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--- Libc/Libc-498.1.7/include/libkern/OSAtomic.h
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-/*
- * Copyright (c) 2004-2006 Apple Computer, Inc. All rights reserved.
- *
- * @APPLE_LICENSE_HEADER_START@
- *
- * This file contains Original Code and/or Modifications of Original Code
- * as defined in and that are subject to the Apple Public Source License
- * Version 2.0 (the 'License'). You may not use this file except in
- * compliance with the License. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
- *
- * The Original Code and all software distributed under the License are
- * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
- * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
- * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
- * Please see the License for the specific language governing rights and
- * limitations under the License.
- *
- * @APPLE_LICENSE_HEADER_END@
- */
-
-#ifndef _OSATOMIC_H_
-#define _OSATOMIC_H_
-
-#include <stddef.h>
-#include <sys/cdefs.h>
-#include <stdint.h>
-#include <stdbool.h>
-
-/* These are the preferred versions of the atomic and synchronization operations.
- * Their implementation is customized at boot time for the platform, including
- * late-breaking errata fixes as necessary. They are thread safe.
- *
- * WARNING: all addresses passed to these functions must be "naturally aligned", ie
- * int32_t's must be 32-bit aligned (low 2 bits of address zero), and int64_t's
- * must be 64-bit aligned (low 3 bits of address zero.)
- *
- * Note that some versions of the atomic functions incorporate memory barriers,
- * and some do not. Barriers strictly order memory access on a weakly-ordered
- * architecture such as PPC. All loads and stores executed in sequential program
- * order before the barrier will complete before any load or store executed after
- * the barrier. On a uniprocessor, the barrier operation is typically a nop.
- * On a multiprocessor, the barrier can be quite expensive on some platforms,
- * eg PPC.
- *
- * Most code will want to use the barrier functions to insure that memory shared
- * between threads is properly synchronized. For example, if you want to initialize
- * a shared data structure and then atomically increment a variable to indicate
- * that the initialization is complete, then you must use OSAtomicIncrement32Barrier()
- * to ensure that the stores to your data structure complete before the atomic add.
- * Likewise, the consumer of that data structure must use OSAtomicDecrement32Barrier(),
- * in order to ensure that their loads of the structure are not executed before
- * the atomic decrement. On the other hand, if you are simply incrementing a global
- * counter, then it is safe and potentially faster to use OSAtomicIncrement32().
- *
- * If you are unsure which version to use, prefer the barrier variants as they are
- * safer.
- *
- * The spinlock and queue operations always incorporate a barrier.
- */
-__BEGIN_DECLS
-
-
-/* Arithmetic functions. They return the new value.
- */
-int32_t OSAtomicAdd32( int32_t __theAmount, volatile int32_t *__theValue );
-int32_t OSAtomicAdd32Barrier( int32_t __theAmount, volatile int32_t *__theValue );
-
-inline static
-int32_t OSAtomicIncrement32( volatile int32_t *__theValue )
- { return OSAtomicAdd32( 1, __theValue); }
-inline static
-int32_t OSAtomicIncrement32Barrier( volatile int32_t *__theValue )
- { return OSAtomicAdd32Barrier( 1, __theValue); }
-
-inline static
-int32_t OSAtomicDecrement32( volatile int32_t *__theValue )
- { return OSAtomicAdd32( -1, __theValue); }
-inline static
-int32_t OSAtomicDecrement32Barrier( volatile int32_t *__theValue )
- { return OSAtomicAdd32Barrier( -1, __theValue); }
-
-#if defined(__ppc64__) || defined(__i386__) || defined(__x86_64__)
-
-int64_t OSAtomicAdd64( int64_t __theAmount, volatile int64_t *__theValue );
-int64_t OSAtomicAdd64Barrier( int64_t __theAmount, volatile int64_t *__theValue );
-
-inline static
-int64_t OSAtomicIncrement64( volatile int64_t *__theValue )
- { return OSAtomicAdd64( 1, __theValue); }
-inline static
-int64_t OSAtomicIncrement64Barrier( volatile int64_t *__theValue )
- { return OSAtomicAdd64Barrier( 1, __theValue); }
-
-inline static
-int64_t OSAtomicDecrement64( volatile int64_t *__theValue )
- { return OSAtomicAdd64( -1, __theValue); }
-inline static
-int64_t OSAtomicDecrement64Barrier( volatile int64_t *__theValue )
- { return OSAtomicAdd64Barrier( -1, __theValue); }
-
-#endif /* defined(__ppc64__) || defined(__i386__) || defined(__x86_64__) */
-
-
-/* Boolean functions (and, or, xor.) These come in four versions for each operation:
- * with and without barriers, and returning the old or new value of the operation.
