They would just convert your high school GPA to a 4 point scale. I think you just subtract 1 to go from a 5 point to 4 point scale, so you would have a 3.8. I’m not completely sure on that though, and I would email the admissions office to check.
http://admissions.indiana.edu/contact/index.html
Also a 29.5 does round up to 30 on the ACT. If you do in fact have a 3.8 GPA on a 4 point scale, you will definitely be directly admitted assuming you get into the university (you will). Test scores and GPA are the only things that matter for being offered direct admission.