Method and apparatus for coordinating data transfer between hardware and software by comparing entry number of data to be transferred data to entry number of transferred data

Abstract

A method and apparatus of coordinating data transfer between hardware and software in a computer system through the use of a semaphore mechanism is disclosed. When a data packet is queued by preparing an entry in a data descriptor ring, software provides the descriptor entry number to a first storage field in a predetermined storage location which is accessible by hardware. Hardware accounts for the transactions it has completed by writing the descriptor entry number to a second storage field in the storage location. To determine if there is additional data to process, hardware compares the contents of the first storage field and the contents of the second storage field. If the contents of both storage fields are equal, the corresponding ring or channel has run out of data and no additional data is to be processed. Under this condition, the corresponding channel goes to sleep until it is waken by a command indicating that software has provided another descriptor entry number to the first storage field in the storage location. If the contents of both storage fields are not equal, hardware continues to process the data represented by the descriptors provided.

Dependencies are inferred from the claim text.