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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Context</a><ul>
<li><a class="reference internal" href="#data-type">Data Type</a></li>
<li><a class="reference internal" href="#constants">Constants</a></li>
<li><a class="reference internal" href="#precision-and-exponents">Precision and Exponents</a></li>
<li><a class="reference internal" href="#rounding">Rounding</a></li>
<li><a class="reference internal" href="#signals-and-conditions">Signals and Conditions</a></li>
<li><a class="reference internal" href="#exponent-clamping">Exponent Clamping</a></li>
<li><a class="reference internal" href="#correct-rounding">Correct Rounding</a></li>
</ul>
</li>
<li><a class="reference internal" href="#context-functions">Context Functions</a><ul>
<li><a class="reference internal" href="#initialization">Initialization</a></li>
<li><a class="reference internal" href="#ieee-interchange-formats">IEEE Interchange Formats</a></li>
<li><a class="reference internal" href="#getters-and-setters">Getters and Setters</a></li>
<li><a class="reference internal" href="#calling-the-trap-handler">Calling the Trap Handler</a></li>
</ul>
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<div class="section" id="context">
<h1>Context</h1>
<p>Most operations are affected by context. Usually, a pointer to the context
is passed as the last parameter to signaling functions or the last but one
parameter to quiet functions.</p>
<div class="section" id="data-type">
<h2>Data Type</h2>
<p>The context is defined as a C struct:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="cp">#include <mpdecimal.h></span>
<span class="k">typedef</span> <span class="k">struct</span> <span class="kt">mpd_context_t</span> <span class="p">{</span>
<span class="kt">mpd_ssize_t</span> <span class="n">prec</span><span class="p">;</span> <span class="c1">// precision</span>
<span class="kt">mpd_ssize_t</span> <span class="n">emax</span><span class="p">;</span> <span class="c1">// max positive exp</span>
<span class="kt">mpd_ssize_t</span> <span class="n">emin</span><span class="p">;</span> <span class="c1">// min negative exp</span>
<span class="kt">uint32_t</span> <span class="n">traps</span><span class="p">;</span> <span class="c1">// status events that should be trapped</span>
<span class="kt">uint32_t</span> <span class="n">status</span><span class="p">;</span> <span class="c1">// status flags</span>
<span class="kt">uint32_t</span> <span class="n">newtrap</span><span class="p">;</span> <span class="c1">// set by mpd_addstatus_raise()</span>
<span class="kt">int</span> <span class="n">round</span><span class="p">;</span> <span class="c1">// rounding mode</span>
<span class="kt">int</span> <span class="n">clamp</span><span class="p">;</span> <span class="c1">// clamp mode</span>
<span class="kt">int</span> <span class="n">allcr</span><span class="p">;</span> <span class="c1">// all functions correctly rounded</span>
<span class="p">}</span> <span class="kt">mpd_context_t</span><span class="p">;</span>
</pre></div>
</div>
</div>
<div class="section" id="constants">
<h2>Constants</h2>
<blockquote>
<div><table border="1" class="docutils">
<colgroup>
<col width="31%" />
<col width="28%" />
<col width="41%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head"> </th>
<th class="head">32-bit</th>
<th class="head">64-bit</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_PREC</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">425000000</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">999999999999999999</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_EMAX</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">425000000</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">999999999999999999</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MIN_EMIN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">-425000000</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">-999999999999999999</span></tt></td>
</tr>
</tbody>
</table>
</div></blockquote>
</div>
<div class="section" id="precision-and-exponents">
<h2>Precision and Exponents</h2>
<blockquote>
<div><table border="1" class="docutils">
<colgroup>
<col width="24%" />
<col width="76%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><em>prec</em></td>
<td>[<tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt>, <tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_PREC</span></tt>]</td>
</tr>
<tr class="row-even"><td><em>emax</em></td>
<td>[<tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt>, <tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_EMAX</span></tt>]</td>
</tr>
<tr class="row-odd"><td><em>emin</em></td>
<td>[<tt class="xref c c-macro docutils literal"><span class="pre">MPD_MIN_EMIN</span></tt>, <tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt>]</td>
</tr>
</tbody>
</table>
</div></blockquote>
<p>Apart from the limits, the following rules must be observed when setting the context manually:</p>
<blockquote>
<div><ul class="simple">
<li><em>prec</em> <= <em>emax</em></li>
<li><em>emin</em> = 1 - <em>emax</em> or <em>emin</em> = <em>-emax</em></li>
</ul>
</div></blockquote>
<p>The specification requires 5 x <em>prec</em> <= <em>emax</em> and recommends 10 x <em>prec</em> <= <em>emax</em>.</p>
</div>
<div class="section" id="rounding">
<h2>Rounding</h2>
<p>The <em>round</em> field can take one of these values:</p>
<blockquote>
<div><table border="1" class="docutils">
<colgroup>
<col width="42%" />
<col width="58%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_UP</span></tt></td>
<td>round away from <tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_DOWN</span></tt></td>
<td>round toward <tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt> (truncate)</td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_CEILING</span></tt></td>
<td>round toward <tt class="xref c c-macro docutils literal"><span class="pre">+infinity</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_FLOOR</span></tt></td>
