Description
Image objects specified as arguments to a kernel can be declared to be read-only or write-only.
For OpenCL C 2.0, or with the __opencl_c_ feature,
image objects specified as arguments to a kernel can additionally be
declared to be read-write.
The __read_only (or read_only) access qualifier specifies that the
image object is only being read by a kernel or function.
The __write_only (or write_only) access qualifier specifies that the
image object is only being written to by a kernel or function.
The __read_write (or read_write) access qualifier specifies that the
image object may be both read from or written to by a kernel or function.
The default access qualifier is read_only, if no access qualifier is declared.
In the following example
kernel void
foo (read_only image2d_t imageA,
write_only image2d_t imageB)
{
...
}imageA is a read-only 2D image object, and imageB is a write-only 2D image
object.
The sampler-less read image and write image built-ins can be used with image
declared with the __read_write (or read_write) qualifier.
Calls to built-ins that read from an image using a sampler for images
declared with the __read_write (or read_write) qualifier will be a
compilation error.
Pipe objects specified as arguments to a kernel also use these access qualifiers. See the detailed description on how these access qualifiers can be used with pipes.
The __read_only, __write_only, __read_write, read_only,
write_only and read_write names are reserved for use as access
qualifiers and shall not be used otherwise.
Document Notes
For more information, see the OpenCL C Specification
This page is extracted from the OpenCL C Specification. Fixes and changes should be made to the Specification, not directly.