1/*
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27 */
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
38class IOMultiMemoryDescriptor : public IOMemoryDescriptor
39{
40    OSDeclareDefaultStructors(IOMultiMemoryDescriptor);
41
42protected:
43
44    IOMemoryDescriptor ** _descriptors;
45    UInt32                _descriptorsCount;
46    bool                  _descriptorsIsAllocated;
47
48    virtual void free();
49
50public:
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 */
111