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diff --git a/doc/html/align/tutorial.html b/doc/html/align/tutorial.html new file mode 100644 index 0000000000..bc95281b50 --- /dev/null +++ b/doc/html/align/tutorial.html @@ -0,0 +1,314 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Tutorial</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../align.html" title="Chapter 2. Boost.Align"> +<link rel="prev" href="rationale.html" title="Rationale"> +<link rel="next" href="examples.html" title="Examples"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="rationale.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../align.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="examples.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="align.tutorial"></a><a class="link" href="tutorial.html" title="Tutorial">Tutorial</a> +</h2></div></div></div> +<div class="toc"><dl class="toc"> +<dt><span class="section"><a href="tutorial.html#align.tutorial.align">align</a></span></dt> +<dt><span class="section"><a href="tutorial.html#align.tutorial.aligned_alloc">aligned_alloc and aligned_free</a></span></dt> +<dt><span class="section"><a href="tutorial.html#align.tutorial.aligned_allocator">aligned_allocator</a></span></dt> +<dt><span class="section"><a href="tutorial.html#align.tutorial.aligned_allocator_adaptor">aligned_allocator_adaptor</a></span></dt> +<dt><span class="section"><a href="tutorial.html#align.tutorial.aligned_delete">aligned_delete</a></span></dt> +<dt><span class="section"><a href="tutorial.html#align.tutorial.alignment_of">alignment_of</a></span></dt> +<dt><span class="section"><a href="tutorial.html#align.tutorial.is_aligned">is_aligned</a></span></dt> +</dl></div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="align.tutorial.align"></a><a class="link" href="tutorial.html#align.tutorial.align" title="align">align</a> +</h3></div></div></div> +<p> + The alignment function can be used to find the first address of a given alignment + value within a given buffer of a given size. It adjusts the pointer provided, + returns that value, and decreases space by the amount advanced, if the alignment + succeeds, provided sufficient space in the buffer. Otherwise it yields a + null pointer to indicate failure due to insufficient space. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">align</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> +<span class="keyword">inline</span> <span class="identifier">T</span><span class="special">*</span> <span class="identifier">make</span><span class="special">(</span><span class="keyword">void</span><span class="special">*</span> <span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">space</span><span class="special">)</span> +<span class="special">{</span> + <span class="keyword">void</span><span class="special">*</span> <span class="identifier">p</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span> + <span class="identifier">align</span><span class="special">(</span><span class="keyword">alignof</span><span class="special">(</span><span class="identifier">T</span><span class="special">),</span> <span class="keyword">sizeof</span><span class="special">(</span><span class="identifier">T</span><span class="special">),</span> <span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">space</span><span class="special">);</span> + <span class="keyword">if</span> <span class="special">(</span><span class="identifier">p</span><span class="special">)</span> <span class="special">{</span> + <span class="keyword">return</span> <span class="special">::</span><span class="keyword">new</span><span class="special">(</span><span class="identifier">p</span><span class="special">)</span> <span class="identifier">T</span><span class="special">();</span> + <span class="special">}</span> <span class="keyword">else</span> <span class="special">{</span> + <span class="keyword">return</span> <span class="keyword">nullptr</span><span class="special">;</span> + <span class="special">}</span> +<span class="special">}</span> + +<span class="keyword">struct</span> <span class="keyword">alignas</span><span class="special">(</span><span class="number">16</span><span class="special">)</span> <span class="identifier">type</span> <span class="special">{</span> + <span class="keyword">float</span> <span class="identifier">data</span><span class="special">[</span><span class="number">4</span><span class="special">];</span> +<span class="special">};</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">char</span> <span class="identifier">c</span><span class="special">[</span><span class="number">48</span><span class="special">];</span> + <span class="identifier">type</span><span class="special">*</span> <span class="identifier">p</span> <span class="special">=</span> <span class="identifier">make</span><span class="special"><</span><span class="identifier">type</span><span class="special">>(</span><span class="identifier">c</span><span class="special">,</span> <span class="keyword">sizeof</span> <span class="identifier">c</span><span class="special">);</span> + <span class="keyword">if</span> <span class="special">(</span><span class="identifier">p</span><span class="special">)</span> <span class="special">{</span> + <span class="identifier">p</span><span class="special">->~</span><span class="identifier">type</span><span class="special">();</span> + <span class="special">}</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="align.tutorial.aligned_alloc"></a><a class="link" href="tutorial.html#align.tutorial.aligned_alloc" title="aligned_alloc and aligned_free">aligned_alloc and aligned_free</a> +</h3></div></div></div> +<p> + Consider these functions alignment enabled versions of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">malloc</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span></code> + and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">free</span><span class="special">(</span><span class="keyword">void</span><span class="special">*)</span></code> or <code class="computeroutput"><span class="special">::</span><span class="keyword">operator</span> <span class="keyword">new</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">no_throw_t</span><span class="special">&)</span></code> and <code class="computeroutput"><span class="special">::</span><span class="keyword">operator</span> <span class="keyword">delete</span><span class="special">(</span><span class="keyword">void</span><span class="special">*)</span></code>. + The aligned allocation function allocates space with the specified size and + alignment. The aligned deallocation function can then deallocate this space. