reactos/subsystems/win32/win32k/eng/semaphor.c

   1 #include <w32k.h>
   2
   3 #define NDEBUG
   4 #include <debug.h>
   5
   6 /*
   7  * @implemented
   8  */
   9 HSEMAPHORE
  10 STDCALL
  11 EngCreateSemaphore ( VOID )
  12 {
  13   // www.osr.com/ddk/graphics/gdifncs_95lz.htm
  14   PERESOURCE psem = ExAllocatePool ( NonPagedPool, sizeof(ERESOURCE) );
  15   if ( !psem )
  16     return NULL;
  17   if ( !NT_SUCCESS(ExInitializeResourceLite ( psem )) )
  18   {
  19     ExFreePool ( psem );
  20     return NULL;
  21   }
  22   return (HSEMAPHORE)psem;
  23 }
  24
  25 /*
  26  * @implemented
  27  */
  28 VOID
  29 STDCALL
  30 EngAcquireSemaphore ( IN HSEMAPHORE hsem )
  31 {
  32   // www.osr.com/ddk/graphics/gdifncs_14br.htm
  33   ASSERT(hsem);
  34   KeEnterCriticalRegion();
  35   ExAcquireResourceExclusiveLite ( (PERESOURCE)hsem, TRUE );
  36 }
  37
  38 /*
  39  * @implemented
  40  */
  41 VOID
  42 STDCALL
  43 EngReleaseSemaphore ( IN HSEMAPHORE hsem )
  44 {
  45   // www.osr.com/ddk/graphics/gdifncs_5u3r.htm
  46   ASSERT(hsem);
  47   ExReleaseResourceLite ( (PERESOURCE)hsem );
  48   KeLeaveCriticalRegion();
  49 }
  50
  51 /*
  52  * @implemented
  53  */
  54 VOID
  55 STDCALL
  56 EngDeleteSemaphore ( IN HSEMAPHORE hsem )
  57 {
  58   // www.osr.com/ddk/graphics/gdifncs_13c7.htm
  59   ASSERT ( hsem );
  60   ExFreePool ( (PVOID)hsem );
  61 }
  62
  63 /*
  64  * @implemented
  65  */
  66 BOOL
  67 STDCALL
  68 EngIsSemaphoreOwned ( IN HSEMAPHORE hsem )
  69 {
  70   // www.osr.com/ddk/graphics/gdifncs_6wmf.htm
  71   ASSERT(hsem);
  72   return (((PERESOURCE)hsem)->ActiveCount > 0);
  73 }
  74
  75 /*
  76  * @implemented
  77  */
  78 BOOL
  79 STDCALL
  80 EngIsSemaphoreOwnedByCurrentThread ( IN HSEMAPHORE hsem )
  81 {
  82   // www.osr.com/ddk/graphics/gdifncs_9yxz.htm
  83   ASSERT(hsem);
  84   return ExIsResourceAcquiredExclusiveLite ( (PERESOURCE)hsem );
  85 }
  86
  87 /*
  88  * @implemented
  89  */
  90 BOOL STDCALL
  91 EngInitializeSafeSemaphore(
  92    OUT ENGSAFESEMAPHORE *Semaphore)
  93 {
  94    HSEMAPHORE hSem;
  95
  96    if (InterlockedIncrement(&Semaphore->lCount) == 1)
  97    {
  98       /* Create the semaphore */
  99       hSem = EngCreateSemaphore();
 100       if (hSem == 0)
 101       {
 102          InterlockedDecrement(&Semaphore->lCount);
 103          return FALSE;
 104       }
 105       InterlockedExchangePointer((volatile PVOID *)&Semaphore->hsem, hSem);
 106    }
 107    else
 108    {
 109       /* Wait for the other thread to create the semaphore */
 110       ASSERT(Semaphore->lCount > 1);
 111       ASSERT_IRQL(PASSIVE_LEVEL);
 112       while (Semaphore->hsem == NULL);
 113    }
 114
 115    return TRUE;
 116 }
 117
 118 /*
 119  * @implemented
 120  */
 121 VOID STDCALL
 122 EngDeleteSafeSemaphore(
 123    IN OUT ENGSAFESEMAPHORE *Semaphore)
 124 {
 125    if (InterlockedDecrement(&Semaphore->lCount) == 0)
 126    {
 127       EngDeleteSemaphore(Semaphore->hsem);
 128       InterlockedExchangePointer((volatile PVOID *)&Semaphore->hsem, NULL);
 129    }
 130 }
 131
 132