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<title>clCreateBuffer</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="clCreateBuffer"></a>
<h1>
clCreateBuffer
</h1>
<p>
Creates a buffer object.
</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="abstractDataTypes.html" target="pagedisplay">cl_mem</a> <strong class="fsfunc">clCreateBuffer</strong>
(</code>
<td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="pagedisplay">cl_context</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">context</var>, </td>
</td>
</tr>
<tr valign="top">
<td> </td>
<td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="enums.html#cl_mem_flags" target="pagedisplay">cl_mem_flags</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">flags</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><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">*host_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_int</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*errcode_ret</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">context</code>
</span>
</dt>
<dd>
<p>A valid OpenCL context used to create the buffer object.</p>
</dd>
<dt>
<span class="term"> <code class="varname">flags</code> </span>
</dt>
<dd>
<p>
A bit-field that is used to specify
allocation and usage information such as the memory arena that should be
used to allocate the buffer object and how it will be used. The following
table describes the possible values for <code class="varname">flags</code>. If
value specified for <code class="varname">flags</code> is 0, the default is used
which is <code class="constant">CL_MEM_READ_WRITE</code>.
</p>
<div class="informaltable">
<table class="informaltable" border="1">
<colgroup>
<col align="left" class="col1" />
<col />
</colgroup>
<thead>
<tr>
<th align="left">cl_mem_flags</th>
<th align="left">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left">
<code class="constant">CL_MEM_READ_WRITE</code>
</td>
<td align="left">
This flag specifies that the memory object will be read and written by a kernel. This
is the default.
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_WRITE_ONLY</code>
</td>
<td align="left">
<p>
This flag specifies that the memory object will be written but not read by
a kernel.
</p>
<p>
Reading from a buffer or image object created with
<code class="constant">CL_MEM_WRITE_ONLY</code> inside a kernel is undefined.
</p>
<p>
<code class="constant">CL_MEM_READ_WRITE</code> and <code class="constant">CL_MEM_WRITE_ONLY</code>
are mutually exclusive.
</p>
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_READ_ONLY</code>
</td>
<td align="left">
<p>
This flag specifies that the memory object is a read-only memory object when
used inside a kernel.
</p>
<p>
Writing to a buffer or image object created with
<code class="constant">CL_MEM_READ_ONLY</code> inside a kernel is undefined.
</p>
<p>
<code class="constant">CL_MEM_READ_WRITE</code> or <code class="constant">CL_MEM_WRITE_ONLY</code>
and <code class="constant">CL_MEM_READ_ONLY</code> are mutually exclusive.
</p>
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_USE_HOST_PTR</code>
</td>
<td align="left">
<p>
This flag is valid only if <code class="varname">host_ptr</code> is not NULL. If
specified, it indicates that the application wants the OpenCL implementation
to use memory referenced by <code class="varname">host_ptr</code> as the storage bits
for the memory object.
</p>
<p>
OpenCL implementations are allowed to cache the buffer contents pointed to by
<code class="varname">host_ptr</code> in device memory. This cached copy can be used when
kernels are executed on a device.
</p>
<p>
The result of OpenCL commands that operate on multiple buffer objects created with
the same <code class="varname">host_ptr</code> or overlapping host regions is considered
to be undefined.
</p>
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_ALLOC_HOST_PTR</code>
</td>
<td align="left">
<p>
This flag specifies that the application wants the OpenCL implementation to
allocate memory from host accessible memory.
</p>
<p>
<code class="constant">CL_MEM_ALLOC_HOST_PTR</code> and
<code class="constant">CL_MEM_USE_HOST_PTR</code> are mutually exclusive.
</p>
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_COPY_HOST_PTR</code>
</td>
<td align="left">
<p>
This flag is valid only if <code class="varname">host_ptr</code> is not NULL. If specified,
it indicates that the application wants the OpenCL implementation to allocate
memory for the memory object and copy the data from memory referenced by
<code class="varname">host_ptr</code>.
</p>
<p>
<code class="constant">CL_MEM_COPY_HOST_PTR</code> and
<code class="constant">CL_MEM_USE_HOST_PTR</code> are mutually exclusive.
</p>
<p>
<code class="constant">CL_MEM_COPY_HOST_PTR</code> can be used with
<code class="constant">CL_MEM_ALLOC_HOST_PTR</code> to initialize the contents of the
<span class="type">cl_mem</span> object allocated using host-accessible (e.g. PCIe) memory.
</p>
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_HOST_WRITE_ONLY</code>
</td>
<td align="left">
<p>
This flag specifies that the host will only write to the memory object (using
OpenCL APIs that enqueue a write or a map for write). This can be used to optimize
write access from the host (e.g. enable write-combined allocations for memory
objects for devices that communicate with the host over a system bus such as PCIe).
</p>
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_HOST_READ_ONLY</code>
</td>
<td align="left">
<p>
This flag specifies that the host will only read the memory object (using OpenCL
APIs that enqueue a read or a map for read).
</p>
<p>
<code class="constant">CL_MEM_HOST_WRITE_ONLY</code> and
<code class="constant">CL_MEM_HOST_READ_ONLY</code> are mutually exclusive.
