Intel IXP400 manual Initializing the IxNpeMh, Interrupt-Driven Operation, Polled Operation

Intel® IXP400 Software

Access-Layer Components: NPE Message Handler (IxNpeMh) API

The solicited callback list contains the list of callbacks corresponding to solicited messages not yet received from the NPE. The solicited messages for a given ID are received in the same order that those soliciting messages are sent, and the first ID-matching callback in the list always corresponds to the next solicited message that is received.

15.3Initializing the IxNpeMh

The IxNpeMh has two modes of operation, interrupted or polled. This refers to how the IxNpeMh will receive messages from the NPEs. When an NPE has a message for the message handler, it will always send an interrupt to the IxNpeMh, but the IxNpeMh must be set up for interrupt driven operation for it to service the interrupt automatically.

15.3.1Interrupt-Driven Operation

This is the preferred method of operation for the message handler. Here is a sample function call to initialize the IxNpeMh component for interrupt driven operation:

ixNpeMhInitialize (IX_NPEMH_NPEINTERRUPTS_YES);

The function takes a yes/no value from an enum, and now all messages from all the NPEs will be serviced by IxNpeMH. The IxNpeMh handles messages from all NPEs and should only be initialized once.

15.3.2Polled Operation

Here is a sample function call to initialize the IxNpeMh component for interrupt driven operation:

ixNpeMhInitialize (IX_NPEMH_NPEINTERRUPTS_NO);

The function takes a yes/no value from an enum, and now all messages from the NPEs must be manually checked. The IxNpeMh handles messages from all NPEs, and should only be initialized once.

After setting up polled operation the client must check for messages coming out of the NPEs. Here is a sample function call that will check to see if NPE-A has a message to send:

ixNpeMhMessagesReceive (IX_NPEMH_NPEID_NPEA);

Three separate function calls are required to check all three of the NPEs.

Note: This function call cannot be made from inside an interrupt service routine as it will use resource protection mechanisms.

April 2005	IXP400 Software Version 2.0	Programmer’s Guide
226	Document Number: 252539, Revision: 007