<!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>Apache Portable Runtime: Atomic Operations</title> <link href="tabs.css" rel="stylesheet" type="text/css"/> <link href="search/search.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="search/search.js"></script> <link href="doxygen.css" rel="stylesheet" type="text/css"/> </head> <body onload='searchBox.OnSelectItem(0);'> <!-- Generated by Doxygen 1.7.3 --> <script type="text/javascript"><!-- var searchBox = new SearchBox("searchBox", "search",false,'Search'); --></script> <div id="top"> <div id="titlearea"> <table cellspacing="0" cellpadding="0"> <tbody> <tr style="height: 56px;"> <td style="padding-left: 0.5em;"> <div id="projectname">Apache Portable Runtime</div> </td> </tr> </tbody> </table> </div> <div id="navrow1" class="tabs"> <ul class="tablist"> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="pages.html"><span>Related Pages</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>Data Structures</span></a></li> <li><a href="files.html"><span>Files</span></a></li> <li id="searchli"> <div id="MSearchBox" class="MSearchBoxInactive"> <span class="left"> <img id="MSearchSelect" src="search/mag_sel.png" onmouseover="return searchBox.OnSearchSelectShow()" onmouseout="return searchBox.OnSearchSelectHide()" alt=""/> <input type="text" id="MSearchField" value="Search" accesskey="S" onfocus="searchBox.OnSearchFieldFocus(true)" onblur="searchBox.OnSearchFieldFocus(false)" onkeyup="searchBox.OnSearchFieldChange(event)"/> </span><span class="right"> <a id="MSearchClose" href="javascript:searchBox.CloseResultsWindow()"><img id="MSearchCloseImg" border="0" src="search/close.png" alt=""/></a> </span> </div> </li> </ul> </div> </div> <div class="header"> <div class="summary"> <a href="#func-members">Functions</a> </div> <div class="headertitle"> <h1>Atomic Operations</h1> </div> <div class="ingroups"><a class="el" href="group___a_p_r.html">Apache Portability Runtime library</a></div></div> <div class="contents"> <table class="memberdecls"> <tr><td colspan="2"><h2><a name="func-members"></a> Functions</h2></td></tr> <tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="group__apr__errno.html#gaf76ee4543247e9fb3f3546203e590a6c">apr_status_t</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#gaa89b4022de39ca4d1c2ae6715e888e97">apr_atomic_init</a> (<a class="el" href="group__apr__pools.html#gaf137f28edcf9a086cd6bc36c20d7cdfb">apr_pool_t</a> *p)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">apr_uint32_t </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#gafba4de90e113d26536cff48418689771">apr_atomic_read32</a> (volatile apr_uint32_t *mem)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#gac689de9df18c093f66959227359328bb">apr_atomic_set32</a> (volatile apr_uint32_t *mem, apr_uint32_t val)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">apr_uint32_t </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#ga3ef16e13b679710fafd5196713e17433">apr_atomic_add32</a> (volatile apr_uint32_t *mem, apr_uint32_t val)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#ga4603396650e844bd987f01358ccb4df1">apr_atomic_sub32</a> (volatile apr_uint32_t *mem, apr_uint32_t val)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">apr_uint32_t </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#ga4af33da5aa6493ec321af14bedfc47a9">apr_atomic_inc32</a> (volatile apr_uint32_t *mem)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#ga7a8d16335fdcd27f2baca90df35ad300">apr_atomic_dec32</a> (volatile apr_uint32_t *mem)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">apr_uint32_t </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#gae45c529f14f8489102382bd3fd4cce22">apr_atomic_cas32</a> (volatile apr_uint32_t *mem, apr_uint32_t with, apr_uint32_t cmp)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">apr_uint32_t </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#ga50850e462d65e0409d5a93a6b4ec26c6">apr_atomic_xchg32</a> (volatile apr_uint32_t *mem, apr_uint32_t val)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">void * </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#gafdd02b41cc39ade873daa2734597b0fa">apr_atomic_casptr</a> (volatile void **mem, void *with, const void *cmp)</td></tr> <tr><td class="memItemLeft" align="right" valign="top">void * </td><td class="memItemRight" valign="bottom"><a class="el" href="group__apr__atomic.html#gaab4c1c5b8be70ded06dd31a1a4f65bf6">apr_atomic_xchgptr</a> (volatile void **mem, void *with)</td></tr> </table> <hr/><h2>Function Documentation</h2> <a class="anchor" id="ga3ef16e13b679710fafd5196713e17433"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_add32" ref="ga3ef16e13b679710fafd5196713e17433" args="(volatile