<td>round toward <tt class="xref c c-macro docutils literal"><span class="pre">-infinity</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_UP</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0.5</span></tt> is rounded up</td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_DOWN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0.5</span></tt> is rounded down</td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_EVEN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0.5</span></tt> is rounded to even</td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_05UP</span></tt></td>
<td>round zero or five away from <tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_TRUNC</span></tt></td>
<td>truncate, but set infinities</td>
</tr>
</tbody>
</table>
</div></blockquote>
</div>
<div class="section" id="signals-and-conditions">
<h2>Signals and Conditions</h2>
<p>The standard distinguishes between <em>signals</em> and <em>conditions</em>. In particular,
the <tt class="xref c c-macro docutils literal"><span class="pre">MPD_IEEE_Invalid_operation</span></tt> <em>signal</em> comprises several <em>conditions</em>.</p>
<p>In a signaling function, the <em>status</em> field of the context is updated with
all conditions that occurred during the execution. It is never reset
automatically, so at any point in a program it contains the cumulative
status of all signaling functions.</p>
<p>The <em>traps</em> field determines which signals invoke the <tt class="xref c c-func docutils literal"><span class="pre">mpd_traphandler</span></tt>
custom function. By default, this function raises <tt class="xref c c-macro docutils literal"><span class="pre">SIGFPE</span></tt>.</p>
<p>If a trap occurs, the <em>newtrap</em> field is set to the value of the respective
condition. This makes it possible to determine the latest error condition
that occurred even when the status has already been “polluted” with previous
error conditions.</p>
<p>Here are the possible <em>signals</em> and <em>conditions</em>:</p>
<blockquote>
<div><table border="1" class="docutils">
<colgroup>
<col width="52%" />
<col width="48%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head">Signals</th>
<th class="head">Conditions</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td rowspan="6"><tt class="xref c c-macro docutils literal"><span class="pre">MPD_IEEE_Invalid_operation</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Conversion_syntax</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Division_impossible</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Division_undefined</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Invalid_context</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Invalid_operation</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Malloc_error</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Clamped</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Clamped</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Division_by_zero</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Division_by_zero</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Fpu_error</span></tt> <a class="footnote-reference" href="#f1" id="id1">[1]</a></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Fpu_error</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Inexact</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Inexact</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Not_implemented</span></tt> <a class="footnote-reference" href="#f2" id="id2">[2]</a></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Not_implemented</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Overflow</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Overflow</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Rounded</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Rounded</span></tt></td>
</tr>
<tr class="row-odd"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Subnormal</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Subnormal</span></tt></td>
</tr>
<tr class="row-even"><td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Underflow</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Underflow</span></tt></td>
</tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="f1" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id1">[1]</a></td><td>deprecated, might be renamed to a user-definable signal.</td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="f2" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id2">[2]</a></td><td>unused, might be renamed to a user-definable signal.</td></tr>
</tbody>
</table>
</div></blockquote>
</div>
<div class="section" id="exponent-clamping">
<h2>Exponent Clamping</h2>
<p>If the <tt class="xref c c-member docutils literal"><span class="pre">clamp</span></tt> field is set to 1, the maximum exponent is reduced to
<em>emax</em> - <em>prec</em> + 1. This is compatible with the IEEE 754 decimal
interchange formats.</p>
</div>
<div class="section" id="correct-rounding">
<h2>Correct Rounding</h2>
<p>Most functions are correctly-rounded by default. If <em>allcr</em> is set
to 1, correct rounding is additionally enabled for <tt class="xref c c-func docutils literal"><span class="pre">mpd_exp</span></tt>,
<tt class="xref c c-func docutils literal"><span class="pre">mpd_ln</span></tt> and <tt class="xref c c-func docutils literal"><span class="pre">mpd_log10</span></tt>.</p>
<p>In this case, all functions except <tt class="xref c c-func docutils literal"><span class="pre">mpd_pow</span></tt> and <tt class="xref c c-func docutils literal"><span class="pre">mpd_invroot</span></tt>
return correctly rounded results.</p>
</div>
</div>
<div class="section" id="context-functions">
<h1>Context Functions</h1>
<div class="section" id="initialization">
<h2>Initialization</h2>
<div class="highlight-c" id="std:topic-mpd_init"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">mpd_init</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">mpd_ssize_t</span> <span class="n">prec</span><span class="p">);</span>
</pre></div>
</div>
<p><em>ctx</em> is initialized by <tt class="xref c c-func docutils literal"><span class="pre">mpd_defaultcontext</span></tt>, using <em>prec</em>.
