<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/> <title>RAUL: DoubleBuffer.hpp Source File</title> <link href="tabs.css" rel="stylesheet" type="text/css"/> <link href="doxygen.css" rel="stylesheet" type="text/css"/> </head> <body> <!-- Generated by Doxygen 1.7.1 --> <div class="navigation" id="top"> <div class="tabs"> <ul class="tablist"> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="modules.html"><span>Modules</span></a></li> <li><a href="namespaces.html"><span>Namespaces</span></a></li> <li><a href="annotated.html"><span>Classes</span></a></li> <li class="current"><a href="files.html"><span>Files</span></a></li> </ul> </div> <div class="tabs2"> <ul class="tablist"> <li><a href="files.html"><span>File List</span></a></li> </ul> </div> <div class="header"> <div class="headertitle"> <h1>DoubleBuffer.hpp</h1> </div> </div> <div class="contents"> <div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* This file is part of Raul.</span> <a name="l00002"></a>00002 <span class="comment"> * Copyright (C) 2007-2009 David Robillard <http://drobilla.net></span> <a name="l00003"></a>00003 <span class="comment"> *</span> <a name="l00004"></a>00004 <span class="comment"> * Raul is free software; you can redistribute it and/or modify it under the</span> <a name="l00005"></a>00005 <span class="comment"> * terms of the GNU General Public License as published by the Free Software</span> <a name="l00006"></a>00006 <span class="comment"> * Foundation; either version 2 of the License, or (at your option) any later</span> <a name="l00007"></a>00007 <span class="comment"> * version.</span> <a name="l00008"></a>00008 <span class="comment"> *</span> <a name="l00009"></a>00009 <span class="comment"> * Raul is distributed in the hope that it will be useful, but WITHOUT ANY</span> <a name="l00010"></a>00010 <span class="comment"> * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS</span> <a name="l00011"></a>00011 <span class="comment"> * FOR A PARTICULAR PURPOSE. See the GNU General Public License for details.</span> <a name="l00012"></a>00012 <span class="comment"> *</span> <a name="l00013"></a>00013 <span class="comment"> * You should have received a copy of the GNU General Public License along</span> <a name="l00014"></a>00014 <span class="comment"> * with this program; if not, write to the Free Software Foundation, Inc.,</span> <a name="l00015"></a>00015 <span class="comment"> * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA</span> <a name="l00016"></a>00016 <span class="comment"> */</span> <a name="l00017"></a>00017 <a name="l00018"></a>00018 <span class="preprocessor">#ifndef RAUL_DOUBLE_BUFFER_HPP</span> <a name="l00019"></a>00019 <span class="preprocessor"></span><span class="preprocessor">#define RAUL_DOUBLE_BUFFER_HPP</span> <a name="l00020"></a>00020 <span class="preprocessor"></span> <a name="l00021"></a>00021 <span class="preprocessor">#include "raul/AtomicInt.hpp"</span> <a name="l00022"></a>00022 <span class="preprocessor">#include "raul/AtomicPtr.hpp"</span> <a name="l00023"></a>00023 <a name="l00024"></a>00024 <span class="keyword">namespace </span>Raul { <a name="l00025"></a>00025 <a name="l00035"></a>00035 <span class="keyword">template</span><<span class="keyword">typename</span> T> <a name="l00036"></a><a class="code" href="classRaul_1_1DoubleBuffer.html">00036</a> <span class="keyword">class </span><a class="code" href="classRaul_1_1DoubleBuffer.html" title="Double buffer.">DoubleBuffer</a> { <a name="l00037"></a>00037 <span class="keyword">public</span>: <a name="l00038"></a>00038 <a name="l00039"></a>00039 <span class="keyword">inline</span> <a class="code" href="classRaul_1_1DoubleBuffer.html" title="Double buffer.">DoubleBuffer</a>(T val) <a name="l00040"></a>00040 : _state(RAUL_DB_READ_WRITE) <a name="l00041"></a>00041 { <a name="l00042"></a>00042 _vals[0] = val; <a