<html lang="en">
<head>
<title>Stab - Using as</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Using as">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Pseudo-Ops.html#Pseudo-Ops" title="Pseudo Ops">
<link rel="prev" href="Space.html#Space" title="Space">
<link rel="next" href="String.html#String" title="String">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
This file documents the GNU Assembler "as".

Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the
section entitled ``GNU Free Documentation License''.

-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
  pre.display { font-family:inherit }
  pre.format  { font-family:inherit }
  pre.smalldisplay { font-family:inherit; font-size:smaller }
  pre.smallformat  { font-family:inherit; font-size:smaller }
  pre.smallexample { font-size:smaller }
  pre.smalllisp    { font-size:smaller }
  span.sc    { font-variant:small-caps }
  span.roman { font-family:serif; font-weight:normal; } 
  span.sansserif { font-family:sans-serif; font-weight:normal; } 
--></style>
<link rel="stylesheet" type="text/css" href="../cs.css">
</head>
<body>
<div class="node">
<a name="Stab"></a>
<p>
Next:&nbsp;<a rel="next" accesskey="n" href="String.html#String">String</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="Space.html#Space">Space</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a>
<hr>
</div>

<h3 class="section">7.104 <code>.stabd, .stabn, .stabs</code></h3>

<p><a name="index-symbolic-debuggers_002c-information-for-457"></a><a name="index-g_t_0040code_007bstab_0040var_007bx_007d_007d-directives-458"></a>There are three directives that begin &lsquo;<samp><span class="samp">.stab</span></samp>&rsquo;. 
All emit symbols (see <a href="Symbols.html#Symbols">Symbols</a>), for use by symbolic debuggers. 
The symbols are not entered in the <samp><span class="command">as</span></samp> hash table: they
cannot be referenced elsewhere in the source file. 
Up to five fields are required:

     <dl>
<dt><var>string</var><dd>This is the symbol's name.  It may contain any character except
&lsquo;<samp><span class="samp">\000</span></samp>&rsquo;, so is more general than ordinary symbol names.  Some
debuggers used to code arbitrarily complex structures into symbol names
using this field.

     <br><dt><var>type</var><dd>An absolute expression.  The symbol's type is set to the low 8 bits of
this expression.  Any bit pattern is permitted, but <code>ld</code>
and debuggers choke on silly bit patterns.

     <br><dt><var>other</var><dd>An absolute expression.  The symbol's &ldquo;other&rdquo; attribute is set to the
low 8 bits of this expression.

     <br><dt><var>desc</var><dd>An absolute expression.  The symbol's descriptor is set to the low 16
bits of this expression.

     <br><dt><var>value</var><dd>An absolute expression which becomes the symbol's value. 
</dl>

   <p>If a warning is detected while reading a <code>.stabd</code>, <code>.stabn</code>,
or <code>.stabs</code> statement, the symbol has probably already been created;
you get a half-formed symbol in your object file.  This is
compatible with earlier assemblers!

     
<a name="index-g_t_0040code_007bstabd_007d-directive-459"></a>
<dl><dt><code>.stabd </code><var>type</var><code> , </code><var>other</var><code> , </code><var>desc</var><dd>
The &ldquo;name&rdquo; of the symbol generated is not even an empty string. 
It is a null pointer, for compatibility.  Older assemblers used a
null pointer so they didn't waste space in object files with empty
strings.

     <p>The symbol's value is set to the location counter,
relocatably.  When your program is linked, the value of this symbol
is the address of the location counter when the <code>.stabd</code> was
assembled.

     <p><a name="index-g_t_0040code_007bstabn_007d-directive-460"></a><br><dt><code>.stabn </code><var>type</var><code> , </code><var>other</var><code> , </code><var>desc</var><code> , </code><var>value</var><dd>The name of the symbol is set to the empty string <code>""</code>.

     <p><a name="index-g_t_0040code_007bstabs_007d-directive-461"></a><br><dt><code>.stabs </code><var>string</var><code> ,  </code><var>type</var><code> , </code><var>other</var><code> , </code><var>desc</var><code> , </code><var>value</var><dd>All five fields are specified. 
</dl>
   <!-- end     have-stabs -->

   </body></html>