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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="boost_asio.reference.SyncRandomAccessReadDevice"></a><a class="link" href="SyncRandomAccessReadDevice.html" title="Buffer-oriented synchronous random-access read device requirements">Buffer-oriented |
| synchronous random-access read device requirements</a> |
| </h3></div></div></div> |
| <p> |
| In the table below, <code class="computeroutput"><span class="identifier">a</span></code> denotes |
| a synchronous random-access read device object, <code class="computeroutput"><span class="identifier">o</span></code> |
| denotes an offset of type <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">uint64_t</span></code>, |
| <code class="computeroutput"><span class="identifier">mb</span></code> denotes an object satisfying |
| <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">mutable buffer |
| sequence</a> requirements, and <code class="computeroutput"><span class="identifier">ec</span></code> |
| denotes an object of type <code class="computeroutput"><span class="identifier">error_code</span></code>. |
| </p> |
| <div class="table"> |
| <a name="id862831"></a><p class="title"><b>Table 31. Buffer-oriented synchronous random-access read device requirements</b></p> |
| <div class="table-contents"><table class="table" summary="Buffer-oriented synchronous random-access read device requirements"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| operation |
| </p> |
| </th> |
| <th> |
| <p> |
| type |
| </p> |
| </th> |
| <th> |
| <p> |
| semantics, pre/post-conditions |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">read_some_at</span><span class="special">(</span><span class="identifier">o</span><span class="special">,</span> |
| <span class="identifier">mb</span><span class="special">);</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">size_t</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Equivalent to: |
| </p> |
| <pre class="programlisting"><span class="identifier">error_code</span> <span class="identifier">ec</span><span class="special">;</span> |
| <span class="identifier">size_t</span> <span class="identifier">s</span> <span class="special">=</span> <span class="identifier">a</span><span class="special">.</span><span class="identifier">read_some_at</span><span class="special">(</span><span class="identifier">o</span><span class="special">,</span> <span class="identifier">mb</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span> |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">ec</span><span class="special">)</span> <span class="keyword">throw</span> <span class="identifier">system_error</span><span class="special">(</span><span class="identifier">ec</span><span class="special">);</span> |
| <span class="keyword">return</span> <span class="identifier">s</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">read_some_at</span><span class="special">(</span><span class="identifier">o</span><span class="special">,</span> |
| <span class="identifier">mb</span><span class="special">,</span> |
| <span class="identifier">ec</span><span class="special">);</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">size_t</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Reads one or more bytes of data from the device <code class="computeroutput"><span class="identifier">a</span></code> |
| at offset <code class="computeroutput"><span class="identifier">o</span></code>.<br> |
| <br> The mutable buffer sequence <code class="computeroutput"><span class="identifier">mb</span></code> |
| specifies memory where the data should be placed. The <code class="computeroutput"><span class="identifier">read_some_at</span></code> operation shall |
| always fill a buffer in the sequence completely before proceeding |
| to the next.<br> <br> If successful, returns the number of |
| bytes read and sets <code class="computeroutput"><span class="identifier">ec</span></code> |
| such that <code class="computeroutput"><span class="special">!</span><span class="identifier">ec</span></code> |
| is true. If an error occurred, returns <code class="computeroutput"><span class="number">0</span></code> |
| and sets <code class="computeroutput"><span class="identifier">ec</span></code> such |
| that <code class="computeroutput"><span class="special">!!</span><span class="identifier">ec</span></code> |
| is true.<br> <br> If the total size of all buffers in the sequence |
| <code class="computeroutput"><span class="identifier">mb</span></code> is <code class="computeroutput"><span class="number">0</span></code>, the function shall return <code class="computeroutput"><span class="number">0</span></code> immediately. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <br class="table-break"> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
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| <td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 Christopher M. Kohlhoff<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>) |
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