sumaunix

MODULE suma;

    FROM SYSTEM IMPORT ADR;
    FROM StrIO IMPORT WriteString, WriteLn;
    FROM NumberIO IMPORT WriteInt, ReadInt;
    FROM lib IMPORT fork, pipe, dup, read, write, close;
    FROM errno IMPORT geterrno;

VAR
    i, n, m, f: INTEGER;
    tdece, pid: INTEGER;
    pfd: ARRAY[0..1] OF INTEGER;
    ulaz, elementi: ARRAY[0..15] OF INTEGER;
    izlaz: INTEGER;
BEGIN

    WriteString("Unesite broj n: ");
    ReadInt(n);



    m := n; (*n predstavlja potreban broj dece*)
    i := 0; (*i predstavlja broj dece jednog roditelja*)
    tdece := i; (*tdece predstavlja *)
    WHILE (1 < n) AND (i < n) DO

        pipe(pfd);
        pid := fork();

        IF pid # 0 THEN (*nije dete*)

            ulaz[i] := dup(pwd[0]);
            INC(i);
            tdece := i;

        ELSE

            FOR j := 0 TO i - 1 DO
                close(ulaz[i]);
            END;

            IF n < ((m - i) + 1) THEN
                close(izlaz);
            END;

            izlaz := dup(pfd[1]);

            DEC(n, i + 1);

            tdece := i;
            i := 0;

        END;

        close(pfd[0]);
        close(pfd[1]);
    END;

    (*racunanje*)
    IF n = 0 THEN
        rezultat := 1;
    ELSIF n = 1 THEN
        rezultat := 1;
    ELSE (*non triv*)

        FOR f := 0 TO tdece - 1 DO
            read(ulaz[f], ADR(elementi[f]), SIZE(elementi[f]));
            close(ulaz[f]);
        END;

        FOR f := 0 TO tdece - 1 DO
            rezultat := rezultat + elementi[f];
        END;

    END;

    (*ispis*)
    IF n = m THEN
        WriteString("rezultat: "); WriteInt(rezultat, 0);
        WriteLn();
    ELSE
        write(izlaz, ADR(rezultat), SIZE(rezultat));
        close(izlaz);
    END;
END suma.