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  25 <div class="refentry">
  26 <a name="boost.compute.copy"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Function template copy</span></h2>
  29 <p>boost::compute::copy</p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../boost_compute/reference.html#header.boost.compute.algorithm.copy_hpp" title="Header &lt;boost/compute/algorithm/copy.hpp&gt;">boost/compute/algorithm/copy.hpp</a>&gt;
  33
  34 </span>
  35 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> InputIterator<span class="special">,</span> <span class="keyword">typename</span> OutputIterator<span class="special">&gt;</span>
  36   <span class="identifier">OutputIterator</span>
  37   <span class="identifier">copy</span><span class="special">(</span><span class="identifier">InputIterator</span> first<span class="special">,</span> <span class="identifier">InputIterator</span> last<span class="special">,</span> <span class="identifier">OutputIterator</span> result<span class="special">,</span>
  38        <span class="identifier">command_queue</span> <span class="special">&amp;</span> queue <span class="special">=</span> <span class="identifier">system</span><span class="special">::</span><span class="identifier">default_queue</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
  39        <span class="keyword">const</span> <a class="link" href="wait_list.html" title="Class wait_list">wait_list</a> <span class="special">&amp;</span> events <span class="special">=</span> <a class="link" href="wait_list.html" title="Class wait_list">wait_list</a><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span></pre></div>
  40 <div class="refsect1">
  41 <a name="idm46113334893120"></a><h2>Description</h2>
  42 <p>Copies the values in the range [<code class="computeroutput">first</code>, <code class="computeroutput">last</code>) to the range beginning at <code class="computeroutput">result</code>.</p>
  43 <p>The generic copy() function can be used for a variety of data transfer tasks and provides a standard interface to the following OpenCL functions:</p>
  44 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  45 <li class="listitem"><p><code class="computeroutput">clEnqueueReadBuffer()</code> </p></li>
  46 <li class="listitem"><p><code class="computeroutput">clEnqueueWriteBuffer()</code> </p></li>
  47 <li class="listitem"><p><code class="computeroutput">clEnqueueCopyBuffer()</code> </p></li>
  48 </ul></div>
  49 <p>
  50 Unlike the aforementioned OpenCL functions, copy() will also work with non-contiguous data-structures (e.g. <code class="computeroutput">std::list&lt;T&gt;</code>) as well as with "fancy" iterators (e.g. <code class="computeroutput"><a class="link" href="transform_iterator.html" title="Class template transform_iterator">transform_iterator</a></code>).</p>
  51 <p>
  52
  53 For example, to copy an array of <code class="computeroutput">int</code> values on the host to a vector on the device: </p>
  54 <pre class="programlisting"><span class="comment">// array on the host</span>
  55 <span class="keyword">int</span> <span class="identifier">data</span><span class="special">[</span><span class="special">]</span> <span class="special">=</span> <span class="special">{</span> <span class="number">1</span><span class="special">,</span> <span class="number">2</span><span class="special">,</span> <span class="number">3</span><span class="special">,</span> <span class="number">4</span> <span class="special">}</span><span class="special">;</span>
  56
  57 <span class="comment">// vector on the device</span>
  58 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">vec</span><span class="special">(</span><span class="number">4</span><span class="special">,</span> <span class="identifier">context</span><span class="special">)</span><span class="special">;</span>
  59
  60 <span class="comment">// copy values to the device vector</span>
  61 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">copy</span><span class="special">(</span><span class="identifier">data</span><span class="special">,</span> <span class="identifier">data</span> <span class="special">+</span> <span class="number">4</span><span class="special">,</span> <span class="identifier">vec</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">queue</span><span class="special">)</span><span class="special">;</span>
  62 </pre>
  63 <p>The copy algorithm can also be used with standard containers such as <code class="computeroutput">std::vector&lt;T&gt;</code>: </p>
  64 <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">host_vector</span> <span class="special">=</span> <span class="special">...</span>
  65 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">device_vector</span> <span class="special">=</span> <span class="special">...</span>
  66
  67 <span class="comment">// copy from the host to the device</span>
  68 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">copy</span><span class="special">(</span>
  69     <span class="identifier">host_vector</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">host_vector</span><span class="special">.</span><span class="identifier">end</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">device_vector</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">queue</span>
  70 <span class="special">)</span><span class="special">;</span>
  71
  72 <span class="comment">// copy from the device to the host</span>
  73 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">copy</span><span class="special">(</span>
  74     <span class="identifier">device_vector</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">device_vector</span><span class="special">.</span><span class="identifier">end</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">host_vector</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">queue</span>
  75 <span class="special">)</span><span class="special">;</span>
  76 </pre>
  77 <p>Space complexity: \Omega(1)</p>
  78 <p><span class="bold"><strong>See Also:</strong></span></p>
  79 <p>copy_n(), copy_if(), copy_async() </p>
  80 <p>
  81 </p>
  82 <p>
  83 </p>
  84 <div class="variablelist"><table border="0" class="variablelist compact">
  85 <colgroup>
  86 <col align="left" valign="top">
  87 <col>
  88 </colgroup>
  89 <tbody>
  90 <tr>
  91 <td><p><span class="term">Parameters:</span></p></td>
  92 <td><div class="variablelist"><table border="0" class="variablelist compact">
  93 <colgroup>
  94 <col align="left" valign="top">
  95 <col>
  96 </colgroup>
  97 <tbody>
  98 <tr>
  99 <td><p><span class="term"><code class="computeroutput">first</code></span></p></td>
 100 <td><p>first element in the range to copy </p></td>
 101 </tr>
 102 <tr>
 103 <td><p><span class="term"><code class="computeroutput">last</code></span></p></td>
 104 <td><p>last element in the range to copy </p></td>
 105 </tr>
 106 <tr>
 107 <td><p><span class="term"><code class="computeroutput">queue</code></span></p></td>
 108 <td><p>command queue to perform the operation</p></td>
 109 </tr>
 110 <tr>
 111 <td><p><span class="term"><code class="computeroutput">result</code></span></p></td>
 112 <td><p>first element in the result range </p></td>
 113 </tr>
 114 </tbody>
 115 </table></div></td>
 116 </tr>
 117 <tr>
 118 <td><p><span class="term">Returns:</span></p></td>
 119 <td><p><code class="computeroutput">OutputIterator</code> to the end of the result range</p></td>
 120 </tr>
 121 </tbody>
 122 </table></div>
 123 </div>
 124 </div>
 125 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 126 <td align="left"></td>
 127 <td align="right"><div class="copyright-footer">Copyright &#169; 2013, 2014 Kyle Lutz<p>
 128         Distributed under the Boost Software License, Version 1.0. (See accompanying
 129         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>)
 130       </p>
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