[29] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
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| 2 | <HTML> |
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| 3 | <HEAD> |
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| 4 | <TITLE>Memory-Mapped Files</TITLE> |
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| 5 | <LINK REL="stylesheet" HREF="../../../../boost.css"> |
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| 6 | <LINK REL="stylesheet" HREF="../theme/iostreams.css"> |
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| 7 | </HEAD> |
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| 8 | <BODY> |
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| 9 | |
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| 10 | <!-- Begin Banner --> |
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| 11 | |
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| 12 | <H1 CLASS="title">Memory-Mapped Files</H1> |
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| 13 | <HR CLASS="banner"> |
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| 14 | |
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| 15 | <!-- End Banner --> |
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| 16 | |
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| 17 | <DL class="page-index"> |
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| 18 | <DT><A href="#overview">Overview</A></DT> |
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| 19 | <DT><A href="#acknowledgments">Acknowledgments</A></DT> |
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| 20 | <DT><A href="#installation">Installation</A></DT> |
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| 21 | <DT><A href="#headers">Headers</A></DT> |
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| 22 | <DT><A href="#reference">Reference</A> |
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| 23 | <OL> |
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| 24 | <LI CLASS="square"><A href="#mapped_file_params">Class <CODE>mapped_file_params</CODE></A></LI> |
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| 25 | <LI CLASS="square"><A href="#mapped_file_source">Class <CODE>mapped_file_source</CODE></A></LI> |
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| 26 | <LI CLASS="square"><A href="#mapped_file_sink">Class <CODE>mapped_file_sink</CODE></A></LI> |
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| 27 | <LI CLASS="square"><A href="#mapped_file">Class <CODE>mapped_file</CODE></A></LI> |
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| 28 | </OL> |
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| 29 | </DT> |
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| 30 | </DL> |
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| 31 | |
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| 32 | <HR> |
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| 33 | |
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| 34 | <A NAME="overview"></A> |
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| 35 | <H2>Overview</H2> |
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| 36 | |
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| 37 | <P> |
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| 38 | The classes <CODE>mapped_file_source</CODE>, <CODE>mapped_file_sink</CODE> and <CODE>mapped_file</CODE> provide access to memory-mapped files on Windows and POSIX systems. These <A HREF="../guide/concepts.html#device_concepts">Devices</A> behave much like the <A HREF="file.html">File Wrappers</A> <CODE>basic_file_source</CODE>, <CODE>basic_file_sink</CODE> and <CODE>basic_file</CODE>, with the following important differences: |
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| 39 | </P> |
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| 40 | <UL> |
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| 41 | <LI CLASS="square">By default, files must exist before being opened, and are not truncated; attempting to write past the end of a file results in an error. To map a file which does not yet exist, use <A HREF="#mapped_file_params_size"><CODE>mapped_file_params::new_file_size</CODE></A>. |
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| 42 | <LI CLASS="square">Files are always opened in binary mode. |
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| 43 | <LI CLASS="square">Wide-character streams are not supported. |
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| 44 | </UL> |
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| 45 | <P> |
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| 46 | Wide-character versions of the memory-mapped file Devices may be defined as follows, using the template <A HREF="code_converter.html"><CODE>code_converter</CODE></A>: |
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| 47 | <PRE CLASS="broken_ie"> <SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/iostreams/code_converter.hpp"><SPAN CLASS="literal"><boost/iostreams/code_converter.hpp></SPAN></A> |
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| 48 | <SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/iostreams/device/mapped_file.hpp"><SPAN CLASS="literal"><boost/iostreams/maped_file.hpp></SPAN></A> |
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| 49 | |
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| 50 | <SPAN CLASS="keyword">typedef</SPAN> code_converter<mapped_file_source> <SPAN CLASS="defined">wmapped_file_source</SPAN>; |
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| 51 | <SPAN CLASS="keyword">typedef</SPAN> code_converter<mapped_file_sink> <SPAN CLASS="defined">wmapped_file_sink</SPAN>;</PRE> |
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| 52 | </P> |
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| 53 | |
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| 54 | <A NAME="acknowledgments"></A> |
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| 55 | <H2>Acknowledgments</H2> |
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| 56 | |
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| 57 | <P> |
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| 58 | The memory-mapped file Devices are based on the work of Craig Henderson (<A CLASS="bib_ref" HREF="../bibliography.html#henderson">[Henderson]</A>). Additionals features were implemented by Jonathan Graehl. |
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| 59 | </P> |
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| 60 | |
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| 61 | <A NAME="installation"></A> |
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| 62 | <H2>Installation</H2> |
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| 63 | |
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| 64 | <P> |
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| 65 | The memory-mapped file Devices depend on the source file <A CLASS="header" HREF="../../src/mapped_file.cpp"><CODE><libs/iostreams/src/mapped_file.cpp></CODE></A>. This source file makes use of Windows or POSIX headers depending on the user's operating system. For installation instructions see <A HREF="../installation.html">Installation</A>. |
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| 66 | </P> |
