IOSubMemoryDescriptor

Inherits from:	IOMemoryDescriptor
Declared In:	IOSubMemoryDescriptor.h

Overview

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

Discussion

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

Functions

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

withSubRange

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

public

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.

Mac Dev Center Mac OS X Reference Library Drivers, Kernel, & Hardware: Kernel Device Drivers Kernel Framework Reference

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Last Updated: 2010-07-29