Abstract: A contention-free burst method for a media access controller to transmit data over a network. The first step is to create descriptors identifying multiple frames to be transmitted by a contention-free burst. Each descriptor comprises a semaphore field indicating whether the frame associated therewith is the last within the contention-free burst, and comprises an exchange time field recording duration of the frame associated therewith. The frames are transferred to a media access controller initiating the contention-free burst. The media access controller tracks an actual amount of elapsed time from when the burst is initiated. The contention-free burst is terminated either when a granted period less the actual amount of elapsed time results in insufficient time for any remaining transmission, or upon detection of a descriptor with a semaphore field indicating the last frame in which case termination is executed following transmission of the frame determined to be last.

Abstract: A method for performing DMA transfers with dynamic descriptor structure. A processor first creates a new chain of descriptors each including an end-of-chain (EOC) entry set to a false value except a dummy descriptor at the end of the new chain having the EOC entry set to a true value. The new descriptor chain can be appended to a previous descriptor chain, if any, by transferring parameters and a link pointer of the first descriptor within the new descriptor chain to a dummy descriptor of the previous descriptor chain. Then the processor changes the EOC entry of the dummy descriptor within the previous chain from the true value to the false value. Therefore, a DMA controller is able to transfer data in accordance with the new descriptor and also the previous one.