Creates 1 of 3 kinds of low-level semaphores with 0 or 1 initial units. FIFO and priority semaphores can contain as many as 65,535 units, which are placed in the semaphore by using multiple calls to knReleaseRtSemaphore, 1 call for each unit.

If a low-level region is created with 0 units, the creating thread holds the region's unit and is therefore the owning thread.

If a low-level region is created with 1 unit, no thread owns the region until it invokes knWaitForRtSemaphore for that region.

This call is non-scheduling and is safe, but not recommended, for use by interrupt handlers.

KNHANDLE knCreateRtSemaphore(
    KNPTR lpSemaporeArea,       // pointer to low-level semaphore area
    DWORD dwSemaphoreFlags      // low-level semaphore flags
);

Parameters

lpSemaphoreArea

A pointer to the area where the semaphore is to be created. This area must be at least KN_SEMAPHORE_SIZE bytes long. For better performance, align the area on a 4-byte boundary.

dwSemaphoreFlags

Specifies the semaphore's attributes:

KN_EXCH_TYPE_MASK	Masks the queuing strategy field. Choose one of the following: KN_FIFO_QUEUING The semaphore uses FIFO queuing. KN_PRIORITY_QUEUING The semaphore uses priority queuing. KN_REGION The exchange is a 1 (or single) unit region.
KN_INITIAL_SEM_STATE_MASK	Masks the number of initial units the semaphore receives. Choose one of these literals: KN_ZERO_UNITS The semaphore is created with no units. KN_ONE_UNIT The semaphore is created with 1 unit.

Note:   

• KN_FIFO_QUEUING , KN_PRIORITY_QUEUING , and KN_REGION are mutually exclusive.
• KN_ZERO_UNITS and KN_ONE_UNIT are mutually exclusive.
• You must OR multiple literals together to produce the dwSemaphoreFlags value passed by the call.

Return Values

Success: a handle for the low-level semaphore.

Failure: the value 0xffffffff is returned if the lpSemaporeArea pointer was not valid, or if the maximum number of semaphore mappings for the process has been exceeded.

Requirements