include "cowgol.coh";

# Damm test on number given as ASCII string
# Returns check digit
sub damm(num: [uint8]): (chk: uint8) is
    var table: uint8[] := {
        0,3,1,7,5,9,8,6,4,2,
        7,0,9,2,1,5,4,8,6,3,
        4,2,0,6,8,7,1,3,5,9,
        1,7,5,0,9,8,3,4,2,6,
        6,1,2,3,0,4,5,9,7,8,
        3,6,7,4,2,0,9,5,8,1,
        5,8,6,9,7,2,0,1,3,4,
        8,9,4,5,3,6,2,0,1,7,
        9,4,3,8,6,1,7,2,0,5,
        2,5,8,1,4,3,6,7,9,0
    };

    chk := 0;
    while [num] != 0 loop
        chk := table[(chk<<1) + (chk<<3) + ([num] - '0')];
        num := @next num;
    end loop;
end sub;

# Test and print
sub test(num: [uint8]) is
    print(num);
    print(":");
    if damm(num) == 0 then
        print("Pass\n");
    else
        print("Fail\n");
    end if;
end sub;

test("5724");
test("5727");
test("112946");
test("112949");