At the same time, <tt class="xref c c-macro docutils literal"><span class="pre">MPD_MINALLOC</span></tt> is initialized to the ideal
value for the given precision. Note that memory usage increases by
setting <tt class="xref c c-macro docutils literal"><span class="pre">MPD_MINALLOC</span></tt> to higher values.</p>
<p>This function can only be used at program start.</p>
<span class="target" id="std:topic-mpd_maxcontext"></span><span class="target" id="std:topic-mpd_defaultcontext"></span><div class="highlight-c" id="std:topic-mpd_basiccontext"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">mpd_maxcontext</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">void</span> <span class="nf">mpd_defaultcontext</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">void</span> <span class="nf">mpd_basiccontext</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
</pre></div>
</div>
<p>Initialize the given context. The values for each function:</p>
<table border="1" class="docutils">
<colgroup>
<col width="10%" />
<col width="29%" />
<col width="29%" />
<col width="32%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head"> </th>
<th class="head">maxcontext</th>
<th class="head">defaultcontext <a class="footnote-reference" href="#f3" id="id3">[3]</a></th>
<th class="head">basiccontext <a class="footnote-reference" href="#f4" id="id4">[4]</a></th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td><em>prec</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_PREC</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">2*MPD_RDIGITS</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">9</span></tt></td>
</tr>
<tr class="row-odd"><td><em>emax</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_EMAX</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_EMAX</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MAX_EMAX</span></tt></td>
</tr>
<tr class="row-even"><td><em>emin</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MIN_EMIN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MIN_EMIN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_MIN_EMIN</span></tt></td>
</tr>
<tr class="row-odd"><td><em>round</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_EVEN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_UP</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_UP</span></tt></td>
</tr>
<tr class="row-even"><td><em>traps</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Traps</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Traps</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_Traps|MPD_Clamped</span></tt></td>
</tr>
<tr class="row-odd"><td><em>status</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-even"><td><em>newtrap</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-odd"><td><em>clamp</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-even"><td><em>allcr</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
</tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="f3" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id3">[3]</a></td><td><strong>libmpdec’s</strong> default context</td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="f4" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id4">[4]</a></td><td>the specification’s <em>basic default context</em></td></tr>
</tbody>
</table>
</div>
<div class="section" id="ieee-interchange-formats">
<h2>IEEE Interchange Formats</h2>
<div class="highlight-c" id="std:topic-mpd_ieee_context"><div class="highlight"><pre><span class="n">MPD_IEEE_CONTEXT_MAX_BITS</span>
<span class="n">MPD_DECIMAL32</span>
<span class="n">MPD_DECIMAL64</span>
<span class="n">MPD_DECIMAL128</span>
<span class="kt">int</span> <span class="nf">mpd_ieee_context</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">int</span> <span class="n">bits</span><span class="p">);</span>
</pre></div>
</div>
<p>Initialize the context to the proper values for one of the IEEE interchange
formats. The argument must be a multiple of 32 and less than
<tt class="xref c c-macro docutils literal"><span class="pre">IEEE_CONTEXT_MAX_BITS</span></tt>.</p>
<p>For the most common values, the following constants are provided:</p>
<table border="1" class="docutils">
<colgroup>
<col width="11%" />
<col width="30%" />
<col width="30%" />
<col width="30%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head"> </th>
<th class="head"><tt class="xref c c-macro docutils literal"><span class="pre">MPD_DECIMAL32</span></tt></th>
<th class="head"><tt class="xref c c-macro docutils literal"><span class="pre">MPD_DECIMAL64</span></tt></th>
<th class="head"><tt class="xref c c-macro docutils literal"><span class="pre">MPD_DECIMAL128</span></tt></th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td><em>prec</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">7</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">16</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">34</span></tt></td>
</tr>
<tr class="row-odd"><td><em>emax</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">96</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">384</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">6144</span></tt></td>
</tr>
<tr class="row-even"><td><em>emin</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">-95</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">-383</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">-6143</span></tt></td>
</tr>
<tr class="row-odd"><td><em>round</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_EVEN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_EVEN</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">MPD_ROUND_HALF_EVEN</span></tt></td>
</tr>
<tr class="row-even"><td><em>traps</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-odd"><td><em>status</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-even"><td><em>newtrap</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">0</span></tt></td>
</tr>
<tr class="row-odd"><td><em>clamp</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
</tr>
