This is a daemon that listens to "xilinx_xvc" (xilinx virtual cable) traffic and 
operates JTAG over GPIOs.

It was written for the NeTV, but the NeTV silvermoon hardware doesn't have the 
necessary GPIO-to-JTAG connections.

I've chosen the following connections:

TDI - GPIO104  - SPARE_IO1 (J102, test point)
TDO - GPIO35   - MMC3_ALT_CMD (available on RP116, bottom)
TCK - GPIO118  - FPGA_CCLK (available between R800 and R801, shared with serial configuration)
TMS - GPIO36   - MMC3_ALT_CLK (available on RP116, bottom)

You should easily be able to make it support other hardware as well.

The daemon listens on port 2542, and multiplexes between multiple connections.

I've tested Impact FPGA Programming, IDCODE looping, and Chipscope.

Have fun!