Message FIFO empty early warning method

In a message passing interface between a requesting module and a receiving module, each module having access to two queues in the message passing interfaces each queue having a Work FIFO for containing message frames to be processed and a Free FIFO for containing free messages, a method of processing messages comprises the steps of:

• monitoring a number of free messages in the Free FIFO of the receiving module;
• sending an early warning level signal to the requesting module when the number of free messages in the Free FIFO of the receiving module is below an early warning level;
• and
• posting additional free messages to the Free FIFO of the receiving module, whereby the receiving module has at least one free message to send the early warning level signal to the requesting module, and the receiving module uses the additional free messages to process messages from the Work FIFO of the receiving module.

A method of passing messages between a requesting module and a receiving module, each module having access to two queues in the message passing interface, each queue having a Work FIFO for containing message frames to be processed and a Free FIFO for containing free messages, comprises the steps of:

• detecting a number of free messages stored in the Free FIFO of the receiving module;
• sending an early warning level signal to the receiving module when the detected number falls below an early warning level, the early warning level being selected to be greater than a FIFO empty level and less than a FIFO full level;
• utilizing one remaining free message in the Free FIFO of the receiving module to alert the requesting module of a low free message status;
• and
• posting additional free messages to the Free FIFO of the receiving module, whereby the receiving module has free messages available to continue processing messages from the Work FIFO of the receiving module.