127 lines
1.7 KiB
C
127 lines
1.7 KiB
C
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/*++
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Copyright (c) 2000-2001 Microsoft Corporation
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Module Name:
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rwlock.h
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Abstract:
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This module contains public declarations for a multiple-reader
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single-writer lock.
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Author:
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Chun Ye (chunye) 20-Dec-2000
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Revision History:
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--*/
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#ifndef _RWLOCK_H_
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#define _RWLOCK_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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//
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// The R/W Lock implements the multiple-reader single-writer locking scheme.
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//
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typedef struct _UL_RW_LOCK
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{
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UL_SPIN_LOCK SpinLock;
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LONG RefCount;
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} UL_RW_LOCK, *PUL_RW_LOCK;
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//
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// R/W Lock functions.
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//
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__inline
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VOID
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FASTCALL
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UlInitializeRWLock(
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OUT PUL_RW_LOCK pLock
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)
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{
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pLock->RefCount = 0;
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UlInitializeSpinLock( &pLock->SpinLock, "RWLock" );
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}
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__inline
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VOID
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FASTCALL
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UlAcquireRWLockForRead(
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IN OUT PUL_RW_LOCK pLock,
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IN OUT PKIRQL pIrql
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)
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{
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UlAcquireSpinLock( &pLock->SpinLock, pIrql );
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InterlockedIncrement( &pLock->RefCount );
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UlReleaseSpinLockFromDpcLevel( &pLock->SpinLock );
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}
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__inline
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VOID
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FASTCALL
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UlAcquireRWLockForWrite(
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IN OUT PUL_RW_LOCK pLock,
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IN OUT PKIRQL pIrql
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)
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{
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UlAcquireSpinLock(&pLock->SpinLock, pIrql);
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while (*((volatile LONG *)&pLock->RefCount) != 0);
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}
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__inline
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VOID
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FASTCALL
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UlReleaseRWLockFromRead(
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IN OUT PUL_RW_LOCK pLock,
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IN KIRQL Irql
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)
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{
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ASSERT( KeGetCurrentIrql() == DISPATCH_LEVEL );
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InterlockedDecrement( &pLock->RefCount );
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KeLowerIrql( Irql );
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}
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__inline
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VOID
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FASTCALL
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UlReleaseRWLockFromWrite(
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IN OUT PUL_RW_LOCK pLock,
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IN KIRQL Irql
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)
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{
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ASSERT( KeGetCurrentIrql() == DISPATCH_LEVEL );
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UlReleaseSpinLock( &pLock->SpinLock, Irql );
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}
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#ifdef __cplusplus
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}; // extern "C"
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#endif
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#endif // _RWLOCK_H_
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