Patent ID: 8065448

Claim:
A direct memory access (DMA) control system, comprising: a plurality of DMA control units controlled in a manner that, while one of the plurality of DMA control units uses a transmission path, the other DMA control units other than the one of the plurality of DMA control units are prevented from using the transmission path; and a transfer instruction unit that receives a request for DMA transfer with respect to a first DMA control unit from among the plurality of DMA control units, and determines, in response to receiving the request, a transfer amount for the first DMA control unit in accordance with a utilization state of a second DMA control unit from among the plurality of the DMA control units, and generates a transfer instruction to be sent to the first DMA control unit, the transfer instruction including the determined transfer amount for the first DMA control unit, wherein if it is determined that the second DMA control unit is not utilized based on the utilization state the transfer instruction unit, in response to detecting a start of utilizing the second DMA control unit after generating the transfer instruction to be sent and before sending the transfer instruction to the first DMA control unit, (i) discards the transfer instruction to be sent to the first DMA control unit, (ii) determines a new transfer amount for the first DMA control unit according to a case where the second DMA control unit is being utilized, and sends a new transfer instruction including the determined new transfer amount to the first DMA control unit.