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27 <a name="boost_asio.reference.SyncRandomAccessReadDevice"></a><a class="link" href="SyncRandomAccessReadDevice.html" title="Buffer-oriented synchronous random-access read device requirements">Buffer-oriented
28 synchronous random-access read device requirements</a>
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31 In the table below, <code class="computeroutput"><span class="identifier">a</span></code> denotes
32 a synchronous random-access read device object, <code class="computeroutput"><span class="identifier">o</span></code>
33 denotes an offset of type <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">uint64_t</span></code>,
34 <code class="computeroutput"><span class="identifier">mb</span></code> denotes an object satisfying
35 <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">mutable buffer
36 sequence</a> requirements, and <code class="computeroutput"><span class="identifier">ec</span></code>
37 denotes an object of type <code class="computeroutput"><span class="identifier">error_code</span></code>.
40 <a name="boost_asio.reference.SyncRandomAccessReadDevice.t0"></a><p class="title"><b>Table 34. Buffer-oriented synchronous random-access read device requirements</b></p>
41 <div class="table-contents"><table class="table" summary="Buffer-oriented synchronous random-access read device requirements">
60 semantics, pre/post-conditions
68 <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>
69 <span class="identifier">mb</span><span class="special">);</span></code>
74 <code class="computeroutput"><span class="identifier">size_t</span></code>
81 <pre class="programlisting"><span class="identifier">error_code</span> <span class="identifier">ec</span><span class="special">;</span>
82 <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>
83 <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>
84 <span class="keyword">return</span> <span class="identifier">s</span><span class="special">;</span>
93 <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>
94 <span class="identifier">mb</span><span class="special">,</span>
95 <span class="identifier">ec</span><span class="special">);</span></code>
100 <code class="computeroutput"><span class="identifier">size_t</span></code>
105 Reads one or more bytes of data from the device <code class="computeroutput"><span class="identifier">a</span></code>
106 at offset <code class="computeroutput"><span class="identifier">o</span></code>.<br>
107 <br> The mutable buffer sequence <code class="computeroutput"><span class="identifier">mb</span></code>
108 specifies memory where the data should be placed. The <code class="computeroutput"><span class="identifier">read_some_at</span></code> operation shall
109 always fill a buffer in the sequence completely before proceeding
110 to the next.<br> <br> If successful, returns the number of
111 bytes read and sets <code class="computeroutput"><span class="identifier">ec</span></code>
112 such that <code class="computeroutput"><span class="special">!</span><span class="identifier">ec</span></code>
113 is true. If an error occurred, returns <code class="computeroutput"><span class="number">0</span></code>
114 and sets <code class="computeroutput"><span class="identifier">ec</span></code> such
115 that <code class="computeroutput"><span class="special">!!</span><span class="identifier">ec</span></code>
116 is true.<br> <br> If the total size of all buffers in the sequence
117 <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.
124 <br class="table-break">
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128 <td align="right"><div class="copyright-footer">Copyright © 2003-2014 Christopher M. Kohlhoff<p>
129 Distributed under the Boost Software License, Version 1.0. (See accompanying
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