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| 67 | |
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| 68 | <A NAME="headers"></A> |
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| 69 | <H2>Headers</H2> |
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| 70 | |
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| 71 | <DL class="page-index"> |
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| 72 | <DT><A CLASS="header" HREF="../../../../boost/iostreams/device/mapped_file.hpp"><CODE><boost/iostreams/device/mapped_file.hpp></CODE></A></DT> |
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| 73 | </DL> |
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| 74 | |
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| 75 | <A NAME="reference"></A> |
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| 76 | <H2>Reference</H2> |
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| 77 | |
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| 78 | <A NAME="mapped_file_params"></A> |
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| 79 | <H3>1. Class <CODE>mapped_file_params</CODE></H3> |
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| 80 | |
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| 81 | <H4>Description</H4> |
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| 82 | |
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| 83 | <P>Class encapsulating the parameters used to open a memory-mapped file.</P> |
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| 84 | |
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| 85 | <H4>Synopsis</H4> |
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| 86 | |
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| 87 | <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
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| 88 | |
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| 89 | <SPAN CLASS="keyword">struct</SPAN> <SPAN CLASS="defined">mapped_file_params</SPAN> { |
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| 90 | <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_params(); |
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| 91 | <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_params(<SPAN CLASS='keyword'>const</SPAN> std::string& path); |
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| 92 | std::string <A CLASS='documented' HREF='#mapped_file_params_hint'>path</A>; |
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| 93 | std::ios_base::openmode <A CLASS='documented' HREF='#mapped_file_params_mode'>mode</A>; |
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| 94 | stream_offset <A CLASS='documented' HREF='#mapped_file_params_offset'>offset</A>; |
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| 95 | std::size_t <A CLASS='documented' HREF='#mapped_file_params_length'>length</A>; |
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| 96 | stream_offset <A CLASS="documented" HREF="#mapped_file_params_size">new_file_size</A>; |
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| 97 | <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_params_hint'>hint</A>; |
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| 98 | }; |
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| 99 | |
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| 100 | } } // End namespace boost::io</PRE> |
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| 101 | |
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| 102 | <A NAME="mapped_file_params_path"></A> |
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| 103 | <H4><CODE>mapped_file_params::path</CODE></H4> |
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| 104 | |
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| 105 | <PRE CLASS="broken_ie"> std::string path;</PRE> |
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| 106 | |
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| 107 | <P>The pathname of the file to map.</P> |
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| 108 | |
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| 109 | <A NAME="mapped_file_params_mode"></A> |
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| 110 | <H4><CODE>mapped_file_params::mode</CODE></H4> |
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| 111 | |
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| 112 | <PRE CLASS="broken_ie"> std::ios_base::openmode mode;</PRE> |
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| 113 | |
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| 114 | <P>Indicates whether the file should be opened with read-access, write-access or both. Ignored by <CODE>mapped_file_source</CODE> and <CODE>mapped_file_sink</CODE> .</P> |
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| 115 | |
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| 116 | <A NAME="mapped_file_params_offset"></A> |
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| 117 | <H4><CODE>mapped_file_params::offset</CODE></H4> |
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| 118 | |
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| 119 | <PRE CLASS="broken_ie"> stream_offset offset;</PRE> |
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| 120 | |
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| 121 | <P>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be abotained via the static member function <A HREF="#mapped_file_alignment"><CODE>alignment</CODE></A> of <CODE>mapped_file_source</CODE>, <CODE>mapped_file_sink</CODE> or <CODE>mapped_file</CODE>. Defaults to <CODE>0</CODE>.</P> |
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| 122 | |
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| 123 | <A NAME="mapped_file_params_length"></A> |
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| 124 | <H4><CODE>mapped_file_params::length</CODE></H4> |
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| 125 | |
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| 126 | <PRE CLASS="broken_ie"> std::size_t length;</PRE> |
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| 127 | |
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| 128 | <P>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</P> |
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| 129 | |
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| 130 | <A NAME="mapped_file_params_size"></A> |
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| 131 | <H4><CODE>mapped_file_params::new_file_size</CODE></H4> |
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| 132 | |
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| 133 | <PRE CLASS="broken_ie"> stream_offset new_file_size;</PRE> |
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| 134 | |
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| 135 | <P>If this value is non-zero it specifies the size of a file to be created. If a file with pathname <I>path</I> already exists, it will be overwritten.</P> |
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| 136 | |
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| 137 | <A NAME="mapped_file_params_hint"></A> |
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| 138 | <H4><CODE>mapped_file_params::hint</CODE></H4> |
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| 139 | |
