System for creating new group of chain descriptors by updating link value of last descriptor of group and rereading link value of the updating descriptor
US5713044A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 1995 |
| Grant date | Jan 27, 1998 |
| Priority date | — |
| Expiry date | Dec 19, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F13/28
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Dynamic appending of chain descriptors is described with reference to a computer system having a host processor, a DMA unit, a host memory and an external memory wherein the DMA unit controls transference of data between the host memory and the external memory based upon data transference parameters specified in chain descriptors created by the host processor and stored as data structures within the host memory. In accordance with one method and apparatus described herein, dynamic appending of chain descriptors is achieved by employing a resume bit stored within a register of the DMA unit. The host processor, upon creating a new group of chain descriptors to be appended to a previous group, updates a link value within a last chain descriptor of the previous group to point to the first chain descriptor of the new group and also sets the resume bit within the DMA unit. The DMA unit reads chain descriptor parameters, including link values, they perform a data transfer operation specified by the chain descriptor parameters. Upon completion of the transfer operation, the DMA unit examines the resume bit and, if set, the DMA unit rereads the link value for the current chain descriptor. I…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.