1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
<bridgehead>Accessing mapped regions of a memory object</bridgehead>
<para>
This section describes the behavior of OpenCL commands that access
mapped regions of a memory object.
</para>
<para>
The contents of the region of a memory object and associated memory objects
(sub-buffer objects or 1D image buffer objects that overlap this region) mapped
for writing (i.e. <constant>CL_MAP_WRITE</constant> or
<constant>CL_MAP_WRITE_INVALIDATE_REGION</constant> is set in <varname>map_flags</varname>
argument to <citerefentry><refentrytitle>clEnqueueMapBuffer</refentrytitle></citerefentry>
or <citerefentry><refentrytitle>clEnqueueMapImage</refentrytitle></citerefentry>) are
considered to be undefined until this region is unmapped.
</para>
<para>
Multiple commands in command-queues can map a region or overlapping regions of a memory
object and associated memory objects (sub-buffer objects or 1D image buffer objects that
overlap this region) for reading (i.e. <varname>map_flags</varname> = <constant>CL_MAP_READ</constant>).
The contents of the regions of a memory object mapped for reading can also be read by kernels
and other OpenCL commands (such as
<citerefentry><refentrytitle>clEnqueueCopyBuffer</refentrytitle></citerefentry>) executing on a device(s).
</para>
<para>
Mapping (and unmapping) overlapped regions in a memory object and/or associated memory
objects (sub-buffer objects or 1D image buffer objects that overlap this region) for writing
is an error and will result in <constant>CL_INVALID_OPERATION</constant> error returned by
<citerefentry><refentrytitle>clEnqueueMapBuffer</refentrytitle></citerefentry>
or <citerefentry><refentrytitle>clEnqueueMapImage</refentrytitle></citerefentry>.
</para>
<para>
If a memory object is currently mapped for writing, the application must ensure that the memory
object is unmapped before any enqueued kernels or commands that read from or write to this
memory object or any of its associated memory objects (sub-buffer or 1D image buffer objects)
or its parent object (if the memory object is a sub-buffer or 1D image buffer object) begin
execution; otherwise the behavior is undefined.
</para>
<para>
If a memory object is currently mapped for reading, the application must ensure that the memory
object is unmapped before any enqueued kernels or commands that write to this memory object
or any of its associated memory objects (sub-buffer or 1D image buffer objects) or its parent
object (if the memory object is a sub-buffer or 1D image buffer object) begin execution;
otherwise the behavior is undefined.
</para>
<para>
Accessing the contents of the memory region referred to by the mapped pointer that has
been unmapped is undefined.
</para>
<para>
The mapped pointer returned by
<citerefentry><refentrytitle>clEnqueueMapBuffer</refentrytitle></citerefentry>
or <citerefentry><refentrytitle>clEnqueueMapImage</refentrytitle></citerefentry> can be used as
<varname>ptr</varname> argument value to
<citerefentry><refentrytitle>clEnqueueReadBuffer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>clEnqueueWriteBuffer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>clEnqueueReadBufferRect</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>clEnqueueWriteBufferRect</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>clEnqueueReadImage</refentrytitle></citerefentry>, and
<citerefentry><refentrytitle>clEnqueueWriteImage</refentrytitle></citerefentry>,
provided the rules described above are adhered to.
</para>
|
