suggestions for generating diffs through the revision list

[Don Zickus <dzickus@redhat.com>]

I am try to walk the revision history for a given path and analyze the
diff (as compared to its parent).  What is the proper way of doing that?

I noticed a bunch of 'library' calls such as

init_revsion(&revs);
setup_revisions(argc, argv, &revs, "HEAD");
prepare_revision_walk(&revs, NULL);
commit = get_revision(&revs);

But what I can't find is the way to generate diffs.  I see lots and lots
of code to do it, but every builtin seems to do it differently.  Not
knowing the internals that well, I was hoping for some advice.

I stumbled upon calls like

run_diff_files
run_diff_index

but I haven't seen how to use them correctly.

Any help would be appreciated.  Thanks.

Cheers,
Don