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68 lines
1,015 B
Modula-2
68 lines
1,015 B
Modula-2
MODULE Days;
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TYPE
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Day* = POINTER TO DayDesc;
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DayDesc = RECORD
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next, prev : Day
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END;
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Week = ARRAY 7 OF Day;
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VAR
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sun*, mon*, tue*, wed*, thu*, fri*, sat* : Day;
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week: Week;
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PROCEDURE Next*(d : Day): Day;
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BEGIN
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RETURN d.next
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END Next;
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PROCEDURE Prev*(d: Day): Day;
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BEGIN
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RETURN d.prev;
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END Prev;
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PROCEDURE inc(VAR j: SHORTINT);
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BEGIN
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IF j = 6 THEN
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j := 0
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ELSE
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INC(j)
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END
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END inc;
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PROCEDURE dec(VAR j: SHORTINT);
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BEGIN
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IF j = 0 THEN
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j := 6
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ELSE
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DEC(j)
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END
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END dec;
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PROCEDURE init(VAR w : Week);
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VAR
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i,j : SHORTINT;
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BEGIN
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i := 0;
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REPEAT
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j := i; inc(j);
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w[i].next := w[j];
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j := i; dec(j);
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w[i].prev := w[j];
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INC(i)
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UNTIL i > 6;
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END init;
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BEGIN
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NEW(sun); NEW(mon); NEW(tue); NEW(wed); NEW(thu); NEW(fri); NEW(sat);
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week[0] := sun;
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week[1] := mon;
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week[2] := tue;
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week[3] := wed;
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week[4] := thu;
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week[5] := fri;
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week[6] := sat;
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init(week);
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END Days.
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