apr_uint32_t *mem, apr_uint32_t val)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">apr_uint32_t apr_atomic_add32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">apr_uint32_t </td> <td class="paramname"><em>val</em> </td> </tr> <tr> <td></td> <td>)</td> <td></td><td></td> </tr> </table> </div> <div class="memdoc"> <p>atomically add 'val' to an apr_uint32_t </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the object </td></tr> <tr><td class="paramname">val</td><td>amount to add </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>old value pointed to by mem </dd></dl> </div> </div> <a class="anchor" id="gae45c529f14f8489102382bd3fd4cce22"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_cas32" ref="gae45c529f14f8489102382bd3fd4cce22" args="(volatile apr_uint32_t *mem, apr_uint32_t with, apr_uint32_t cmp)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">apr_uint32_t apr_atomic_cas32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">apr_uint32_t </td> <td class="paramname"><em>with</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">apr_uint32_t </td> <td class="paramname"><em>cmp</em> </td> </tr> <tr> <td></td> <td>)</td> <td></td><td></td> </tr> </table> </div> <div class="memdoc"> <p>compare an apr_uint32_t's value with 'cmp'. If they are the same swap the value with 'with' </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the value </td></tr> <tr><td class="paramname">with</td><td>what to swap it with </td></tr> <tr><td class="paramname">cmp</td><td>the value to compare it to </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>the old value of *mem </dd></dl> </div> </div> <a class="anchor" id="gafdd02b41cc39ade873daa2734597b0fa"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_casptr" ref="gafdd02b41cc39ade873daa2734597b0fa" args="(volatile void **mem, void *with, const void *cmp)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">void* apr_atomic_casptr </td> <td>(</td> <td class="paramtype">volatile void ** </td> <td class="paramname"><em>mem</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">void * </td> <td class="paramname"><em>with</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">const void * </td> <td class="paramname"><em>cmp</em> </td> </tr> <tr> <td></td> <td>)</td> <td></td><td></td> </tr> </table> </div> <div class="memdoc"> <p>compare the pointer's value with cmp. If they are the same swap the value with 'with' </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the pointer </td></tr> <tr><td class="paramname">with</td><td>what to swap it with </td></tr> <tr><td class="paramname">cmp</td><td>the value to compare it to </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>the old value of the pointer </dd></dl> </div> </div> <a class="anchor" id="ga7a8d16335fdcd27f2baca90df35ad300"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_dec32" ref="ga7a8d16335fdcd27f2baca90df35ad300" args="(volatile apr_uint32_t *mem)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">int apr_atomic_dec32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em></td><td>)</td> <td></td> </tr> </table> </div> <div class="memdoc"> <p>atomically decrement an apr_uint32_t by 1 </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the atomic value </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>zero if the value becomes zero on decrement, otherwise non-zero </dd></dl> </div> </div> <a class="anchor" id="ga4af33da5aa6493ec321af14bedfc47a9"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_inc32" ref="ga4af33da5aa6493ec321af14bedfc47a9" args="(volatile apr_uint32_t *mem)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">apr_uint32_t apr_atomic_inc32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em></td><td>)</td> <td></td> </tr> </table> </div> <div class="memdoc"> <p>atomically increment an apr_uint32_t by 1 </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the object </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>old value pointed to by mem </dd></dl> </div> </div> <a class="anchor" id="gaa89b4022de39ca4d1c2ae6715e888e97"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_init" ref="gaa89b4022de39ca4d1c2ae6715e888e97" args="(apr_pool_t *p)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname"><a class="el" href="group__apr__errno.html#gaf76ee4543247e9fb3f3546203e590a6c">apr_status_t</a> apr_atomic_init </td> <td>(</td> <td class="paramtype"><a class="el" href="group__apr__pools.html#gaf137f28edcf9a086cd6bc36c20d7cdfb">apr_pool_t</a> * </td> <td class="paramname"><em>p</em></td><td>)</td> <td></td> </tr> </table> </div> <div