| 摘要 |
PROBLEM TO BE SOLVED: To make accessible to a data buffer different from the buffer accessed the last time just after polling. SOLUTION: A polling is executed by a DMA control part on the basis of a logical state of a flag, and a first pointer and a second pointer in a descriptor 1617 are read again by the DMA control part after finishing the polling, and the content of the descriptor is renewed before finishing the polling to allow the access of the data buffer 1609 different from the access of the last time just after the polling. The content of the descriptor is renewed before finishing the polling, and can be changed to a different chain row just after the polling, and in that case, an overhead is reduced more than a method for designating a separate chain row by the next descriptor of the descriptor stopped on chain block transfer.
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