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<li><a class="reference internal" href="#">Context</a><ul>
<li><a class="reference internal" href="#implicit-thread-local-context">Implicit thread local context</a></li>
<li><a class="reference internal" href="#context-class">Context class</a></li>
<li><a class="reference internal" href="#factory-functions">Factory functions</a></li>
<li><a class="reference internal" href="#tls-context-caveats">TLS context caveats</a><ul>
<li><a class="reference internal" href="#main-thread">Main thread</a></li>
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<div class="section" id="context">
<h1>Context</h1>
<div class="section" id="implicit-thread-local-context">
<h2>Implicit thread local context</h2>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="k">extern</span> <span class="n">Context</span> <span class="n">context_template</span><span class="p">;</span> <span class="cm">/* template for new thread local contexts */</span>
<span class="cp">#if defined(__OpenBSD__) || defined(__sun) || defined(_MSC_VER) && defined(_DLL)</span>
<span class="cm">/* Each translation unit gets its own static reference to the thread local</span>
<span class="cm"> context. The semantics should be identical to the regular C++11 extern</span>
<span class="cm"> thread local context below. */</span>
<span class="n">IMPORTEXPORT</span> <span class="n">Context</span><span class="o">&</span> <span class="n">getcontext</span><span class="p">();</span>
<span class="k">static</span> <span class="k">thread_local</span> <span class="n">Context</span><span class="o">&</span> <span class="n">context</span><span class="p">{</span><span class="n">getcontext</span><span class="p">()};</span>
<span class="cp">#else</span>
<span class="k">extern</span> <span class="k">thread_local</span> <span class="n">Context</span> <span class="n">context</span><span class="p">;</span> <span class="cm">/* thread local context */</span>
<span class="cp">#endif</span>
</pre></div>
</div>
<p>Most functions use a context. If the context is not passed explicitly as an
argument, the implicit thread local context is used.</p>
<p>For new threads <cite>context</cite> is initialized automatically from <cite>context_template</cite>.
<cite>context_template</cite> itself can be set to user defined values at program startup.</p>
</div>
<div class="section" id="context-class">
<h2>Context class</h2>
<dl class="class">
<dt id="_CPPv4N7decimal7ContextE">
<span id="_CPPv3N7decimal7ContextE"></span><span id="_CPPv2N7decimal7ContextE"></span><span id="decimal::Context"></span><em class="property">class </em><code class="descname">Context</code><br /></dt>
<dd><div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">Context</span><span class="p">(</span><span class="n">mpd_ssize_t</span> <span class="n">prec</span><span class="o">=</span><span class="n">context_template</span><span class="p">.</span><span class="n">prec</span><span class="p">(),</span>
<span class="n">mpd_ssize_t</span> <span class="n">emax</span><span class="o">=</span><span class="n">context_template</span><span class="p">.</span><span class="n">emax</span><span class="p">(),</span>
<span class="n">mpd_ssize_t</span> <span class="n">emin</span><span class="o">=</span><span class="n">context_template</span><span class="p">.</span><span class="n">emin</span><span class="p">(),</span>
<span class="kt">int</span> <span class="n">round</span><span class="o">=</span><span class="n">context_template</span><span class="p">.</span><span class="n">round</span><span class="p">(),</span>
<span class="kt">uint32_t</span> <span class="n">traps</span><span class="o">=</span><span class="n">context_template</span><span class="p">.</span><span class="n">traps</span><span class="p">(),</span>
<span class="kt">int</span> <span class="n">clamp</span><span class="o">=</span><span class="n">context_template</span><span class="p">.</span><span class="n">clamp</span><span class="p">(),</span>
<span class="kt">int</span> <span class="n">allcr</span><span class="o">=</span><span class="n">context_template</span><span class="p">.</span><span class="n">allcr</span><span class="p">());</span>
</pre></div>
</div>
<p>Default constructor. Values that are not explicitly given are initialized
from <cite>context_template</cite>.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">Context</span><span class="p">(</span><span class="k">const</span> <span class="n">Context</span><span class="o">&</span> <span class="n">c</span><span class="p">)</span> <span class="k">noexcept</span><span class="p">;</span>
</pre></div>
</div>
<p>Copy constructor. This is just <cite>C struct</cite> assignment.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">Context</span><span class="p">(</span><span class="k">const</span> <span class="n">Context</span><span class="o">&&</span> <span class="n">c</span><span class="p">)</span> <span class="k">noexcept</span><span class="p">;</span>
</pre></div>
</div>
