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| <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" |
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| |
| <refentry> |
| <refentryinfo> |
| <keywordset> |
| <keyword>clEnqueueReadImage</keyword> |
| </keywordset> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle> |
| clEnqueueReadImage |
| </refentrytitle> |
| |
| <refmiscinfo> |
| <copyright> |
| <year>2007-2013</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="clEnqueueReadImage"> |
| <refname> |
| clEnqueueReadImage |
| </refname> |
| |
| <refpurpose> |
| Enqueue commands to read from an image or image array 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>clEnqueueReadImage</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>image</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>*origin</parameter> |
| </paramdef> |
| <paramdef>const |
| <link xlink:href="scalarDataTypes.html">size_t</link> |
| <parameter>*region</parameter> |
| </paramdef> |
| <paramdef> |
| <link xlink:href="scalarDataTypes.html">size_t</link> |
| <parameter>row_pitch</parameter> |
| </paramdef> |
| <paramdef> |
| <link xlink:href="scalarDataTypes.html">size_t</link> |
| <parameter>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> |
| Refers to the host command-queue in which the read command will be |
| queued. <varname>command_queue</varname> and <varname>image</varname> |
| must be created with the same OpenCL context. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> <varname> image </varname> </term> |
| <listitem> |
| <para> |
| Refers to a valid image or image array object. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> <varname> blocking_read </varname> </term> |
| <listitem> |
| <para> |
| Indicates if the read operations are <varname>blocking</varname> or |
| <varname>non-blocking</varname>. |
| </para> |
| |
| <para> |
| If <varname>blocking_read</varname> is <constant>CL_TRUE</constant> |
| i.e. the read command is blocking, <function>clEnqueueReadImage</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. map operation is non-blocking, <function>clEnqueueReadImage</function> |
| queues a non-blocking 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 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> origin </varname> </term> |
| <listitem> |
| <para> |
| Defines the (<emphasis>x, y, z</emphasis>) offset in pixels in the 1D, 2D, or |
| 3D image, the (<emphasis>x, y</emphasis>) offset and the image index in the |
| image array or the (x) offset and the image index in the 1D image array. If |
| <varname>image</varname> is a 2D image object, <varname>origin</varname>[2] |
| must be 0. If <varname>image</varname> is a 1D image or 1D image buffer |
| object, <varname>origin</varname>[1] and <varname>origin</varname>[2] |
| must be 0. If <varname>image</varname> is a 1D image array object, |
| <varname>origin</varname>[2] must be 0. If <varname>image</varname> |
| is a 1D image array object, <varname>origin</varname>[1] describes the |
| image index in the 1D image array. If <varname>image</varname> is a 2D |
| image array object, <varname>origin</varname>[2] describes the image |
| index in the 2D image array. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> <varname> region </varname> </term> |
| <listitem> |
| <para> |
| Defines the (<emphasis>width, height, depth</emphasis>) in pixels of the |
| 1D, 2D or 3D rectangle, the (<emphasis>width, height</emphasis>) in pixels |
| of the 2D rectangle and the number of images of a 2D image array or the |
| (<emphasis>width</emphasis>) in pixels of the 1D rectangle and the number |
| of images of a 1D image array. If <varname>image</varname> is a 2D image |
| object, <varname>region</varname>[2] must be 1. If <varname>image</varname> |
| is a 1D image or 1D image buffer object, <varname>region</varname>[1] |
| and <varname>region</varname>[2] must be 1. If image is a 1D image array |
| object, <varname>region</varname>[2] must be 1. The values in <varname>region</varname> cannot be 0. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> <varname> row_pitch </varname> </term> |
| <listitem> |
| <para> |
| The length of each row in bytes. This value must be greater than or |
| equal to the element size in bytes * <varname>width</varname>. If |
| <varname>row_pitch</varname> is set to 0, the appropriate row pitch |
| is calculated based on the size of each element in bytes multiplied by |
| <varname>width</varname>. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> <varname> slice_pitch </varname> </term> |
| <listitem> |
| <para> |
| Size in bytes of the 2D slice of the 3D region of a 3D image or |
| each image of a 1D or 2D image array being read. This must be 0 if |
| <varname>image</varname> is a 1D or 2D image. Otherwise this value must be greater |
| than or equal to <varname>row_pitch</varname> * <varname>height</varname>. |
| If <varname>slice_pitch</varname> is set to 0, the appropriate slice |
| pitch is calculated based on the <varname>row_pitch</varname> * |
| <varname>height</varname>. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> <varname> ptr </varname> </term> |
| <listitem> |
| <para> |
| The pointer to a buffer in host memory where image data is to be written to. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> <varname> |
| event_wait_list |
| ,</varname> |
| <varname> |
| num_events_in_wait_list |
| </varname> |
| </term> |
| |
| <listitem> |
| <para> |
| 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. The memory associated with <varname>event_wait_list</varname> |
| can be reused or freed after the function returns. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term> |
| <varname> |
| event |
| </varname> |
| </term> |
| |
| <listitem> |
| <para> |
| 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. If the |
| <varname>event_wait_list</varname> and the <varname>event</varname> |
