iokit/IOKit/IOMultiMemoryDescriptor.h

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  28
  29 #ifndef _IOMULTIMEMORYDESCRIPTOR_H
  30 #define _IOMULTIMEMORYDESCRIPTOR_H
  31
  32 #include <IOKit/IOMemoryDescriptor.h>
  33
  34 /*! @class IOMultiMemoryDescriptor : public IOMemoryDescriptor
  35     @abstract The IOMultiMemoryDescriptor object describes a memory area made up of several other IOMemoryDescriptors.
  36     @discussion 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. */
  37
  38 class IOMultiMemoryDescriptor : public IOMemoryDescriptor
  39 {
  40     OSDeclareDefaultStructors(IOMultiMemoryDescriptor);
  41
  42 protected:
  43
  44     IOMemoryDescriptor ** _descriptors;
  45     UInt32                _descriptorsCount;
  46     bool                  _descriptorsIsAllocated;
  47
  48     virtual void free();
  49
  50 public:
  51
  52 /*! @function withDescriptors
  53     @abstract Create an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
  54     @discussion 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.
  55     @param descriptors An array of IOMemoryDescriptors which make up the memory to be described.
  56     @param withCount The object count for the descriptors array.
  57     @param withDirection An I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
  58     @param asReference If false, the IOMultiMemoryDescriptor object will make a copy of the descriptors array, otherwise, the array will be used in situ, avoiding an extra allocation.
  59     @result The created IOMultiMemoryDescriptor on success, to be released by the caller, or zero on failure. */
  60
  61     static IOMultiMemoryDescriptor * withDescriptors(
  62                                   IOMemoryDescriptor ** descriptors,
  63                                   UInt32                withCount,
  64                                   IODirection           withDirection,
  65                                   bool                  asReference = false );
  66
  67 /*! @function withDescriptors
  68     @abstract Initialize an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
  69     @discussion 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.
  70     @param descriptors An array of IOMemoryDescriptors which make up the memory to be described.
  71     @param withCount The object count for the descriptors array.
  72     @param withDirection An I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
  73     @param asReference If false, the IOMultiMemoryDescriptor object will make a copy of the descriptors array, otherwise, the array will be used in situ, avoiding an extra allocation.
  74     @result The created IOMultiMemoryDescriptor on success, to be released by the caller, or zero on failure. */
  75
  76     virtual bool initWithDescriptors(
  77                                   IOMemoryDescriptor ** descriptors,
  78                                   UInt32                withCount,
  79                                   IODirection           withDirection,
  80                                   bool                  asReference = false );
  81
  82 /*! @function getPhysicalSegment
  83     @abstract Break a memory descriptor into its physically contiguous segments.
  84     @discussion 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.
  85     @param offset A byte offset into the memory whose physical address to return.
  86     @param length If non-zero, getPhysicalSegment will store here the length of the physically contiguous segement at the given offset.
  87     @result A physical address, or zero if the offset is beyond the length of the memory. */
  88
  89     virtual addr64_t getPhysicalSegment( IOByteCount   offset,
  90                                          IOByteCount * length,
  91                                          IOOptionBits  options = 0 );
  92
  93 /*! @function prepare
  94     @abstract Prepare the memory for an I/O transfer.
  95     @discussion 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.
  96     @param forDirection The direction of the I/O just completed, or kIODirectionNone for the direction specified by the memory descriptor.
  97     @result An IOReturn code. */
  98
  99     virtual IOReturn prepare(IODirection forDirection = kIODirectionNone);
 100
 101 /*! @function complete
 102     @abstract Complete processing of the memory after an I/O transfer finishes.
 103     @discussion 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.
 104     @param forDirection The direction of the I/O just completed, or kIODirectionNone for the direction specified by the memory descriptor.
 105     @result An IOReturn code. */
 106
 107     virtual IOReturn complete(IODirection forDirection = kIODirectionNone);
 108 };
 109
 110 #endif /* !_IOMULTIMEMORYDESCRIPTOR_H */