Design method for implementing high memory algorithm on low internal memory processor using a direct memory access (DMA) engine

A design method for implementing a high-memory algorithm for motion estimation and compensation uses a low internal memory processor and a DMA engine that interacts with the processor and the algorithm. The DMA takes care of large data transfers from an external memory to the processor internal memory and vice-versa, without using the CPU clock cycles. The design method is scalable and is suited to handle huge bandwidths without slowing down the processor. To prevent the processor from being idle during DMA, the processing is pipelined and staggered so that motion compensation is performed on an earlier block or data that is available, while DMA fetches the reference data for the current block. Several DMAs may be set up under an ISR if necessary. The invention has application in video decoders including those conforming to H.264, VC-1, and MPEG-4 ASP.