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">aligned_alloc</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> + +<span class="keyword">void</span> <span class="identifier">use</span><span class="special">(</span><span class="keyword">void</span><span class="special">*</span> <span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span> +<span class="special">{</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">ptr</span><span class="special">;</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">size</span><span class="special">;</span> +<span class="special">}</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">void</span><span class="special">*</span> <span class="identifier">p</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_alloc</span><span class="special">(</span><span class="number">16</span><span class="special">,</span> <span class="number">100</span><span class="special">);</span> + <span class="keyword">if</span> <span class="special">(</span><span class="identifier">p</span><span class="special">)</span> <span class="special">{</span> + <span class="identifier">use</span><span class="special">(</span><span class="identifier">p</span><span class="special">,</span> <span class="number">100</span><span class="special">);</span> + <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_free</span><span class="special">(</span><span class="identifier">p</span><span class="special">);</span> + <span class="special">}</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="align.tutorial.aligned_allocator"></a><a class="link" href="tutorial.html#align.tutorial.aligned_allocator" title="aligned_allocator">aligned_allocator</a> +</h3></div></div></div> +<p> + Consider this class template a superior version of the default allocator, + <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span></code>, because it can be used with + types that are over-aligned. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">aligned_allocator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> + +<span class="keyword">struct</span> <span class="keyword">alignas</span><span class="special">(</span><span class="number">16</span><span class="special">)</span> <span class="identifier">type</span> <span class="special">{</span> + <span class="keyword">float</span> <span class="identifier">data</span><span class="special">[</span><span class="number">4</span><span class="special">];</span> +<span class="special">};</span> + +<span class="keyword">void</span> <span class="identifier">use</span><span class="special">(</span><span class="identifier">type</span><span class="special">*</span> <span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span> +<span class="special">{</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">ptr</span><span class="special">;</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">size</span><span class="special">;</span> +<span class="special">}</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span> + <span class="identifier">aligned_allocator</span><span class="special"><</span><span class="identifier">type</span><span class="special">></span> <span class="special">></span> <span class="identifier">v</span><span class="special">(</span><span class="number">100</span><span class="special">);</span> + <span class="identifier">use</span><span class="special">(&</span><span class="identifier">v</span><span class="special">[</span><span class="number">0</span><span class="special">],</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">size</span><span class="special">());</span> +<span class="special">}</span> +</pre> +<p> + The optional template parameter of this class allows specifying a minimum + alignment to use for allocations. The default minimum alignment is 1. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">aligned_allocator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> + +<span class="keyword">void</span> <span class="identifier">use</span><span class="special">(</span><span class="keyword">char</span><span class="special">*</span> <span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span> +<span class="special">{</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">ptr</span><span class="special">;</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">size</span><span class="special">;</span> +<span class="special">}</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span> + <span class="identifier">aligned_allocator</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="number">16</span><span class="special">></span> <span class="special">></span> <span class="identifier">v</span><span class="special">(</span><span class="number">100</span><span class="special">);</span> + <span class="identifier">use</span><span class="special">(&</span><span class="identifier">v</span><span class="special">[</span><span class="number">0</span><span class="special">],</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">size</span><span class="special">());</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="align.tutorial.aligned_allocator_adaptor"></a><a class="link" href="tutorial.html#align.tutorial.aligned_allocator_adaptor" title="aligned_allocator_adaptor">aligned_allocator_adaptor</a> +</h3></div></div></div> +<p> + This class template can turn any existing allocator type, C++11 or C++03, + stateful or stateless, into one that supports types which are over-aligned. