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  27 <a name="boost_multiprecision.ref.cpp_int_ref"></a><a class="link" href="cpp_int_ref.html" title="cpp_int">cpp_int</a>
  28 </h3></div></div></div>
  29 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">multiprecision</span><span class="special">{</span>
  30
  31 <span class="keyword">typedef</span> <span class="identifier">unspecified</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">limb_type</span><span class="special">;</span>
  32
  33 <span class="keyword">enum</span> <span class="identifier">cpp_integer_type</span>    <span class="special">{</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span> <span class="special">};</span>
  34 <span class="keyword">enum</span> <span class="identifier">cpp_int_check_type</span>  <span class="special">{</span> <span class="identifier">checked</span><span class="special">,</span> <span class="identifier">unchecked</span> <span class="special">};</span>
  35
  36 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">unsigned</span> <span class="identifier">MinDigits</span> <span class="special">=</span> <span class="number">0</span><span class="special">,</span>
  37           <span class="keyword">unsigned</span> <span class="identifier">MaxDits</span> <span class="special">=</span> <span class="number">0</span><span class="special">,</span>
  38           <span class="identifier">cpp_integer_type</span> <span class="identifier">SignType</span> <span class="special">=</span> <span class="identifier">signed_magnitude</span><span class="special">,</span>
  39           <span class="identifier">cpp_int_check_type</span> <span class="identifier">Checked</span> <span class="special">=</span> <span class="identifier">unchecked</span><span class="special">,</span>
  40           <span class="keyword">class</span> <span class="identifier">Allocator</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span><span class="special">&lt;</span><span class="identifier">limb_type</span><span class="special">&gt;</span> <span class="special">&gt;</span>
  41 <span class="keyword">class</span> <span class="identifier">cpp_int_backend</span><span class="special">;</span>
  42 <span class="comment">//</span>
  43 <span class="comment">// Expression templates default to et_off if there is no allocator:</span>
  44 <span class="comment">//</span>
  45 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">unsigned</span> <span class="identifier">MinDigits</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="identifier">MaxDigits</span><span class="special">,</span> <span class="identifier">cpp_integer_type</span> <span class="identifier">SignType</span><span class="special">,</span> <span class="identifier">cpp_int_check_type</span> <span class="identifier">Checked</span><span class="special">&gt;</span>
  46 <span class="keyword">struct</span> <span class="identifier">expression_template_default</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="identifier">MinDigits</span><span class="special">,</span> <span class="identifier">MaxDigits</span><span class="special">,</span> <span class="identifier">SignType</span><span class="special">,</span> <span class="identifier">Checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>
  47 <span class="special">{</span> <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">expression_template_option</span> <span class="identifier">value</span> <span class="special">=</span> <span class="identifier">et_off</span><span class="special">;</span> <span class="special">};</span>
  48
  49 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;&gt;</span> <span class="special">&gt;</span>              <span class="identifier">cpp_int</span><span class="special">;</span>    <span class="comment">// arbitrary precision integer</span>
  50 <span class="keyword">typedef</span> <span class="identifier">rational_adaptor</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;&gt;</span> <span class="special">&gt;</span>    <span class="identifier">cpp_rational_backend</span><span class="special">;</span>
  51 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_rational_backend</span><span class="special">&gt;</span>            <span class="identifier">cpp_rational</span><span class="special">;</span> <span class="comment">// arbitrary precision rational number</span>
  52
  53 <span class="comment">// Fixed precision unsigned types:</span>
  54 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">128</span><span class="special">,</span> <span class="number">128</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>   <span class="identifier">uint128_t</span><span class="special">;</span>
  55 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">256</span><span class="special">,</span> <span class="number">256</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>   <span class="identifier">uint256_t</span><span class="special">;</span>
  56 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">512</span><span class="special">,</span> <span class="number">512</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>   <span class="identifier">uint512_t</span><span class="special">;</span>
  57 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">1024</span><span class="special">,</span> <span class="number">1024</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="identifier">uint1024_t</span><span class="special">;</span>
  58
  59 <span class="comment">// Fixed precision signed types:</span>
  60 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">128</span><span class="special">,</span> <span class="number">128</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">int128_t</span><span class="special">;</span>
  61 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">256</span><span class="special">,</span> <span class="number">256</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">int256_t</span><span class="special">;</span>
  62 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">512</span><span class="special">,</span> <span class="number">512</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">int512_t</span><span class="special">;</span>
  63 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">1024</span><span class="special">,</span> <span class="number">1024</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">unchecked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>   <span class="identifier">int1024_t</span><span class="special">;</span>
  64
  65 <span class="comment">// Over again, but with checking enabled this time:</span>
  66 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">&gt;</span> <span class="special">&gt;</span>                 <span class="identifier">checked_cpp_int</span><span class="special">;</span>
  67 <span class="keyword">typedef</span> <span class="identifier">rational_adaptor</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">&gt;</span> <span class="special">&gt;</span>       <span class="identifier">checked_cpp_rational_backend</span><span class="special">;</span>
