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     STAB(5)                                                   STAB(5)

          stab - symbol table types

          #include <stab.h>

          The include file `<stab.h>' defines some values of the
          `n_type' field of the symbol table of object files; see
          a.out(5). These are the types for permanent symbols used by
          the compilers cc(1) and f77(1) and the debugger pi(9.1).
          Symbol table entries are produced by assembler directives:

          .stabs  specifies a name in quotes " ", a symbol type
                  (`n_type'), one char (`n_other'), one short
                  (`n_desc),' and an unsigned long (`n_value', usually
                  an address).
          .stabd  the same, referring to the current location without
                  an explicit name.
          .stabn  generates entries with no name.

          The loader ld(1) preserves the order of symbol table entries
          produced by these directives.

          The low bits of the `n_type' field place a symbol into at
          most one segment, according to the following masks, defined
          in <a.out.h>.

          #define N_UNDF  0x0   /* undefined */
          #define N_ABS   0x2   /* absolute */
          #define N_TEXT  0x4   /* text */
          #define N_DATA  0x6   /* data */
          #define N_BSS   0x8   /* bss */
          #define N_EXT   0x1   /* external bit, or'ed in */

          The `n_value' field of a symbol is relocated by ld as an
          address within the appropriate segment, or is unchanged for
          a symbol not in any segment.  In addition, the loader will
          discard certain symbols, according to rules of its own,
          unless the `n_type' field has one of the following bits set:

          #define N_STAB  0xe0

          This allows up to 112 symbol types, split among the various
          segments.  Some of these have already been claimed.  Option
          -g of cc uses the following values, all 4 mod 16, for text
          symbols.  Comments show the pertinent fields of the .stabs

          #define N_BFUN  0x24  /* procedure: name,,0,lineno,address */

     STAB(5)                                                   STAB(5)

          #define N_FUN   0x24
          #define N_NARGS 0x34  /* function call: ,,0,nbytes,address */
          #define N_SLINE 0x44  /* src line: ,,0,lineno,address */
          #define N_SO    0x64  /* source file: name,,0,lineno,address */
          #define N_SOL   0x84  /* #include file: name,,0,lineno,address */
          #define N_ESO   0x94  /* end source file: name,,0,lineno,address */
          #define N_ENTRY 0xa4  /* alternate entry: name,,0,lineno,address */
          #define N_RFUN  0xb4  /* return from function: ,,0,lineno,address */
          #define N_LBRAC 0xc4  /* left  bracket: ,,0,level,address */
          #define N_RBRAC 0xd4  /* right bracket: ,,0,level,address */
          #define N_EFUN  0xf4  /* end of function: name,,0,lineno,address */

          These values, all 8 mod 16, are used for data symbols:

          #define N_LCSYM 0x28  /* .lcomm symbol: name,,0,type,address */
          #define N_ECOML 0xe8  /* end common (local name): ,,address */

          And these for non-relocated symbols:

          #define N_GSYM  0x20  /* global symbol: name,,0,type,0 */
          #define N_FNAME 0x22  /* procedure name (f77 kludge): name,,0 */
          #define N_STFUN 0x32  /* static function: name,,0,type,0 */
          #define N_RSYM  0x40  /* register sym: name,,0,type,register */
          #define N_BSTR  0x5c  /* begin structure: name,,0,type,length */
          #define N_ESTR  0x5e  /* end structure: name,,0,type,length */
          #define N_SSYM  0x60  /* structure elt: name,,0,type,offset */
          #define N_SFLD  0x70  /* structure field: name,,0,type,offset */
          #define N_LSYM  0x80  /* local sym: name,,0,type,offset */
          #define N_PSYM  0xa0  /* parameter: name,,0,type,offset */
          #define N_BCOMM 0xe2  /* begin common: name,, */
          #define N_ECOMM 0xe4  /* end common: name,, */
          #define N_VER   0xf0  /* symbol table version number */
          #define N_TYID  0xfa  /* struct, union, or enum name */
          #define N_DIM   0xfc  /* dimension for arrays */

          Field `n_desc' holds a type specifier in the form used by
          cc(1), by up to 6 qualifiers, with q1 most significant:

          struct  desc   {
                  short  q6:2, q5:2, q4:2, q3:2, q2:2, q1:2;
                  short  basic:5;

          The qualifiers are coded thus:
          0       none                    2       function
          1       pointer                 3       array

         The basic types are coded thus:
         0       undefined
         1       function argument
         2       character
         3       short

    STAB(5)                                                   STAB(5)

     4       int
     5       long
     6       float
     7       double

STAB(5)                                                   STAB(5)

     8       structure
     9       union
     10      enumeration
     11      member of enumeration
     12      unsigned character
     13      unsigned short
     14      unsigned int
     15      unsigned long
     16      void

STAB(5)                                                   STAB(5)

     The Pascal compiler, pc(A), uses the following `n_type'

     #define N_PC   0x30/* global pascal symbol:
     name,,0,subtype,line */

     and uses the following subtypes to do type checking across
     separately compiled files:
     1       source file name        6       global variable
     2       included file name      7       global function
     3       global label            8       global procedure
     4       global constant         9       external function
     5       global type             10      external procedure

     a.out(5), pi(9.1), as(1), ld(1)

     The loader's relocation conventions limit the number of use-
     ful `n_type' values.