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| <title>write_pipe</title> | |
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| <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="write_pipe"></a> | |
| <h1>write_pipe</h1> | |
| <p> | |
| Read packet from <code xmlns="http://www.w3.org/1999/xhtml" class="varname">pipe</code> into <code xmlns="http://www.w3.org/1999/xhtml" class="varname">ptr</code>. | |
| </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">int</a> | |
| <strong class="fsfunc"> | |
| write_pipe | |
| </strong> | |
| (</code> | |
| <td>write_only pipe gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">p</var>, </td> | |
| </td> | |
| </tr> | |
| <tr valign="top"> | |
| <td> </td> | |
| <td>const gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*ptr</var><code>)</code></td> | |
| </tr> | |
| </table> | |
| </div> | |
| <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">int</a> | |
| <strong class="fsfunc"> | |
| write_pipe | |
| </strong> | |
| (</code> | |
| <td>write_only pipe gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">p</var>, </td> | |
| </td> | |
| </tr> | |
| <tr valign="top"> | |
| <td> </td> | |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="enums.html#reserve_id_t" target="pagedisplay">reserve_id_t</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">reserve_id</var>, </td> | |
| </tr> | |
| <tr valign="top"> | |
| <td> </td> | |
| <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="pagedisplay">uint</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">index</var>, </td> | |
| </tr> | |
| <tr valign="top"> | |
| <td> </td> | |
| <td>const gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*ptr</var><code>)</code></td> | |
| </tr> | |
| </table> | |
| </div> | |
| </div> | |
| <div class="refsect1"> | |
| <a id="description"></a> | |
| <h2>Description</h2> | |
| <p> | |
| For the form without <code class="varname">reserve_id</code>, | |
| write packet specified by <code class="varname">ptr</code> | |
| into pipe <code class="varname">p</code>. Returns 0 if | |
| <code class="function">write_pipe</code> is successful and a negative value if the | |
| pipe is full. | |
| </p> | |
| <p> | |
| For the form using <code class="varname">reserve_id</code>, | |
| write packet specified by <code class="varname">ptr</code> to the reserved area of | |
| the pipe referred to by <code class="varname">reserve_id</code> and <code class="varname">index</code>. | |
| The reserved pipe entries are referred to by indices | |
| that go from 0 … <code class="varname">num_packets</code> – 1. | |
| Returns 0 if <code class="function">write_pipe</code> is successful and a negative | |
| value otherwise. | |
| </p> | |
| <p> | |
| We use the generic type name gentype to indicate the built-in | |
| OpenCL C scalar or vector integer or floating-point data types or any user defined type built | |
| from these scalar and vector data types can be used as the type for the arguments to the pipe | |
| functions listed in this section. | |
| The half scalar and vector types can only be used if the | |
| <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a> | |
| extension is supported. The <span class="type">double</span> scalar | |
| and vector types can only be used if double precision is supported. | |
| </p> | |
| <h4><a id="id-1.5.5"></a>General information about pipes</h4> | |
| <p> | |
| A pipe is identified by specifying the <code class="code">pipe</code> | |
| keyword with a type. The data type specifies the | |
| size of each packet in the pipe. The <code class="code">pipe</code> | |
| keyword is a type modifier. When it is applied to | |
| another type <code class="code">T</code>, the result is a pipe type | |
| whose elements (or packets) are of type <code class="code">T</code>. The packet | |
| type <code class="code">T</code> may be any supported OpenCL C scalar | |
| and vector integer or floating-point data types, or | |
| a user-defined type built from these scalar and vector data types. | |
| </p> | |
| <p> | |
| The | |
| <a class="citerefentry" href="qualifiers.html"><span class="citerefentry"><span class="refentrytitle">read_only</span></span></a> | |
| (or <code class="code">__read_only</code>) and | |
| <a class="citerefentry" href="qualifiers.html"><span class="citerefentry"><span class="refentrytitle">write_only</span></span></a> | |
| (or <code class="code">__write_only</code>) qualifiers | |
| must be used with the pipe qualifier when a pipe | |
| is a parameter of a kernel or of a user-defined | |
| function to identify if a pipe can be read from | |
| or written to by a kernel and its callees and | |
| enqueued child kernels. If no qualifier is specified, | |
