From 3fde0e7edf310245e5658b767840e742c9341597 Mon Sep 17 00:00:00 2001 From: Clyne Sullivan Date: Thu, 10 Sep 2015 11:30:41 -0400 Subject: yeah --- include/SDL2/SDL_atomic.h | 520 +++++++++++++++++++++++----------------------- 1 file changed, 260 insertions(+), 260 deletions(-) (limited to 'include/SDL2/SDL_atomic.h') diff --git a/include/SDL2/SDL_atomic.h b/include/SDL2/SDL_atomic.h index bb3a9b6..f319b89 100644 --- a/include/SDL2/SDL_atomic.h +++ b/include/SDL2/SDL_atomic.h @@ -1,260 +1,260 @@ -/* - Simple DirectMedia Layer - Copyright (C) 1997-2014 Sam Lantinga - - 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; - -/** - * \brief Try to lock a spin lock by setting it to a non-zero value. - * - * \param lock Points to the lock. - * - * \return SDL_TRUE if the lock succeeded, SDL_FALSE if the lock is already held. - */ -extern DECLSPEC SDL_bool SDLCALL SDL_AtomicTryLock(SDL_SpinLock *lock); - -/** - * \brief Lock a spin lock by setting it to a non-zero value. - * - * \param lock Points to the lock. - */ -extern DECLSPEC void SDLCALL SDL_AtomicLock(SDL_SpinLock *lock); - -/** - * \brief Unlock a spin lock by setting it to 0. Always returns immediately - * - * \param lock Points to the lock. - */ -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) -void _ReadWriteBarrier(void); -#pragma intrinsic(_ReadWriteBarrier) -#define SDL_CompilerBarrier() _ReadWriteBarrier() -#elif defined(__GNUC__) -#define SDL_CompilerBarrier() __asm__ __volatile__ ("" : : : "memory") -#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 - */ -#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(__arm__) -#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__) -#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__) -#ifdef __thumb__ -/* The mcr instruction isn't available in thumb mode, use real functions */ -extern DECLSPEC void SDLCALL SDL_MemoryBarrierRelease(); -extern DECLSPEC void SDLCALL SDL_MemoryBarrierAcquire(); -#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 /* __GNUC__ && __arm__ */ -#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 - -/** - * \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; - -/** - * \brief Set an atomic variable to a new value if it is currently an old value. - * - * \return SDL_TRUE if the atomic variable was set, SDL_FALSE otherwise. - * - * \note If you don't know what this function is for, you shouldn't use it! -*/ -extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval); - -/** - * \brief Set an atomic variable to a value. - * - * \return The previous value of the atomic variable. - */ -extern DECLSPEC int SDLCALL SDL_AtomicSet(SDL_atomic_t *a, int v); - -/** - * \brief Get the value of an atomic variable - */ -extern DECLSPEC int SDLCALL SDL_AtomicGet(SDL_atomic_t *a); - -/** - * \brief Add to an atomic variable. - * - * \return The previous value of the atomic variable. - * - * \note This same style can be used for any number operation - */ -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 - -/** - * \brief Set a pointer to a new value if it is currently an old value. - * - * \return SDL_TRUE if the pointer was set, SDL_FALSE otherwise. - * - * \note If you don't know what this function is for, you shouldn't use it! -*/ -extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCASPtr(void **a, void *oldval, void *newval); - -/** - * \brief Set a pointer to a value atomically. - * - * \return The previous value of the pointer. - */ -extern DECLSPEC void* SDLCALL SDL_AtomicSetPtr(void **a, void* v); - -/** - * \brief Get the value of a pointer atomically. - */ -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: */ +/* + Simple DirectMedia Layer + Copyright (C) 1997-2014 Sam Lantinga + + 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; + +/** + * \brief Try to lock a spin lock by setting it to a non-zero value. + * + * \param lock Points to the lock. + * + * \return SDL_TRUE if the lock succeeded, SDL_FALSE if the lock is already held. + */ +extern DECLSPEC SDL_bool SDLCALL SDL_AtomicTryLock(SDL_SpinLock *lock); + +/** + * \brief Lock a spin lock by setting it to a non-zero value. + * + * \param lock Points to the lock. + */ +extern DECLSPEC void SDLCALL SDL_AtomicLock(SDL_SpinLock *lock); + +/** + * \brief Unlock a spin lock by setting it to 0. Always returns immediately + * + * \param lock Points to the lock. + */ +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) +void _ReadWriteBarrier(void); +#pragma intrinsic(_ReadWriteBarrier) +#define SDL_CompilerBarrier() _ReadWriteBarrier() +#elif defined(__GNUC__) +#define SDL_CompilerBarrier() __asm__ __volatile__ ("" : : : "memory") +#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 + */ +#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(__arm__) +#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__) +#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__) +#ifdef __thumb__ +/* The mcr instruction isn't available in thumb mode, use real functions */ +extern DECLSPEC void SDLCALL SDL_MemoryBarrierRelease(); +extern DECLSPEC void SDLCALL SDL_MemoryBarrierAcquire(); +#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 /* __GNUC__ && __arm__ */ +#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 + +/** + * \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; + +/** + * \brief Set an atomic variable to a new value if it is currently an old value. + * + * \return SDL_TRUE if the atomic variable was set, SDL_FALSE otherwise. + * + * \note If you don't know what this function is for, you shouldn't use it! +*/ +extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval); + +/** + * \brief Set an atomic variable to a value. + * + * \return The previous value of the atomic variable. + */ +extern DECLSPEC int SDLCALL SDL_AtomicSet(SDL_atomic_t *a, int v); + +/** + * \brief Get the value of an atomic variable + */ +extern DECLSPEC int SDLCALL SDL_AtomicGet(SDL_atomic_t *a); + +/** + * \brief Add to an atomic variable. + * + * \return The previous value of the atomic variable. + * + * \note This same style can be used for any number operation + */ +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 + +/** + * \brief Set a pointer to a new value if it is currently an old value. + * + * \return SDL_TRUE if the pointer was set, SDL_FALSE otherwise. + * + * \note If you don't know what this function is for, you shouldn't use it! +*/ +extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCASPtr(void **a, void *oldval, void *newval); + +/** + * \brief Set a pointer to a value atomically. + * + * \return The previous value of the pointer. + */ +extern DECLSPEC void* SDLCALL SDL_AtomicSetPtr(void **a, void* v); + +/** + * \brief Get the value of a pointer atomically. + */ +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: */ -- cgit v1.2.3