Source code of Windows XP (NT5)
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/*
Copyright (c) 1992 Microsoft Corporation
Module Name:
swmr.h
Abstract:
This module contains the Single writer-Multi reader access structures
Also the lock-list-count structures.
Author:
Jameel Hyder (microsoft!jameelh)
Revision History:
25 Apr 1992 Initial Version
Notes: Tab stop: 4
--*/
#ifndef _SWMR_
#define _SWMR_
#if DBG
#define SWMR_SIGNATURE *(DWORD *)"SWMR"
#define VALID_SWMR(pSwmr) (((pSwmr) != NULL) && \
((pSwmr)->Signature == SWMR_SIGNATURE))
#else
#define VALID_SWMR(pSwmr) ((pSwmr) != NULL)
#endif
#define SWMR_SOMEONE_WAITING( _pSwmr ) ((_pSwmr)->swmr_cExclWaiting || \
(_pSwmr)->swmr_cSharedWaiting)
typedef struct _SingleWriterMultiReader
{
#if DBG
DWORD Signature;
#endif
BYTE swmr_cOwnedExclusive; // # of times a single thread has owned it exclusively
BYTE swmr_cExclWaiting; // Number of writers waiting
BYTE swmr_cSharedOwners; // Count of threads owning shared access
BYTE swmr_cSharedWaiting; // Count of threads waiting for shared access
PETHREAD swmr_ExclusiveOwner; // Owning thread for exclusive access
KSEMAPHORE swmr_ExclSem; // semaphore for Exclusive owners
KSEMAPHORE swmr_SharedSem; // Semaphore for Shared owners
} SWMR, *PSWMR;
extern
VOID FASTCALL
AfpSwmrInitSwmr(
IN OUT PSWMR pSwmr
);
extern
VOID FASTCALL
AfpSwmrAcquireShared(
IN PSWMR pSwmr
);
VOID FASTCALL
AfpSwmrAcquireExclusive(
IN PSWMR pSwmr
);
extern
VOID FASTCALL
AfpSwmrRelease(
IN PSWMR pSwmr
);
extern
BOOLEAN FASTCALL
AfpSwmrUpgradeToExclusive(
IN PSWMR pSwmr
);
extern
VOID FASTCALL
AfpSwmrDowngradeToShared(
IN PSWMR pSwmr
);
#define AfpSwmrLockedShared(pSwmr) \
(((pSwmr)->swmr_cSharedOwners != 0) && \
((pSwmr)->swmr_cOwnedExclusive == 0))
#define AfpSwmrLockedExclusive(pSwmr) \
(((pSwmr)->swmr_cOwnedExclusive != 0) && \
((pSwmr)->swmr_ExclusiveOwner == PsGetCurrentThread()))
#endif // _SWMR_