| <a class="citerefentry" href="qualifiers.html"><span class="citerefentry"><span class="refentrytitle">read_only</span></span></a> | |
| is assumed. | |
| </p> | |
| <p> | |
| A kernel cannot read from and write to the same pipe object. Using the | |
| <a class="citerefentry" href="qualifiers.html"><span class="citerefentry"><span class="refentrytitle">read_write </span></span></a> | |
| (or <code class="code">__read_write</code>) qualifier with the pipe qualifier is a compilation error. | |
| </p> | |
| <p> | |
| The macro <code class="constant">CLK_NULL_RESERVE_ID</code> refers to an invalid reservation ID. | |
| </p> | |
| <p> | |
| NOTE: The | |
| <a class="citerefentry" href="read_pipe.html"><span class="citerefentry"><span class="refentrytitle">read_pipe</span></span></a> and | |
| <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a> | |
| functions that take a reservation ID as an argument can | |
| be used to read from or write to a packet index. These built-ins can be used to read from or write | |
| to a packet index one or multiple times. If a packet index that is reserved for writing is not | |
| written to using the | |
| <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a> | |
| function, the contents of that packet in the pipe are undefined. | |
| <a class="citerefentry" href="commit_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_read_pipe</span></span></a> and | |
| <a class="citerefentry" href="work_group_commit_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">work_group_commit_read_pipe</span></span></a> | |
| remove the entries reserved for reading from the pipe. | |
| <a class="citerefentry" href="commit_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_write_pipe</span></span></a> and | |
| <a class="citerefentry" href="work_group_commit_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">work_group_commit_write_pipe</span></span></a> | |
| ensures that the entries reserved for writing are all added in-order | |
| as one contiguous set of packets to the pipe. | |
| </p> | |
| <p> | |
| There can only be <code class="constant">CL_DEVICE_PIPE_MAX_ACTIVE_RESERVATIONS</code> | |
| (refer to the list of possible values for <code class="varname">parame_name</code> | |
| for <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>(table 4.3)) | |
| reservations active (i.e. reservation IDs that have been reserved | |
| but not committed) per work-item or work-group for a | |
| pipe in a kernel executing on a device. | |
| </p> | |
| <p> | |
| Work-item based reservations made by a work-item are ordered in the pipe as they are ordered in | |
| the program. Reservations made by different work-items that belong to the same work-group | |
| can be ordered using the work-group barrier function. The order of work-item based | |
| reservations that belong to different work-groups is implementation defined. | |
| </p> | |
| <p> | |
| Work-group based reservations made by a work-group are ordered in the pipe as they are ordered | |
| in the program. The order of work-group based reservations by different work-groups is | |
| implementation defined. | |
| </p> | |
| <h4><a id="id-1.5.14"></a>Restrictions</h4> | |
| <p> | |
| Pipes can only be passed as arguments to a function | |
| (including kernel functions). The C | |
| <a class="citerefentry" href="operators.html"><span class="citerefentry"><span class="refentrytitle">operators</span></span></a> | |
| (refer to section 6.3 of the OpenCL 2.0 specification) cannot be used with | |
| variables declared with the <code class="code">pipe</code> qualifier. | |
| </p> | |
| <p> | |
| The <code class="code">pipe</code> qualifier cannot be used with | |
| variables declared inside a kernel, a structure or | |
| union field, a pointer type, an array, global variables | |
| declared in program scope or the return type of a function. | |
| </p> | |
| <p> | |
| The following behavior is undefined: | |
| </p> | |
| <p> | |
| </p> | |
| <div class="itemizedlist"> | |
| <ul class="itemizedlist" style="list-style-type: disc; "> | |
| <li class="listitem"> | |
| A kernel fails to call | |
| <code class="function">reserve_pipe</code> | |
| before calling | |
| <a class="citerefentry" href="read_pipe.html"><span class="citerefentry"><span class="refentrytitle">read_pipe</span></span></a> or | |
| <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a> that take a | |
| reservation ID. | |
| </li> | |
| <li class="listitem"> | |
| A kernel calls | |
| <a class="citerefentry" href="read_pipe.html"><span class="citerefentry"><span class="refentrytitle">read_pipe</span></span></a>, | |
| <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a>, | |
| <a class="citerefentry" href="commit_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_read_pipe</span></span></a> or | |
