Can I extract the output of the MUXCY (XST)?

[eng.amr2009]

BCD Adder

Hi all

I'm Implementing a BCD full adder

my code adds 2 vectors of 16 bits but the problem is that adding 2 BCD8421 digits may produce wrong output for example



9 + 5 = 14 = (0000 1110) where it should be (0001 0100) in correct BCD8421 format



when i examined the truth table i found that i need to extract the carry after each 4 bit addittion to be able to detect the wrong combination in the sum

when i examined the technology schematic i found that the XST uses the carry chain logic to implement the adder where the carry is implemented using the MUXCY

the output of the MUXCY is an internal signal



IS there anyway to extract this internal signal (the output of the MUXCY) ?!!!!!!!!!!!


here is the schematic


**broken link removed**


thanks in advance