The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 11, 2001
Filed:
Jan. 08, 1999
Shih-ho Wu, Mesa, AZ (US);
David Ross Evoy, Tempe, AZ (US);
VLSI Technology, Inc., San Jose, CA (US);
Abstract
A direct memory access engine (DMA) system and method for maximizing DMA transfers of arbitrarily aligned data. The present invention utilizes physical region descriptors (PRD) stored in memory to track locations and descriptions of scattered data in a main memory. The direct memory access circuit retrieves the data in accordance with the PRD and configures the data into pieces such that intermediate pieces of data between a first piece and a last piece are the maximum amount of information a communication burst is capable of transferring and the intermediate pieces of data are aligned to a natural boundary address. The DMA engine also communicates the first piece of data and the last piece of data in a manner that minimizes memory accesses and in transfer sizes that are compatible with requirements and limitations of a system in which DMA engine is implemented. The DMA rotates bytes of the data to compensate for misalignment between a source address and a destination address and merges the data into a concatenated stream.