| <?xml version="1.0" encoding="UTF-8"?> |
| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> |
| <!-- saved from url=(0013)about:internet --> |
| <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" xmlns:xlink="http://www.w3.org/1999/xlink" pref:renderer="mathplayer-dl"> |
| <head> |
| <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> |
| <style xmlns="" type="text/css"> |
| /* This style sets a margin around the entire page */ |
| html, body { |
| margin: 10px; |
| } |
| |
| p { |
| font: normal 16px verdana, sans-serif; |
| margin: 0; |
| padding-bottom:12px; |
| } |
| |
| h1 { |
| font: bold 25px verdana, sans-serif; |
| margin-top: 0; |
| margin-bottom: 3px; |
| padding-top: 0; |
| padding-bottom: 0; |
| } |
| |
| h2 { |
| font: bold 19px verdana, sans-serif; |
| margin-top: 28px; |
| margin-bottom: 3px; |
| padding-top: 0; |
| padding-bottom: 0; |
| } |
| |
| h3 { |
| font: bold 19px verdana, sans-serif !important; |
| margin-top: 28px; |
| margin-bottom: 3px; |
| padding-top: 0; |
| padding-bottom: 0; |
| } |
| |
| li { |
| font: normal 16px verdana, sans-serif; |
| margin-top: 0; |
| margin-bottom: 18px; |
| padding-top: 0; |
| padding-bottom: 0; |
| } |
| |
| .pdparam { |
| font: italic 16px verdana, sans-serif; |
| } |
| |
| .term { |
| font: italic 16px verdana, sans-serif; |
| font-weight: normal; |
| } |
| |
| .type { |
| font: normal 16px verdana, sans-serif !important; |
| } |
| |
| .parameter { |
| font-style: italic; |
| } |
| |
| a:link, a:visited { |
| color: blue; |
| text-decoration: none; |
| font: normal 16px; |
| } |
| |
| a:hover { |
| background-color: #FFFF99; |
| font: normal 16px; |
| } |
| |
| div.funcsynopsis { |
| text-align: left; |
| background-color: #e6e6e6; |
| font: normal 16px verdana, sans-serif; |
| padding-top: 10px; |
| padding-bottom: 10px; |
| } |
| |
| div.funcsynopsis table { |
| border-collapse: separate; |
| font: normal 16px verdana, sans-serif; |
| } |
| |
| div.funcsynopsis td { |
| background-color: #e6e6e6; |
| border: 0 solid #000; |
| padding: 1px; |
| font: normal 16px verdana, sans-serif; |
| } |
| |
| div.refsect1 { |
| font-family: verdana, sans-serif; |
| font-size: 16px; |
| } |
| |
| code.constant { |
| font: normal 16px courier new, monospace !important; |
| } |
| |
| span.errorname { |
| font: normal 16px verdana, sans-serif !important; |
| } |
| |
| code.function { |
| font: bold 16px verdana, sans-serif !important; |
| } |
| |
| b.fsfunc { |
| font: bold 16px verdana, sans-serif !important; |
| } |
| |
| code.varname { |
| font: italic 16px verdana, sans-serif; |
| } |
| |
| code.replaceable { |
| font: italic 16px courier new, monospace; |
| } |
| |
| code.funcdef { |
| font: normal 16px verdana, sans-serif !important; |
| } |
| |
| .citerefentry { |
| font: normal 16px verdana, sans-serif !important; |
| } |
| |
| .parameter { |
| font-style: italic; |
| } |
| |
| code.fsfunc { |
| font: normal 16px verdana, sans-serif !important; |
| } |
| |
| /* PARAMETER: This style controls spacing between the terms in Parameter section */ |
| dt { |
| margin-top: 15px; |
| } |
| |
| /* TABLES: These styles apply to all tables OTHER than the Synopsis and Example tables */ |
| div.refsect1 table { |
| width: 100%; |
| margin-top: 10px; |
| background-color: #FFF; |
| border-collapse: collapse; |
| border-color: #000; |
| border-width: 1px; |
| font: normal 16px verdana, sans-serif; |
| } |
| |
| div.refsect1 th { |
| border-collapse: collapse; |
| border-color: #000; |
| border-width: 1px; |
| font: bold 16px verdana, sans-serif; |
| } |
| |
| div.refsect1 td { |
| background-color: #FFF; |
| padding: 5px; |
| vertical-align: text-top; |
| border-collapse: collapse; |
| border-color: #000; |
| border-width: 1px; |
| font: normal 16px verdana, sans-serif; |
| } |
| |
| div.refsect1 p{ |
| font: normal 16px verdana, sans-serif; |
| margin-top: 8px; |
| margin-bottom: 8px; |
| padding-top: 0; |
| padding-bottom: 0; |
| } |
| |
| |
| /* EXAMPLE: These styles apply only to the Example section */ |
| div.refsect2 { |
| font: normal 16px courier new, monospace !important; |
| } |
| |
| div.refsect2 table { |
| margin-top: 0; |
| background-color: #e6e6e6; |
| width: 100%; |
| border: 0 solid #000; |
| padding: 2px; |
| font: normal 16px courier new, monospace !important; |
| } |
| |
| div.refsect2 td { |
| background-color: #e6e6e6; |
| font: normal 16px courier new, monospace !important; |
| white-space:pre; |
| } |
| |
| /* COPYRIGHT: This style formats the text of the copyright statement at the bottom of the page */ |