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| 140 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* hint;</PRE> |
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| 141 | |
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| 142 | <P>Suggests a location in the process's address space for the mapping to begin.</P> |
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| 143 | |
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| 144 | <A NAME="mapped_file_source"></A> |
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| 145 | <H3>2. Class <CODE>mapped_file_source</CODE></H3> |
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| 146 | |
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| 147 | <H4>Description</H4> |
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| 148 | |
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| 149 | <P>Model of <A HREF="../concepts/source.html">Source</A> providing read-only access to memory-mapped files on Windows and POSIX systems.</P> |
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| 150 | |
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| 151 | <H4>Synopsis</H4> |
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| 152 | |
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| 153 | <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
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| 154 | |
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| 155 | <SPAN CLASS="keyword">class</SPAN> <SPAN CLASS="defined">mapped_file_source</SPAN> { |
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| 156 | <SPAN CLASS="keyword">public</SPAN>: |
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| 157 | <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>char</SPAN> char_type; |
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| 158 | <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN> category; |
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| 159 | <A CLASS='documented' HREF='#mapped_file_source_default_ctor'>mapped_file_source</A>(); |
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| 160 | <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_source_params_ctor'>mapped_file_source</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
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| 161 | <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_source_basic_ctor'>mapped_file_source</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 162 | size_type length = max_length, |
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| 163 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
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| 164 | void <A CLASS='documented' HREF='#mapped_file_source_params_open'>open</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
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| 165 | void <A CLASS='documented' HREF='#mapped_file_source_basic_open'>open</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 166 | size_type length = max_length, |
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| 167 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
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| 168 | <SPAN CLASS='keyword'>bool</SPAN> <A CLASS='documented' HREF='#mapped_file_source_is_open'>is_open</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 169 | <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_source_close'>close</A>(); |
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| 170 | size_type <A CLASS='documented' HREF='#mapped_file_source_size'>size</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 171 | <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_source_data'>data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 172 | <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> <A CLASS='documented' HREF='#mapped_file_source_alignment'>alignment</A>(); |
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| 173 | }; |
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| 174 | |
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| 175 | } } // End namespace boost::io</PRE> |
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| 176 | |
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| 177 | <A NAME="mapped_file_source_default_ctor"></A> |
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| 178 | <H4><CODE>mapped_file_source::mapped_file_source</CODE></H4> |
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| 179 | |
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| 180 | <PRE CLASS="broken_ie"> mapped_file_source();</PRE> |
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| 181 | |
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| 182 | <P>Constructs a <CODE>mapped_file_source</CODE> which must be opened before it can be used to perform i/o.</P> |
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| 183 | |
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| 184 | <A NAME="mapped_file_source_params_ctor"></A> |
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| 185 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_source(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
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| 186 | |
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| 187 | <P>Constructs a <CODE>mapped_file_source</CODE> from the given parameters.</P> |
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| 188 | |
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| 189 | <A NAME="mapped_file_source_basic_ctor"></A> |
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| 190 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_source( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 191 | size_type length = max_length, |
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| 192 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
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| 193 | |
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| 194 | <P>Constructs a <CODE>mapped_file_source</CODE> to access a specified file. The parameters have the following interpretation:</P> |
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| 195 | |
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| 196 | <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
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| 197 | <TR> |
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| 198 | <TR> |
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| 199 | <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 200 | <TD>The pathname of the file to map.</TD> |
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| 201 | </TR> |
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| 202 | <TR> |
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| 203 | <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 204 | <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
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| 205 | </TR> |
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| 206 | <TR> |
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| 207 | <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 208 | <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_source_alignment'><CODE>alignment</CODE></A>.</TD> |
