' Gray code
PROGRAM "graycode"
VERSION "0.0001"

DECLARE FUNCTION Entry()
INTERNAL FUNCTION Encode(v&)
INTERNAL FUNCTION Decode(v&)

FUNCTION Entry()
  PRINT "decimal  binary   gray    decoded"
  FOR i& = 0 TO 31
    g& = Encode(i&)
    d& = Decode(g&)
    PRINT FORMAT$("  ##", i&); "     "; BIN$(i&, 5); "   "; BIN$(g&, 5);
    PRINT "   "; BIN$(d&, 5); FORMAT$("  ##", d&)
  NEXT i&
END FUNCTION

FUNCTION Encode(v&)
END FUNCTION v& ^ (v& >> 1)

FUNCTION Decode(v&)
  result& = 0
  DO WHILE v& > 0
    result& = result& ^ v&
    v& = v& >> 1
  LOOP
END FUNCTION result&

END PROGRAM