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">aligned_allocator_adaptor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Allocator</span><span class="special">></span> +<span class="keyword">class</span> <span class="identifier">utility</span> <span class="special">{</span> +<span class="keyword">public</span><span class="special">:</span> + <span class="identifier">utility</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span> + <span class="special">:</span> <span class="identifier">v</span><span class="special">(</span><span class="identifier">size</span><span class="special">)</span> <span class="special">{</span> + <span class="special">}</span> +<span class="keyword">private</span><span class="special">:</span> + <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span> + <span class="identifier">aligned_allocator_adaptor</span><span class="special"><</span><span class="identifier">Allocator</span><span class="special">></span> <span class="special">></span> <span class="identifier">v</span><span class="special">;</span> +<span class="special">};</span> + +<span class="keyword">struct</span> <span class="keyword">alignas</span><span class="special">(</span><span class="number">16</span><span class="special">)</span> <span class="identifier">type</span> <span class="special">{</span> + <span class="keyword">float</span> <span class="identifier">data</span><span class="special">[</span><span class="number">4</span><span class="special">];</span> +<span class="special">};</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="identifier">utility</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span><span class="special"><</span><span class="identifier">type</span><span class="special">></span> <span class="special">></span> <span class="identifier">u</span><span class="special">(</span><span class="number">100</span><span class="special">);</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">u</span><span class="special">;</span> +<span class="special">}</span> +</pre> +<p> + The optional template parameter of this class allows specifying a minimum + alignment to use for allocations. The default minimum alignment is 1. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">aligned_allocator_adaptor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <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">size_t</span> <span class="identifier">Alignment</span><span class="special">></span> +<span class="keyword">class</span> <span class="identifier">utility</span> <span class="special">{</span> +<span class="keyword">public</span><span class="special">:</span> + <span class="identifier">utility</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span> + <span class="special">:</span> <span class="identifier">v</span><span class="special">(</span><span class="identifier">size</span><span class="special">)</span> <span class="special">{</span> + <span class="special">}</span> +<span class="keyword">private</span><span class="special">:</span> + <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span> + <span class="identifier">aligned_allocator_adaptor</span><span class="special"><</span><span class="identifier">Allocator</span><span class="special">,</span> <span class="identifier">Alignment</span><span class="special">></span> <span class="special">></span> <span class="identifier">v</span><span class="special">;</span> +<span class="special">};</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="identifier">utility</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span><span class="special"><</span><span class="keyword">char</span><span class="special">>,</span> <span class="number">16</span><span class="special">></span> <span class="identifier">u</span><span class="special">(</span><span class="number">100</span><span class="special">);</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">u</span><span class="special">;</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="align.tutorial.aligned_delete"></a><a class="link" href="tutorial.html#align.tutorial.aligned_delete" title="aligned_delete">aligned_delete</a> +</h3></div></div></div> +<p> + Consider this class an alignment aware version of the <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">default_delete</span></code> + deleter class template. It is a deleter that destroys the object and then + deallocates space using our aligned deallocation function. It should be used + with constructed objects that were allocated with our aligned allocation + function and is useful with deleter enabled types like <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">unique_ptr</span></code>. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">aligned_delete</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">memory</span><span class="special">></span> + +<span class="keyword">struct</span> <span class="keyword">alignas</span><span class="special">(</span><span class="number">16</span><span class="special">)</span> <span class="identifier">type</span> <span class="special">{</span> + <span class="keyword">float</span> <span class="identifier">data</span><span class="special">[</span><span class="number">4</span><span class="special">];</span> +<span class="special">};</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">void</span><span class="special">*</span> <span class="identifier">p</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span> + <span class="identifier">aligned_alloc</span><span class="special">(</span><span class="keyword">alignof</span><span class="special">(</span><span class="identifier">type</span><span class="special">),</span> <span