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| 209 | </TR> |
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| 210 | </TABLE> |
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| 211 | |
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| 212 | <A NAME="mapped_file_source_params_open"></A> |
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| 213 | <H4><CODE>mapped_file_source::open</CODE></H4> |
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| 214 | |
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| 215 | <PRE CLASS="broken_ie"> void open(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
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| 216 | |
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| 217 | <P>Connects this <CODE>mapped_file_source</CODE> to a memory-mapped file obtained as described by the given parameters.</P> |
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| 218 | |
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| 219 | <A NAME="mapped_file_source_basic_open"></A> |
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| 220 | <PRE CLASS="broken_ie"> void open( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 221 | size_type length = max_length, |
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| 222 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
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| 223 | |
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| 224 | <P>Connects this <CODE>mapped_file_source</CODE> to a memory-mapped file obtained as described by the given parameters, which have the following interpretation:</P> |
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| 225 | |
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| 226 | <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
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| 227 | <TR> |
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| 228 | <TR> |
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| 229 | <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 230 | <TD>The pathname of the file to map.</TD> |
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| 231 | </TR> |
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| 232 | <TR> |
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| 233 | <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 234 | <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
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| 235 | </TR> |
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| 236 | <TR> |
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| 237 | <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 238 | <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_source_alignment'><CODE>alignment</CODE></A>.</TD> |
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| 239 | </TR> |
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| 240 | </TABLE> |
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| 241 | |
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| 242 | <A NAME="mapped_file_source_is_open"></A> |
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| 243 | <H4><CODE>mapped_file_source::is_open</CODE></H4> |
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| 244 | |
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| 245 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>bool</SPAN> is_open() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 246 | |
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| 247 | <P>Returns <CODE>true</CODE> if this <CODE>mapped_file_source</CODE> has been successfully opened without subsequently having been closed.</P> |
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| 248 | |
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| 249 | <A NAME="mapped_file_source_close"></A> |
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| 250 | <H4><CODE>mapped_file_source::close</CODE></H4> |
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| 251 | |
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| 252 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>void</SPAN> close();</PRE> |
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| 253 | |
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| 254 | <P>Frees the mapping associated with this <CODE>mapped_file_source</CODE>.</P> |
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| 255 | |
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| 256 | <A NAME="mapped_file_source_size"></A> |
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| 257 | <H4><CODE>mapped_file_source::size</CODE></H4> |
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| 258 | |
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| 259 | <PRE CLASS="broken_ie"> size_type size() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 260 | |
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| 261 | <P>Returns the size in bytes of the mapping associated with this <CODE>mapped_file_source</CODE>.</P> |
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| 262 | |
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| 263 | <A NAME="mapped_file_source_data"></A> |
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| 264 | <H4><CODE>mapped_file_source::data</CODE></H4> |
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| 265 | |
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| 266 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 267 | |
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| 268 | <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file_source</CODE>.</P> |
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| 269 | |
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| 270 | <A NAME="mapped_file_source_alignment"></A> |
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| 271 | <H4><CODE>mapped_file_source::alignment</CODE></H4> |
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| 272 | |
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| 273 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> alignment();</PRE> |
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| 274 | |
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| 275 | <P>Returns the operating system's virtual memory allocation granularity.</P> |
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| 276 | |
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| 277 | <A NAME="mapped_file_sink"></A> |
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| 278 | <H3>3. Class <CODE>mapped_file_sink</CODE></H3> |
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| 279 | |
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| 280 | <H4>Description</H4> |
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| 281 | |
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| 282 | <P>Model of <A HREF="../concepts/sink.html">Sink</A> providing write-only access to memory-mapped files on Windows and POSIX systems.</P> |
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| 283 | |
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| 284 | <H4>Synopsis</H4> |
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| 285 | |
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| 286 | <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
