IOSubMemoryDescriptor

Inherits from
IOMemoryDescriptor
Availability
Available in OS X v10.0 and later.
Declared in
IOSubMemoryDescriptor.h

Overview

The IOSubMemoryDescriptor object describes a memory area made up of a portion of another IOMemoryDescriptor.

The IOSubMemoryDescriptor object represents a subrange of memory, specified as a portion of another IOMemoryDescriptor.

Tasks

Miscellaneous

Instance Methods

withSubRange

Create an IOMemoryDescriptor to describe a subrange of an existing descriptor.

static IOSubMemoryDescriptor * withSubRange( IOMemoryDescriptor *of, IOByteCount offset, IOByteCount length, IOOptionBits options);
Parameters
of

The parent IOMemoryDescriptor of which a subrange is to be used for the new descriptor, which will be retained by the subrange IOMemoryDescriptor.

offset

A byte offset into the parent memory descriptor's memory.

length

The length of the subrange.

options

kIOMemoryDirectionMask (options:direction) This nibble indicates the I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.

Return Value

The created IOMemoryDescriptor on success, to be released by the caller, or zero on failure.

Discussion

This method creates and initializes an IOMemoryDescriptor for memory consisting of a subrange of the specified memory descriptor. The parent memory descriptor is retained by the new descriptor.