| div.refsect3 { |
| font: normal 11px verdana, sans-serif; |
| margin-top: 50px; |
| margin-bottom: 20px; |
| padding-top: 0; |
| padding-bottom: 0; |
| } |
| |
| </style> |
| <title>clEnqueueReadBuffer</title> |
| <meta name="generator" content="DocBook XSL Stylesheets V1.79.1" /> |
| <meta name="keywords" content="clEnqueueReadBuffer" /> |
| </head> |
| <body> |
| <div class="refentry"> |
| <a id="id-1"></a> |
| <div class="titlepage"></div> |
| <div xmlns="" class="refnamediv"> |
| <a xmlns="http://www.w3.org/1999/xhtml" id="clEnqueueReadBuffer"></a> |
| <h1> |
| clEnqueueReadBuffer |
| </h1> |
| <p> |
| Enqueue commands to read from a buffer object to host memory. |
| </p> |
| </div> |
| <div class="refsynopsisdiv"> |
| <h2></h2> |
| <div class="funcsynopsis"> |
| <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"> |
| <tr valign="bottom"> |
| <td> |
| <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef"> |
| <a class="link" href="scalarDataTypes.html" target="pagedisplay">cl_int</a> |
| <strong class="fsfunc">clEnqueueReadBuffer</strong> |
| (</code> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="pagedisplay">cl_command_queue</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">command_queue</var>, </td> |
| </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="pagedisplay">cl_mem</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">buffer</var>, </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="enums.html#cl_bool" target="pagedisplay">cl_bool</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">blocking_read</var>, </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="pagedisplay">size_t</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">offset</var>, </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="pagedisplay">size_t</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">size</var>, </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="pagedisplay">void</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*ptr</var>, </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="pagedisplay">cl_uint</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">num_events_in_wait_list</var>, </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td>const <a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="pagedisplay">cl_event</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*event_wait_list</var>, </td> |
| </tr> |
| <tr valign="top"> |
| <td> </td> |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="pagedisplay">cl_event</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*event</var><code>)</code></td> |
| </tr> |
| </table> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a id="parameters"></a> |
| <h2>Parameters</h2> |
| <div class="variablelist"> |
| <dl class="variablelist"> |
| <dt> |
| <span class="term"> |
| <code class="varname">command_queue</code> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Is a valid host command-queue in which the read command will be |
| queued. <code class="varname">command_queue</code> and <code class="varname">buffer</code> |
| must be created with the same OpenCL context. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="varname">buffer</code> |
| </span> |
| </dt> |
| <dd> |
| <p>Refers to a valid buffer object.</p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="varname">blocking_read</code> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Indicates if the read operations are |
| <code class="varname">blocking</code> or <code class="varname">non-blocking</code>. |
| </p> |
| <p> |
| If <code class="varname">blocking_read</code> is <code class="constant">CL_TRUE</code> |
| i.e. the read command is blocking, <code class="function">clEnqueueReadBuffer</code> |
| does not return until the buffer data has been read and copied into memory |
| pointed to by <code class="varname">ptr</code>. |
| </p> |
| <p> |
| If <code class="varname">blocking_read</code> is <code class="constant">CL_FALSE</code> |
| i.e. the read command is <code class="varname">non-blocking</code>, |
| <code class="function">clEnqueueReadBuffer</code> queues a |
| <code class="varname">non-blocking</code> read command and returns. The contents of |
| the buffer that <code class="varname">ptr</code> points to cannot be used until the |
| read command has completed. The <code class="varname">event</code> argument returns |
| an event object which can be used to query the execution status of the |
| read command. When the read command has completed, the contents of the |
