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| <li><a class="reference internal" href="#">Decimals</a><ul> |
| <li><a class="reference internal" href="#data-type">Data Type</a></li> |
| <li><a class="reference internal" href="#allocation-functions">Allocation Functions</a></li> |
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| <div class="section" id="decimals"> |
| <h1>Decimals</h1> |
| <div class="section" id="data-type"> |
| <h2>Data Type</h2> |
| <p>The decimal data type is called <tt class="xref c c-macro docutils literal"><span class="pre">mpd_t</span></tt>, which is short for |
| <em>multi precision decimal</em>.</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_t</span> <span class="p">{</span> |
| <span class="kt">uint8_t</span> <span class="n">flags</span><span class="p">;</span> <span class="c1">// [memory flags] | [specials] | sign</span> |
| <span class="kt">mpd_ssize_t</span> <span class="n">exp</span><span class="p">;</span> <span class="c1">// exponent</span> |
| <span class="kt">mpd_ssize_t</span> <span class="n">digits</span><span class="p">;</span> <span class="c1">// number of decimal digits</span> |
| <span class="kt">mpd_ssize_t</span> <span class="n">len</span><span class="p">;</span> <span class="c1">// number of words in use</span> |
| <span class="kt">mpd_ssize_t</span> <span class="n">alloc</span><span class="p">;</span> <span class="c1">// number of allocated words</span> |
| <span class="kt">mpd_uint_t</span> <span class="o">*</span><span class="n">data</span><span class="p">;</span> <span class="c1">// words</span> |
| <span class="p">}</span> <span class="kt">mpd_t</span><span class="p">;</span> |
| </pre></div> |
| </div> |
| <p>The flags contain two types of information: The lowest bit is the sign of the |
| decimal. The following three bits determine whether the decimal is Infinity, |
| NaN or sNaN. The upper four bits carry the information how the storage was |
| allocated. The normal case is that both the struct and the data have been |
| dynamically allocated by <tt class="xref c c-func docutils literal"><span class="pre">mpd_new</span></tt>. More on this in the section |
| <a class="reference internal" href="memory.html#advanced-memory-handling"><em>Advanced Memory Handling</em></a>.</p> |
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| <div class="section" id="allocation-functions"> |
| <h2>Allocation Functions</h2> |
| <span class="target" id="std:topic-mpd_qnew"></span><div class="highlight-c" id="std:topic-mpd_new"><div class="highlight"><pre><span class="kt">mpd_t</span> <span class="o">*</span><span class="nf">mpd_qnew</span><span class="p">(</span><span class="kt">void</span><span class="p">);</span> |
| <span class="kt">mpd_t</span> <span class="o">*</span><span class="nf">mpd_new</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><tt class="xref c c-func docutils literal"><span class="pre">mpd_qnew</span></tt> attempts to allocate a dynamic decimal with <tt class="xref c c-macro docutils literal"><span class="pre">MPD_MINALLOC</span></tt> |
| words reserved for the coefficient. If successful, the return value is the new |
| pointer, <tt class="xref c c-macro docutils literal"><span class="pre">NULL</span></tt> otherwise. <tt class="xref c c-func docutils literal"><span class="pre">mpd_new</span></tt> is the same, but raises the |
| <tt class="xref c c-macro docutils literal"><span class="pre">MPD_Malloc_error</span></tt> exception on failure.</p> |
| <div class="highlight-c" id="std:topic-mpd_qnew_size"><div class="highlight"><pre><span class="kt">mpd_t</span> <span class="o">*</span><span class="nf">mpd_qnew_size</span><span class="p">(</span><span class="kt">mpd_ssize_t</span> <span class="n">size</span><span class="p">);</span> |
| </pre></div> |
| </div> |
| <p>Same as <tt class="xref c c-func docutils literal"><span class="pre">mpd_qnew</span></tt>, but the <em>size</em> argument indicates that <em>size</em> words |
| should be allocated for the coefficient rather than <tt class="xref c c-macro docutils literal"><span class="pre">MPD_MINALLOC</span></tt> words.</p> |
| <div class="highlight-c" id="std:topic-mpd_del"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">mpd_del</span><span class="p">(</span><span class="kt">mpd_t</span> <span class="o">*</span><span class="n">dec</span><span class="p">);</span> |
| </pre></div> |
| </div> |
| <p><tt class="xref c c-func docutils literal"><span class="pre">mpd_del</span></tt> frees all storage allocated for a decimal. The function may |
| also be called with a completely or partly static decimal as an argument, see |
| <a class="reference internal" href="memory.html#advanced-memory-handling"><em>Advanced Memory Handling</em></a>.</p> |
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