linenum(4)                                             linenum(4)



     NAME
          linenum - line number entries in a common object file

     SYNOPSIS
          #include <linenum.h>

     DESCRIPTION
          The C compiler generates an entry in the object file for
          each C source line on which a breakpoint is possible (when
          invoked with the -g option; see cc(1)).  Users can then
          reference line numbers when using the appropriate software
          test system (see sdb(1)).  The structure of these line
          number entries appears below.

             struct  lineno
             {
                     union
                     {
                             long     l_symndx ;
                             long     l_paddr ;
                     }                l_addr ;
                     unsigned short   l_lnno ;
             } ;

          Numbering starts with one for each function.  The initial
          line number entry for a function has l_lnno equal to zero,
          and the symbol table index of the function's entry is in
          l_symndx.  Otherwise, l_lnno is non-zero, and l_paddr is the
          physical address of the code for the referenced line.  Thus
          the overall structure is the following:

                    l_addr                   l_lnno

                    function symtab index    0
                    physical address         line
                    physical address         line
                    ...

                    function symtab index    0
                    physical address         line
                    physical address         line
                    ...

     SEE ALSO
          cc(1), sdb(1), a.out(4).










     April, 1990                                                     1