Method and apparatus for transferring messages between source and destination users through a shared memory.

摘要

The memory comprises a linear space and a buffered space, each page of the buffered space is divided in a number m+1 of buffers of equal capacity, with m buffers devoted to the storage of data and one control buffer divided into m control blocks. There is a fixed relationship between one buffer control block and one data buffer. The control blocks are devoted to the storage of buffer and message chaining information. The linear space comprises queue control blocks, with one queue control block per user. The messages are received by memory interface 22 from the source users and then are enqueued in link inbound queues (LIQ) which are dynamically built by taking buffers from the buffered space, chaining the buffers by writing buffer and message chaining information in the corresponding buffer control blocks and writing the queue head and queue tail addresses in the user queue control block. A centralized control means is designed to process enqueue, dequeue and release orders upon requests from a user selected by an arbitrating means. When a link inbound queue becomes not empty, the memory interface 22 sends a dequeue order request to the centralized control means, said request identifying the corresponding user queue control block. The message address is provided in response thereto with the identification of the queue control block of the destination user. Then, the memory interface 22 sends an enqueue request to the centralized control means, said request identifying the address of the message to be enqueued and the queue control block of the destination user. The processing of this enqueue request by the centralized control means causes the messages to be enqueued in an outbound queue from which it is transferred to the destination user, by memory interface 22.