102 lines
3.8 KiB
HTML
102 lines
3.8 KiB
HTML
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<title>Macro define and undefine - STABS</title>
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<a name="Macro-define-and-undefine"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Symbol-Tables.html#Symbol-Tables">Symbol Tables</a>,
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Previous: <a rel="previous" accesskey="p" href="Types.html#Types">Types</a>,
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Up: <a rel="up" accesskey="u" href="index.html#Top">Top</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><span class="option">-g3</span></samp>
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<samp><span class="option">-gstabs</span></samp> when using GCC).
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<p>A <code>#define </code><var>macro-name</var> <var>macro-body</var> is represented with
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an <code>N_MAC_DEFINE</code> stab with a string field of
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<var>macro-name</var> <var>macro-body</var>.
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<a name="index-N_005fMAC_005fDEFINE-51"></a>
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An <code>#undef </code><var>macro-name</var> is represented with an
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<code>N_MAC_UNDEF</code> stabs with a string field of simply
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<var>macro-name</var>.
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<a name="index-N_005fMAC_005fUNDEF-52"></a>
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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>For example, the following C code:
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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>
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<p class="noindent">produces the following stabs (as well as many others):
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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>
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<p class="noindent">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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</body></html>
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