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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.AsyncRandomAccessWriteDevice"></a><a class="link" href="AsyncRandomAccessWriteDevice.html" title="Buffer-oriented asynchronous random-access write device requirements"> Buffer-oriented
asynchronous random-access write device requirements</a>
</h3></div></div></div>
<p>
In the table below, <code class="computeroutput"><span class="identifier">a</span></code> denotes
an asynchronous write stream 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">cb</span></code> denotes an object satisfying
<a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">constant buffer sequence</a>
requirements, and <code class="computeroutput"><span class="identifier">h</span></code> denotes
an object satisfying <a class="link" href="WriteHandler.html" title="Write handler requirements">write handler</a>
requirements.
</p>
<div class="table">
<a name="id531924"></a><p class="title"><b>Table 2. Buffer-oriented asynchronous random-access write
device requirements</b></p>
<div class="table-contents"><table class="table" summary="Buffer-oriented asynchronous random-access write
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">get_io_service</span><span class="special">();</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">io_service</span><span class="special">&</span></code>
</p>
</td>
<td>
<p>
Returns the <code class="computeroutput"><span class="identifier">io_service</span></code>
object through which the <code class="computeroutput"><span class="identifier">async_write_some_at</span></code>
handler <code class="computeroutput"><span class="identifier">h</span></code> will be invoked.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">async_write_some_at</span><span class="special">(</span><span class="identifier">o</span><span class="special">,</span> <span class="identifier">cb</span><span class="special">,</span> <span class="identifier">h</span><span class="special">);</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="keyword">void</span></code>
</p>
</td>
<td>
<p>
Initiates an asynchronous operation to write one or more bytes of data
to the device <code class="computeroutput"><span class="identifier">a</span></code> at
offset <code class="computeroutput"><span class="identifier">o</span></code>. The operation
is performed via the <code class="computeroutput"><span class="identifier">io_service</span></code>
object <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">get_io_service</span><span class="special">()</span></code>
and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous
operation</a> requirements.<br> <br> The constant buffer sequence
<code class="computeroutput"><span class="identifier">cb</span></code> specifies memory
where the data to be written is located. The <code class="computeroutput"><span class="identifier">async_write_some_at</span></code>
operation shall always write a buffer in the sequence completely before
proceeding to the next.<br> <br> The implementation shall maintain
one or more copies of <code class="computeroutput"><span class="identifier">cb</span></code>
until such time as the write operation no longer requires access to
the memory specified by the buffers in the sequence. The program must
ensure the memory is valid until:<br> <br> — the last copy of <code class="computeroutput"><span class="identifier">cb</span></code> is destroyed, or<br> <br>
— the handler for the asynchronous write operation is invoked,<br>
<br> whichever comes first.<br> <br> If the total size of all
buffers in the sequence <code class="computeroutput"><span class="identifier">cb</span></code>
is <code class="computeroutput"><span class="number">0</span></code>, the asynchronous
write operation shall complete immediately and pass <code class="computeroutput"><span class="number">0</span></code>
as the argument to the handler that specifies the number of bytes written.
</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>
<td align="left"></td>
<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>)
</p>
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