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    <title>clEnqueueWriteBuffer</title>
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    <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="clEnqueueWriteBuffer"></a>
        <h1>
            clEnqueueWriteBuffer
        </h1>
        <p>
            Enqueue commands to write to a buffer object from 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">clEnqueueWriteBuffer</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_write</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>const <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> 
                        Refers to the command-queue in which the write 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_write </code> </span>
            </dt>
            <dd>
              <p>
                       Indicates if the write operations are
                      <code class="varname">blocking</code> or <code class="varname">nonblocking</code>.
                    </p>
              <p>
                      If <code class="varname">blocking_write</code> is <code class="constant">CL_TRUE</code>, the
                      OpenCL implementation copies the data referred to by <code class="varname">ptr</code>
                      and enqueues the write operation in the command-queue. The memory pointed
                      to by <code class="varname">ptr</code> can be reused by the application after the
                      <code class="function">clEnqueueWriteBuffer</code> call returns.
                    </p>
              <p>
                      If <code class="varname">blocking_write</code> is <code class="constant">CL_FALSE</code>,
                      the OpenCL implementation will use <code class="varname">ptr</code> to perform a
                      nonblocking write. As the write is non-blocking the implementation can return
                      immediately. The memory pointed to by <code class="varname">ptr</code> cannot be reused
                      by the application after the call returns. The <code class="varname">event</code>
                      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 <code class="varname">ptr</code> can then be reused 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 write to.
                    </p>
            </dd>
            <dt>
              <span class="term"> <code class="varname"> size </code> </span>
            </dt>
            <dd>
              <p> 
                        The size in bytes of data being written.
                    </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 written from.
                    </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 write 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.
                    </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
          Calling <code class="function">clEnqueueWriteBuffer</code> to update the latest bits
          in 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 written 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">
              The host memory region given by <span class="emphasis"><em>(host_ptr + offset, cb)</em></span>
              contains the latest bits when the enqueued write 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">clEnqueueWriteBuffer</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 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 written 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 or if size is 0.
            </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> greater than
              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
              <a class="citerefentry" href="clEnqueueWriteBuffer.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueWriteBuffer</span></span></a>
              is called on <code class="varname">buffer</code> which has been
              created with <code class="constant">CL_MEM_HOST_READ_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="http://www.khronos.org/registry/cl/specs/opencl-1.2.pdf#page=72" 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="clEnqueueReadBuffer.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueReadBuffer</span></span></a>,
            <a class="citerefentry" href="clEnqueueReadBufferRect.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueReadBufferRect</span></span></a>,
            <a class="citerefentry" href="clEnqueueWriteBufferRect.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueWriteBufferRect</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 © 2007-2011 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
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