sdk/1.1/docs/man/clEnqueueReadBufferRect.xml

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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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<refentry>
    <refentryinfo>
        <keywordset>
            <keyword>clEnqueueReadBufferRect</keyword>
        </keywordset>
    </refentryinfo>

    <refmeta>
        <refentrytitle>       
            clEnqueueReadBufferRect
        </refentrytitle>

        <refmiscinfo>
            <copyright>
                <year>2007-2010</year>
                <holder>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.</holder>
            </copyright>
        </refmiscinfo>
        <manvolnum>3</manvolnum>
  
    </refmeta>


<!-- ================================ SYNOPSIS -->  

    <refnamediv id="clEnqueueReadBufferRect">
        <refname>     
            clEnqueueReadBufferRect
        </refname> 

        <refpurpose>          
            Enqueue commands to read from a rectangular region from a buffer object to host memory.
        </refpurpose> 
    </refnamediv> 

    <refsynopsisdiv xmlns:xlink="http://www.w3.org/1999/xlink"><title></title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>
                    <link xlink:href="scalarDataTypes.html">cl_int</link>
 <function>clEnqueueReadBufferRect</function>
                </funcdef>

                    <paramdef><link xlink:href="abstractDataTypes.html">cl_command_queue</link><parameter>command_queue</parameter></paramdef>
                    <paramdef><link xlink:href="abstractDataTypes.html">cl_mem</link><parameter>buffer</parameter></paramdef>
                    <paramdef><link xlink:href="enums.html#cl_bool">cl_bool</link><parameter>blocking_read</parameter></paramdef>
                    <paramdef>const <link xlink:href="scalarDataTypes.html">size_t</link><parameter>buffer_origin</parameter>[3]</paramdef>
                    <paramdef>const <link xlink:href="scalarDataTypes.html">size_t</link><parameter>host_origin</parameter>[3]</paramdef>
                    <paramdef>const <link xlink:href="scalarDataTypes.html">size_t</link><parameter>region</parameter>[3]</paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">size_t</link><parameter>buffer_row_pitch</parameter></paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">size_t</link><parameter>buffer_slice_pitch</parameter></paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">size_t</link><parameter>host_row_pitch</parameter></paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">size_t</link><parameter>host_slice_pitch</parameter></paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">void</link><parameter>*ptr</parameter></paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">cl_uint</link><parameter>num_events_in_wait_list</parameter></paramdef>
                    <paramdef>const <link xlink:href="abstractDataTypes.html">cl_event</link><parameter>*event_wait_list</parameter></paramdef>
                    <paramdef><link xlink:href="abstractDataTypes.html">cl_event</link><parameter>*event</parameter></paramdef>                         
            </funcprototype>
        </funcsynopsis>     
    </refsynopsisdiv>


<!-- ================================ PARAMETERS --> 

    <refsect1 id="parameters">
        <title>Parameters</title>
        <variablelist>

            <varlistentry>
                <term><varname>command_queue</varname></term>
                <listitem>
                    <para> <!-- parameter description -->
                        Refers to the command-queue in which the read command will be
                        queued. <varname>command_queue</varname> and <varname>buffer</varname> must be created with the same OpenCL context.
                    </para>
               </listitem>
            </varlistentry>
            <varlistentry>
                <term><varname>buffer</varname></term>
                <listitem>
                    <para>Refers to a valid buffer object.</para>
               </listitem>
            </varlistentry>
            <varlistentry>
                <term><varname>blocking_read</varname></term>
                <listitem>
                    <para> <!-- parameter description -->
                        Indicates if the read operations are <varname>blocking</varname> or non-blocking. If <varname>blocking_read</varname> is <constant>CL_TRUE</constant> i.e. the read command is blocking, <function>clEnqueueReadBufferRect</function> does not return until the buffer data has been read and copied into memory pointed to by <varname>ptr</varname>.
                    </para>
                    <para>
                        If <varname>blocking_read</varname> is <constant>CL_FALSE</constant> i.e. the read command is <varname>non-blocking</varname>, <function>clEnqueueReadBufferRect</function>
                        queues a <varname>non-blocking</varname> read command and returns. The contents of the buffer that <varname>ptr</varname> points to
                        cannot be used until the read command has completed. The <varname>event</varname> argument 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 <varname>ptr</varname> points to can be used by the application.
                    </para>
               </listitem>
            </varlistentry>
            <varlistentry>
                <term><varname>buffer_origin</varname></term>
                <listitem>
                    <para>The (<emphasis>x, y, z</emphasis>) offset in the memory region associated with <varname>buffer</varname>. For a 2D rectangle region, the <varname>z</varname> value given by <varname>buffer_origin</varname>[2] should be 0. The offset in bytes is computed as <varname>buffer_origin</varname>[2] * <varname>buffer_slice_pitch</varname> + <varname>buffer_origin</varname>[1] * <varname>buffer_row_pitch</varname> + <varname>buffer_origin</varname>[0].</para>
               </listitem>
            </varlistentry>
            