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| 287 | |
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| 288 | <SPAN CLASS="keyword">class</SPAN> <SPAN CLASS="defined">mapped_file_sink</SPAN> { |
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| 289 | <SPAN CLASS="keyword">public</SPAN>: |
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| 290 | <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>char</SPAN> char_type; |
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| 291 | <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN> category; |
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| 292 | <A CLASS='documented' HREF='#mapped_file_sink_default_ctor'>mapped_file_sink</A>(); |
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| 293 | <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_params_ctor'>mapped_file_sink</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
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| 294 | <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_basic_ctor'>mapped_file_sink</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 295 | size_type length = max_length, |
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| 296 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
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| 297 | void <A CLASS='documented' HREF='#mapped_file_sink_params_open'>open</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
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| 298 | void <A CLASS='documented' HREF='#mapped_file_sink_basic_open'>open</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 299 | size_type length = max_length, |
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| 300 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
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| 301 | <SPAN CLASS='keyword'>bool</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_is_open'>is_open</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 302 | <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_close'>close</A>(); |
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| 303 | size_type <A CLASS='documented' HREF='#mapped_file_sink_size'>size</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 304 | <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_sink_data'>data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 305 | <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> <A CLASS='documented' HREF='#mapped_file_sink_alignment'>alignment</A>(); |
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| 306 | }; |
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| 307 | |
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| 308 | } } // End namespace boost::io</PRE> |
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| 309 | |
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| 310 | <A NAME="mapped_file_sink_default_ctor"></A> |
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| 311 | <H4><CODE>mapped_file_sink::mapped_file_sink</CODE></H4> |
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| 312 | |
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| 313 | <PRE CLASS="broken_ie"> mapped_file_sink();</PRE> |
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| 314 | |
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| 315 | <P>Constructs a <CODE>mapped_file_sink</CODE> which must be opened before it can be used to perform i/o.</P> |
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| 316 | |
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| 317 | <A NAME="mapped_file_sink_params_ctor"></A> |
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| 318 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_sink(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
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| 319 | |
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| 320 | <P>Constructs a <CODE>mapped_file_sink</CODE> from the given parameters.</P> |
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| 321 | |
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| 322 | <A NAME="mapped_file_sink_basic_ctor"></A> |
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| 323 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file_sink( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 324 | size_type length = max_length, |
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| 325 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
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| 326 | |
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| 327 | <P>Constructs a <CODE>mapped_file_sink</CODE> to access a specified file. The parameters have the following interpretation:</P> |
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| 328 | |
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| 329 | <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
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| 330 | <TR> |
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| 331 | <TR> |
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| 332 | <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 333 | <TD>The pathname of the file to map.</TD> |
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| 334 | </TR> |
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| 335 | <TR> |
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| 336 | <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 337 | <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
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| 338 | </TR> |
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| 339 | <TR> |
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| 340 | <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 341 | <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_sink_alignment'><CODE>alignment</CODE></A>.</TD> |
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| 342 | </TR> |
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| 343 | </TABLE> |
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| 344 | |
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| 345 | <A NAME="mapped_file_sink_params_open"></A> |
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| 346 | <H4><CODE>mapped_file_sink::open</CODE></H4> |
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| 347 | |
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| 348 | <PRE CLASS="broken_ie"> void open(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
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| 349 | |
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| 350 | <P>Connects this <CODE>mapped_file_sink</CODE> to a memory-mapped file obtained as described by the given parameters.</P> |
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| 351 | |
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| 352 | <A NAME="mapped_file_sink_basic_open"></A> |
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| 353 | <PRE CLASS="broken_ie"> void open( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 354 | size_type length = max_length, |
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| 355 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
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| 356 | |
