Patent ID: 7508836

Claim:
A data processing apparatus for handling transactions issued to a slave device from a master device, each transaction involving the transfer of one or more data packets between the master device and the slave device, the data processing apparatus comprising: a buffer storage operable to buffer the data packets of one or more transactions during transfer of those data packets between the master and slave devices; buffer control logic operable to control the operation of the buffer storage; in a normal mode of operation the buffer control logic being operable to cause the buffer storage to operate as a FIFO storage for buffering the data packets so as to maintain the temporal order of those data packets; upon receipt of a high priority transaction, the buffer control logic being operable to cause the buffer storage to operate in an alternative mode of operation in which an allocated portion of the buffer storage is reserved for buffering data packets associated with that high priority transaction, whilst a remaining portion of the buffer storage is retained for buffering of the data packets of other transactions; whereby when the buffer storage is operating in the alternative mode of operation data packets in the allocated portion may be output from the buffer storage out of temporal order with respect to data packets in the remaining portion.