<tr class="row-even"><td><em>allcr</em></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
<td><tt class="xref c c-macro docutils literal"><span class="pre">1</span></tt></td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="getters-and-setters">
<h2>Getters and Setters</h2>
<span class="target" id="std:topic-mpd_getprec"></span><span class="target" id="std:topic-mpd_getemax"></span><span class="target" id="std:topic-mpd_getemin"></span><span class="target" id="std:topic-mpd_getround"></span><span class="target" id="std:topic-mpd_gettraps"></span><span class="target" id="std:topic-mpd_getstatus"></span><span class="target" id="std:topic-mpd_getclamp"></span><div class="highlight-c" id="std:topic-mpd_getcr"><div class="highlight"><pre><span class="kt">size_t</span> <span class="nf">mpd_getprec</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">mpd_ssize_t</span> <span class="nf">mpd_getemax</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">mpd_ssize_t</span> <span class="nf">mpd_getemin</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_getround</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">uint32_t</span> <span class="nf">mpd_gettraps</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">uint32_t</span> <span class="nf">mpd_getstatus</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_getclamp</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_getcr</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
</pre></div>
</div>
<p>Get the individual values.</p>
<div class="highlight-c" id="std:topic-mpd_etiny"><div class="highlight"><pre><span class="kt">mpd_ssize_t</span> <span class="nf">mpd_etiny</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
</pre></div>
</div>
<p>Return the lowest possible exponent of a subnormal number: <em>emin</em> - <em>prec</em> + 1</p>
<div class="highlight-c" id="std:topic-mpd_etop"><div class="highlight"><pre><span class="kt">mpd_ssize_t</span> <span class="nf">mpd_etop</span><span class="p">(</span><span class="k">const</span> <span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">);</span>
</pre></div>
</div>
<p>Return the highest possible exponent of a normal number: <em>emax</em> - <em>prec</em> + 1</p>
<p>Only relevant if <em>clamp</em> is set to 1.</p>
<span class="target" id="std:topic-mpd_qsetprec"></span><span class="target" id="std:topic-mpd_qsetemax"></span><span class="target" id="std:topic-mpd_qsetemin"></span><span class="target" id="std:topic-mpd_qsetround"></span><span class="target" id="std:topic-mpd_qsettraps"></span><span class="target" id="std:topic-mpd_qsetstatus"></span><span class="target" id="std:topic-mpd_qsetclamp"></span><div class="highlight-c" id="std:topic-mpd_qsetcr"><div class="highlight"><pre><span class="kt">int</span> <span class="nf">mpd_qsetprec</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">mpd_ssize_t</span> <span class="n">prec</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_qsetemax</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">mpd_ssize_t</span> <span class="n">emax</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_qsetemin</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">mpd_ssize_t</span> <span class="n">emin</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_qsetround</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">int</span> <span class="n">newround</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_qsettraps</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">uint32_t</span> <span class="n">flags</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_qsetstatus</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">uint32_t</span> <span class="n">flags</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_qsetclamp</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">int</span> <span class="n">c</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">mpd_qsetcr</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">int</span> <span class="n">c</span><span class="p">);</span>
</pre></div>
</div>
<p>Quietly set the individual values. These functions check the limits, but they
are not foolproof: For example, they still allow setting a <em>prec</em> that does
not agree with <em>emax</em>. The functions return 1 on success and 0 on failure.
They are quiet since raising an <tt class="xref c c-macro docutils literal"><span class="pre">MPD_Invalid_context</span></tt> condition would
not make sense in most cases.</p>
</div>
<div class="section" id="calling-the-trap-handler">
<h2>Calling the Trap Handler</h2>
<span class="target" id="std:topic-mpd_addstatus_raise"></span><span class="target" id="std:topic-mpd_dflt_traphandler"></span><div class="highlight-c" id="std:topic-mpd_traphandler"><div class="highlight"><pre><span class="k">extern</span> <span class="nf">void</span> <span class="p">(</span><span class="o">*</span> <span class="n">mpd_traphandler</span><span class="p">)(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="p">);</span>
<span class="kt">void</span> <span class="nf">mpd_dflt_traphandler</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="p">);</span>
<span class="kt">void</span> <span class="nf">mpd_addstatus_raise</span><span class="p">(</span><span class="kt">mpd_context_t</span> <span class="o">*</span><span class="n">ctx</span><span class="p">,</span> <span class="kt">uint32_t</span> <span class="n">flags</span><span class="p">);</span>
</pre></div>
</div>
<p>Add <em>flags</em> to the <em>status</em> field of <em>ctx</em>. If a condition is trapped, set
<em>newtrap</em> to the condition and call <tt class="xref c c-func docutils literal"><span class="pre">mpd_traphandler</span></tt>. By default,
<tt class="xref c c-func docutils literal"><span class="pre">mpd_traphandler</span></tt> is points to <tt class="xref c c-func docutils literal"><span class="pre">mpd_dflt_traphandler</span></tt>, which
raises <tt class="xref c c-macro docutils literal"><span class="pre">SIGFPE</span></tt>.</p>
</div>
</div>
</div>
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