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| 357 | <P>Connects this <CODE>mapped_file_sink</CODE> to a memory-mapped file obtained as described by the given parameters, which have the following interpretation:</P> |
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| 358 | |
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| 359 | <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
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| 360 | <TR> |
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| 361 | <TR> |
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| 362 | <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 363 | <TD>The pathname of the file to map.</TD> |
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| 364 | </TR> |
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| 365 | <TR> |
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| 366 | <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 367 | <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
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| 368 | </TR> |
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| 369 | <TR> |
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| 370 | <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 371 | <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_sink_alignment'><CODE>alignment</CODE></A>.</TD> |
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| 372 | </TR> |
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| 373 | </TABLE> |
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| 374 | |
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| 375 | <A NAME="mapped_file_sink_is_open"></A> |
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| 376 | <H4><CODE>mapped_file_sink::is_open</CODE></H4> |
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| 377 | |
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| 378 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>bool</SPAN> is_open() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 379 | |
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| 380 | <P>Returns <CODE>true</CODE> if this <CODE>mapped_file_sink</CODE> has been successfully opened without subsequently having been closed.</P> |
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| 381 | |
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| 382 | <A NAME="mapped_file_sink_close"></A> |
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| 383 | <H4><CODE>mapped_file_sink::close</CODE></H4> |
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| 384 | |
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| 385 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>void</SPAN> close();</PRE> |
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| 386 | |
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| 387 | <P>Frees the mapping associated with this <CODE>mapped_file_sink</CODE>.</P> |
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| 388 | |
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| 389 | <A NAME="mapped_file_sink_size"></A> |
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| 390 | <H4><CODE>mapped_file_sink::size</CODE></H4> |
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| 391 | |
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| 392 | <PRE CLASS="broken_ie"> size_type size() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 393 | |
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| 394 | <P>Returns the size in bytes of the mapping associated with this <CODE>mapped_file_sink</CODE>.</P> |
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| 395 | |
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| 396 | <A NAME="mapped_file_sink_data"></A> |
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| 397 | <H4><CODE>mapped_file_sink::data</CODE></H4> |
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| 398 | |
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| 399 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>char</SPAN>* data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 400 | |
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| 401 | <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file_sink</CODE>.</P> |
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| 402 | |
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| 403 | <A NAME="mapped_file_sink_alignment"></A> |
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| 404 | <H4><CODE>mapped_file_sink::alignment</CODE></H4> |
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| 405 | |
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| 406 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> alignment();</PRE> |
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| 407 | |
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| 408 | <P>Returns the operating system's virtual memory allocation granularity.</P> |
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| 409 | |
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| 410 | <A NAME="mapped_file"></A> |
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| 411 | <H3>4. Class <CODE>mapped_file</CODE></H3> |
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| 412 | |
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| 413 | <H4>Description</H4> |
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| 414 | |
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| 415 | <P>Model of <A HREF="../concepts/seekable_device.html">SeekableDevice</A> providing read-write access to memory-mapped files on Windows and POSIX systems.</P> |
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| 416 | |
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| 417 | <H4>Synopsis</H4> |
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| 418 | |
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| 419 | <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
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| 420 | |
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| 421 | <SPAN CLASS="keyword">class</SPAN> <SPAN CLASS="defined">mapped_file</SPAN> { |
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| 422 | <SPAN CLASS="keyword">public</SPAN>: |
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| 423 | <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>char</SPAN> char_type; |
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| 424 | <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN> category; |
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| 425 | <A CLASS='documented' HREF='#mapped_file_default_ctor'>mapped_file</A>(); |
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| 426 | <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_params_ctor'>mapped_file</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
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| 427 | <SPAN CLASS='keyword'>explicit</SPAN> <A CLASS='documented' HREF='#mapped_file_basic_ctor'>mapped_file</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 428 | std::ios_base::openmode mode = |
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| 429 | std::ios_base | std::ios_base, |
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| 430 | size_type length = max_length, |
