[Oberon] Texts.WriteInt

[Paul Reed]

Dear all,

>> IF ROR(x, 31) = 1 ...
...
>   IF x = {31} ...

But x is not a SET, it's an INTEGER.  And as some people have pointed out,
it's not really self-documenting, nor indeed is the ROR version in the
first place.  In the following, I've attempted to establish the loop
invariant for the the edge case:

  PROCEDURE WriteInt* (VAR W: Writer; x, n: LONGINT);
    VAR i: INTEGER; x0: LONGINT;
      a: ARRAY 10 OF CHAR;
  BEGIN
    IF x < 0 THEN DEC(n); x0 := -x ELSE x0 := x END;
    IF x0 < 0 THEN a[0] := "8"; i := 1; x0 := 214748364 ELSE i := 0 END;
    REPEAT
      a[i] := CHR(x0 MOD 10 + 30H); x0 := x0 DIV 10; INC(i)
    UNTIL x0 = 0;
    WHILE n > i DO Write(W, " "); DEC(n) END;
    IF x < 0 THEN Write(W, "-") END;
    REPEAT DEC(i); Write(W, a[i]) UNTIL i = 0
  END WriteInt;

Any advances on this? :)

Cheers,
Paul