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: sem.c,v 1.14 2003/11/02 01:15:15 ekohl Exp $
  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 <ddk/ntddk.h>
  32 #include <internal/ke.h>
  33 #include <internal/ps.h>
  34 #include <internal/id.h>
  35
  36 #define NDEBUG
  37 #include <internal/debug.h>
  38
  39 /* FUNCTIONS *****************************************************************/
  40
  41 /*
  42  * @implemented
  43  */
  44 VOID STDCALL
  45 KeInitializeSemaphore (PKSEMAPHORE      Semaphore,
  46                        LONG             Count,
  47                        LONG             Limit)
  48 {
  49    KeInitializeDispatcherHeader(&Semaphore->Header,
  50                                 InternalSemaphoreType,
  51                                 sizeof(KSEMAPHORE)/sizeof(ULONG),
  52                                 Count);
  53    Semaphore->Limit=Limit;
  54 }
  55
  56 /*
  57  * @implemented
  58  */
  59 LONG STDCALL
  60 KeReadStateSemaphore (PKSEMAPHORE       Semaphore)
  61 {
  62    return(Semaphore->Header.SignalState);
  63 }
  64
  65 /*
  66  * @implemented
  67  */
  68 LONG STDCALL
  69 KeReleaseSemaphore (PKSEMAPHORE Semaphore,
  70                     KPRIORITY   Increment,
  71                     LONG                Adjustment,
  72                     BOOLEAN             Wait)
  73 /*
  74  * FUNCTION: KeReleaseSemaphore releases a given semaphore object. This
  75  * routine supplies a runtime priority boost for waiting threads. If this
  76  * call sets the semaphore to the Signaled state, the semaphore count is
  77  * augmented by the given value. The caller can also specify whether it
  78  * will call one of the KeWaitXXX routines as soon as KeReleaseSemaphore
  79  * returns control.
  80  * ARGUMENTS:
  81  *       Semaphore = Points to an initialized semaphore object for which the
  82  *                   caller provides the storage.
  83  *       Increment = Specifies the priority increment to be applied if
  84  *                   releasing the semaphore causes a wait to be
  85  *                   satisfied.
  86  *       Adjustment = Specifies a value to be added to the current semaphore
  87  *                    count. This value must be positive
  88  *       Wait = Specifies whether the call to KeReleaseSemaphore is to be
  89  *              followed immediately by a call to one of the KeWaitXXX.
  90  * RETURNS: If the return value is zero, the previous state of the semaphore
  91  *          object is Not-Signaled.
  92  */
  93 {
  94   ULONG InitialState;
  95   KIRQL OldIrql;
  96
  97   DPRINT("KeReleaseSemaphore(Semaphore %x, Increment %d, Adjustment %d, "
  98           "Wait %d)\n", Semaphore, Increment, Adjustment, Wait);
  99
 100   OldIrql = KeAcquireDispatcherDatabaseLock();
 101
 102   InitialState = Semaphore->Header.SignalState;
 103   if (Semaphore->Limit < (LONG) InitialState + Adjustment ||
 104       InitialState > InitialState + Adjustment)
 105     {
 106       ExRaiseStatus(STATUS_SEMAPHORE_LIMIT_EXCEEDED);
 107     }
 108
 109   Semaphore->Header.SignalState += Adjustment;
 110   if (InitialState == 0)
 111     {
 112       KeDispatcherObjectWake(&Semaphore->Header);
 113     }
 114
 115   if (Wait == FALSE)
 116     {
 117       KeReleaseDispatcherDatabaseLock(OldIrql);
 118     }
 119   else
 120     {
 121       KTHREAD *Thread = KeGetCurrentThread();
 122       Thread->WaitNext = Wait;
 123       Thread->WaitIrql = OldIrql;
 124     }
 125
 126   return(InitialState);
 127 }
 128
 129 /* EOF */