Read-write buffer for gathering write requests and resolving read conflicts based on a generated byte mask code

Claim 1

Apparatus for receiving an incoming read request from a CPU and passing the incoming request to a memory unit via a bus, the incoming read request having an address word and a control word for obtaining data from said memory unit, said apparatus including an internal buffer having more than two ranks for receiving and for sequentially storing a plurality of write requests, said apparatus comprising: means for generating a byte mask code for each of the stored write requests and for the incoming read request, said byte mask code for each of the stored write requests identifying data bytes of said stored write requests to be overwritten during a write masking operation and said byte mask code for the incoming read request identifying a byte of data to be read from the memory; means, coupled to said byte mask code generating means, for comparing the address word and byte mask code of the incoming read request with each of the address words and byte mask codes of the stored write requests; and means, coupled to said comparing means, for delivering a data word of a stored write request to said CPU directly from said internal buffer, without using the bus between said internal buffer and said memory unit, when the address word and byte mask code of the incoming read request match the address word and the byte mask code of that stored write request.