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IOInterleavedMemoryDescriptor |
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| Declared In: |
The IOInterleavedMemoryDescriptor object describes a memory area made up of portions of several other IOMemoryDescriptors.
The IOInterleavedMemoryDescriptor object represents interleaved ranges of memory, specified as an ordered list of portions of individual IOMemoryDescriptors. The portions are chained end-to-end to make up a single contiguous buffer.
Clear all of the IOMemoryDescriptors currently contained in and reset the IOInterleavedMemoryDescriptor.
Complete processing of the memory after an I/O transfer finishes.
Break a memory descriptor into its physically contiguous segments.
Initialize an IOInterleavedMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
Prepare the memory for an I/O transfer.
Add a portion of an IOMemoryDescriptor to the IOInterleavedMemoryDescriptor.
Create an IOInterleavedMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
clearMemoryDescriptors |
Clear all of the IOMemoryDescriptors currently contained in and reset the IOInterleavedMemoryDescriptor.
public
virtual void clearMemoryDescriptors( IODirection direction = kIODirectionNone );
directionAn I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
Clears each IOMemoryDescriptor by completing (if needed) and releasing. The IOInterleavedMemoryDescriptor is then reset and may accept new descriptors up to the capacity specified when it was created.
complete |
Complete processing of the memory after an I/O transfer finishes.
public
virtual IOReturn complete( IODirection forDirection = kIODirectionNone);
forDirectionThe direction of the I/O just completed, or kIODirectionNone for the direction specified by the memory descriptor.
An IOReturn code.
This method should not be called unless a prepare was previously issued; the prepare() and complete() must occur in pairs, before and after an I/O transfer involving pageable memory.
getPhysicalSegment |
Break a memory descriptor into its physically contiguous segments.
public
virtual IOPhysicalAddress getPhysicalSegment( IOByteCount offset, IOByteCount *length );
offsetA byte offset into the memory whose physical address to return.
lengthIf non-zero, getPhysicalSegment will store here the length of the physically contiguous segement at the given offset.
A physical address, or zero if the offset is beyond the length of the memory.
This method returns the physical address of the byte at the given offset into the memory, and optionally the length of the physically contiguous segment from that offset.
initWithCapacity |
Initialize an IOInterleavedMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
public
virtual bool initWithCapacity( UInt32 capacity, IODirection direction );
capacityThe maximum number of IOMemoryDescriptors that may be subsequently added to this IOInterleavedMemoryDescriptor.
directionAn I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
The created IOInterleavedMemoryDescriptor on success, to be released by the caller, or zero on failure.
This method initializes an IOInterleavedMemoryDescriptor for memory consisting of portions of a number of other IOMemoryDescriptors, chained end-to-end (in the order they appear in the array) to represent a single contiguous memory buffer.
prepare |
Prepare the memory for an I/O transfer.
public
virtual IOReturn prepare( IODirection forDirection = kIODirectionNone);
forDirectionThe direction of the I/O to be performed, or kIODirectionNone for the direction specified by the memory descriptor.
An IOReturn code.
This involves paging in the memory, if necessary, and wiring it down for the duration of the transfer. The complete() method completes the processing of the memory after the I/O transfer finishes. This method need not called for non-pageable memory.
setMemoryDescriptor |
Add a portion of an IOMemoryDescriptor to the IOInterleavedMemoryDescriptor.
public
virtual bool setMemoryDescriptor( IOMemoryDescriptor *descriptor, IOByteCount offset, IOByteCount length );
descriptorAn IOMemoryDescriptor to be added to the IOInterleavedMemoryDescriptor. Its direction must be compatible with that of the IOInterleavedMemoryDescriptor.
offsetThe offset into the IOMemoryDescriptor of the portion that will be added to the virtualized buffer.
lengthThe length of the portion of the IOMemoryDescriptor to be added to the virtualized buffer.
Returns true the portion was successfully added.
This method adds the portion of an IOMemoryDescriptor described by the offset and length parameters to the end of the IOInterleavedMemoryDescriptor. A single IOMemoryDescriptor may be added as many times as there is room for it. The offset and length must describe a portion entirely within the IOMemoryDescriptor.
withCapacity |
Create an IOInterleavedMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
public
static IOInterleavedMemoryDescriptor * withCapacity( UInt32 capacity, IODirection direction);
capacityThe maximum number of IOMemoryDescriptors that may be subsequently added to this IOInterleavedMemoryDescriptor.
directionAn I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
The created IOInterleavedMemoryDescriptor on success, to be released by the caller, or zero on failure.
This method creates and initializes an IOInterleavedMemoryDescriptor for memory consisting of portions of a number of other IOMemoryDescriptors, chained end-to-end (in the order they appear in the array) to represent a single contiguous memory buffer.
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Last Updated: 2008-12-19