name="l00043"></a>00043 _read_val = &_vals[0]; <a name="l00044"></a>00044 } <a name="l00045"></a>00045 <a name="l00046"></a>00046 <span class="keyword">inline</span> <a class="code" href="classRaul_1_1DoubleBuffer.html" title="Double buffer.">DoubleBuffer</a>(<span class="keyword">const</span> <a class="code" href="classRaul_1_1DoubleBuffer.html" title="Double buffer.">DoubleBuffer</a>& copy) <a name="l00047"></a>00047 : _state(RAUL_DB_READ_WRITE) <a name="l00048"></a>00048 { <a name="l00049"></a>00049 T val = copy.get(); <a name="l00050"></a>00050 _vals[0] = val; <a name="l00051"></a>00051 _read_val = &_vals[0]; <a name="l00052"></a>00052 } <a name="l00053"></a>00053 <a name="l00054"></a>00054 <span class="keyword">inline</span> T& <span class="keyword">get</span>() <span class="keyword">const</span> { <a name="l00055"></a>00055 <span class="keywordflow">return</span> *_read_val.get(); <a name="l00056"></a>00056 } <a name="l00057"></a>00057 <a name="l00058"></a>00058 <span class="keyword">inline</span> <span class="keywordtype">bool</span> <span class="keyword">set</span>(T new_val) { <a name="l00059"></a>00059 <span class="keywordflow">if</span> (_state.compare_and_exchange(RAUL_DB_READ_WRITE, RAUL_DB_READ_LOCK)) { <a name="l00060"></a>00060 <a name="l00061"></a>00061 <span class="comment">// locked _vals[1] for write</span> <a name="l00062"></a>00062 _vals[1] = new_val; <a name="l00063"></a>00063 _read_val = &_vals[1]; <a name="l00064"></a>00064 _state = RAUL_DB_WRITE_READ; <a name="l00065"></a>00065 <span class="keywordflow">return</span> <span class="keyword">true</span>; <a name="l00066"></a>00066 <a name="l00067"></a>00067 <span class="comment">// concurrent calls here are fine. good, actually - caught</span> <a name="l00068"></a>00068 <span class="comment">// the WRITE_READ state immediately after it was set above</span> <a name="l00069"></a>00069 <a name="l00070"></a>00070 } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (_state.compare_and_exchange(RAUL_DB_WRITE_READ, RAUL_DB_LOCK_READ)) { <a name="l00071"></a>00071 <a name="l00072"></a>00072 <span class="comment">// locked _vals[0] for write</span> <a name="l00073"></a>00073 _vals[0] = new_val; <a name="l00074"></a>00074 _read_val = &_vals[0]; <a name="l00075"></a>00075 _state = RAUL_DB_READ_WRITE; <a name="l00076"></a>00076 <span class="keywordflow">return</span> <span class="keyword">true</span>; <a name="l00077"></a>00077 <a name="l00078"></a>00078 } <span class="keywordflow">else</span> { <a name="l00079"></a>00079 <a name="l00080"></a>00080 <span class="keywordflow">return</span> <span class="keyword">false</span>; <a name="l00081"></a>00081 <a name="l00082"></a>00082 } <a name="l00083"></a>00083 } <a name="l00084"></a>00084 <a name="l00085"></a>00085 <span class="keyword">private</span>: <a name="l00086"></a>00086 <span class="keyword">enum</span> States { <a name="l00087"></a>00087 <span class="comment">// vals[0] state _ vals[1] state</span> <a name="l00088"></a>00088 RAUL_DB_READ_WRITE = 0, <a name="l00089"></a>00089 RAUL_DB_READ_LOCK, <a name="l00090"></a>00090 RAUL_DB_WRITE_READ, <a name="l00091"></a>00091 RAUL_DB_LOCK_READ <a name="l00092"></a>00092 }; <a name="l00093"></a>00093 <a name="l00094"></a>00094 AtomicInt _state; <a name="l00095"></a>00095 AtomicPtr<T> _read_val; <a name="l00096"></a>00096 T _vals[2]; <a name="l00097"></a>00097 }; <a name="l00098"></a>00098 <a name="l00099"></a>00099 <a name="l00100"></a>00100 } <span class="comment">// namespace Raul</span> <a name="l00101"></a>00101 <a name="l00102"></a>00102 <span class="preprocessor">#endif // RAUL_DOUBLE_BUFFER_HPP</span> </pre></div></div> </div> <hr class="footer"/><address class="footer"><small>Generated on Wed Oct 6 2010 for RAUL by <a href="http://www.doxygen.org/index.html"> <img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.7.1 </small></address> </body> </html>