| buffer that <code class="varname">ptr</code> points to can be used by the application. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="varname">offset</code> |
| </span> |
| </dt> |
| <dd> |
| <p>The offset in bytes in the buffer object to read from.</p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="varname">size</code> |
| </span> |
| </dt> |
| <dd> |
| <p>The size in bytes of data being read.</p> |
| </dd> |
| <dt> |
| <span class="term"> <code class="varname">ptr </code> </span> |
| </dt> |
| <dd> |
| <p> |
| The pointer to buffer in host memory where data is to be read into. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="varname">event_wait_list</code> |
| , </span> |
| <span class="term"> |
| <code class="varname">num_events_in_wait_list</code> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| <code class="varname">event_wait_list</code> |
| and <code class="varname">num_events_in_wait_list</code> specify events that |
| need to complete before this particular command can be executed. |
| If <code class="varname">event_wait_list</code> is NULL, then this particular command |
| does not wait on any event to complete. If <code class="varname">event_wait_list</code> |
| is NULL, <code class="varname">num_events_in_wait_list</code> must be 0. If |
| <code class="varname">event_wait_list</code> is not NULL, the list of events |
| pointed to by <code class="varname">event_wait_list</code> must be valid |
| and <code class="varname">num_events_in_wait_list</code> must be greater |
| than 0. The events specified in <code class="varname">event_wait_list</code> |
| act as synchronization points. The context associated with events in |
| <code class="varname">event_wait_list</code> and <code class="varname">command_queue</code> must |
| be the same. The memory associated with <code class="varname">event_wait_list</code> |
| can be reused or freed after the function returns. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> <code class="varname"> event </code> </span> |
| </dt> |
| <dd> |
| <p> |
| Returns an event object that identifies |
| this particular read command and can be used to query or queue a wait |
| for this particular command to complete. <code class="varname">event</code> can be |
| NULL in which case it will not be possible for the application to query |
| the status of this command or queue a wait for this command to complete. |
| If the <code class="varname">event_wait_list</code> and the <code class="varname">event</code> arguments are |
| not NULL, the <code class="varname">event</code> argument should not refer to an |
| element of the <code class="varname">event_wait_list</code> array. |
| </p> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a id="notes"></a> |
| <h2>Notes</h2> |
| <p> |
| Calling <code class="function">clEnqueueReadBuffer</code> to read a region of the buffer object |
| with the <code class="varname">ptr</code> argument value set to <code class="varname">host_ptr</code> |
| + <code class="varname">offset</code>, where <code class="varname">host_ptr</code> is a pointer to |
| the memory region specified when the buffer object being read is created with |
| <code class="constant">CL_MEM_USE_HOST_PTR</code>, must meet the following requirements in |
| order to avoid undefined behavior: |
| </p> |
| <div class="itemizedlist"> |
| <ul class="itemizedlist" style="list-style-type: disc; "> |
| <li class="listitem" style="list-style-type: disc"> |
| All commands that use this buffer object or a memory object (buffer or image) |
| created from this buffer object have finished execution before the read command |
| begins execution. |
| </li> |
| <li class="listitem" style="list-style-type: disc"> |
| The buffer object or memory objects created from this buffer object are not mapped. |
| </li> |
| <li class="listitem" style="list-style-type: disc"> |
| The buffer object or memory objects created from this buffer object are not used |
| by any command-queue until the read command has finished execution. |
| </li> |
| </ul> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a id="errors"></a> |
| <h2>Errors</h2> |
| <p> |
| <code class="function">clEnqueueReadBuffer</code> returns <span class="errorname">CL_SUCCESS</span> if |
| the function is executed successfully. Otherwise, it returns one of the following errors: |
| </p> |
| <div class="itemizedlist"> |
| <ul class="itemizedlist" style="list-style-type: disc; "> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_COMMAND_QUEUE</span> if <code class="varname">command_queue</code> |
