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<title>STABS: Macro define and undefine</title>
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<a name="Macro-define-and-undefine"></a>
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<div class="header">
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<p>
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Next: <a href="Symbol-Tables.html#Symbol-Tables" accesskey="n" rel="next">Symbol Tables</a>, Previous: <a href="Types.html#Types" accesskey="p" rel="previous">Types</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Representation-of-_0023define-and-_0023undef"></a>
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<h2 class="chapter">6 Representation of #define and #undef</h2>
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<p>This section describes the stabs support for macro define and undefine
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information, supported on some systems. (e.g., with <samp>-g3</samp>
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<samp>-gstabs</samp> when using GCC).
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</p>
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<p>A <code>#define <var>macro-name</var> <var>macro-body</var></code> is represented with
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an <code>N_MAC_DEFINE</code> stab with a string field of
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<code><var>macro-name</var> <var>macro-body</var></code>.
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<a name="index-N_005fMAC_005fDEFINE"></a>
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</p>
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<p>An <code>#undef <var>macro-name</var></code> is represented with an
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<code>N_MAC_UNDEF</code> stabs with a string field of simply
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<code><var>macro-name</var></code>.
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<a name="index-N_005fMAC_005fUNDEF"></a>
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</p>
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<p>For both <code>N_MAC_DEFINE</code> and <code>N_MAC_UNDEF</code>, the desc field is
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the line number within the file where the corresponding <code>#define</code>
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or <code>#undef</code> occurred.
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</p>
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<p>For example, the following C code:
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</p>
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<div class="example">
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<pre class="example"> #define NONE 42
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#define TWO(a, b) (a + (a) + 2 * b)
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#define ONE(c) (c + 19)
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main(int argc, char *argv[])
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{
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func(NONE, TWO(10, 11));
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func(NONE, ONE(23));
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#undef ONE
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#define ONE(c) (c + 23)
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func(NONE, ONE(-23));
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return (0);
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}
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int global;
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func(int arg1, int arg2)
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{
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global = arg1 + arg2;
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}
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</pre></div>
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<p>produces the following stabs (as well as many others):
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</p>
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<div class="example">
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<pre class="example"> .stabs "NONE 42",54,0,1,0
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.stabs "TWO(a,b) (a + (a) + 2 * b)",54,0,2,0
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.stabs "ONE(c) (c + 19)",54,0,3,0
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.stabs "ONE",58,0,10,0
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.stabs "ONE(c) (c + 23)",54,0,11,0
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</pre></div>
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<p>NOTE: In the above example, <code>54</code> is <code>N_MAC_DEFINE</code> and
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<code>58</code> is <code>N_MAC_UNDEF</code>.
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