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Update Boost.Integer meta-programming classes to work with intmax_t where possible - ie to be 64-bit clean.
Added quickbook based docs - updated as necessary. Removed old html docs. [SVN r57926]
This commit is contained in:
John Maddock
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<html>
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<head>
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<title>Integer Type Selection</title>
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="boost_integer.integer"></a><a class="link" href="integer.html" title="Integer Type Selection"> Integer Type Selection</a>
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</h2></div></div></div>
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<div class="toc"><dl>
|
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<dt><span class="section"><a href="integer.html#boost_integer.integer.synopsis"> Synopsis</a></span></dt>
|
||||
<dt><span class="section"><a href="integer.html#boost_integer.integer.easiest"> Easiest-to-Manipulate
|
||||
Types</a></span></dt>
|
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<dt><span class="section"><a href="integer.html#boost_integer.integer.sized"> Sized Types</a></span></dt>
|
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<dt><span class="section"><a href="integer.html#boost_integer.integer.example">Example</a></span></dt>
|
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<dt><span class="section"><a href="integer.html#boost_integer.integer.demonstration_program">Demonstration
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Program</a></span></dt>
|
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<dt><span class="section"><a href="integer.html#boost_integer.integer.rationale">Rationale</a></span></dt>
|
||||
<dt><span class="section"><a href="integer.html#boost_integer.integer.alternative">Alternative</a></span></dt>
|
||||
<dt><span class="section"><a href="integer.html#boost_integer.integer.credits">Credits</a></span></dt>
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</dl></div>
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||||
<p>
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The <a href="../../../../../boost/integer.hpp" target="_top"><boost/integer.hpp></a>
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type selection templates allow integer types to be selected based on desired
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characteristics such as number of bits or maximum value. This facility is particularly
|
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useful for solving generic programming problems.
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</p>
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<div class="section" lang="en">
|
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<div class="titlepage"><div><div><h3 class="title">
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<a name="boost_integer.integer.synopsis"></a><a class="link" href="integer.html#boost_integer.integer.synopsis" title="Synopsis"> Synopsis</a>
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</h3></div></div></div>
|
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<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span>
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<span class="special">{</span>
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<span class="comment">// fast integers from least integers
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</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">LeastInt</span><span class="special">></span>
|
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<span class="keyword">struct</span> <span class="identifier">int_fast_t</span>
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<span class="special">{</span>
|
||||
<span class="keyword">typedef</span> <span class="emphasis"><em>implementation-defined-type</em></span> <span class="identifier">fast</span><span class="special">;</span>
|
||||
<span class="special">};</span>
|
||||
|
||||
<span class="comment">// signed
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||||
</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">int</span> <span class="identifier">Bits</span><span class="special">></span>
|
||||
<span class="keyword">struct</span> <span class="identifier">int_t</span>
|
||||
<span class="special">{</span>
|
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<span class="keyword">typedef</span> <span class="emphasis"><em>implementation-defined-type</em></span> <span class="identifier">least</span><span class="special">;</span>
|
||||
<span class="keyword">typedef</span> <span class="identifier">int_fast_t</span><span class="special"><</span><span class="identifier">least</span><span class="special">>::</span><span class="identifier">fast</span> <span class="identifier">fast</span><span class="special">;</span>
|
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<span class="special">};</span>
|
||||
|
||||
<span class="comment">// unsigned
|
||||
</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">int</span> <span class="identifier">Bits</span><span class="special">></span>
|
||||
<span class="keyword">struct</span> <span class="identifier">uint_t</span>
|
||||
<span class="special">{</span>
|
||||
<span class="keyword">typedef</span> <span class="emphasis"><em>implementation-defined-type</em></span> <span class="identifier">least</span><span class="special">;</span>
|
||||
<span class="keyword">typedef</span> <span class="identifier">int_fast_t</span><span class="special"><</span><span class="identifier">least</span><span class="special">>::</span><span class="identifier">fast</span> <span class="identifier">fast</span><span class="special">;</span>
|
||||
<span class="special">};</span>
|
||||
|
||||
<span class="comment">// signed
|
||||
</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">MaxValue</span><span class="special">></span>
|
||||
<span class="keyword">struct</span> <span class="identifier">int_max_value_t</span>
|
||||
<span class="special">{</span>
|
||||
<span class="keyword">typedef</span> <span class="emphasis"><em>implementation-defined-type</em></span> <span class="identifier">least</span><span class="special">;</span>
|
||||