<p>Move constructor. This is just <cite>C struct</cite> assignment.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="k">explicit</span> <span class="nf">Context</span><span class="p">(</span><span class="k">const</span> <span class="n">mpd_context_t</span> <span class="o">&</span><span class="n">c</span><span class="p">)</span> <span class="k">noexcept</span><span class="p">;</span>
</pre></div>
</div>
<p>Construct from an mpd_t context.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">Context</span><span class="o">&</span> <span class="k">operator</span><span class="o">=</span> <span class="p">(</span><span class="k">const</span> <span class="n">Context</span><span class="o">&</span> <span class="n">c</span><span class="p">)</span> <span class="k">noexcept</span><span class="p">;</span>
</pre></div>
</div>
<p>Copy the context. This is just <cite>C struct</cite> assignment.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">Context</span><span class="o">&</span> <span class="k">operator</span><span class="o">=</span> <span class="p">(</span><span class="k">const</span> <span class="n">Context</span><span class="o">&&</span> <span class="n">c</span><span class="p">)</span> <span class="k">noexcept</span><span class="p">;</span>
</pre></div>
</div>
<p>Move the context. This is just <cite>C struct</cite> assignment.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">bool</span> <span class="k">operator</span><span class="o">==</span> <span class="p">(</span><span class="k">const</span> <span class="n">Context</span><span class="o">&</span> <span class="n">other</span><span class="p">)</span> <span class="k">const</span> <span class="k">noexcept</span><span class="p">;</span>
</pre></div>
</div>
<p>Determine if <cite>self == other</cite>.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">bool</span> <span class="k">operator</span><span class="o">!=</span> <span class="p">(</span><span class="k">const</span> <span class="n">Context</span><span class="o">&</span> <span class="n">other</span><span class="p">)</span> <span class="k">const</span> <span class="k">noexcept</span><span class="p">;</span>
</pre></div>
</div>
<p>Determine if <cite>self != other</cite>.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">mpd_context_t</span> <span class="o">*</span><span class="nf">get</span><span class="p">();</span>
</pre></div>
</div>
<p>Return a pointer to the underlying <cite>mpd_t</cite> context.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="k">const</span> <span class="n">mpd_context_t</span> <span class="o">*</span><span class="n">getconst</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return a const pointer to the underlying <cite>mpd_t</cite> context.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">mpd_ssize_t</span> <span class="nf">prec</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>prec</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">mpd_ssize_t</span> <span class="nf">emax</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>emax</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">mpd_ssize_t</span> <span class="nf">emin</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>emin</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">int</span> <span class="nf">round</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>round</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">uint32_t</span> <span class="nf">status</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>status</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">uint32_t</span> <span class="nf">traps</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>traps</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">int</span> <span class="nf">clamp</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>clamp</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">int</span> <span class="nf">allcr</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return the internal <cite>allcr</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">prec</span><span class="p">(</span><span class="n">mpd_ssize_t</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>prec</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">emax</span><span class="p">(</span><span class="n">mpd_ssize_t</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>emax</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">emin</span><span class="p">(</span><span class="n">mpd_ssize_t</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>emin</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">round</span><span class="p">(</span><span class="kt">int</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>round</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">status</span><span class="p">(</span><span class="kt">uint32_t</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>status</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">traps</span><span class="p">(</span><span class="kt">uint32_t</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>traps</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">clamp</span><span class="p">(</span><span class="kt">int</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>clamp</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">allcr</span><span class="p">(</span><span class="kt">int</span> <span class="n">v</span><span class="p">);</span>
