VideoPortInterlockedExchange - NtDoc
Native API online documentation, based on the System Informer
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headers
// video.h
VIDEOPORT_API LONG VideoPortInterlockedExchange(
[in, out] IN OUT PLONG Target,
[in] IN LONG Value
);
View the official Windows Driver Kit DDI referenceNo description available.
The VideoPortInterlockedExchange function locks or unlocks a block of memory by setting a user-defined lock variable to TRUE or FALSE, respectively. It returns the previously-held value of the lock variable.
Target [in, out]Pointer to a user-defined lock variable that is used to control access to a memory buffer.
Value [in]Specifies the value to be stored in Target, which indicates whether the memory buffer is to be locked or unlocked. Use TRUE to lock the memory buffer, and FALSE to unlock the memory buffer.
VideoPortInterlockedExchange returns the value that Target had prior to the function call.
VideoPortInterlockedExchange can be used to prevent DMA common-buffer contention in multiple-processor systems.
When the buffer is not being read from or written to, the lock variable should have a value of FALSE. A subsequent call to VideoPortInterlockedExchange with its Target parameter set to TRUE resets the lock variable to TRUE, after which this function returns FALSE. The buffer is now locked, preventing access by other threads. When the current operations on the buffer are complete, unlock the buffer with a call to VideoPortInterlockedExchange with its Target parameter set to FALSE.