</p>
</td>
</tr>
<tr>
<td align="left">
<code class="constant">CL_MEM_HOST_NO_ACCESS</code>
</td>
<td align="left">
<p>
This flag specifies that the host will not read or write the memory object.
</p>
<p>
<code class="constant">CL_MEM_HOST_WRITE_ONLY</code> or
<code class="constant">CL_MEM_HOST_READ_ONLY</code> and
<code class="constant">CL_MEM_HOST_NO_ACCESS</code> are mutually exclusive.
</p>
</td>
</tr>
</tbody>
</table>
</div>
</dd>
<dt>
<span class="term">
<code class="varname">size</code>
</span>
</dt>
<dd>
<p>The size in bytes of the buffer memory object to be allocated.</p>
</dd>
<dt>
<span class="term">
<code class="varname">host_ptr</code>
</span>
</dt>
<dd>
<p>
A pointer to the buffer data that may
already be allocated by the application. The size of the buffer that
<code class="varname">host_ptr</code> points to must be ≥ <code class="varname">size</code>
bytes.
</p>
</dd>
<dt>
<span class="term">
<code class="varname">errcode_ret</code>
</span>
</dt>
<dd>
<p>
Returns an appropriate error code. If
<code class="varname">errcode_ret</code> is NULL, no error code is returned.
</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1">
<a id="notes"></a>
<h2>Notes</h2>
<p>
The user is responsible for ensuring that data passed into and out of OpenCL images are natively
aligned relative to the start of the buffer as per kernel language or IL requirements. OpenCL
buffers created with <code class="constant">CL_MEM_USE_HOST_PTR</code> need to provide an appropriately aligned host
memory pointer that is aligned to the data types used to access these buffers in a kernel(s).
</p>
<p>
If <code class="function">clCreateBuffer</code> is called with a pointer
returned by <code class="function">clSVMAlloc</code> as its
<code class="varname">host_ptr</code> argument, and
<code class="constant">CL_MEM_USE_HOST_PTR</code> is set in its
<code class="varname">flags</code> argument, <code class="function">clCreateBuffer</code>
will succeed and return a valid non-zero buffer
object as long as the <code class="varname">size</code> argument to
<code class="function">clCreateBuffer</code> is no larger than the
<code class="varname">size</code> argument passed in the original
<code class="function">clSVMAlloc</code> call. The new buffer object returned has the
shared memory as the underlying storage. Locations in
the buffer's underlying shared memory
can be operated on using atomic operations to the device's
level of support as defined in the
memory model.
</p>
</div>
<div class="refsect1">
<a id="errors"></a>
<h2>Errors</h2>
<p>
Returns a valid non-zero buffer object and <code class="varname">errcode_ret</code>
is set to <span class="errorname">CL_SUCCESS</span> if the buffer object is created
successfully. Otherwise, it returns a NULL value with one of the following error
values returned in <code class="varname">errcode_ret</code>:
</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_CONTEXT</span> if <code class="varname">context</code> is not
a valid context.
</li>
<li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_VALUE</span> if values specified in
<code class="varname">flags</code> are not valid as defined in the table above.
</li>
<li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_BUFFER_SIZE</span> if <code class="varname">size</code> is 0.
<p>
Implementations may return <code class="constant">CL_INVALID_BUFFER_SIZE</code> if <code class="varname">size</code>
is greater than the <code class="constant">CL_DEVICE_MAX_MEM_ALLOC_SIZE</code> value
specified in the table of allowed values for <code class="varname">param_name</code>
for <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>
for all <code class="varname">devices</code> in context.
</p></li>
<li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_HOST_PTR</span> if <code class="varname">host_ptr</code>
is NULL and <code class="constant">CL_MEM_USE_HOST_PTR</code> or
<code class="constant">CL_MEM_COPY_HOST_PTR</code> are set in <code class="varname">flags</code> or if
<code class="varname">host_ptr</code> is not NULL but <code class="constant">CL_MEM_COPY_HOST_PTR</code>
or <code class="constant">CL_MEM_USE_HOST_PTR</code> are not set in <code class="varname">flags</code>.
</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 buffer object.
</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="https://www.khronos.org/registry/cl/specs/opencl-2.1.pdf#page=104" target="OpenCL Spec">OpenCL Specification</a>
</p>
</div>
<div class="refsect1">
<a id="seealso"></a>
<h2>Also see</h2>
<p>
<a class="citerefentry" href="clEnqueueReadBuffer.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueReadBuffer</span></span></a>,
<a class="citerefentry" href="clEnqueueWriteBuffer.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueWriteBuffer</span></span></a>,
<a class="citerefentry" href="clEnqueueCopyBuffer.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueCopyBuffer</span></span></a>,
<a class="citerefentry" href="clCreateSubBuffer.html"><span class="citerefentry"><span class="refentrytitle">clCreateSubBuffer</span></span></a>,
<a class="citerefentry" href="classDiagram.html"><span class="citerefentry"><span class="refentrytitle">Cardinality Diagram</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
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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