isdn_ppp_if_get_unit(char *name)
{
	int len,
		i,
		unit = 0,
		deci;

	len = strlen(name);

	if (strncmp("ippp", name, 4) || len > 8)
		return -1;

	for (i = 0, deci = 1; i < len; i++, deci *= 10) {
		char a = name[len - i - 1];
		if (a >= '0' && a <= '9')
			unit += (a - '0') * deci;
		else
			break;
	}
	if (!i || len - i != 4)
		unit = -1;

	return unit;
}
Unknown