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| 431 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
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| 432 | void <A CLASS='documented' HREF='#mapped_file_params_open'>open</A>(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params); |
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| 433 | void <A CLASS='documented' HREF='#mapped_file_basic_open'>open</A>( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 434 | std::ios_base::openmode mode = |
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| 435 | std::ios_base | std::ios_base, |
---|
| 436 | size_type length = max_length, |
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| 437 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> ); |
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| 438 | <SPAN CLASS='keyword'>bool</SPAN> <A CLASS='documented' HREF='#mapped_file_is_open'>is_open</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 439 | <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#mapped_file_close'>close</A>(); |
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| 440 | size_type <A CLASS='documented' HREF='#mapped_file_size'>size</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 441 | <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_data'>data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 442 | <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* <A CLASS='documented' HREF='#mapped_file_data'>const_data</A>() <SPAN CLASS='keyword'>const</SPAN>; |
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| 443 | <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> <A CLASS='documented' HREF='#mapped_file_alignment'>alignment</A>(); |
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| 444 | }; |
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| 445 | |
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| 446 | } } // End namespace boost::io</PRE> |
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| 447 | |
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| 448 | <A NAME="mapped_file_default_ctor"></A> |
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| 449 | <H4><CODE>mapped_file::mapped_file</CODE></H4> |
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| 450 | |
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| 451 | <PRE CLASS="broken_ie"> mapped_file();</PRE> |
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| 452 | |
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| 453 | <P>Constructs a <CODE>mapped_file</CODE> which must be opened before it can be used to perform i/o.</P> |
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| 454 | |
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| 455 | <A NAME="mapped_file_params_ctor"></A> |
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| 456 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
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| 457 | |
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| 458 | <P>Constructs a <CODE>mapped_file</CODE> from the given parameters.</P> |
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| 459 | |
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| 460 | <A NAME="mapped_file_basic_ctor"></A> |
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| 461 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>explicit</SPAN> mapped_file( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 462 | std::ios_base::openmode mode = |
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| 463 | std::ios_base | std::ios_base, |
---|
| 464 | size_type length = max_length, |
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| 465 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
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| 466 | |
---|
| 467 | <P>Constructs a <CODE>mapped_file</CODE> to access a specified file. The parameters have the following interpretation:</P> |
---|
| 468 | |
---|
| 469 | <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
---|
| 470 | <TR> |
---|
| 471 | <TR> |
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| 472 | <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
---|
| 473 | <TD>The pathname of the file to map.</TD> |
---|
| 474 | </TR> |
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| 475 | <TR> |
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| 476 | <TD VALIGN="top"><I>mode</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 477 | <TD>Indicates whether the file should be opened with read-access, write-access or both.</TD> |
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| 478 | </TR> |
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| 479 | <TR> |
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| 480 | <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
---|
| 481 | <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
---|
| 482 | </TR> |
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| 483 | <TR> |
---|
| 484 | <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
---|
| 485 | <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_alignment'><CODE>alignment</CODE></A>.</TD> |
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| 486 | </TR> |
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| 487 | </TABLE> |
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| 488 | |
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| 489 | <A NAME="mapped_file_params_open"></A> |
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| 490 | <H4><CODE>mapped_file::open</CODE></H4> |
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| 491 | |
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| 492 | <PRE CLASS="broken_ie"> void open(<A CLASS='documented' HREF='#mapped_file_params'>mapped_file_params</A> params);</PRE> |
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| 493 | |
---|
| 494 | <P>Connects this <CODE>mapped_file</CODE> to a memory-mapped file obtained as described by the given parameters.</P> |
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| 495 | |
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| 496 | <A NAME="mapped_file_basic_open"></A> |
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| 497 | <PRE CLASS="broken_ie"> void open( <SPAN CLASS='keyword'>const</SPAN> std::string& path, |
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| 498 | std::ios_base::openmode mode = |
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| 499 | std::ios_base | std::ios_base, |
---|
| 500 | size_type length = max_length, |
---|
| 501 | boost::intmax_t offset = <SPAN CLASS='numeric_literal'>0</SPAN> );</PRE> |
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| 502 | |
---|
| 503 | <P>Connects this <CODE>mapped_file</CODE> to a memory-mapped file obtained as described by the given parameters, which have the following interpretation:</P> |
---|
| 504 | |
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| 505 | <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
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| 506 | <TR> |
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| 507 | <TR> |
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| 508 | <TD VALIGN="top"><I>path</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
---|
