sdk/1.1/docs/man/clEnqueueWriteBuffer.xml

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<refentry>
    <refentryinfo>
        <keywordset>
            <keyword>clEnqueueWriteBuffer</keyword>
        </keywordset>
    </refentryinfo>

    <refmeta>
        <refentrytitle>       
            clEnqueueWriteBuffer
        </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="clEnqueueWriteBuffer">
        <refname>     
            clEnqueueWriteBuffer
        </refname> 

        <refpurpose>          
            Enqueue commands to write to a buffer object from 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>clEnqueueWriteBuffer</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_write</parameter></paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">size_t</link><parameter>offset</parameter></paramdef>
                    <paramdef><link xlink:href="scalarDataTypes.html">size_t</link><parameter>cb</parameter></paramdef>
                    <paramdef>const <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> <!-- parameter name -->
                        command_queue
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        Refers to the command-queue in which the write 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> <!-- parameter name -->
                        buffer
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        Refers to a valid buffer object.
                    </para>
               </listitem>
            </varlistentry>
            
            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        blocking_write
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        Indicates if the write operations are <varname>blocking</varname> or <varname>nonblocking</varname>.
                    </para>
                    <para>
                        If <varname>blocking_write</varname> is <constant>CL_TRUE</constant>, the OpenCL implementation copies the data referred to by <varname>ptr</varname>
                        and enqueues the write operation in the command-queue. The memory pointed to by <varname>ptr</varname> can be
                        reused by the application after the <function>clEnqueueWriteBuffer</function> call returns.
                    </para>
                    <para>
                        If <varname>blocking_write</varname> is <constant>CL_FALSE</constant>, the OpenCL implementation will use <varname>ptr</varname> to perform a nonblocking
                        write. As the write is non-blocking the implementation can return immediately. The
                        memory pointed to by <varname>ptr</varname> cannot be reused by the application after the call returns. The <varname>event</varname>
                        argument returns an event object which can be used to query the execution status of the write
                        command. When the write command has completed, the memory pointed to by <varname>ptr</varname> can then be
                        reused by the application.                  
                    </para>                 
               </listitem>
            </varlistentry>

            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        offset
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        The offset in bytes in the buffer object to write to.
                    </para>
               </listitem>
            </varlistentry>

            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        cb 
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        The size in bytes of data being written.
                    </para>
               </listitem>
            </varlistentry>

            <varlistentry>
                <term>
                    <varname> <!-- parameter name -->
                        ptr 
                    </varname>
                </term>

                <listitem>
                    <para> <!-- parameter description -->
                        The pointer to buffer in host memory where data is to be written from.
                    </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 write 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>             

        </variablelist>
    </refsect1>

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

    <refsect1 id="notes"><title>Notes</title>
            <para>
                Calling <function>clEnqueueWriteBuffer</function> to update the latest bits in a region of the buffer object with 
                the <varname>ptr</varname> argument value set to <varname>host_ptr</varname> + <varname>offset</varname>, where <varname>host_ptr</varname> 
                is a pointer to the memory region specified when the buffer object being written is created with <function>CL_MEM_USE_HOST_PTR</function>, 
                must meet the following requirements in order to avoid undefined behavior:
            </para>
        <itemizedlist mark="disc">
            <listitem>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.</listitem>
            <listitem>The buffer object or memory objects created from this buffer object are not mapped.</listitem>
            <listitem>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.</listitem>
        </itemizedlist>
    </refsect1>
    

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


    <refsect1 id="errors"><title>Errors</title>
        <para>
            <function>clEnqueueWriteBuffer</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 written specified by (<varname>offset</varname>, 
                <varname>cb</varname>) is out of bounds or if <varname>ptr</varname> is a NULL value.
            </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  -->  
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            Example
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<!-- ================================ SPECIFICATION  -->        
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        <para>
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            <olink uri="clEnqueueWriteBuffer">OpenCL Specification</olink>
        </para>
    </refsect1>     


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

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

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

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

</refentry>