hexValue(const FileInfo *file, const widechar *digits, int length) {
	int k;
	unsigned int binaryValue = 0;
	for (k = 0; k < length; k++) {
		unsigned int hexDigit = 0;
		if (digits[k] >= '0' && digits[k] <= '9')
			hexDigit = digits[k] - '0';
		else if (digits[k] >= 'a' && digits[k] <= 'f')
			hexDigit = digits[k] - 'a' + 10;
		else if (digits[k] >= 'A' && digits[k] <= 'F')
			hexDigit = digits[k] - 'A' + 10;
		else {
			compileError(file, "invalid %d-digit hexadecimal number", length);
			return (widechar)0xffffffff;
		}
		binaryValue |= hexDigit << (4 * (length - 1 - k));
	}
	return (widechar)binaryValue;
}