DUE ethernet performance on W5200 with SPI and SPI+DMA

Hardware Arduino Due
3

I've added the SPI+DMA w5200 Ethernet results to git link below. With DMA and SPI clock at 28 MHz, one gets nearly 16 million bits/second, about 3 times the SPI-only performance. The file w5100.cpp.dma1 is the modified version of w5100.cpp that supports w5200 and DMA+SPI. Results are in wizperf.txt at

DMA code is modified from fat16lib's SD work.