<span class="keyword">typedef</span> <span class="identifier">int_fast_t</span><span class="special"><</span><span class="identifier">least</span><span class="special">>::</span><span class="identifier">fast</span> <span class="identifier">fast</span><span class="special">;</span>
|
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<span class="special">};</span>
|
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|
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">MinValue</span><span class="special">></span>
|
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<span class="keyword">struct</span> <span class="identifier">int_min_value_t</span>
|
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<span class="special">{</span>
|
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<span class="keyword">typedef</span> <span class="emphasis"><em>implementation-defined-type</em></span> <span class="identifier">least</span><span class="special">;</span>
|
||||
<span class="keyword">typedef</span> <span class="identifier">int_fast_t</span><span class="special"><</span><span class="identifier">least</span><span class="special">>::</span><span class="identifier">fast</span> <span class="identifier">fast</span><span class="special">;</span>
|
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<span class="special">};</span>
|
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|
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<span class="comment">// unsigned
|
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</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">Value</span><span class="special">></span>
|
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<span class="keyword">struct</span> <span class="identifier">uint_value_t</span>
|
||||
<span class="special">{</span>
|
||||
<span class="keyword">typedef</span> <span class="emphasis"><em>implementation-defined-type</em></span> <span class="identifier">least</span><span class="special">;</span>
|
||||
<span class="keyword">typedef</span> <span class="identifier">int_fast_t</span><span class="special"><</span><span class="identifier">least</span><span class="special">>::</span><span class="identifier">fast</span> <span class="identifier">fast</span><span class="special">;</span>
|
||||
<span class="special">};</span>
|
||||
<span class="special">}</span> <span class="comment">// namespace boost
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||||
</span></pre>
|
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</div>
|
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<div class="section" lang="en">
|
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<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_integer.integer.easiest"></a><a class="link" href="integer.html#boost_integer.integer.easiest" title="Easiest-to-Manipulate Types"> Easiest-to-Manipulate
|
||||
Types</a>
|
||||
</h3></div></div></div>
|
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<p>
|
||||
The <code class="literal">int_fast_t</code> class template maps its input type to the
|
||||
next-largest type that the processor can manipulate the easiest, or to itself
|
||||
if the input type is already an easy-to-manipulate type. For instance, processing
|
||||
a bunch of <code class="literal">char</code> objects may go faster if they were converted
|
||||
to <code class="literal">int</code> objects before processing. The input type, passed
|
||||
as the only template parameter, must be a built-in integral type, except
|
||||
<code class="literal">bool</code>. Unsigned integral types can be used, as well as
|
||||
signed integral types, despite the name. The output type is given as the
|
||||
class member <code class="literal">fast</code>.
|
||||
</p>
|
||||
<p>
|
||||
<span class="bold"><strong>Implementation Notes:</strong></span> By default, the output
|
||||
type is identical to the input type. Eventually, this code's implementation
|
||||
should be conditionalized for each platform to give accurate mappings between
|
||||
the built-in types and the easiest-to-manipulate built-in types. Also, there
|
||||
is no guarantee that the output type actually is easier to manipulate than
|
||||
the input type.
|
||||
</p>
|
||||
</div>
|
||||
<div class="section" lang="en">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_integer.integer.sized"></a><a class="link" href="integer.html#boost_integer.integer.sized" title="Sized Types"> Sized Types</a>
|
||||
</h3></div></div></div>
|
||||
<p>
|
||||
The <code class="literal">int_t</code>, <code class="literal">uint_t</code>, <code class="literal">int_max_value_t</code>,
|
||||
<code class="literal">int_min_value_t</code>, and <code class="literal">uint_value_t</code> class
|
||||
templates find the most appropiate built-in integral type for the given template
|
||||
parameter. This type is given by the class member <code class="literal">least</code>.
|
||||
The easiest-to-manipulate version of that type is given by the class member
|
||||
<code class="literal">fast</code>. The following table describes each template's criteria.
|
||||
</p>
|
||||
<div class="table">
|
||||
<a name="id673121"></a><p class="title"><b>Table<EFBFBD>1.<2E>Criteria for the Sized Type Class Templates</b></p>
|
||||
<div class="table-contents"><table class="table" summary="Criteria for the Sized Type Class Templates">
|
||||
<colgroup>
|
||||
<col>
|
||||
<col>
|
||||
</colgroup>
|
||||
<thead><tr>
|
||||
<th>
|
||||
<p>
|
||||
Class Template
|
||||
</p>
|
||||
</th>
|
||||
<th>
|
||||
<p>
|
||||
Template Parameter Mapping
|
||||
</p>
|
||||
</th>
|
||||
</tr></thead>
|
||||
<tbody>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="literal">boost::int_t<N></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
The smallest built-in signed integral type with at least <span class="emphasis"><em>N</em></span>
|
||||
bits, including the sign bit. The parameter should be a positive number.
|
||||
A compile-time error results if the parameter is larger than the number
|
||||
of bits in the largest integer type.
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="literal">boost::uint_t<N></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
The smallest built-in unsigned integral type with at least <span class="emphasis"><em>N</em></span>
|
||||
bits. The parameter should be a positive number. A compile-time error
|
||||
results if the parameter is larger than the number of bits in the largest
|
||||
integer type.