| 509 | <TD>The pathname of the file to map.</TD> |
---|
| 510 | </TR> |
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| 511 | <TR> |
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| 512 | <TD VALIGN="top"><I>mode</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 513 | <TD>Indicates whether the file should be opened with read-access, write-access or both.</TD> |
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| 514 | </TR> |
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| 515 | <TR> |
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| 516 | <TD VALIGN="top"><I>length</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 517 | <TD>The number of bytes to map. If this parameter is not specified, the entire file is mapped.</TD> |
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| 518 | </TR> |
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| 519 | <TR> |
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| 520 | <TD VALIGN="top"><I>offset</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
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| 521 | <TD>The offset where the mapping is to begin. This value must be a multiple of the operating system's virtual memory allocation granularity, which can be obtained using the static member function <A HREF='#mapped_file_alignment'><CODE>alignment</CODE></A>.</TD> |
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| 522 | </TR> |
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| 523 | </TABLE> |
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| 524 | |
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| 525 | <A NAME="mapped_file_is_open"></A> |
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| 526 | <H4><CODE>mapped_file::is_open</CODE></H4> |
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| 527 | |
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| 528 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>bool</SPAN> is_open() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 529 | |
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| 530 | <P>Returns <CODE>true</CODE> if this <CODE>mapped_file</CODE> has been successfully opened without subsequently having been closed.</P> |
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| 531 | |
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| 532 | <A NAME="mapped_file_close"></A> |
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| 533 | <H4><CODE>mapped_file::close</CODE></H4> |
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| 534 | |
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| 535 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>void</SPAN> close();</PRE> |
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| 536 | |
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| 537 | <P>Frees the mapping associated with this <CODE>mapped_file</CODE>.</P> |
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| 538 | |
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| 539 | <A NAME="mapped_file_size"></A> |
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| 540 | <H4><CODE>mapped_file::size</CODE></H4> |
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| 541 | |
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| 542 | <PRE CLASS="broken_ie"> size_type size() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 543 | |
---|
| 544 | <P>Returns the size in bytes of the mapping associated with this <CODE>mapped_file</CODE>.</P> |
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| 545 | |
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| 546 | <A NAME="mapped_file_data"></A> |
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| 547 | <H4><CODE>mapped_file::data</CODE></H4> |
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| 548 | |
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| 549 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>char</SPAN>* data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 550 | |
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| 551 | <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file</CODE>, if it was opened with write-access, and a null pointer otherwise.</P> |
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| 552 | |
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| 553 | <A NAME="mapped_file_data"></A> |
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| 554 | <H4><CODE>mapped_file::data</CODE></H4> |
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| 555 | |
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| 556 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>const</SPAN> <SPAN CLASS='keyword'>char</SPAN>* const_data() <SPAN CLASS='keyword'>const</SPAN>;</PRE> |
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| 557 | |
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| 558 | <P>Returns a pointer to the first byte of data in the mapping associated with this <CODE>mapped_file</CODE>.</P> |
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| 559 | |
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| 560 | <A NAME="mapped_file_alignment"></A> |
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| 561 | <H4><CODE>mapped_file::alignment</CODE></H4> |
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| 562 | |
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| 563 | <PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>static</SPAN> <SPAN CLASS='keyword'>int</SPAN> alignment();</PRE> |
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| 564 | |
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| 565 | <P>Returns the operating system's virtual memory allocation granularity.</P> |
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| 566 | |
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| 567 | <!-- Begin Footer --> |
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| 568 | |
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| 569 | <HR> |
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| 570 | <P CLASS="copyright">Revised |
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| 571 | <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
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| 572 | 20 May, 2004 |
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| 573 | <!--webbot bot="Timestamp" endspan i-checksum="38504" --> |
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| 574 | </P> |
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| 575 | |
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| 576 | <P CLASS="copyright">© Copyright <A HREF="http://www.kangaroologic.com" TARGET="_top">Jonathan Turkanis</A>, 2004</P> |
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| 577 | <P CLASS="copyright"> |
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| 578 | 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">http://www.boost.org/LICENSE_1_0.txt</A>) |
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| 579 | </P> |
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| 580 | |
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| 581 | <!-- End Footer --> |
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| 582 | |
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| 583 | </BODY> |
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