A DMA controller maintains a count of data transferred in each DMA operation, and saves the transferred data count at the end of the DMA operation. The DMA controller may then begin a subsequent DMA transfer operation, without waiting for a processor to read the transferred data count. The transferred...http://www.google.de/patents/US7433977?utm_source=gb-gplus-sharePatent US7433977 - DMAC to handle transfers of unknown lengths