</pre></div>
</div>
<p>Set the internal <cite>allcr</cite> field.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">raise</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 flags to the internal status field and raise a signal if the respective traps are set.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">add_status</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 selected flags to the status. This is only used when working with several
temporary contexts and the flags need to be merged into a single one.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">clear_status</span><span class="p">();</span>
</pre></div>
</div>
<p>Clear all status flags.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">clear_status</span><span class="p">(</span><span class="kt">uint32_t</span> <span class="n">flags</span><span class="p">);</span>
</pre></div>
</div>
<p>Clear the selected status flags.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">add_traps</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 the selected traps.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">clear_traps</span><span class="p">();</span>
</pre></div>
</div>
<p>Clear all traps.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">clear_traps</span><span class="p">(</span><span class="kt">uint32_t</span> <span class="n">flags</span><span class="p">);</span>
</pre></div>
</div>
<p>Clear the selected traps.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">repr</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>
</pre></div>
</div>
<p>Return a human readable representation of the context.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="k">friend</span> <span class="n">std</span><span class="o">::</span><span class="n">ostream</span><span class="o">&</span> <span class="k">operator</span><span class="o"><<</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">ostream</span><span class="o">&</span> <span class="n">os</span><span class="p">,</span> <span class="k">const</span> <span class="n">Context</span><span class="o">&</span> <span class="n">c</span><span class="p">);</span>
</pre></div>
</div>
<p>The stream operator uses <cite>repr</cite>.</p>
</dd></dl>
</div>
<div class="section" id="factory-functions">
<h2>Factory functions</h2>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="n">Context</span> <span class="nf">MaxContext</span><span class="p">();</span>
</pre></div>
</div>
<p>Return a context with maximum values for <cite>emax</cite>, <cite>emin</cite> and <cite>prec</cite>. Used when computations must be
exact and unrounded under all circumstances.</p>
<p>You still need to check for <cite>DecRounded</cite> and <cite>DecInexact</cite> or set the respective traps.</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cm">/* common arguments */</span>
<span class="k">constexpr</span> <span class="kt">int</span> <span class="n">DECIMAL32</span> <span class="o">=</span> <span class="n">MPD_DECIMAL32</span><span class="p">;</span>
<span class="k">constexpr</span> <span class="kt">int</span> <span class="n">DECIMAL64</span> <span class="o">=</span> <span class="n">MPD_DECIMAL64</span><span class="p">;</span>
<span class="k">constexpr</span> <span class="kt">int</span> <span class="n">DECIMAL128</span> <span class="o">=</span> <span class="n">MPD_DECIMAL128</span><span class="p">;</span>
<span class="cm">/* maximum argument value */</span>
<span class="k">constexpr</span> <span class="kt">int</span> <span class="n">IEEE_CONTEXT_MAX_BITS</span> <span class="o">=</span> <span class="n">MPD_IEEE_CONTEXT_MAX_BITS</span><span class="p">;</span>
<span class="n">IEEEContext</span><span class="p">(</span><span class="kt">int</span> <span class="n">bits</span><span class="p">);</span>
</pre></div>
</div>
<p>Return a context initialized to the proper values for one of the <cite>IEEE</cite>
interchange formats. The argument must be a multiple of 32 and less
than <cite>IEEE_CONTEXT_MAX_BITS</cite>. For the most common values, the constants
<cite>DECIMAL32</cite>, <cite>DECIMAL64</cite> and <cite>DECIMAL128</cite> are provided.</p>
</div>
<div class="section" id="tls-context-caveats">
<h2>TLS context caveats</h2>
<p>These TLS issues are not specific to libmpdec++, but deserve to be mentioned.</p>
<div class="section" id="main-thread">
<h3>Main thread</h3>
<p>On Linux/FreeBSD/OpenBSD automatic initialization of <cite>context</cite> on first access
also works for the main thread. However, this is not guaranteed by the standard,
so <cite>context</cite> should be initialized explicitly if it is used in the main thread.</p>
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