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="literal">boost::int_max_value_t<V></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
The smallest built-in signed integral type that can hold all the values
|
||||
in the inclusive range <span class="emphasis"><em>0 - V</em></span>. The parameter should
|
||||
be a positive number.
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="literal">boost::int_min_value_t<V></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
The smallest built-in signed integral type that can hold all the values
|
||||
in the inclusive range <span class="emphasis"><em>V-0</em></span>. The parameter should
|
||||
be a negative number.
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>
|
||||
<p>
|
||||
<code class="literal">boost::uint_value_t<V></code>
|
||||
</p>
|
||||
</td>
|
||||
<td>
|
||||
<p>
|
||||
The smallest built-in unsigned integral type that can hold all positive
|
||||
values up to and including <span class="emphasis"><em>V</em></span>. The parameter should
|
||||
be a positive number.
|
||||
</p>
|
||||
</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table></div>
|
||||
</div>
|
||||
<br class="table-break">
|
||||
</div>
|
||||
<div class="section" lang="en">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_integer.integer.example"></a><a class="link" href="integer.html#boost_integer.integer.example" title="Example">Example</a>
|
||||
</h3></div></div></div>
|
||||
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">integer</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
|
||||
|
||||
<span class="comment">//...
|
||||
</span>
|
||||
<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">int_t</span><span class="special"><</span><span class="number">24</span><span class="special">>::</span><span class="identifier">least</span> <span class="identifier">my_var</span><span class="special">;</span> <span class="comment">// my_var has at least 24-bits
|
||||
</span> <span class="comment">//...
|
||||
</span> <span class="comment">// This one is guarenteed not to be truncated:
|
||||
</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">int_max_value_t</span><span class="special"><</span><span class="number">1000</span><span class="special">>::</span><span class="identifier">least</span> <span class="identifier">my1000</span> <span class="special">=</span> <span class="number">1000</span><span class="special">;</span>
|
||||
<span class="comment">//...
|
||||
</span> <span class="comment">// This one is guarenteed not to be truncated, and as fast
|
||||
</span> <span class="comment">// to manipulate as possible, it's size may be greater than
|
||||
</span> <span class="comment">// that of my1000:
|
||||
</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">int_max_value_t</span><span class="special"><</span><span class="number">1000</span><span class="special">>::</span><span class="identifier">fast</span> <span class="identifier">my_fast1000</span> <span class="special">=</span> <span class="number">1000</span><span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section" lang="en">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_integer.integer.demonstration_program"></a><a class="link" href="integer.html#boost_integer.integer.demonstration_program" title="Demonstration Program">Demonstration
|
||||
Program</a>
|
||||
</h3></div></div></div>
|
||||
<p>
|
||||
The program <a href="../../../test/integer_test.cpp" target="_top">integer_test.cpp</a>
|
||||
is a simplistic demonstration of the results from instantiating various examples
|
||||
of the sized type class templates.
|
||||
</p>
|
||||
</div>
|
||||
<div class="section" lang="en">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_integer.integer.rationale"></a><a class="link" href="integer.html#boost_integer.integer.rationale" title="Rationale">Rationale</a>
|
||||
</h3></div></div></div>
|
||||
<p>
|
||||
The rationale for the design of the templates in this header includes:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul type="disc">
|
||||
<li>
|
||||
Avoid recursion because of concern about C++'s limited guaranteed recursion
|
||||
depth (17).
|
||||
</li>
|
||||
<li>
|
||||
Avoid macros on general principles.
|
||||
</li>
|
||||
<li>
|
||||
Try to keep the design as simple as possible.
|
||||
</li>
|
||||
</ul></div>
|
||||
</div>
|
||||
<div class="section" lang="en">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_integer.integer.alternative"></a><a class="link" href="integer.html#boost_integer.integer.alternative" title="Alternative">Alternative</a>
|
||||
</h3></div></div></div>
|
||||
<p>
|
||||
If the number of bits required is known beforehand, it may be more appropriate
|
||||
to use the types supplied in <a href="../../../../../boost/cstdint.hpp" target="_top"><boost/cstdint.hpp></a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="section" lang="en">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_integer.integer.credits"></a><a class="link" href="integer.html#boost_integer.integer.credits" title="Credits">Credits</a>
|
||||
</h3></div></div></div>
|
||||
<p>
|
||||
The author of most of the Boost integer type choosing templates is <a href="http://www.boost.org/people/beman_dawes.html" target="_top">Beman Dawes</a>. He
|
||||
gives thanks to Valentin Bonnard and <a href="http://www.boost.org/people/kevlin_henney.htm" target="_top">Kevlin
|
||||
Henney</a> for sharing their designs for similar templates. <a href="http://www.boost.org/people/daryle_walker.html" target="_top">Daryle
|
||||
Walker</a> designed the value-based sized templates.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <20> 2001 -2009 Beman Dawes, Daryle Walker, Gennaro Prota,
|
||||
John Maddock<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
</div></td>
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
||||
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Reference in New Issue
Block a user