compiling mesa hostmot for custom spartan6 board

hello dear friends 
i want to build a  mesa card with my custom spartan board i have rpi4 with latest linuxcnc image unfortunatly i can not afford the official mesa board 
my custom board does not have any ADC and anything just Sram and spi flash and a programmer 
i just want to have a 3 axis with spindle and 10 io . trying to build a closed loop system.
i have 7c81 hostmot firmware i know vhdl but source is too complicated 
please help me to compile firmware and connect my custom board to rpi 
and tailor other section of source that i did not need those module 
3 axis + spindle closeloop  with stepgen or pwm and 10 IO just these options .
i am trying to set UCF file 
in forum PCW said that you need configure PINxx file but i can not understand the instruction
please help me 

my best regards

Yes, you would need to make a UCF file, card file and pinout file for that hardware
Does it really only have 20 I/O pins? That's would be a bit tight for 3 axis:

3 Axis step/dir = 6
SPI interface =4
PWM = 1 to 3 (2,3 if you have enable or direction)
Spindle encoder = 3 (if needed)

thank you for your repilay our mesa angel and savior

yes want to make card and pin file but how can i do this is there any document to do that
i know UCF file and do that with no problem

yes i know that pin count is problem but if i am successful in compiling i redesign my own custom board
i need information for compiling and talking to rpi4 after that i have solve the pin count problem
for example there is twiddle module in source of hostmot2 I could not understand the usage and a lot of module like dumbass8w soft processor.
so another thing i want to delete unused module for better study .

thanks

You really only need to worry about getting the 3 files to match your hardware.
You normally don't deal with anything at the module level unless you need to change a module.

Note that the SPI interface requires using a GCLK pin for the SPI clock
so make sure you chose a GCLK capable pin for the SPI clock in the UCF file.

The 3 files are created by starting with existing ones and modifying them
to suit your hardware. The card files all end with "card.vhd".
For example the 7C81 card file is c81x9card.vhd.
The pin files all start with "PIN"

so how can i determine which module i need for my need?

Which modules are included in a build is determined by the pinout file, I would suggest reading a few to get an idea of how they work.