class="memdoc"> <p>this function is required on some platforms to initialize the atomic operation's internal structures </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">p</td><td>pool </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>APR_SUCCESS on successful completion </dd></dl> <dl class="remark"><dt><b>Remarks:</b></dt><dd>Programs do NOT need to call this directly. APR will call this automatically from apr_initialize. </dd></dl> </div> </div> <a class="anchor" id="gafba4de90e113d26536cff48418689771"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_read32" ref="gafba4de90e113d26536cff48418689771" args="(volatile apr_uint32_t *mem)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">apr_uint32_t apr_atomic_read32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em></td><td>)</td> <td></td> </tr> </table> </div> <div class="memdoc"> <p>atomically read an apr_uint32_t from memory </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>the pointer </td></tr> </table> </dd> </dl> </div> </div> <a class="anchor" id="gac689de9df18c093f66959227359328bb"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_set32" ref="gac689de9df18c093f66959227359328bb" args="(volatile apr_uint32_t *mem, apr_uint32_t val)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">void apr_atomic_set32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">apr_uint32_t </td> <td class="paramname"><em>val</em> </td> </tr> <tr> <td></td> <td>)</td> <td></td><td></td> </tr> </table> </div> <div class="memdoc"> <p>atomically set an apr_uint32_t in memory </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the object </td></tr> <tr><td class="paramname">val</td><td>value that the object will assume </td></tr> </table> </dd> </dl> </div> </div> <a class="anchor" id="ga4603396650e844bd987f01358ccb4df1"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_sub32" ref="ga4603396650e844bd987f01358ccb4df1" args="(volatile apr_uint32_t *mem, apr_uint32_t val)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">void apr_atomic_sub32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">apr_uint32_t </td> <td class="paramname"><em>val</em> </td> </tr> <tr> <td></td> <td>)</td> <td></td><td></td> </tr> </table> </div> <div class="memdoc"> <p>atomically subtract 'val' from an apr_uint32_t </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the object </td></tr> <tr><td class="paramname">val</td><td>amount to subtract </td></tr> </table> </dd> </dl> </div> </div> <a class="anchor" id="ga50850e462d65e0409d5a93a6b4ec26c6"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_xchg32" ref="ga50850e462d65e0409d5a93a6b4ec26c6" args="(volatile apr_uint32_t *mem, apr_uint32_t val)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">apr_uint32_t apr_atomic_xchg32 </td> <td>(</td> <td class="paramtype">volatile apr_uint32_t * </td> <td class="paramname"><em>mem</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">apr_uint32_t </td> <td class="paramname"><em>val</em> </td> </tr> <tr> <td></td> <td>)</td> <td></td><td></td> </tr> </table> </div> <div class="memdoc"> <p>exchange an apr_uint32_t's value with 'val'. </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the value </td></tr> <tr><td class="paramname">val</td><td>what to swap it with </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>the old value of *mem </dd></dl> </div> </div> <a class="anchor" id="gaab4c1c5b8be70ded06dd31a1a4f65bf6"></a><!-- doxytag: member="apr_atomic.h::apr_atomic_xchgptr" ref="gaab4c1c5b8be70ded06dd31a1a4f65bf6" args="(volatile void **mem, void *with)" --> <div class="memitem"> <div class="memproto"> <table class="memname"> <tr> <td class="memname">void* apr_atomic_xchgptr </td> <td>(</td> <td class="paramtype">volatile void ** </td> <td class="paramname"><em>mem</em>, </td> </tr> <tr> <td class="paramkey"></td> <td></td> <td class="paramtype">void * </td> <td class="paramname"><em>with</em> </td> </tr> <tr> <td></td> <td>)</td> <td></td><td></td> </tr> </table> </div> <div class="memdoc"> <p>exchange a pair of pointer values </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">mem</td><td>pointer to the pointer </td></tr> <tr><td class="paramname">with</td><td>what to swap it with </td></tr> </table> </dd> </dl> <dl class="return"><dt><b>Returns:</b></dt><dd>the old value of the pointer </dd></dl> </div> </div> </div> <!--- window showing the filter options --> <div id="MSearchSelectWindow" onmouseover="return searchBox.OnSearchSelectShow()" onmouseout="return searchBox.OnSearchSelectHide()" onkeydown="return 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