please tell me how to subtract a binary A by 3 (A-3) in the best way ( except the way that using a subtract block from FA to have the result)
thanks a lot !!!
Are you talking about programming A-3 (A being a binary number of n bits and 3 being 00....011) in a HDL?
Is the subtract block you're talking about, something like a Xilinx coregen block?
As Iouri suggested, the '-' operator in HDL (such as Verilog or VHDL) is easy to use, and usually generates well-optimized logic for your target device. The results will probably be as small and fast as anything you create yourself.
you can do A + 1's complement of B + 1 if A > B
it will give output = A-B
in ur case B is 3 (0011), so take 1's complement of it and follow the process....
that you can do using full adder.......