Can't do it. But (if you can stand it) you might try
func(x,x,x, caseid)
{
switch(caseid) {
case 1: blah blah blah ; break;
case 2: blah blah; break;
}
/* Common stuff */
}
BTW, original K&R C had "entry" defined as a keyword but never told you what
to do with it! Look it up, you will find it in the list of reserved keywords!