Receive Operation Example - HP 30240A Installation And Service Manual

Thinlan 3000/v link local area network interface controller (lanlc)

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Receive Operation Example

The host allocates one or more receive buffers and enters RECV commands

containing the buffer descriptors and IDs into the CQ. The LANIC removes

these descriptors from the CQ and puts them on an internal queue. and turns the

82586 LCC receiver on. The LCC prepares for packet reception by taking the

first buffer descriptor off the internal queue. The LCC looks at the destination

address of all packets on the network. When the destination address matches the

LANIC station address. the LCC deserializes the packet and starts writing it to

system memory using the current receive buffer descriptor. At the end of the

packet. the LCC compares the CRC and re-uses the buffer descriptor if there was

an error in packet reception. Otherwise. the LCC records the packet reception.

prepares the next buffer descriptor from the internal queue. and interrupts the

microprocessor. When the microprocessor acknowledges the interrupt, the LCC

adds the status and ID number of the completed packet(s) to the RQ.

Principles of Operation

3-7

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