6.4 Timing considerations using double buffering. After the first buffer is filled, subsequent buffers are emptied and filled with minimal waiting time since only a DMA transfer set-up is required for each operation to occur concurrently with processing
Only extra time in addition to the normal buffer processing time is the DMA set-up time. Although this set-up time varies from computer to computer, the total time required is normally less than 20 us. For most machines, the buffer starting and ending address are loaded into certain registers along with a peripheral address code and a DMA transfer request is then initiated. Since a DMA set-up is required to empty buffers, two such DMA set-up times are required to empty the two decompression buffers.