IOMultiMemoryDescriptor |
| Inherits from: | |
| Declared In: |
The IOMultiMemoryDescriptor object describes a memory area made up of several other IOMemoryDescriptors.
The IOMultiMemoryDescriptor object represents multiple ranges of memory, specified as an ordered list of IOMemoryDescriptors. The descriptors are chained end-to-end to make up a single contiguous buffer.
Complete processing of the memory after an I/O transfer finishes.
Break a memory descriptor into its physically contiguous segments.
Initialize an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
Prepare the memory for an I/O transfer.
Create an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
Initialize an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
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 addr64_t getPhysicalSegment( IOByteCount offset, IOByteCount *length, IOOptionBits options = 0 );
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.
initWithDescriptors |
Initialize an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
public
virtual bool initWithDescriptors( IOMemoryDescriptor **descriptors, UInt32 withCount, IODirection withDirection, bool asReference = false );
descriptorsAn array of IOMemoryDescriptors which make up the memory to be described.
withCountThe object count for the descriptors array.
withDirectionAn I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
asReferenceIf false, the IOMultiMemoryDescriptor object will make a copy of the descriptors array, otherwise, the array will be used in situ, avoiding an extra allocation.
The created IOMultiMemoryDescriptor on success, to be released by the caller, or zero on failure.
This method initializes an IOMultiMemoryDescriptor for memory consisting 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. Passing the descriptor array as a reference will avoid an extra allocation.
prepare |
Prepare the memory for an I/O transfer.
public
virtual IOReturn prepare( 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 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 needn't called for non-pageable memory.
withDescriptors(IOMemoryDescriptor **, UInt32, IODirection, bool) |
Create an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
public
static IOMultiMemoryDescriptor * withDescriptors( IOMemoryDescriptor **descriptors, UInt32 withCount, IODirection withDirection, bool asReference = false );
descriptorsAn array of IOMemoryDescriptors which make up the memory to be described.
withCountThe object count for the descriptors array.
withDirectionAn I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
asReferenceIf false, the IOMultiMemoryDescriptor object will make a copy of the descriptors array, otherwise, the array will be used in situ, avoiding an extra allocation.
The created IOMultiMemoryDescriptor on success, to be released by the caller, or zero on failure.
This method creates and initializes an IOMultiMemoryDescriptor for memory consisting 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. Passing the descriptor array as a reference will avoid an extra allocation.
withDescriptors(IOMemoryDescriptor **, UInt32, IODirection, bool) |
Initialize an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
public
virtual bool initWithDescriptors( IOMemoryDescriptor **descriptors, UInt32 withCount, IODirection withDirection, bool asReference = false );
descriptorsAn array of IOMemoryDescriptors which make up the memory to be described.
withCountThe object count for the descriptors array.
withDirectionAn I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
asReferenceIf false, the IOMultiMemoryDescriptor object will make a copy of the descriptors array, otherwise, the array will be used in situ, avoiding an extra allocation.
The created IOMultiMemoryDescriptor on success, to be released by the caller, or zero on failure.
This method initializes an IOMultiMemoryDescriptor for memory consisting 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. Passing the descriptor array as a reference will avoid an extra allocation.
Last Updated: 2010-07-29