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76 lines
2.5 KiB
HTML
76 lines
2.5 KiB
HTML
<html>
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<head>
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<title>BOOST_PP_SUB_D</title>
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<link rel="stylesheet" type="text/css" href="../styles.css">
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<script language="javascript" type="text/javascript" src="../scripts.js"></script>
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</head>
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<body onload="init('sample');">
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<div style="margin-left: 0px;">
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The <b>BOOST_PP_SUB_D</b> macro expands to the difference between its second and third arguments.
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It reenters <b>BOOST_PP_WHILE</b> with maximum efficiency.
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</div>
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<h4>Usage</h4>
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<div class="code">
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<b>BOOST_PP_SUB_D</b>(<i>d</i>, <i>x</i>, <i>y</i>)
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</div>
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<h4>Arguments</h4>
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<dl>
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<dt>d</dt>
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<dd>
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The next available <b>BOOST_PP_WHILE</b> iteration.
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</dd>
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<dt>x</dt>
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<dd>
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The minuend of the operation.
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Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.
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</dd>
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<dt>y</dt>
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<dd>
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The subtrahend of the operation.
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Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.
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</dd>
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</dl>
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<h4>Remarks</h4>
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<div>
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If the difference between <i>x</i> and <i>y</i> is less than <i>0</i>, the result is saturated to <i>0</i>.
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</div>
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<h4>See Also</h4>
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<ul>
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<li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
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<li><a href="sub.html">BOOST_PP_SUB</a></li>
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</ul>
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<h4>Requirements</h4>
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<div>
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<b>Header:</b> <a href="../headers/arithmetic/sub.hpp.html"><boost/preprocessor/arithmetic/sub.hpp></a>
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</div>
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<h4><a class="local" onclick="toggle('sample');" onmouseover="change(this);" onmouseout="revert(this);">Sample Code</a></h4>
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<div id="sample"><pre>
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#include <boost/preprocessor/arithmetic/sub.hpp>
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#include <boost/preprocessor/arithmetic/dec.hpp>
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#include <boost/preprocessor/control/while.hpp>
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#include <boost/preprocessor/tuple/elem.hpp>
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#define PRED(d, data) BOOST_PP_TUPLE_ELEM(2, 0, data)
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#define OP(d, data) /* ............... */ \
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( \
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BOOST_PP_DEC( \
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BOOST_PP_TUPLE_ELEM(2, 0, data) \
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), \
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BOOST_PP_SUB_D( \
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d, \
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BOOST_PP_TUPLE_ELEM(2, 1, data), \
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2 \
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) \
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) \
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/**/
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// decrement 'x' by 2 'n' times
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#define STRIDE(x, n) BOOST_PP_TUPLE_ELEM(2, 1, BOOST_PP_WHILE(PRED, OP, (n, x)))
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STRIDE(10, 2) // expands to 6
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STRIDE(14, 6) // expands to 2
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<pre></div>
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</body>
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</html>
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