IMPLEMENTATION MODULE CStr;

FROM SYSTEM IMPORT ADDRESS;

PROCEDURE m2_c_strlen (s : ADDRESS) : INTEGER;
  EXTERNAL;

PROCEDURE m2_cstr_copy (VAR dst : ARRAY OF CHAR;
                        src : ADDRESS) : CARDINAL;
  EXTERNAL;

PROCEDURE Length (s : CString) : CARDINAL;
  VAR n : INTEGER;
  BEGIN
    IF s = NIL THEN RETURN 0 END;
    n := m2_c_strlen(s);
    IF n < 0 THEN RETURN 0 END;
    RETURN VAL(CARDINAL, n)
  END Length;

PROCEDURE Copy (s : CString; VAR dst : ARRAY OF CHAR) : CARDINAL;
  BEGIN
    RETURN m2_cstr_copy(dst, s)
  END Copy;

PROCEDURE IsNil (s : CString) : BOOLEAN;
  BEGIN
    RETURN s = NIL
  END IsNil;

END CStr.