reactos/ntoskrnl/ex/fmutex.c

   1 /*
   2  *  ReactOS kernel
   3  *  Copyright (C) 1998, 1999, 2000, 2001 ReactOS Team
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19 /* $Id$
  20  *
  21  * PROJECT:         ReactOS kernel
  22  * FILE:            ntoskrnl/ex/fmutex.c
  23  * PURPOSE:         Implements fast mutexes
  24  * PROGRAMMER:      David Welch (welch@cwcom.net)
  25  * PORTABILITY:     Checked.
  26  * UPDATE HISTORY:
  27  *                  Created 22/05/98
  28  */
  29
  30 /* INCLUDES *****************************************************************/
  31
  32 #include <ntoskrnl.h>
  33 #include <internal/debug.h>
  34
  35 /* FUNCTIONS *****************************************************************/
  36
  37 /*
  38  * @implemented
  39  */
  40 VOID FASTCALL
  41 ExAcquireFastMutexUnsafe(PFAST_MUTEX FastMutex)
  42 {
  43   ASSERT(FastMutex->Owner != KeGetCurrentThread());
  44   InterlockedIncrementUL(&FastMutex->Contention);
  45   while (InterlockedExchange(&FastMutex->Count, 0) == 0)
  46      {
  47        KeWaitForSingleObject(&FastMutex->Event,
  48                              Executive,
  49                              KernelMode,
  50                              FALSE,
  51                              NULL);
  52      }
  53   InterlockedDecrementUL(&FastMutex->Contention);
  54   FastMutex->Owner = KeGetCurrentThread();
  55 }
  56
  57 /*
  58  * @implemented
  59  */
  60 VOID FASTCALL
  61 ExReleaseFastMutexUnsafe(PFAST_MUTEX FastMutex)
  62 {
  63   ASSERT(FastMutex->Owner == KeGetCurrentThread());
  64   FastMutex->Owner = NULL;
  65   InterlockedExchange(&FastMutex->Count, 1);
  66   if (FastMutex->Contention > 0)
  67     {
  68       KeSetEvent(&FastMutex->Event, 0, FALSE);
  69     }
  70 }
  71
  72 /* EOF */