Compressed message exchange initiated by basic command accompanied by enhancement code

摘要

A controller and a properly equipped peripheral device of a computer system easily exchange messages having a compressed data format. Both the controller and the peripheral device are configured to communicate using a predefined basic command set employing a predefined communications format. The controller first verifies that the peripheral device supports a second predefined communications format in addition to the first predefined communications format. Compared to the first format, the second format utilizes messages with greater compression, i.e., an optimized bit stream ("OBS"). The controller next sends the peripheral device a number of commands, including a command of the basic command set accompanied by an OBS enable code. In the case of a write operation, the controller also sends the peripheral device an encoded dataset having the second predefined communications format and representing an underlying unencoded dataset. Although the basic command alone would alert the peripheral device to the transmission of uncompressed data, the presence of the OBS enable code signals a compressed dataset. The peripheral device receives the encoded dataset and, resulting from the received OBS enable code and the command of the basic command set, processes the encoded dataset to obtain the unencoded dataset. In the case of a read operation, the controller receives an encoded dataset, in the second predefined format, from the peripheral device.