[chuck-users] Looping Sample Playback

Hello all, I was wondering if there is a ugen that will handle arbitrary looping points? I have some samples for various instruments (ie piano, mellotron strings, etc), and would like to hook them up in ChucK. Basically, if the sndbuf ugen is the starting point for this, then do I need to write my own "looping" function to ensure that it gets back to the proper points within the sample. Or has someone already implemented this functionality and would be interested in "sharing"? Thanks, Mike