_SpinLock *lock); - -/** - * Lock a spin lock by setting it to a non-zero value. - * - * ***Please note that spinlocks are dangerous if you don't know what you're - * doing. Please be careful using any sort of spinlock!*** - * - * \param lock a pointer to a lock variable - * - * \since This function is available since SDL 2.0.0. - * - * \sa SDL_AtomicTryLock - * \sa SDL_AtomicUnlock - */ -extern DECLSPEC void SDLCALL SDL_AtomicLock(SDL_SpinLock *lock); - -/** - * Unlock a spin lock by setting it to 0. - * - * Always returns immediately. - * - * ***Please note that spinlocks are dangerous if you don't know what you're - * doing. Please be careful using any sort of spinlock!*** - * - * \param lock a pointer to a lock variable - * - * \since This function is available since SDL 2.0.0. - * - * \sa SDL_AtomicLock - * \sa SDL_AtomicTryLock - */ -extern DECLSPEC void SDLCALL SDL_AtomicUnlock(SDL_SpinLock *lock); - -/* @} *//* SDL AtomicLock */ - - -/** - * The compiler barrier prevents the compiler from reordering - * reads and writes to globally visible variables across the call. - */ -#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 - -/** - * Memory barriers are designed to prevent reads and writes from being - * reordered by the compiler and being seen out of order on multi-core CPUs. - * - * A typical pattern would be for thread A to write some data and a flag, and - * for thread B to read the flag and get the data. In this case you would - * insert a release barrier between writing the data and the flag, - * guaranteeing that the data write completes no later than the flag is - * written, and you would insert an acquire barrier between reading the flag - * and reading the data, to ensure that all the reads associated with the flag - * have completed. - * - * In this pattern you should always see a release barrier paired with an - * acquire barrier and you should gate the data reads/writes with a single - * flag variable. - * - * For more information on these semantics, take a look at the blog post: - * http://preshing.com/20120913/acquire-and-release-semantics - * - * \since This function is available since SDL 2.0.6. - */ -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 - -/* "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 SDL_CPUPauseInstruction() __asm__ __volatile__("pause\n") /* Some assemblers can't do REP NOP, so go with PAUSE. */ -#elif (defined(__arm__) && __ARM_ARCH >= 7) || defined(__aarch64__) - #define SDL_CPUPauseInstruction() __asm__ __volatile__("yield" ::: "memory") -#elif (defined(__powerpc__) || defined(__powerpc64__)) - #define SDL_CPUPauseInstruction() __asm__ __volatile__("or 27,27,27"); -#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) - #define SDL_CPUPauseInstruction() _mm_pause() /* this is actually "rep nop" and not a SIMD instruction. No inline asm in MSVC x86-64! */ -#elif defined(_MSC_VER) && (defined(_M_ARM) || defined(_M_ARM64)) - #define SDL_CPUPauseInstruction() __yield() -#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 SDL_CPUPauseInstruction(void); - #pragma aux SDL_CPUPauseInstruction = "db 0f3h,90h" -#else - #define SDL_CPUPauseInstruction() -#endif - - -/** - * \brief A type representing an atomic integer value. It is a struct - * so people don't accidentally use numeric operations on it. - */ -typedef struct { int value; } SDL_atomic_t; - -/** - * Set an atomic variable to a new value if it is currently an old value. - * - * ***Note: If you don't know what this function is for, you shouldn't use - * it!*** - * - * \param a a pointer to an SDL_atomic_t variable to be modified - * \param oldval the old value - * \param newval the new value - * \returns SDL_TRUE if the atomic variable was set, SDL_FALSE otherwise. - * - * \since This function is available since SDL 2.0.0. - * - * \sa SDL_AtomicCASPtr - * \sa SDL_AtomicGet - * \sa SDL_AtomicSet - */ -extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval); - -/** - * Set an atomic variable to a value. - * - * This function also acts as a full memory barrier. - * - * ***Note: If you don't know what this function is for, you shouldn't use - * it!*** - * - * \param a a pointer to an SDL_atomic_t variable to be modified - * \param v the desired value - * \returns the previous value of the atomic variable. - * - * \since This function is available since SDL 2.0.2. - * - * \sa SDL_AtomicGet - */ -extern DECLSPEC int SDLCALL SDL_AtomicSet(SDL_atomic_t *a, int v); - -/** - * Get the value of an atomic variable. - * - * ***Note: If you don't know what this function is for, you shouldn't use - * it!*** - * - * \param a a pointer to an SDL_atomic_t variable - * \returns the current value of an atomic variable. - * - * \since This function is available since SDL 2.0.2. - * - * \sa SDL_AtomicSet - */ -extern DECLSPEC int SDLCALL SDL_AtomicGet(SDL_atomic_t *a); - -/** - * Add to an atomic variable. - * - * This function also acts as a full memory barrier. - * - * ***Note: If you don't know what this function is for, you shouldn't use - * it!*** - * - * \param a a pointer to an SDL_atomic_t variable to be modified - * \param v the desired value to add - * \returns the previous value of the atomic variable. - * - * \since This function is available since SDL 2.0.2. - * - * \sa SDL_AtomicDecRef - * \sa SDL_AtomicIncRef - */ -extern DECLSPEC int SDLCALL SDL_AtomicAdd(SDL_atomic_t *a, int v); - -/** - * \brief Increment an atomic variable used as a reference count. - */ -#ifndef SDL_AtomicIncRef -#define SDL_AtomicIncRef(a) SDL_AtomicAdd(a, 1) -#endif - -/** - * \brief Decrement an atomic variable used as a reference count. - * - * \return SDL_TRUE if the variable reached zero after decrementing, - * SDL_FALSE otherwise - */ -#ifndef SDL_AtomicDecRef -#define SDL_AtomicDecRef(a) (SDL_AtomicAdd(a, -1) == 1) -#endif - -/** - * Set a pointer to a new value if it is currently an old value. - * - * ***Note: If you don't know what this function is for, you shouldn't use - * it!*** - * - * \param a a pointer to a pointer - * \param oldval the old pointer value - * \param newval the new pointer value - * \returns SDL_TRUE if the pointer was set, SDL_FALSE otherwise. - * - * \since This function is available since SDL 2.0.0. - * - * \sa SDL_AtomicCAS - * \sa SDL_AtomicGetPtr - * \sa SDL_AtomicSetPtr - */ -extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCASPtr(void **a, void *oldval, void *newval); - -/** - * Set a pointer to a value atomically. - * - * ***Note: If you don't know what this function is for, you shouldn't use - * it!*** - * - * \param a a pointer to a pointer - * \param v the desired pointer value - * \returns the previous value of the pointer. - * - * \since This function is available since SDL 2.0.2. - * - * \sa SDL_AtomicCASPtr - * \sa SDL_AtomicGetPtr - */ -extern DECLSPEC void* SDLCALL SDL_AtomicSetPtr(void **a, void* v); - -/** - * Get the value of a pointer atomically. - * - * ***Note: If you don't know what this function is for, you shouldn't use - * it!*** - * - * \param a a pointer to a pointer - * \returns the current value of a pointer. - * - * \since This function is available since SDL 2.0.2. - * - * \sa SDL_AtomicCASPtr - * \sa SDL_AtomicSetPtr - */ -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_ */ - -/* vi: set ts=4 sw=4 expandtab: */ |