  68 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">checked_cpp_rational_backend</span><span class="special">&gt;</span>                                      <span class="identifier">checked_cpp_rational</span><span class="special">;</span>
  69
  70 <span class="comment">// Checked fixed precision unsigned types:</span>
  71 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">128</span><span class="special">,</span> <span class="number">128</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">checked_uint128_t</span><span class="special">;</span>
  72 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">256</span><span class="special">,</span> <span class="number">256</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">checked_uint256_t</span><span class="special">;</span>
  73 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">512</span><span class="special">,</span> <span class="number">512</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">checked_uint512_t</span><span class="special">;</span>
  74 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">1024</span><span class="special">,</span> <span class="number">1024</span><span class="special">,</span> <span class="identifier">unsigned_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>   <span class="identifier">checked_uint1024_t</span><span class="special">;</span>
  75
  76 <span class="comment">// Fixed precision signed types:</span>
  77 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">128</span><span class="special">,</span> <span class="number">128</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>       <span class="identifier">checked_int128_t</span><span class="special">;</span>
  78 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">256</span><span class="special">,</span> <span class="number">256</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>       <span class="identifier">checked_int256_t</span><span class="special">;</span>
  79 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">512</span><span class="special">,</span> <span class="number">512</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>       <span class="identifier">checked_int512_t</span><span class="special">;</span>
  80 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">cpp_int_backend</span><span class="special">&lt;</span><span class="number">1024</span><span class="special">,</span> <span class="number">1024</span><span class="special">,</span> <span class="identifier">signed_magnitude</span><span class="special">,</span> <span class="identifier">checked</span><span class="special">,</span> <span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">checked_int1024_t</span><span class="special">;</span>
  81
  82 <span class="special">}}</span> <span class="comment">// namespaces</span>
  83 </pre>
  84 <p>
  85         Class template <code class="computeroutput"><span class="identifier">cpp_int_backend</span></code>
  86         fulfils all of the requirements for a <a class="link" href="backendconc.html" title="Backend Requirements">Backend</a>
  87         type. Its members and non-member functions are deliberately not documented:
  88         these are considered implementation details that are subject to change.
  89       </p>
  90 <p>
  91         The template arguments are:
  92       </p>
  93 <div class="variablelist">
  94 <p class="title"><b></b></p>
  95 <dl class="variablelist">
  96 <dt><span class="term">MinBits</span></dt>
  97 <dd><p>
  98               Determines the number of Bits to store directly within the object before
  99               resorting to dynamic memory allocation. When zero, this field is determined
 100               automatically based on how many bits can be stored in union with the
 101               dynamic storage header: setting a larger value may improve performance
 102               as larger integer values will be stored internally before memory allocation
 103               is required.
 104             </p></dd>
 105 <dt><span class="term">MaxBits</span></dt>
 106 <dd><p>
 107               Determines the maximum number of bits to be stored in the type: resulting
 108               in a fixed precision type. When this value is the same as MinBits,
 109               then the Allocator parameter is ignored, as no dynamic memory allocation
 110               will ever be performed: in this situation the Allocator parameter should
 111               be set to type <code class="computeroutput"><span class="keyword">void</span></code>. Note
 112               that this parameter should not be used simply to prevent large memory
 113               allocations, not only is that role better performed by the allocator,
 114               but fixed precision integers have a tendency to allocate all of MaxBits
 115               of storage more often than one would expect.
 116             </p></dd>
 117 <dt><span class="term">SignType</span></dt>
 118 <dd><p>
 119               Determines whether the resulting type is signed or not. Note that for
 120               <a href="http://en.wikipedia.org/wiki/Arbitrary-precision_arithmetic" target="_top">arbitrary
 121               precision</a> types this parameter must be <code class="computeroutput"><span class="identifier">signed_magnitude</span></code>.
 122               For fixed precision types then this type may be either <code class="computeroutput"><span class="identifier">signed_magnitude</span></code> or <code class="computeroutput"><span class="identifier">unsigned_magnitude</span></code>.
 123             </p></dd>
 124 <dt><span class="term">Checked</span></dt>
 125 <dd><p>
 126               This parameter has two values: <code class="computeroutput"><span class="identifier">checked</span></code>
 127               or <code class="computeroutput"><span class="identifier">unchecked</span></code>. See the
 128               <a class="link" href="../tut/ints/cpp_int.html" title="cpp_int">tutorial</a>
 129               for more information.
 130             </p></dd>
 131 <dt><span class="term">Allocator</span></dt>
 132 <dd><p>
 133               The allocator to use for dynamic memory allocation, or type <code class="computeroutput"><span class="keyword">void</span></code> if MaxBits == MinBits.
 134             </p></dd>
 135 </dl>
 136 </div>
 137 <p>
 138         The type of <code class="computeroutput"><span class="identifier">number_category</span><span class="special">&lt;</span><span class="identifier">cpp_int</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">...&gt;</span> <span class="special">&gt;::</span><span class="identifier">type</span></code> is <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">int_</span><span class="special">&lt;</span><span class="identifier">number_kind_integer</span><span class="special">&gt;</span></code>.
 139       </p>
 140 <p>
 141         More information on this type can be found in the <a class="link" href="../tut/ints/cpp_int.html" title="cpp_int">tutorial</a>.
 142       </p>
 143 </div>
 144 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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