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[apple/xnu.git] / iokit / IOKit / IOMultiMemoryDescriptor.h

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#ifndef _IOMULTIMEMORYDESCRIPTOR_H
#define _IOMULTIMEMORYDESCRIPTOR_H

#include <IOKit/IOMemoryDescriptor.h>

/*! @class IOMultiMemoryDescriptor : public IOMemoryDescriptor
    @abstract The IOMultiMemoryDescriptor object describes a memory area made up of several other IOMemoryDescriptors.
    @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. */

class IOMultiMemoryDescriptor : public IOMemoryDescriptor
{
    OSDeclareDefaultStructors(IOMultiMemoryDescriptor);

protected:

    IOMemoryDescriptor ** _descriptors;
    UInt32                _descriptorsCount;
    bool                  _descriptorsIsAllocated;

    virtual void free() APPLE_KEXT_OVERRIDE;

public:

/*! @function withDescriptors
    @abstract Create an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
    @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.
    @param descriptors An array of IOMemoryDescriptors which make up the memory to be described.
    @param withCount The object count for the descriptors array.
    @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.
    @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.
    @result The created IOMultiMemoryDescriptor on success, to be released by the caller, or zero on failure. */

    static IOMultiMemoryDescriptor * withDescriptors(
                                  IOMemoryDescriptor ** descriptors,
                                  UInt32                withCount,
                                  IODirection           withDirection,
                                  bool                  asReference = false );

/*! @function withDescriptors
    @abstract Initialize an IOMultiMemoryDescriptor to describe a memory area made up of several other IOMemoryDescriptors.
    @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.
    @param descriptors An array of IOMemoryDescriptors which make up the memory to be described.
    @param withCount The object count for the descriptors array.
    @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.
    @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.
    @result The created IOMultiMemoryDescriptor on success, to be released by the caller, or zero on failure. */

    virtual bool initWithDescriptors(
                                  IOMemoryDescriptor ** descriptors,
                                  UInt32                withCount,
                                  IODirection           withDirection,
                                  bool                  asReference = false );

/*! @function getPhysicalSegment
    @abstract Break a memory descriptor into its physically contiguous segments.
    @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.
    @param offset A byte offset into the memory whose physical address to return.
    @param length If non-zero, getPhysicalSegment will store here the length of the physically contiguous segement at the given offset.
    @result A physical address, or zero if the offset is beyond the length of the memory. */

    virtual addr64_t getPhysicalSegment( IOByteCount   offset,
                                         IOByteCount * length,
                                         IOOptionBits  options = 0 ) APPLE_KEXT_OVERRIDE;

/*! @function prepare
    @abstract Prepare the memory for an I/O transfer.
    @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.
    @param forDirection The direction of the I/O just completed, or kIODirectionNone for the direction specified by the memory descriptor.
    @result An IOReturn code. */

    virtual IOReturn prepare(IODirection forDirection = kIODirectionNone) APPLE_KEXT_OVERRIDE;

/*! @function complete
    @abstract Complete processing of the memory after an I/O transfer finishes.
    @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.
    @param forDirection The direction of the I/O just completed, or kIODirectionNone for the direction specified by the memory descriptor.
    @result An IOReturn code. */

    virtual IOReturn complete(IODirection forDirection = kIODirectionNone) APPLE_KEXT_OVERRIDE;

    virtual IOReturn setPurgeable(IOOptionBits newState, IOOptionBits * oldState) APPLE_KEXT_OVERRIDE;

/*! @function getPageCounts
    @abstract Retrieve the number of resident and/or dirty pages encompassed by an IOMemoryDescriptor.
    @discussion This method returns the number of resident and/or dirty pages encompassed by an IOMemoryDescriptor.
    @param residentPageCount - If non-null, a pointer to a byte count that will return the number of resident pages encompassed by this IOMemoryDescriptor.
    @param dirtyPageCount - If non-null, a pointer to a byte count that will return the number of dirty pages encompassed by this IOMemoryDescriptor.
    @result An IOReturn code. */

    IOReturn getPageCounts(IOByteCount * residentPageCount,
                           IOByteCount * dirtyPageCount);

#define IOMULTIMEMORYDESCRIPTOR_SUPPORTS_GETPAGECOUNTS	1

private:
    virtual IOReturn doMap(vm_map_t           addressMap,
                           IOVirtualAddress * atAddress,
                           IOOptionBits       options,
                           IOByteCount        sourceOffset = 0,
                           IOByteCount        length = 0 ) APPLE_KEXT_OVERRIDE;
};

#endif /* !_IOMULTIMEMORYDESCRIPTOR_H */