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Publish the cl_img_swap_ops extension specification. (#1201)
* Publish the cl_img_swap_ops extension specification. * Update extensions/cl_img_swap_ops.asciidoc Listing the initial extension version. Co-authored-by: Ben Ashbaugh <[email protected]> * Update cl_img_swap_ops.asciidoc Defining behavior as undefined for cases when the number of work-items is not evenly divisible by four and if some work-items in the block of four are inactive, defining 1-dimensional local ID as a base for grouping work-items. --------- Co-authored-by: Ben Ashbaugh <[email protected]>
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‎extensions/cl_img_swap_ops.asciidoc

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include::../config/attribs.txt[]
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= cl_img_swap_ops
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== Name Strings
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`cl_img_swap_ops`
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== Contact
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Imagination Technologies Developer Forum: +
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https://forums.imgtec.com/
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Tomasz Platek, Imagination Technologies (Tomasz.Platek 'at' imgtec.com)
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== Contributors
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CY Cheng, Imagination Technologies. +
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Tomasz Platek, Imagination Technologies.
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== Notice
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Copyright (c) 2024 Imagination Technologies Ltd. All Rights Reserved.
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== Status
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Final Draft
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== Version
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Built On: {docdate} +
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Version: 1.0.0
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== Dependencies
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This extension is written against the OpenCL C Specification Version V3.0.16.
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== Overview
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This extension adds built-in functions that exercise hardware capabilities of Imagination GPU IP and expose cross work-items swap functions.
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== New OpenCL C Feature Names
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[source,c]
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----
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__opencl_img_swap
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----
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== New OpenCL C Functions
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Perform the swap operation:
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[source,c]
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----
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gentype img_swap_x(gentype value);
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gentype img_swap_y(gentype value);
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----
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== Modifications to the OpenCL C Specification
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(Add to Table 16 - Built-in Scalar and Vector Argument Common Functions in Section 6.15.4 - Common Functions) ::
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+
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--
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[cols="1,2",options="header"]
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|====
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| Function | Description
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| gentype *img_swap_x*(gentype value)
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a| `img_swap_x` swaps `values` between work-items in the following way: all work-items are divided into blocks of four consecutive elements. For each block:
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* In the first work-item, `img_swap_x` returns `value` passed as an argument in the second work-item.
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* In the second work-item, `img_swap_x` returns `value` passed as an argument in the first work-item.
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* In the third work-item, `img_swap_x` returns `value` passed as an argument in the fourth work-item.
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* In the fourth work-item, `img_swap_x` returns `value` passed as an argument in the third work-item.
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The work-items are assigned into blocks based on their 1-dimensional local ID (see `get_local_linear_id`).
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The number of work-items that make up a work-group must be evenly divisible by four; otherwise, the behaviour is undefined.
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The function must be called in all four work-items of the block; otherwise, the behaviour is undefined.
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Requires that the `__opencl_img_swap` feature macro is defined.
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| gentype *img_swap_y*(gentype value)
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a| `img_swap_y` swaps `values` between work-items in the following way: all work-items are divided into blocks of four consecutive elements. For each block:
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* In the first work-item, `img_swap_y` returns `value` passed as an argument in the third work-item.
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* In the third work-item, `img_swap_y` returns `value` passed as an argument in the first work-item.
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* In the second work-item, `img_swap_y` returns `value` passed as an argument in the fourth work-item.
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* In the fourth work-item, `img_swap_y` returns `value` passed as an argument in the second work-item.
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The work-items are assigned into blocks based on their 1-dimensional local ID (see `get_local_linear_id`).
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The number of work-items that make up a work-group must be evenly divisible by four; otherwise, the behaviour is undefined.
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The function must be called in all four work-items of the block; otherwise, the behaviour is undefined.
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Requires that the `__opencl_img_swap` feature macro is defined.
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|====
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--
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== Coding Sample
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This coding sample shows how to use the *img_swap_x* function:
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[source]
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----
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__kernel void swap() {
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int i = get_global_id(0);
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int res = img_swap_x(i);
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printf("id: %d, res = [ %d ]\n", i, res);
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}
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----
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Executing four work-items of this kernel in one work-group gives the following result:
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[source]
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----
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id: 0, res = [ 1 ]
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id: 1, res = [ 0 ]
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id: 2, res = [ 3 ]
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id: 3, res = [ 2 ]
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----
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== Version History
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[cols="5,15,15,70"]
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[grid="rows"]
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[options="header"]
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|====
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| Version | Date | Author | Changes
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| 1.0.0 | 2024-06-19 | Tomasz Platek | *Initial revision*
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|====
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‎extensions/extensions.txt

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<<<
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include::cl_img_mem_properties.asciidoc[]
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<<<
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include::cl_img_swap_ops.asciidoc[]
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<<<
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include::cl_img_use_gralloc_ptr.asciidoc[]
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<<<
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include::cl_img_yuv_image.asciidoc[]

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