1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>Buffer-oriented asynchronous random-access read device requirements</title>
<link rel="stylesheet" href="../../boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
<link rel="home" href="../../boost_asio.html" title="Boost.Asio">
<link rel="up" href="../reference.html" title="Reference">
<link rel="prev" href="AcceptHandler.html" title="Accept handler requirements">
<link rel="next" href="AsyncRandomAccessWriteDevice.html" title="Buffer-oriented asynchronous random-access write device requirements">
</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="AcceptHandler.html"><img src="../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="AsyncRandomAccessWriteDevice.html"><img src="../../../../doc/html/images/next.png" alt="Next"></a>
</div>
<div class="section" title="Buffer-oriented asynchronous random-access read device requirements">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_asio.reference.AsyncRandomAccessReadDevice"></a><a class="link" href="AsyncRandomAccessReadDevice.html" title="Buffer-oriented asynchronous random-access read device requirements"> Buffer-oriented
asynchronous 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
an asynchronous 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">h</span></code>
denotes an object satisfying <a class="link" href="ReadHandler.html" title="Read handler requirements">read
handler</a> requirements.
</p>
<div class="table">
<a name="id614614"></a><p class="title"><b>Table 1. Buffer-oriented asynchronous random-access read
device requirements</b></p>
<div class="table-contents"><table class="table" summary="Buffer-oriented asynchronous 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">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_read_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_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">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 read one or more bytes of data
from the device <code class="computeroutput"><span class="identifier">a</span></code> at
the 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 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">async_read_some_at</span></code>
operation shall always fill 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">mb</span></code>
until such time as the read 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">mb</span></code> is destroyed, or<br> <br>
— the handler for the asynchronous read 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">mb</span></code>
is <code class="computeroutput"><span class="number">0</span></code>, the asynchronous
read 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 read.
</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>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="AcceptHandler.html"><img src="../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="AsyncRandomAccessWriteDevice.html"><img src="../../../../doc/html/images/next.png" alt="Next"></a>
</div>
</body>
</html>
|
