24 lines
618 B
Prolog
24 lines
618 B
Prolog
:- module(adder,[sum/3]).
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sum([B],[S],(S==B)).
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sum([B1,B2|Bs],Sum,F1*F2*F3) :-
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split([B1,B2|Bs],Xs,Ys),
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sum(Xs,S1,F1), sum(Ys,S2,F2),add(S1,S2,Sum,F3).
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split([],[],[]).
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split([X],[X],[0]).
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split([X,Y|XYs],[X|Xs],[Y|Ys]) :- split(XYs,Xs,Ys).
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add([X|Xs],[Y|Ys],[Z|Zs],(Z==SumXY)*Sum) :-
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halfadder(X,Y,SumXY,CarryXY),
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adder(Xs,Ys,CarryXY,Zs,Sum).
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adder([],[],Carry,[Z],Z==Carry).
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adder([X|Xs],[Y|Ys],Carry,[Z|Zs],(Z==SumXY)*Rest) :-
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fulladder(X,Y,Carry,SumXY,CarryXY),
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adder(Xs,Ys,CarryXY,Zs,Rest).
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fulladder(X, Y, C, (X xor Y xor C), (C->(X+Y);(X*Y)) ).
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halfadder(X, Y, (X xor Y), X*Y ).
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