- * The "Orig" versions return the original value, ie before the operation, the non-Orig
- * versions return the value after the operation. All are layered on top of
- * compare-and-swap.
- */
-int32_t OSAtomicOr32( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicOr32Barrier( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicOr32Orig( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicOr32OrigBarrier( uint32_t __theMask, volatile uint32_t *__theValue );
-
-int32_t OSAtomicAnd32( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicAnd32Barrier( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicAnd32Orig( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicAnd32OrigBarrier( uint32_t __theMask, volatile uint32_t *__theValue );
-
-int32_t OSAtomicXor32( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicXor32Barrier( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicXor32Orig( uint32_t __theMask, volatile uint32_t *__theValue );
-int32_t OSAtomicXor32OrigBarrier( uint32_t __theMask, volatile uint32_t *__theValue );
-
-
-/* Compare and swap. They return true if the swap occured. There are several versions,
- * depending on data type and whether or not a barrier is used.
- */
-bool OSAtomicCompareAndSwap32( int32_t __oldValue, int32_t __newValue, volatile int32_t *__theValue );
-bool OSAtomicCompareAndSwap32Barrier( int32_t __oldValue, int32_t __newValue, volatile int32_t *__theValue );
-bool OSAtomicCompareAndSwapPtr( void *__oldValue, void *__newValue, void * volatile *__theValue );
-bool OSAtomicCompareAndSwapPtrBarrier( void *__oldValue, void *__newValue, void * volatile *__theValue );
-bool OSAtomicCompareAndSwapInt( int __oldValue, int __newValue, volatile int *__theValue );
-bool OSAtomicCompareAndSwapIntBarrier( int __oldValue, int __newValue, volatile int *__theValue );
-bool OSAtomicCompareAndSwapLong( long __oldValue, long __newValue, volatile long *__theValue );
-bool OSAtomicCompareAndSwapLongBarrier( long __oldValue, long __newValue, volatile long *__theValue );
-
-#if defined(__ppc64__) || defined(__i386__) || defined(__x86_64__)
-
-bool OSAtomicCompareAndSwap64( int64_t __oldValue, int64_t __newValue, volatile int64_t *__theValue );
-bool OSAtomicCompareAndSwap64Barrier( int64_t __oldValue, int64_t __newValue, volatile int64_t *__theValue );
-
-#endif /* defined(__ppc64__) || defined(__i386__) || defined(__x86_64__) */
-
-
-/* Test and set. They return the original value of the bit, and operate on bit (0x80>>(n&7))
- * in byte ((char*)theAddress + (n>>3)).
- */
-bool OSAtomicTestAndSet( uint32_t __n, volatile void *__theAddress );
-bool OSAtomicTestAndSetBarrier( uint32_t __n, volatile void *__theAddress );
-bool OSAtomicTestAndClear( uint32_t __n, volatile void *__theAddress );
-bool OSAtomicTestAndClearBarrier( uint32_t __n, volatile void *__theAddress );
-
-
-/* Spinlocks. These use memory barriers as required to synchronize access to shared
- * memory protected by the lock. The lock operation spins, but employs various strategies
- * to back off if the lock is held, making it immune to most priority-inversion livelocks.
- * The try operation immediately returns false if the lock was held, true if it took the
- * lock. The convention is that unlocked is zero, locked is nonzero.
- */
-#define OS_SPINLOCK_INIT 0
-
-typedef int32_t OSSpinLock;
-
-bool OSSpinLockTry( volatile OSSpinLock *__lock );
-void OSSpinLockLock( volatile OSSpinLock *__lock );
-void OSSpinLockUnlock( volatile OSSpinLock *__lock );
-
-
-/* Lockless atomic enqueue and dequeue. These routines manipulate singly
- * linked LIFO lists. Ie, a dequeue will return the most recently enqueued
- * element, or NULL if the list is empty. The "offset" parameter is the offset
- * in bytes of the link field within the data structure being queued. The
- * link field should be a pointer type. Memory barriers are incorporated as
- * needed to permit thread-safe access to the queue element.
- */
-#if defined(__x86_64__)
-
-typedef volatile struct {
- void *opaque1;
- long opaque2;
-} OSQueueHead __attribute__ ((aligned (16)));
-
-#else
-
-typedef volatile struct {
- void *opaque1;
- long opaque2;
-} OSQueueHead;
-
-#endif
-
-#define OS_ATOMIC_QUEUE_INIT { NULL, 0 }
-
-void OSAtomicEnqueue( OSQueueHead *__list, void *__new, size_t __offset);
-void* OSAtomicDequeue( OSQueueHead *__list, size_t __offset);
-
-
-/* Memory barrier. It is both a read and write barrier.
- */
-void OSMemoryBarrier( void );
-
-
-__END_DECLS
-
-#endif /* _OSATOMIC_H_ */