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 = ExAllocatePoolWithTag( NonPagedPool, sizeof(ERESOURCE), TAG_GSEM );
  15   if ( !psem )
  16     return NULL;
  17   if ( !NT_SUCCESS(ExInitializeResourceLite ( psem )) )
  18   {
  19     ExFreePoolWithTag ( psem, TAG_GSEM );
  20     return NULL;
  21   }
  22   return (HSEMAPHORE)psem;
  23 }
  24
  25 VOID
  26 FASTCALL
  27 IntGdiAcquireSemaphore ( HSEMAPHORE hsem )
  28 {
  29   KeEnterCriticalRegion();
  30   ExAcquireResourceExclusiveLite ( (PERESOURCE)hsem, TRUE );
  31 }
  32
  33 /*
  34  * @implemented
  35  */
  36 VOID
  37 STDCALL
  38 EngAcquireSemaphore ( IN HSEMAPHORE hsem )
  39 {
  40   // www.osr.com/ddk/graphics/gdifncs_14br.htm
  41   PW32THREAD W32Thread;
  42   ASSERT(hsem);
  43   IntGdiAcquireSemaphore ( hsem );
  44   W32Thread = PsGetThreadWin32Thread(PsGetCurrentThread());
  45   if (W32Thread) W32Thread->dwEngAcquireCount++;
  46 }
  47
  48
  49 VOID
  50 FASTCALL
  51 IntGdiReleaseSemaphore ( HSEMAPHORE hsem )
  52 {
  53   ExReleaseResourceLite ( (PERESOURCE)hsem );
  54   KeLeaveCriticalRegion();
  55 }
  56
  57 /*
  58  * @implemented
  59  */
  60 VOID
  61 STDCALL
  62 EngReleaseSemaphore ( IN HSEMAPHORE hsem )
  63 {
  64   // www.osr.com/ddk/graphics/gdifncs_5u3r.htm
  65   PW32THREAD W32Thread;
  66   ASSERT(hsem);
  67   W32Thread = PsGetThreadWin32Thread(PsGetCurrentThread());
  68   if (W32Thread) --W32Thread->dwEngAcquireCount;
  69   IntGdiReleaseSemaphore ( hsem );
  70 }
  71
  72 /*
  73  * @implemented
  74  */
  75 VOID
  76 STDCALL
  77 EngDeleteSemaphore ( IN HSEMAPHORE hsem )
  78 {
  79   // www.osr.com/ddk/graphics/gdifncs_13c7.htm
  80   ASSERT ( hsem );
  81
  82   ExDeleteResourceLite((PERESOURCE)hsem);
  83
  84   ExFreePoolWithTag( (PVOID)hsem, TAG_GSEM);
  85 }
  86
  87 /*
  88  * @implemented
  89  */
  90 BOOL
  91 STDCALL
  92 EngIsSemaphoreOwned ( IN HSEMAPHORE hsem )
  93 {
  94   // www.osr.com/ddk/graphics/gdifncs_6wmf.htm
  95   ASSERT(hsem);
  96   return (((PERESOURCE)hsem)->ActiveCount > 0);
  97 }
  98
  99 /*
 100  * @implemented
 101  */
 102 BOOL
 103 STDCALL
 104 EngIsSemaphoreOwnedByCurrentThread ( IN HSEMAPHORE hsem )
 105 {
 106   // www.osr.com/ddk/graphics/gdifncs_9yxz.htm
 107   ASSERT(hsem);
 108   return ExIsResourceAcquiredExclusiveLite ( (PERESOURCE)hsem );
 109 }
 110
 111 /*
 112  * @implemented
 113  */
 114 BOOL STDCALL
 115 EngInitializeSafeSemaphore(
 116    OUT ENGSAFESEMAPHORE *Semaphore)
 117 {
 118    HSEMAPHORE hSem;
 119
 120    if (InterlockedIncrement(&Semaphore->lCount) == 1)
 121    {
 122       /* Create the semaphore */
 123       hSem = EngCreateSemaphore();
 124       if (hSem == 0)
 125       {
 126          InterlockedDecrement(&Semaphore->lCount);
 127          return FALSE;
 128       }
 129       /* FIXME - not thread-safe! Check result of InterlockedCompareExchangePointer
 130                  and delete semaphore if already initialized! */
 131       (void)InterlockedExchangePointer((volatile PVOID *)&Semaphore->hsem, hSem);
 132    }
 133    else
 134    {
 135       /* Wait for the other thread to create the semaphore */
 136       ASSERT(Semaphore->lCount > 1);
 137       ASSERT_IRQL_LESS_OR_EQUAL(PASSIVE_LEVEL);
 138       while (Semaphore->hsem == NULL);
 139    }
 140
 141    return TRUE;
 142 }
 143
 144 /*
 145  * @implemented
 146  */
 147 VOID STDCALL
 148 EngDeleteSafeSemaphore(
 149    IN OUT ENGSAFESEMAPHORE *Semaphore)
 150 {
 151    if (InterlockedDecrement(&Semaphore->lCount) == 0)
 152    {
 153       /* FIXME - not thread-safe! Use result of InterlockedCompareExchangePointer! */
 154       EngDeleteSemaphore(Semaphore->hsem);
 155       (void)InterlockedExchangePointer((volatile PVOID *)&Semaphore->hsem, NULL);
 156    }
 157 }
 158
 159