Patent ID: 7075938

Claim:
A common buffer memory control apparatus controlling a common buffer memory which is used to store message data items each of which is divided into a plurality of cells based on an asynchronous transfer mode, said apparatus comprising: first management means for managing whether each of a plurality of blocks into which said common buffer memory divided is free or used; block selecting means for selecting one block of said common buffer memory which is free based on information obtained by said first management means, to use for a single data item; user management means for managing the blocks of said common buffer memory by a user management table in which a block storing a head cell positioned at a head of the message data corresponds to user identification information extracted from the head cell; cell writing control means for controlling a write operation for the single message data item so that the respective cells of the single message data item are accumulated in the one block, selected by said block selecting means, of said common buffer memory, wherein said cell writing control means controls, based on information obtained by said user management means, the write operation so that each of cells positioned in mid-portion of the message data is written in the block corresponding to the user identification information extracted from said each of the cells; and single message extracting means for extracting the respective cells written in the one block by said cell writing control means as the single message data item from the one block which is specified by the user identification information extracted from a cell at a tail of the single message data item when the cell at the tail of the single message data item is received.