reactos/ntoskrnl/ke/sem.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/ke/sem.c
  23  * PURPOSE:         Implements kernel semaphores
  24  * PROGRAMMER:      David Welch (welch@mcmail.com)
  25  * UPDATE HISTORY:
  26  *                  Created 22/05/98
  27  */
  28
  29 /* INCLUDES *****************************************************************/
  30
  31 #include <ntoskrnl.h>
  32 #define NDEBUG
  33 #include <internal/debug.h>
  34
  35 /* FUNCTIONS *****************************************************************/
  36
  37 /*
  38  * @implemented
  39  */
  40 VOID STDCALL
  41 KeInitializeSemaphore (PKSEMAPHORE      Semaphore,
  42                        LONG             Count,
  43                        LONG             Limit)
  44 {
  45    KeInitializeDispatcherHeader(&Semaphore->Header,
  46                                 InternalSemaphoreType,
  47                                 sizeof(KSEMAPHORE)/sizeof(ULONG),
  48                                 Count);
  49    Semaphore->Limit=Limit;
  50 }
  51
  52 /*
  53  * @implemented
  54  */
  55 LONG STDCALL
  56 KeReadStateSemaphore (PKSEMAPHORE       Semaphore)
  57 {
  58    return(Semaphore->Header.SignalState);
  59 }
  60
  61 /*
  62  * @implemented
  63  */
  64 LONG STDCALL
  65 KeReleaseSemaphore (PKSEMAPHORE Semaphore,
  66                     KPRIORITY   Increment,
  67                     LONG                Adjustment,
  68                     BOOLEAN             Wait)
  69 /*
  70  * FUNCTION: KeReleaseSemaphore releases a given semaphore object. This
  71  * routine supplies a runtime priority boost for waiting threads. If this
  72  * call sets the semaphore to the Signaled state, the semaphore count is
  73  * augmented by the given value. The caller can also specify whether it
  74  * will call one of the KeWaitXXX routines as soon as KeReleaseSemaphore
  75  * returns control.
  76  * ARGUMENTS:
  77  *       Semaphore = Points to an initialized semaphore object for which the
  78  *                   caller provides the storage.
  79  *       Increment = Specifies the priority increment to be applied if
  80  *                   releasing the semaphore causes a wait to be
  81  *                   satisfied.
  82  *       Adjustment = Specifies a value to be added to the current semaphore
  83  *                    count. This value must be positive
  84  *       Wait = Specifies whether the call to KeReleaseSemaphore is to be
  85  *              followed immediately by a call to one of the KeWaitXXX.
  86  * RETURNS: If the return value is zero, the previous state of the semaphore
  87  *          object is Not-Signaled.
  88  */
  89 {
  90   ULONG InitialState;
  91   KIRQL OldIrql;
  92
  93   DPRINT("KeReleaseSemaphore(Semaphore %x, Increment %d, Adjustment %d, "
  94           "Wait %d)\n", Semaphore, Increment, Adjustment, Wait);
  95
  96   OldIrql = KeAcquireDispatcherDatabaseLock();
  97
  98   InitialState = Semaphore->Header.SignalState;
  99   if (Semaphore->Limit < (LONG) InitialState + Adjustment ||
 100       InitialState > InitialState + Adjustment)
 101     {
 102       ExRaiseStatus(STATUS_SEMAPHORE_LIMIT_EXCEEDED);
 103     }
 104
 105   Semaphore->Header.SignalState += Adjustment;
 106   if (InitialState == 0)
 107     {
 108       KiDispatcherObjectWake(&Semaphore->Header);
 109     }
 110
 111   if (Wait == FALSE)
 112     {
 113       KeReleaseDispatcherDatabaseLock(OldIrql);
 114     }
 115   else
 116     {
 117       KTHREAD *Thread = KeGetCurrentThread();
 118       Thread->WaitNext = TRUE;
 119       Thread->WaitIrql = OldIrql;
 120     }
 121
 122   return(InitialState);
 123 }
 124
 125 /* EOF */