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Kogge-Stone CLA Subtracting?

CX gamer

Jun 9, 2011
4
Joined
Jun 9, 2011
Messages
4
Hi, I've successfully built a working Kogge-Stone CLA that adds properly. But I want to learn it to subtract. Since the absence of a Cin input, I decided to replace the first bit's half adder with a full adder, leaving everything else intact.
This circuit, however, fails, as the 4-value-bit won't propagate correctly when both x0, y0, Cin and x1 are active. Any help here?

Thank you in advance,

CX
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
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Jan 21, 2010
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25,510
To subtract you add the 2's complement.
 

CX gamer

Jun 9, 2011
4
Joined
Jun 9, 2011
Messages
4
Yes I know, I invert both inputs and enabling the Cin in the full adder which replaced the 1-value-bit's half adder. But it isn't working. :(
 
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