Method and apparatus for state-independent non-interrupt-driven handshake with positive acknowledgement

摘要

A method and apparatus for non-interrupt-driven handshake with acknowledgment are provided. A first software resource in a data processing system communicates a data value to a second software resource by writing the data value to a first register field, where it may be read by the second software resource. On writing the data, the first resource sets a write signal in a second register field. If the second software resource attempts to read the data value before it is written by the first resource, a reset value in the second field informs the second resource that any data in the first field is invalid. The second resource then sets a first predetermined value in a third field which informs the first resource that the second has attempted a read. If the data is valid when the second resource attempts the read, the data is retrieved, and the second resource echos the value in a fourth field. The second resource also sets a second predetermined data value in the third field which informs the first resource that the data has been read. The first resource then reads the value echoed in the fourth field to determine that the read by the second resource was error free.