[ns] How to debug c++ code of ns?

["Yi-Hsien Tseng" <yhtseng@inrg.csie.ntu.edu.tw>]

Hi all:
         I use gdb to debug ns code!
         But I have a problem as following:
        ---------------------------------------------------------------
         $gdb ns
         (gdb)run test.tcl
                  .
                  .
                  .
          stop in Mac::recv(),segment fall...core dump!

         (gdb)list
          9959 out of range, there are 2295 lines total!
         --------------------------------------------------------------

         I know the code is in mac.cc,but how can I list the code of mac.cc??
         use (gdb)load mac.cc , right??

        And can anyone can tell me the most common instruction using in gdb when debuging ns2?

        Thank you !

         Best Regard !