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STAB(5)                       1986			  STAB(5)



N\bNA\bAM\bME\bE
     stab - symbol table types

S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
     #\b#i\bin\bnc\bcl\blu\bud\bde\be <\b<s\bst\bta\bab\bb.\b.h\bh>\b>

D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
     _\bS_\bt_\ba_\bb._\bh defines some values of the n_type field of the symbol
     table of a.out files.  These are the types for permanent
     symbols (i.e. not local labels, etc.) used by the old
     debugger _\bs_\bd_\bb and the Berkeley Pascal compiler _\bp_\bc(1).  Symbol
     table entries can be produced by the ._\bs_\bt_\ba_\bb_\bs assembler direc-
     tive.  This allows one to specify a double-quote delimited
     name, a symbol type, one char and one short of information
     about the symbol, and an unsigned long (usually an address).
     To avoid having to produce an explicit label for the address
     field, the ._\bs_\bt_\ba_\bb_\bd directive can be used to implicitly
     address the current location.  If no name is needed, symbol
     table entries can be generated using the ._\bs_\bt_\ba_\bb_\bn directive.
     The loader promises to preserve the order of symbol table
     entries produced by ._\bs_\bt_\ba_\bb directives.  As described in
     _\ba._\bo_\bu_\bt(5), an element of the symbol table consists of the
     following structure:

     /*
      * Format of a symbol table entry.
      */
     struct nlist {
	     union {
		      char  *n_name; /* for use when in-core */
		      long  n_strx;  /* index into file string table */
	     } n_un;
	     unsigned char  n_type;  /* type flag */
	     char	    n_other; /* unused */
	     short	    n_desc;  /* see struct desc, below */
	     unsigned n_value;	     /* address or offset or line */
     };

     The low bits of the n_type field are used to place a symbol
     into at most one segment, according to the following masks,
     defined in <_\ba._\bo_\bu_\bt._\bh>.  A symbol can be in none of these seg-
     ments by having none of these segment bits set.

     /*
      * Simple values for n_type.
      */
     #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 */




Printed 7/27/90                May				1






STAB(5)                       1986			  STAB(5)



     #define N_EXT   01    /* external bit, or'ed in */

     The n_value field of a symbol is relocated by the linker,
     _\bl_\bd(1) as an address within the appropriate segment.  N_value
     fields of symbols not in any segment are unchanged by the
     linker.  In addition, the linker will discard certain sym-
     bols, according to rules of its own, unless the n_type field
     has one of the following bits set:

     /*
      * Other permanent symbol table entries have some of the N_STAB bits set.
      * These are given in <stab.h>
      */
     #define N_STAB	   0xe0/* if any of these bits set, don't discard */


     This allows up to 112 (7 * 16) symbol types, split between
     the various segments.  Some of these have already been
     claimed.  The old symbolic debugger, _\bs_\bd_\bb, uses the following
     n_type values:

     #define N_GSYM  0x20  /* global symbol: name,,0,type,0 */
     #define N_FNAME 0x22  /* procedure name (f77 kludge): name,,0 */
     #define N_FUN   0x24  /* procedure: name,,0,linenumber,address */
     #define N_STSYM 0x26  /* static symbol: name,,0,type,address */
     #define N_LCSYM 0x28  /* .lcomm symbol: name,,0,type,address */
     #define N_RSYM  0x40  /* register sym: name,,0,type,register */
     #define N_SLINE 0x44  /* src line: 0,,0,linenumber,address */
     #define N_SSYM  0x60  /* structure elt: name,,0,type,struct_offset */
     #define N_SO    0x64  /* source file name: name,,0,0,address */
     #define N_LSYM  0x80  /* local sym: name,,0,type,offset */
     #define N_SOL   0x84  /* #included file name: name,,0,0,address */
     #define N_PSYM  0xa0  /* parameter: name,,0,type,offset */
     #define N_ENTRY 0xa4  /* alternate entry: name,linenumber,address */
     #define N_LBRAC 0xc0  /* left bracket: 0,,0,nesting level,address */
     #define N_RBRAC 0xe0  /* right bracket: 0,,0,nesting level,address */
     #define N_BCOMM 0xe2  /* begin common: name,, */
     #define N_ECOMM 0xe4  /* end common: name,, */
     #define N_ECOML 0xe8  /* end common (local name): ,,address */
     #define N_LENG  0xfe  /* second stab entry with length information */

     where the comments give _\bs_\bd_\bb conventional use for ._\bs_\bt_\ba_\bbs and
     the n_name, n_other, n_desc, and n_value fields of the given
     n_type. _\bS_\bd_\bb uses the n_desc field to hold a type specifier
     in the form used by the Portable C Compiler, _\bc_\bc(1); see the
     header file _\bp_\bc_\bc._\bh for details on the format of these type
     values.

     The Berkeley Pascal compiler, _\bp_\bc(1), uses the following
     n_type value:





Printed 7/27/90                May				2






STAB(5)                       1986			  STAB(5)



     #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
	     2	     included file name
	     3	     global label
	     4	     global constant
	     5	     global type
	     6	     global variable
	     7	     global function
	     8	     global procedure
	     9	     external function
	     10      external procedure
	     11      library variable
	     12      library routine

S\bSE\bEE\bE A\bAL\bLS\bSO\bO
     as(1), ld(1), dbx(1), a.out(5)

B\bBU\bUG\bGS\bS
     More basic types are needed.

































Printed 7/27/90                May				3