            <varlistentry>
                <term><varname>host_origin</varname></term>
                <listitem>
                    <para>The (<emphasis>x, y, z</emphasis>) offset in the memory region pointed to by <varname>ptr</varname>. For a 2D rectangle region, the <varname>z</varname> value given by <varname>host_origin</varname>[2] should be 0. The offset in bytes is computed as <varname>host_origin</varname>[2] * <varname>host_slice_pitch</varname> + <varname>host_origin</varname>[1] * <varname>host_row_pitch</varname> + <varname>host_origin</varname>[0].</para>
               </listitem>
            </varlistentry>
            
            <varlistentry>
                <term><varname>region</varname></term>
                <listitem>
                    <para>The (<emphasis>width, height, depth</emphasis>) in bytes of the 2D or 3D rectangle being read or written. For a 2D rectangle copy, the <varname>depth</varname> value given by <varname>region</varname>[2] should be 1. </para>
               </listitem>
            </varlistentry>
            
            <varlistentry>
                <term><varname>buffer_row_pitch</varname></term>
                <listitem>
                    <para>The length of each row in bytes to be used for the memory region associated with <varname>buffer</varname>. If <varname>buffer_row_pitch</varname> is 0, <varname>buffer_row_pitch</varname> is computed as <varname>region</varname>[0]. </para>
               </listitem>
            </varlistentry>
            
            <varlistentry>
                <term><varname>buffer_slice_pitch</varname></term>
                <listitem>
                    <para>The length of each 2D slice in bytes to be used for the memory region associated with <varname>buffer</varname>. If <varname>buffer_slice_pitch</varname> is 0, <varname>buffer_slice_pitch</varname> is computed as <varname>region</varname>[1] * <varname>buffer_row_pitch</varname>.</para>
               </listitem>
            </varlistentry>
            
            <varlistentry>
                <term><varname>host_row_pitch</varname></term>
                <listitem>
                    <para>The length of each row in bytes to be used for the memory region pointed to by <varname>ptr</varname>. If <varname>host_row_pitch</varname> is 0, <varname>host_row_pitch</varname> is computed as <varname>region</varname>[0].</para>
               </listitem>
            </varlistentry>
            
            <varlistentry>
                <term><varname>host_slice_pitch</varname></term>
                <listitem>
                    <para>The length of each 2D slice in bytes to be used for the memory region pointed to by <varname>ptr</varname>. If <varname>host_slice_pitch</varname> is 0, <varname>host_slice_pitch</varname> is computed as <varname>region</varname>[1] * <varname>host_row_pitch</varname>. </para>
               </listitem>
            </varlistentry>           
            
            <varlistentry>
                <term>
                    <varname>ptr </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        The pointer to buffer in host memory where data is to be read into.
                    </para>
               </listitem>
            </varlistentry>
            
               <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        event_wait_list 
                    </varname>
                </term>
                <term>
                    <varname> <!-- parameter name -->
                        num_events_in_wait_list 
                    </varname>
                </term>
                
                <listitem>
                    <para> <!-- parameter description -->
                        <varname>event_wait_list</varname> and <varname>num_events_in_wait_list</varname> specify events that need to complete before this particular command can be executed. If <varname>event_wait_list</varname> is NULL, then this particular command
does not wait on any event to complete. If <varname>event_wait_list</varname> is NULL, <varname>num_events_in_wait_list</varname> must be 0. If <varname>event_wait_list</varname> is not NULL, the list of events pointed to by <varname>event_wait_list</varname> must be valid and <varname>num_events_in_wait_list</varname> must be greater than 0. The events specified in <varname>event_wait_list</varname> act as synchronization points. The context associated with events in <varname>event_wait_list</varname> and <varname>command_queue</varname> must be the same.
                    </para>
               </listitem>
            </varlistentry> 
            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        event 
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        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. <varname>event</varname> 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.
                    </para>
               </listitem>
            </varlistentry>             

        

 
            <!-- END PARAMETER TABLE  -->          





        </variablelist>
    </refsect1>

    
<!-- ================================ NOTES  -->        
 

    <refsect1 id="notes"><title>Notes</title>
            <para>
                Calling <function>clEnqueueReadBufferRect</function> to read a region of the buffer object with the 
                <varname>ptr</varname> argument value set to <varname>host_ptr</varname> and <varname>host_origin</varname>,
                <varname>buffer_origin</varname> values are the same, where <varname>host_ptr</varname> is a pointer to the 
                memory region specified when the buffer object being read is created with CL_MEM_USE_HOST_PTR, must meet the 
                same requirements given for <citerefentry><refentrytitle>clEnqueueReadBuffer</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    

