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IOMbufNaturalMemoryCursor

Overview

An IOMbufMemoryCursor subclass that outputs a vector of IOPhysicalSegments in the natural byte orientation for the cpu.

Discussion

The IOMbufNaturalMemoryCursor would be used when it is too difficult to implement an OutputSegmentFunc that is more appropriate for your hardware. This cursor just outputs an array of IOPhysicalSegments.

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Functions

getPhysicalSegments

Generates a cpu natural physical scatter/gather list from a given mbuf.

getPhysicalSegmentsWithCoalesce

Generates a cpu natural physical scatter/gather list from a given mbuf.

withSpecification

Factory function that creates and initializes an IOMbufNaturalMemoryCursor in one operation.

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getPhysicalSegments

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Generates a cpu natural physical scatter/gather list from a given mbuf.

public

UInt32 getPhysicalSegments(
    mbuf_t packet, 
    struct IOMemoryCursor::PhysicalSegment *vector, 
    UInt32 numVectorSegments = 0); 

Parameters

packet

The mbuf packet.

vector

Pointer to an array of IOPhysicalSegments for the output physical scatter/gather list.

numVectorSegments

Maximum number of IOPhysicalSegments accepted.

Return Value

Returns the number of segments that were filled in, or 0 if an error occurred.

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getPhysicalSegmentsWithCoalesce

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Generates a cpu natural physical scatter/gather list from a given mbuf.

public

UInt32 getPhysicalSegmentsWithCoalesce(
    mbuf_t packet, 
    struct IOMemoryCursor::PhysicalSegment *vector, 
    UInt32 numVectorSegments = 0); 

Parameters

packet

The mbuf packet.

vector

Pointer to an array of IOPhysicalSegments for the output physical scatter/gather list.

numVectorSegments

Maximum number of IOPhysicalSegments accepted.

Return Value

Returns the number of segments that were filled in, or 0 if an error occurred.

Discussion

Generate a cpu natural physical scatter/gather list from a given mbuf. Coalesce mbuf chain when the number of segments in the scatter/gather list exceeds numVectorSegments.

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withSpecification

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Factory function that creates and initializes an IOMbufNaturalMemoryCursor in one operation.

public

static IOMbufNaturalMemoryCursor * withSpecification(
    UInt32 maxSegmentSize, 
    UInt32 maxNumSegments); 

Parameters

maxSegmentSize

Maximum allowable size for one segment.

maxNumSegments

Maximum number of segments.

Return Value

Returns a new mbuf cursor if successfully created and initialized, 0 otherwise.

Discussion

See also IOMbufMemoryCursor::initWithSpecification.

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Last Updated: 2008-12-19