reverse engineering functions in .o files

[esp5]

Ok, I'm paring down the undefined functions I get when linking libc.so, and 
I've come across the following five that I don't *think* I'll be able to get
around:

__rem64
__div64
__mul64
__urem64
__udiv64

Now, I guess my question was - how can I define these functions? I was thinking
that the best way would be to go into the system libc.so, and reverse engineer
what they do back into assembly. However, I have no idea how I'd begin to
do that.

Any help on this would be greatly appreciated. I'd rather submit the patch for 
solaris2.6 when I was done with the work.. however if this requires lots 
of info on the part of someone who knows solaris 2.6 inside and out, I'm 
willing to post what I have..

Ed