<!-- ================================ ERRORS  -->       


    <refsect1 id="errors"><title>Errors</title>
        <para>
            <function>clEnqueueReadBufferRect</function> returns <errorname>CL_SUCCESS</errorname> if the function is
            executed successfully. Otherwise, it returns one of the following errors:
        </para>
        <itemizedlist mark="disc">
            <listitem>
                <errorname>CL_INVALID_COMMAND_QUEUE</errorname> if <varname>command_queue</varname> is not a valid command-queue.
            </listitem>
            <listitem>
                <errorname>CL_INVALID_CONTEXT</errorname> if the context associated with <varname>command_queue</varname> 
                and <varname>buffer</varname> are not the same or if the context associated with <varname>command_queue</varname> 
                and events in <varname>event_wait_list</varname> are not the same.
            </listitem>
            <listitem>          
                <errorname>CL_INVALID_MEM_OBJECT</errorname> if <varname>buffer</varname> is not a valid buffer object.
            </listitem>
            <listitem>
                <errorname>CL_INVALID_VALUE</errorname> if the region being read specified by (<varname>buffer_origin</varname>, <varname>region</varname>) is out of bounds.
            </listitem>
            <listitem>
                <errorname>CL_INVALID_EVENT_WAIT_LIST</errorname> if <varname>event_wait_list</varname> is NULL and
                <varname>num_events_in_wait_list</varname> greater than 0, or <varname>event_wait_list</varname> is not NULL and <varname>num_events_in_wait_list</varname> is 0, or if event objects in <varname>event_wait_list</varname> are not valid events.
            </listitem>
            
            <listitem>
                <errorname>CL_MISALIGNED_SUB_BUFFER_OFFSET</errorname> if <varname>buffer</varname> is a sub-buffer object and <varname>offset</varname> specified when the sub-buffer object is created is not aligned to CL_DEVICE_MEM_BASE_ADDR_ALIGN value for device associated with <varname>queue</varname>.
            </listitem>
            
            <listitem>
                <errorname>CL_EXEC_STATUS_ERROR_FOR_EVENTS_IN_WAIT_LIST</errorname> if the read and write operations are blocking and the execution status of any of the events in <varname>event_wait_list</varname> is a negative integer value.
            </listitem>
            
            <listitem>
                <errorname>CL_MEM_OBJECT_ALLOCATION_FAILURE</errorname> if there is a failure to allocate memory for
                data store associated with <varname>buffer</varname>.
            </listitem>
            <listitem>
                <errorname>CL_OUT_OF_RESOURCES</errorname> if there is a failure to allocate resources required by the
OpenCL implementation on the device.
            </listitem>
            <listitem>
                <errorname>CL_OUT_OF_HOST_MEMORY</errorname> if there is a failure to allocate resources required by the
                OpenCL implementation on the host.  
            </listitem>

        </itemizedlist>
    </refsect1>
    

<!-- ================================ EXAMPLE  -->  
<!-- DO NOT DELETE IN CASE AN EXAMPLE IS ADDED IN THE FUTURE -->
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    <refsect2 id="example1">
        <title>
            Example
        </title>

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            <tgroup cols="1" align="left" colsep="0" rowsep="0">
                <colspec colname="col1" colnum="1" />
                <tbody>
                    <row>
                        <entry>
                            Example goes here - it will be set in "code" type with white space preserved.
                        </entry>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>   
    </refsect2>  
--> 


<!-- ================================ SPECIFICATION  -->        
<!-- Set the "uri" attribute in the <olink /> element to the "named destination" for the PDF page
-->     
    <refsect1 id="specification"><title>Specification</title>
        <para>
            <imageobject>
                <imagedata fileref="pdficon_small1.gif" format="gif" />
            </imageobject>
            
                      
            <olink uri="clEnqueueReadBufferRect">OpenCL Specification</olink>
        </para>
    </refsect1>     


<!-- ================================ ALSO SEE  -->     
   

    <refsect1 id="seealso"><title>Also see</title>
        <para>
            <citerefentry><refentrytitle>clEnqueueCopyBuffer</refentrytitle></citerefentry>, 
            <citerefentry><refentrytitle>clEnqueueCopyBufferRect</refentrytitle></citerefentry>, 
            <citerefentry><refentrytitle>clEnqueueWriteBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>clEnqueueWriteBufferRect</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>clEnqueueReadBuffer</refentrytitle></citerefentry>
        </para>
    </refsect1>

<!-- ================================ COPYRIGHT  -->  
<!-- Content included from copyright.inc.xsl -->

    <refsect3 id="Copyright"><title></title>
        <imageobject>
                <imagedata fileref="KhronosLogo.jpg" format="jpg" />
        </imageobject>
        <para />
    </refsect3>

</refentry>