getPhysicalSegments
Generates a big endian physical scatter/gather list given a memory descriptor.
Declaration
virtual UInt32 getPhysicalSegments(
IOMemoryDescriptor *descriptor,
IOByteCount fromPosition,
PhysicalSegment *segments,
UInt32 maxSegments,
UInt32 inMaxTransferSize = 0,
IOByteCount *transferSize = 0)Parameters
- descriptor:
IOMemoryDescriptor that describes the data associated with an I/O request.
- fromPosition:
Starting location of the I/O within a memory descriptor.
- segments:
Pointer to an array of IOMemoryCursor::PhysicalSegments for the output physical scatter/gather list.
- maxSegments:
Maximum number of segments that can be written to segments array.
- inMaxTransferSize:
Maximum transfer size is limited to that many bytes, otherwise it defaults to the maximum transfer size specified when the memory cursor was initialized.
- transferSize:
Pointer to an IOByteCount variable that can contain the total size of the transfer being described. Defaults to 0 indicating that no transfer size need be returned.
Return Value
If the descriptor is exhausted of memory, a zero is returned, otherwise the number of segments that were filled in is returned.
Overview
Generates a list of physical segments from the given memory descriptor, relative to the current position of the descriptor. Wraps IOMemoryCursor::genPhysicalSegments.