mingw/info/stabs/Stabs-Format.html

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  12 Node:<a name="Stabs%20Format">Stabs Format</a>,
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  19 <h3 class="section">Overview of Stab Format</h3>
  20
  21    <p>There are three overall formats for stab assembler directives,
  22 differentiated by the first word of the stab.  The name of the directive
  23 describes which combination of four possible data fields follows.  It is
  24 either <code>.stabs</code> (string), <code>.stabn</code> (number), or <code>.stabd</code>
  25 (dot).  IBM's XCOFF assembler uses <code>.stabx</code> (and some other
  26 directives such as <code>.file</code> and <code>.bi</code>) instead of
  27 <code>.stabs</code>, <code>.stabn</code> or <code>.stabd</code>.
  28
  29    <p>The overall format of each class of stab is:
  30
  31 <pre class="example">     .stabs "<var>string</var>",<var>type</var>,<var>other</var>,<var>desc</var>,<var>value</var>
  32      .stabn <var>type</var>,<var>other</var>,<var>desc</var>,<var>value</var>
  33      .stabd <var>type</var>,<var>other</var>,<var>desc</var>
  34      .stabx "<var>string</var>",<var>value</var>,<var>type</var>,<var>sdb-type</var>
  35      </pre>
  36
  37    <p>For <code>.stabn</code> and <code>.stabd</code>, there is no <var>string</var> (the
  38 <code>n_strx</code> field is zero; see <a href="Symbol-Tables.html#Symbol%20Tables">Symbol Tables</a>).  For
  39 <code>.stabd</code>, the <var>value</var> field is implicit and has the value of
  40 the current file location.  For <code>.stabx</code>, the <var>sdb-type</var> field
  41 is unused for stabs and can always be set to zero.  The <var>other</var>
  42 field is almost always unused and can be set to zero.
  43
  44    <p>The number in the <var>type</var> field gives some basic information about
  45 which type of stab this is (or whether it <em>is</em> a stab, as opposed
  46 to an ordinary symbol).  Each valid type number defines a different stab
  47 type; further, the stab type defines the exact interpretation of, and
  48 possible values for, any remaining <var>string</var>, <var>desc</var>, or
  49 <var>value</var> fields present in the stab.  See <a href="Stab-Types.html#Stab%20Types">Stab Types</a>, for a list
  50 in numeric order of the valid <var>type</var> field values for stab directives.
  51
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