+++ /dev/null
-/*
- Simple DirectMedia Layer
- Copyright (C) 1997-2013 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"
-
-/* Need to do this here because intrin.h has C++ code in it */
-/* Visual Studio 2005 has a bug where intrin.h conflicts with winnt.h */
-#if defined(_MSC_VER) && (_MSC_VER >= 1500)
-#include <intrin.h>
-#define HAVE_MSC_ATOMICS 1
-#endif
-
-/* 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
-
-
-/* Platform specific optimized versions of the atomic functions,
- * you can disable these by defining SDL_DISABLE_ATOMIC_INLINE
- */
-#if defined(SDL_ATOMIC_DISABLED) && SDL_ATOMIC_DISABLED
-#define SDL_DISABLE_ATOMIC_INLINE
-#endif
-#ifndef SDL_DISABLE_ATOMIC_INLINE
-
-#ifdef HAVE_MSC_ATOMICS
-
-#define SDL_AtomicSet(a, v) _InterlockedExchange((long*)&(a)->value, (v))
-#define SDL_AtomicAdd(a, v) _InterlockedExchangeAdd((long*)&(a)->value, (v))
-#define SDL_AtomicCAS(a, oldval, newval) (_InterlockedCompareExchange((long*)&(a)->value, (newval), (oldval)) == (oldval))
-#define SDL_AtomicSetPtr(a, v) _InterlockedExchangePointer((a), (v))
-#if _M_IX86
-#define SDL_AtomicCASPtr(a, oldval, newval) (_InterlockedCompareExchange((long*)(a), (long)(newval), (long)(oldval)) == (long)(oldval))
-#else
-#define SDL_AtomicCASPtr(a, oldval, newval) (_InterlockedCompareExchangePointer((a), (newval), (oldval)) == (oldval))
-#endif
-
-#elif defined(__MACOSX__)
-#include <libkern/OSAtomic.h>
-
-#define SDL_AtomicCAS(a, oldval, newval) OSAtomicCompareAndSwap32Barrier((oldval), (newval), &(a)->value)
-#ifdef __LP64__
-#define SDL_AtomicCASPtr(a, oldval, newval) OSAtomicCompareAndSwap64Barrier((int64_t)(oldval), (int64_t)(newval), (int64_t*)(a))
-#else
-#define SDL_AtomicCASPtr(a, oldval, newval) OSAtomicCompareAndSwap32Barrier((int32_t)(oldval), (int32_t)(newval), (int32_t*)(a))
-#endif
-
-#elif defined(HAVE_GCC_ATOMICS)
-
-#define SDL_AtomicSet(a, v) __sync_lock_test_and_set(&(a)->value, v)
-#define SDL_AtomicAdd(a, v) __sync_fetch_and_add(&(a)->value, v)
-#define SDL_AtomicSetPtr(a, v) __sync_lock_test_and_set(a, v)
-#define SDL_AtomicCAS(a, oldval, newval) __sync_bool_compare_and_swap(&(a)->value, oldval, newval)
-#define SDL_AtomicCASPtr(a, oldval, newval) __sync_bool_compare_and_swap(a, oldval, newval)
-
-#endif
-
-#endif /* !SDL_DISABLE_ATOMIC_INLINE */
-
-
-/**
- * \brief A type representing an atomic integer value. It is a struct
- * so people don't accidentally use numeric operations on it.
- */
-#ifndef SDL_atomic_t_defined
-typedef struct { int value; } SDL_atomic_t;
-#endif
-
-/**
- * \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!
-*/
-#ifndef SDL_AtomicCAS
-extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval);
-#endif
-
-/**
- * \brief Set an atomic variable to a value.
- *
- * \return The previous value of the atomic variable.
- */
-#ifndef SDL_AtomicSet
-SDL_FORCE_INLINE int SDL_AtomicSet(SDL_atomic_t *a, int v)
-{
- int value;
- do {
- value = a->value;
- } while (!SDL_AtomicCAS(a, value, v));
- return value;
-}
-#endif
-
-/**
- * \brief Get the value of an atomic variable
- */
-#ifndef SDL_AtomicGet
-SDL_FORCE_INLINE int SDL_AtomicGet(SDL_atomic_t *a)
-{
- int value = a->value;
- SDL_CompilerBarrier();
- return value;
-}
-#endif
-
-/**
- * \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
- */
-#ifndef SDL_AtomicAdd
-SDL_FORCE_INLINE int SDL_AtomicAdd(SDL_atomic_t *a, int v)
-{
- int value;
- do {
- value = a->value;
- } while (!SDL_AtomicCAS(a, value, (value + v)));
- return value;
-}
-#endif
-
-/**
- * \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!
-*/
-#ifndef SDL_AtomicCASPtr
-extern DECLSPEC SDL_bool SDLCALL SDL_AtomicCASPtr(void* *a, void *oldval, void *newval);
-#endif
-
-/**
- * \brief Set a pointer to a value atomically.
- *
- * \return The previous value of the pointer.
- */
-#ifndef SDL_AtomicSetPtr
-SDL_FORCE_INLINE void* SDL_AtomicSetPtr(void* *a, void* v)
-{
- void* value;
- do {
- value = *a;
- } while (!SDL_AtomicCASPtr(a, value, v));
- return value;
-}
-#endif
-
-/**
- * \brief Get the value of a pointer atomically.
- */
-#ifndef SDL_AtomicGetPtr
-SDL_FORCE_INLINE void* SDL_AtomicGetPtr(void* *a)
-{
- void* value = *a;
- SDL_CompilerBarrier();
- return value;
-}
-#endif
-
-
-/* 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: */
git.r.bdr.sh / rbdr / super-polarity / blobdiff