default:
		if (tok <= 0) return "end of file";
		if (tok < 040 || tok >= 0177) {
			return "bad token";
		}
		/* fall through */
	case '\n':
	case '\f':
	case '\v':
	case '\r':
	case '\t':
		index = (index+2) & (SIZBUF-1);
		buf[index] = tok;
		return &buf[index];
	}
}