reactos/ntoskrnl/ke/sem.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS kernel
   4  * FILE:            ntoskrnl/ke/sem.c
   5  * PURPOSE:         Implements kernel semaphores
   6  * PROGRAMMER:      David Welch (welch@mcmail.com)
   7  * UPDATE HISTORY:
   8  *                  Created 22/05/98
   9  */
  10
  11 /* INCLUDES *****************************************************************/
  12
  13 #include <ddk/ntddk.h>
  14 #include <internal/ke.h>
  15
  16 #define NDEBUG
  17 #include <internal/debug.h>
  18
  19 /* FUNCTIONS *****************************************************************/
  20
  21 VOID KeInitializeSemaphore(PKSEMAPHORE Semaphore,
  22                            LONG Count,
  23                            LONG Limit)
  24 {
  25    KeInitializeDispatcherHeader(&Semaphore->Header,
  26                                 InternalSemaphoreType,
  27                                 sizeof(KSEMAPHORE)/sizeof(ULONG),
  28                                 Count);
  29    Semaphore->Limit=Limit;
  30 }
  31
  32 LONG KeReadStateSemaphore(PKSEMAPHORE Semaphore)
  33 {
  34    return(Semaphore->Header.SignalState);
  35 }
  36
  37 LONG KeReleaseSemaphore(PKSEMAPHORE Semaphore,
  38                         KPRIORITY Increment,
  39                         LONG Adjustment,
  40                         BOOLEAN Wait)
  41 /*
  42  * FUNCTION: KeReleaseSemaphore releases a given semaphore object. This
  43  * routine supplies a runtime priority boost for waiting threads. If this
  44  * call sets the semaphore to the Signaled state, the semaphore count is
  45  * augmented by the given value. The caller can also specify whether it
  46  * will call one of the KeWaitXXX routines as soon as KeReleaseSemaphore
  47  * returns control.
  48  * ARGUMENTS:
  49  *       Semaphore = Points to an initialized semaphore object for which the
  50  *                   caller provides the storage.
  51  *       Increment = Specifies the priority increment to be applied if
  52  *                   releasing the semaphore causes a wait to be
  53  *                   satisfied.
  54  *       Adjustment = Specifies a value to be added to the current semaphore
  55  *                    count. This value must be positive
  56  *       Wait = Specifies whether the call to KeReleaseSemaphore is to be
  57  *              followed immediately by a call to one of the KeWaitXXX.
  58  * RETURNS: If the return value is zero, the previous state of the semaphore
  59  *          object is Not-Signaled.
  60  */
  61 {
  62    ULONG initState = Semaphore->Header.SignalState;
  63
  64    DPRINT("KeReleaseSemaphore(Semaphore %x, Increment %d, Adjustment %d, "
  65           "Wait %d)\n", Semaphore, Increment, Adjustment, Wait);
  66
  67    KeAcquireDispatcherDatabaseLock(Wait);
  68
  69    if (Semaphore->Limit < initState+Adjustment
  70        || initState > initState+Adjustment)
  71      {
  72         ExRaiseStatus(STATUS_SEMAPHORE_LIMIT_EXCEEDED);
  73      }
  74
  75    Semaphore->Header.SignalState+=Adjustment;
  76    DPRINT("initState %d\n", initState);
  77    if(initState == 0)
  78      {
  79         //  wake up SignalState waiters
  80         DPRINT("Waking waiters\n");
  81         KeDispatcherObjectWake(&Semaphore->Header);
  82      }
  83
  84   KeReleaseDispatcherDatabaseLock(Wait);
  85   return initState;
  86 }
  87