class="keyword">sizeof</span><span class="special">(</span><span class="identifier">type</span><span class="special">));</span> + <span class="keyword">if</span> <span class="special">(</span><span class="identifier">p</span><span class="special">)</span> <span class="special">{</span> + <span class="identifier">type</span><span class="special">*</span> <span class="identifier">q</span> <span class="special">=</span> <span class="special">::</span><span class="keyword">new</span><span class="special">(</span><span class="identifier">p</span><span class="special">)</span> <span class="identifier">type</span><span class="special">();</span> + <span class="identifier">std</span><span class="special">::</span><span class="identifier">unique_ptr</span><span class="special"><</span><span class="identifier">type</span><span class="special">,</span> + <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_delete</span><span class="special">></span> <span class="identifier">u</span><span class="special">(</span><span class="identifier">q</span><span class="special">);</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">u</span><span class="special">;</span> + <span class="special">}</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="align.tutorial.alignment_of"></a><a class="link" href="tutorial.html#align.tutorial.alignment_of" title="alignment_of">alignment_of</a> +</h3></div></div></div> +<p> + This type trait can be used to query the alignment requirement of a type + at compile time. It is useful in static assertions to validate type alignment. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">alignment_of</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> + +<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> +<span class="keyword">class</span> <span class="identifier">utility</span> <span class="special">{</span> + <span class="keyword">static_assert</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span> + <span class="identifier">alignment_of</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value</span> <span class="special">==</span> <span class="number">16</span><span class="special">,</span> <span class="string">""</span><span class="special">);</span> +<span class="keyword">public</span><span class="special">:</span> + <span class="identifier">utility</span><span class="special">()</span> + <span class="special">:</span> <span class="identifier">object</span><span class="special">()</span> <span class="special">{</span> + <span class="special">}</span> +<span class="keyword">private</span><span class="special">:</span> + <span class="identifier">T</span> <span class="identifier">object</span><span class="special">;</span> +<span class="special">};</span> + +<span class="keyword">struct</span> <span class="keyword">alignas</span><span class="special">(</span><span class="number">16</span><span class="special">)</span> <span class="identifier">type</span> <span class="special">{</span> + <span class="keyword">float</span> <span class="identifier">data</span><span class="special">[</span><span class="number">4</span><span class="special">];</span> +<span class="special">};</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="identifier">utility</span><span class="special"><</span><span class="identifier">type</span><span class="special">></span> <span class="identifier">u</span><span class="special">;</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">u</span><span class="special">;</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="align.tutorial.is_aligned"></a><a class="link" href="tutorial.html#align.tutorial.is_aligned" title="is_aligned">is_aligned</a> +</h3></div></div></div> +<p> + This function is used to compare the alignment of a pointer. It is useful + in assertions that validate a pointer value is aligned on a given boundary. + </p> +<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">align</span><span class="special">/</span><span class="identifier">is_aligned</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> +<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">cassert</span><span class="special">></span> + +<span class="keyword">void</span> <span class="identifier">use</span><span class="special">(</span><span class="keyword">void</span><span class="special">*</span> <span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span> +<span class="special">{</span> + <span class="identifier">assert</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">is_aligned</span><span class="special">(</span><span class="identifier">ptr</span><span class="special">,</span> <span class="number">16</span><span class="special">));</span> + <span class="special">(</span><span class="keyword">void</span><span class="special">)</span><span class="identifier">size</span><span class="special">;</span> +<span class="special">}</span> + +<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">alignas</span><span class="special">(</span><span class="number">16</span><span class="special">)</span> <span class="keyword">char</span> <span class="identifier">c</span><span class="special">[</span><span class="number">100</span><span class="special">];</span> + <span class="identifier">use</span><span class="special">(</span><span class="identifier">c</span><span class="special">,</span> <span class="keyword">sizeof</span> <span class="identifier">c</span><span class="special">);</span> +<span class="special">}</span> +</pre> +</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 © 2014 Glen Fernandes<p> + Distributed under the <a href="http://boost.org/LICENSE_1_0.txt" target="_top">Boost + Software License, Version 1.0</a>. + </p> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="rationale.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../align.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="examples.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> |