| arguments are not NULL, the <varname>event</varname> argument should not |
| refer to an element of the <varname>event_wait_list</varname> array. |
| </para> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| </refsect1> |
| |
| <!-- ================================ NOTES --> |
| |
| <refsect1 id="notes"><title>Notes</title> |
| <para> |
| Calling <function>clEnqueueReadImage</function> to read a region of the |
| <varname>image</varname> with the <varname>ptr</varname> argument value set to |
| <varname>host_ptr</varname> + (<varname>origin</varname>[2] * <varname>image |
| slice pitch</varname> + <varname>origin</varname>[1] * <varname>image |
| row pitch</varname> + <varname>origin</varname>[0] * <varname>bytes per |
| pixel</varname>), where <varname>host_ptr</varname> is a pointer to the memory |
| region specified when the <varname>image</varname> being read is created with |
| <constant>CL_MEM_USE_HOST_PTR</constant>, must meet the following requirements in |
| order to avoid undefined behavior: |
| </para> |
| |
| <itemizedlist mark="disc"> |
| <listitem> |
| All commands that use this image object have finished execution before the read |
| command begins execution. |
| </listitem> |
| |
| <listitem> |
| The <varname>row_pitch</varname> and <varname>slice_pitch</varname> argument |
| values in <function>clEnqueueReadImage</function> must be set to the image row |
| pitch and slice pitch. |
| </listitem> |
| |
| <listitem> |
| The image object is not mapped. |
| </listitem> |
| |
| <listitem> |
| The image object is not used by any command-queue until the read command has |
| finished execution. |
| </listitem> |
| </itemizedlist> |
| |
| <para> |
| If the mipmap extensions are enabled with <citerefentry><refentrytitle>cl_khr_mipmap_image</refentrytitle></citerefentry>, |
| calls to <function>clEnqueueReadImage</function>, |
| <citerefentry><refentrytitle>clEnqueueWriteImage</refentrytitle></citerefentry> and |
| <citerefentry><refentrytitle>clEnqueueMapImage</refentrytitle></citerefentry> can be used to read |
| from or write to a specific mip-level of a mip-mapped image. |
| If image argument is a 1D image, <varname>origin</varname>[1] specifies the mip-level to use. |
| If image argument is a 1D image array, <varname>origin</varname>[2] specifies the mip-level to use. |
| If image argument is a 2D image, <varname>origin</varname>[3] specifies the mip-level to use. |
| If image argument is a 2D image array or a 3D image, <varname>origin</varname>[3] specifies the mip-level to use. |
| </para> |
| |
| </refsect1> |
| |
| <!-- ================================ ERRORS --> |
| |
| <refsect1 id="errors"><title>Errors</title> |
| <para> |
| <function>clEnqueueReadImage</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 host command-queue. |
| </listitem> |
| |
| <listitem> |
| <errorname>CL_INVALID_CONTEXT</errorname> if the context associated with |
| <varname>command_queue</varname> and <varname>image</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>image</varname> is not |
| a valid image object. |
| </listitem> |
| |
| <listitem> |
| <errorname>CL_INVALID_VALUE</errorname> if the region being read specified by |
| <varname>origin</varname> and <varname>region</varname> is out of bounds or if |
| <varname>ptr</varname> is a NULL value. |
| </listitem> |
| |
| <listitem> |
| <errorname>CL_INVALID_VALUE</errorname> if values in <varname>origin</varname> |
| and <varname>region</varname> do not follow rules described in the argument |
| description for <varname>origin</varname> and <varname>region</varname>. |
| </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> > 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_INVALID_IMAGE_SIZE</errorname> if image dimensions (image width, |
| height, specified or compute row and/or slice pitch) for <varname>image</varname> |
| are not supported by device associated with <varname>queue</varname>. |
| </listitem> |
| |
| <listitem> |
| <errorname>CL_IMAGE_FORMAT_NOT_SUPPORTED</errorname> if image format (image channel |
| order and data type) for <varname>image</varname> are not supported by device |
| associated with <varname>queue</varname>. |
| </listitem> |
| |
| <listitem> |
| <errorname>CL_MEM_OBJECT_ALLOCATION_FAILURE</errorname> if there is a failure to |
| allocate memory for data store associated with <varname>image</varname>. |
| </listitem> |
| |
| <listitem> |
| <errorname>CL_INVALID_OPERATION</errorname> if the device associated |
| with <varname>command_queue</varname> does not support images |
| (i.e. <constant>CL_DEVICE_IMAGE_SUPPORT</constant> specified in |
| the table of allowed values for <varname>param_name</varname> for |
| <citerefentry><refentrytitle>clGetDeviceInfo</refentrytitle></citerefentry> |
| is <constant>CL_FALSE</constant>). |
| </listitem> |
| |
| <listitem> |
| <errorname>CL_INVALID_OPERATION</errorname> if |
| <function>clEnqueueReadImage</function> is called on <varname>image</varname> |
| which has been created with <constant>CL_MEM_HOST_WRITE_ONLY</constant> or |
| <constant>CL_MEM_HOST_NO_ACCESS</constant> |
| </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_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 --> |
| <!-- |
| <refsect2 id="example1"> |
| <title> |
| Example |
| </title> |
| |
| <informaltable frame="none"> |
| <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="clEnqueueReadImage">OpenCL Specification</olink> |
| </para> |
| </refsect1> |
| |
| <!-- ================================ ALSO SEE --> |
| |
| <refsect1 id="seealso"><title>Also see</title> |
| <para> |
| <citerefentry><refentrytitle>clEnqueueWriteImage</refentrytitle></citerefentry>, |
| <citerefentry><refentrytitle>clEnqueueCopyImage</refentrytitle></citerefentry>, |
| <citerefentry><refentrytitle>cl_khr_mipmap_image</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> |
| |
| <!-- 8-Dec-2013, rev. 19 --> |
| </refentry> |
| |
