μCsim: VCD file dumper

# VCD file dumper

1. specify output file:
0> set hw vcd[0] file "name.vcd"
2. add locations to dump (sorry, I didn't remember correctly, bits can not be dumped yet):
0> set hw vcd[0] add pc_odr
0> set hw vcd[0] add rom[0x500a]
You can set the name of the module if you want (set hw vcd[0] module name), it will be
ucsim_vcd_0 by default.
3. start recording:
0> set hw vcd[0] start
4. run the program

5. you can suspend/resume recording:
0> set hw vcd[0] pause
0> set hw vcd[0] restart
You can create an additional recorder with "set hw vcd[0] new id" and setup it with "set
hw vcd[id] ..." commands ("id" must be a number).
6. stop recording and close the vcd file:
0> set hw vcd[0] stop
After "stop", you have to specify a new file, because "start" overwrites the old one!
For examine, I use gtkwave on linux.