public int read() throws IOException {
	int ret = 0;
	int first, second;
	
	do {
		first = in.read();
		if (first == -1) {
			return -1;
		}
	} while (Character.isWhitespace((char) first));
	
	second = in.read();
	if (second == -1) {
		return -1;
	}

	ret |= parseNibble((char) first) << 8;
	ret |= parseNibble((char) second);
	
	return ret;
}

private int parseNibble(char c) throws IOException {
	if ('0' <= c && c <= '9') {
		return c - '0';
	} else if ('a' <= c && c <= 'f') {
		return c - 'a';
	} else if ('A' <= c && c <= 'F') {
		return c - 'A';
	} else {
		throw new IOException("Invalid character " + c);
	}
}