The DMA Sniffer is part of the RP2040 DMA engine. It can perform a variety of functions on the DMA'd data, including CRCs, accumulation, bit-reversal, etc. I use the accumulation function to increment the address contained in the HyperRAM command packet after each scan line is DMA'd from HyperRAM to the scan line buffer. This allows re-use of the HyperRAM command packet, eliminating the need for a per scan line packet (3 uint_32s per scanline). Important for the emulator, as it runs out of RP2040 RAM (vs. flash).