syms(4)                    DG/UX 4.30                     syms(4)



     NAME
          syms - common object file symbol table format

     SYNOPSIS
          #include  <syms.h>

     DESCRIPTION
          Common object files contain information to support symbolic
          software testing [see sdb(1)].  Line number entries,
          linenum(4), and extensive symbolic information permit
          testing at the C source level.  Every object file's symbol
          table is organized as shown below.

                    File name 1.
                         Function 1.
                              Local symbols for function 1.
                         Function 2.
                              Local symbols for function 2.
                         ...
                         Static externs for file 1.

                    File name 2.
                         Function 1.
                              Local symbols for function 1.
                         Function 2.
                              Local symbols for function 2.
                         ...
                         Static externs for file 2.
                    ...

                    Defined global symbols.
                    Undefined global symbols.

          The entry for a symbol is a fixed-length structure.  The
          members of the structure hold the name (null padded), its
          value, and other information.  The C structure is given
          below.

          #define  SYMNMLEN  8
          #define  FILNMLEN  14
          #define  DIMNUM    4

          struct  syment
          {
              union                         /* all ways to get symbol name */
              {
                  char        _n_name[SYMNMLEN]; /* symbol name */
                  struct
                  {
                      long    _n_zeroes;    /* == 0L when in string table */
                      long    _n_offset;    /* location of name in table */
                  } _n_n;



     Licensed material--property of copyright holder(s)         Page 1

     syms(4)                    DG/UX 4.30                     syms(4)



                  char        *_n_nptr[2];  /* allows overlaying */
              } _n;
              long            n_value;      /* value of symbol */
              short           n_scnum;      /* section number */
              unsigned short  n_type;       /* type and derived type */
              char            n_sclass;     /* storage class */
              char            n_numaux;     /* number of aux entries */
              char            n_pad1;       /* pad to 4 byte multiple */
              char            n_pad2;       /* pad to 4 byte multiple */
          };
          };
          };

          #define  n_name    _n._n_name
          #define  n_zeroes  _n._n_n._n_zeroes
          #define  n_offset  _n._n_n._n_offset
          #define  n_nptr    _n._n_nptr[1]

          Meaningful values and explanations for them are given in
          both syms.h and Common Object File Format.  Anyone who needs
          to interpret the entries should seek more information in
          these sources.  Some symbols require more information than a
          single entry; they are followed by auxiliary entries that
          are the same size as a symbol entry.  The format follows.

          union auxent
          {
                 struct
                 {
                        long            x_tagndx;
                        union
                        {
                               struct
                               {
                                        unsigned short  x_lnno;
                                        unsigned short  x_size;
                               } x_lnsz;
                               long     x_fsize;
                        } x_misc;
                        union
                        {
                               struct
                               {
                                        long   x_lnnoptr;
                                        long   x_endndx;
                               }        x_fcn;
                               struct
                               {
                                        unsigned short  x_dimen[DIMNUM];
                               }        x_ary;
                        }               x_fcnary;
                        unsigned short  x_tvndx;



     Licensed material--property of copyright holder(s)         Page 2

     syms(4)                    DG/UX 4.30                     syms(4)



                        char   pad1;
                        char   pad2;
                 }      x_sym;
                 struct
                 {
                        char   x_fname[FILNMLEN];
                 }      x_file;
                  struct
                  {
                          long    x_scnlen;
                          unsigned short  x_nreloc;
                          unsigned short  x_nlinno;
                  }       x_scn;

                 struct
                 {
                        long            x_tvfill;
                        unsigned short  x_tvlen;
                        unsigned short  x_tvran[2];
                 }      x_tv;
          };

          Indexes of symbol table entries begin at zero.

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

     WARNINGS
          On machines on which ints are equivalent to longs, all longs
          have their type changed to int.  Thus the information about
          which symbols are declared as longs and which, as ints, does
          not show up in the symbol table.























     Licensed material--property of copyright holder(s)         Page 3