Modul Conversion

Jan Burse, erstellt 20. Mai 2019
* Simulation of some Jekejeke-Prolog number conversion.
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:- module(conversion, [hex_codes/2]).
* hex_codes(I, L):
* If L is a list of codes, the predicates succeeds in I
* with the hex integer represented by the codes L. Otherwise
* the predicate succeeds in L with the codes of the
* hex integer I.
% hex_codes(-+Integer, +-List)
codes_to_hex(L, I).
hex_to_codes(I, L).
codes_to_hex([0'-|L], I) :- !,
codes_to_hex(L, 0, J),
I is -J.
codes_to_hex(L, 0, I).
codes_to_hex([C|L], I, J) :-
code_type(C, xdigit(D)),
H is I*16+D,
codes_to_hex(L, H, J).
codes_to_hex([], I, I).
I < 0, !,
J is -I,
hex_to_codes(J, [], R),
L = [0'-|R].
L = [0'0].
hex_to_codes(I, [], L).
hex_to_codes(0, L, R) :- !,
R = L.
hex_to_codes(I, L, R) :-
D is I mod 16,
code_type(C, xdigit(D)),
J is I//16,
hex_to_codes(J, [C|L], R).