| <a class="citerefentry" href="commit_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_write_pipe</span></span></a> with | |
| an invalid reservation ID. | |
| </li> | |
| <li class="listitem"> | |
| A kernel calls | |
| <a class="citerefentry" href="read_pipe.html"><span class="citerefentry"><span class="refentrytitle">read_pipe</span></span></a> or | |
| <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a> | |
| with an valid reservation ID but with an <code class="varname">index</code> | |
| that is not a value from 0 ... <code class="varname">num_packets</code> - 1 | |
| specified to the corresponding call to | |
| <code class="function">reserve_pipe</code>. | |
| </li> | |
| <li class="listitem"> | |
| A kernel calls | |
| <a class="citerefentry" href="read_pipe.html"><span class="citerefentry"><span class="refentrytitle">read_pipe</span></span></a> or | |
| <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a> | |
| with a reservation ID that has already been committed (i.e. a | |
| <a class="citerefentry" href="commit_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_read_pipe</span></span></a> or | |
| <a class="citerefentry" href="commit_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_write_pipe</span></span></a> | |
| with this reservation ID has | |
| already been called). | |
| </li> | |
| <li class="listitem"> | |
| A kernel fails to call | |
| <a class="citerefentry" href="commit_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_read_pipe</span></span></a> | |
| for any reservation ID obtained by a prior call | |
| to <a class="citerefentry" href="reserve_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">reserve_read_pipe</span></span></a>. | |
| </li> | |
| <li class="listitem"> | |
| A kernel fails to call | |
| <a class="citerefentry" href="commit_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_write_pipe</span></span></a> | |
| for any reservation ID obtained by a prior call | |
| to <a class="citerefentry" href="reserve_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">reserve_write_pipe</span></span></a>. | |
| </li> | |
| <li class="listitem"> | |
| The contents of the reserved data packets in the pipe are undefined if the kernel does not | |
| call <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a> | |
| for all entries that were reserved by the corresponding call to | |
| <code class="function">reserve_pipe</code>. | |
| </li> | |
| <li class="listitem"> | |
| Calls to | |
| <a class="citerefentry" href="read_pipe.html"><span class="citerefentry"><span class="refentrytitle">read_pipe</span></span></a> | |
| that takes a reservation ID and | |
| <a class="citerefentry" href="commit_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_read_pipe</span></span></a> or | |
| <a class="citerefentry" href="write_pipe.html"><span class="citerefentry"><span class="refentrytitle">write_pipe</span></span></a> that | |
| takes a reservation ID and | |
| <a class="citerefentry" href="commit_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">commit_write_pipe</span></span></a> | |
| for a given reservation ID must be called | |
| by the same kernel that made the reservation using | |
| <a class="citerefentry" href="reserve_read_pipe.html"><span class="citerefentry"><span class="refentrytitle">reserve_read_pipe</span></span></a> or | |
| <a class="citerefentry" href="reserve_write_pipe.html"><span class="citerefentry"><span class="refentrytitle">reserve_write_pipe</span></span></a>. | |
| The reservation ID cannot be passed to another kernel including | |
| child kernels. | |
| </li> | |
| </ul> | |
| </div> | |
| <p> | |
| </p> | |
| <div class="refsect2"> | |
| <a id="example1"></a> | |
| <h3> | |
| Example | |
| </h3> | |
| <p> | |
| In the following example | |
| </p> | |
| <div class="informaltable"> | |
| <table border="0"> | |
| <colgroup> | |
| <col align="left" class="col1" /> | |
| </colgroup> | |
| <tbody> | |
| <tr> | |
| <td align="left"> | |
| kernel void | |
| foo (read_only pipe fooA_t pipeA, | |
| write_only pipe fooB_t pipeB) | |
| { | |
| ... | |
| } | |
| </td> | |
| </tr> | |
| </tbody> | |
| </table> | |
| </div> | |
| <p> | |
| <code class="code">pipeA</code> is a read-only pipe object, | |
| and <code class="code">pipeB</code> is a write-only pipe object. | |
| </p> | |
| </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-openclc.pdf#page=158" target="OpenCL Spec">OpenCL Specification</a> | |
| </p> | |
| </div> | |
| <div class="refsect1"> | |
| <a id="seealso"></a> | |
| <h2>Also see</h2> | |
| <p> | |
| <a class="citerefentry" href="pipeFunctions.html"><span class="citerefentry"><span class="refentrytitle">Pipe Functions</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 | |
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