| is not a valid host command-queue. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_CONTEXT</span> if the context associated with |
| <code class="varname">command_queue</code> and <code class="varname">buffer</code> are not the same |
| or if the context associated with <code class="varname">command_queue</code> and events in |
| <code class="varname">event_wait_list</code> are not the same. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_MEM_OBJECT</span> if <code class="varname">buffer</code> is not |
| a valid buffer object. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_VALUE</span> if the region being read specified by |
| (<code class="varname">offset</code>, <code class="varname">size</code>) is out of bounds or if |
| <code class="varname">ptr</code> is a NULL value. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_EVENT_WAIT_LIST</span> |
| if <code class="varname">event_wait_list</code> is NULL and |
| <code class="varname">num_events_in_wait_list</code> > |
| 0, or <code class="varname">event_wait_list</code> is not NULL and |
| <code class="varname">num_events_in_wait_list</code> is 0, or if event objects in |
| <code class="varname">event_wait_list</code> are not valid events. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_MISALIGNED_SUB_BUFFER_OFFSET</span> if |
| <code class="varname">buffer</code> is a sub-buffer object and <code class="varname">offset</code> |
| specified when the sub-buffer object is created is not aligned to |
| <code class="constant">CL_DEVICE_MEM_BASE_ADDR_ALIGN</code> value for device associated |
| with <code class="varname">queue</code>. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_EXEC_STATUS_ERROR_FOR_EVENTS_IN_WAIT_LIST</span> if the read |
| and write operations are blocking and the execution status of any of the events |
| in <code class="varname">event_wait_list</code> is a negative integer value. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_MEM_OBJECT_ALLOCATION_FAILURE</span> if there is a failure to |
| allocate memory for data store associated with <code class="varname">buffer</code>. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_OPERATION</span> if |
| <code class="function">clEnqueueReadBuffer</code> is called on <code class="varname">buffer</code> |
| which has been created with <code class="constant">CL_MEM_HOST_WRITE_ONLY</code> or |
| <code class="constant">CL_MEM_HOST_NO_ACCESS</code>. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_OUT_OF_RESOURCES</span> if there is a failure to allocate |
| resources required by the OpenCL implementation on the device. |
| </li> |
| <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_OUT_OF_HOST_MEMORY</span> if there is a failure to allocate |
| resources required by the OpenCL implementation on the host. |
| </li> |
| </ul> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a id="specification"></a> |
| <h2>Specification</h2> |
| <p> |
| <img src="pdficon_small1.gif" /> |
| |
| <a href="https://www.khronos.org/registry/cl/specs/opencl-2.1.pdf#page=110" target="OpenCL Spec">OpenCL Specification</a> |
| </p> |
| </div> |
| <div class="refsect1"> |
| <a id="seealso"></a> |
| <h2>Also see</h2> |
| <p> |
| <a class="citerefentry" href="clEnqueueCopyBuffer.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueCopyBuffer</span></span></a>, |
| <a class="citerefentry" href="clEnqueueWriteBuffer.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueWriteBuffer</span></span></a>, |
| <a class="citerefentry" href="clEnqueueWriteBufferRect.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueWriteBufferRect</span></span></a>, |
| <a class="citerefentry" href="clEnqueueReadBufferRect.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueReadBufferRect</span></span></a> |
| </p> |
| </div> |
| <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2015 The Khronos Group Inc. |
| Permission is hereby granted, free of charge, to any person obtaining a |
| copy of this software and/or associated documentation files (the |
| "Materials"), to deal in the Materials without restriction, including |
| without limitation the rights to use, copy, modify, merge, publish, |
| distribute, sublicense, and/or sell copies of the Materials, and to |
| permit persons to whom the Materials are furnished to do so, subject to |
| the condition that this copyright notice and permission notice shall be included |
| in all copies or substantial portions of the Materials. |
| </div> |
| </div> |
| </body> |
| </html> |
