How to find how much "shared" is a process's memory?

From: Fernando Nunes (spam_at_domus.online.pt)
Date: 11/28/03 

Date: Fri, 28 Nov 2003 17:38:10 +0000

Is ther a tool or method to find out how much memory of a process memory map is being shared with other processes?
Also, how can I find out how much of a resident size os a process is composed by shared libraries?

Apparently in Linux this can be done with top...

Regards.