VideoPortAllocateCommonBuffer - NtDoc
Native API online documentation, based on the System Informer
(formerly Process Hacker) phnt
headers
// video.h
VIDEOPORT_DEPRECATED VIDEOPORT_API PVOID VideoPortAllocateCommonBuffer(
[in] IN PVOID HwDeviceExtension,
[in] IN PVP_DMA_ADAPTER VpDmaAdapter,
[in] IN ULONG DesiredLength,
[out] OUT PPHYSICAL_ADDRESS LogicalAddress,
[in] IN BOOLEAN CacheEnabled,
[out] OUT PVOID Reserved
);
View the official Windows Driver Kit DDI referenceNo description available.
The VideoPortAllocateCommonBuffer function allocates and maps system memory so that it is simultaneously accessible from both the processor and a device for common-buffer DMA operations.
HwDeviceExtension [in]Pointer to the miniport driver's device extension.
VpDmaAdapter [in]Pointer to the VP_DMA_ADAPTER structure that represents the bus-master adapter. This structure was returned by a previous call to VideoPortGetDmaAdapter.
DesiredLength [in]Specifies the requested number of bytes of memory.
LogicalAddress [out]Pointer to a memory location that receives the logical address to be used by the adapter to access the allocated buffer.
CacheEnabled [in]Specifies whether the allocated memory can be cached. For more information, see the description of the CacheEnabled parameter for AllocateCommonBuffer.
Reserved [out]Is currently ignored by the video port driver; should be set to NULL.
VideoPortAllocateCommonBuffer returns the base virtual address of the allocated buffer if successful; otherwise, it returns NULL if the buffer cannot be allocated.
When the buffer is no longer needed, the video miniport driver should release it by calling VideoPortReleaseCommonBuffer.