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[oneDPL] Create a dedicated page for buffer wrappers (#566)
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source/elements/oneDPL/source/parallel_api/buffer_wrappers.rst
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.. SPDX-FileCopyrightText: 2019-2022 Intel Corporation | ||
.. SPDX-FileCopyrightText: Contributors to the oneAPI Specification project. | ||
.. | ||
.. SPDX-License-Identifier: CC-BY-4.0 | ||
Buffer Wrappers | ||
--------------- | ||
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.. code:: cpp | ||
// Defined in <oneapi/dpl/iterator> | ||
namespace oneapi { | ||
namespace dpl { | ||
template < typename T, typename AllocatorT, typename TagT > | ||
/*unspecified*/ begin( sycl::buffer<T, /*dim=*/1, AllocatorT> buf, | ||
TagT tag = sycl::read_write ); | ||
template < typename T, typename AllocatorT, typename TagT > | ||
/*unspecified*/ begin( sycl::buffer<T, /*dim=*/1, AllocatorT> buf, | ||
TagT tag, sycl::property::no_init ); | ||
template < typename T, typename AllocatorT > | ||
/*unspecified*/ begin( sycl::buffer<T, /*dim=*/1, AllocatorT> buf, | ||
sycl::property::no_init ); | ||
template < typename T, typename AllocatorT, typename TagT > | ||
/*unspecified*/ end( sycl::buffer<T, /*dim=*/1, AllocatorT> buf, | ||
TagT tag = sycl::read_write ); | ||
template < typename T, typename AllocatorT, typename TagT > | ||
/*unspecified*/ end( sycl::buffer<T, /*dim=*/1, AllocatorT> buf, | ||
TagT tag, sycl::property::no_init ); | ||
template < typename T, typename AllocatorT > | ||
/*unspecified*/ end( sycl::buffer<T, /*dim=*/1, AllocatorT> buf, | ||
sycl::property::no_init ); | ||
} | ||
} | ||
``oneapi::dpl::begin`` and ``oneapi::dpl::end`` are helper functions | ||
for passing `SYCL`_ buffers to oneDPL algorithms. | ||
These functions accept a buffer and return an object | ||
of an unspecified type that satisfies the following requirements: | ||
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- it is ``CopyConstructible``, ``CopyAssignable``, and comparable | ||
with operators ``==`` and ``!=``; | ||
- the following expressions are valid: ``a + n``, ``a - n``, | ||
``a - b``, where ``a`` and ``b`` are objects of the type, | ||
and ``n`` is an integer value; | ||
- it provides the ``get_buffer()`` method that returns the buffer | ||
passed to the ``begin`` or ``end`` function. | ||
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When invoking an algorithm, the buffer passed to ``begin`` should be the same | ||
as the buffer passed to ``end``. Otherwise, the behavior is undefined. | ||
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SYCL deduction tags (the ``TagT`` parameters) and ``sycl::property::no_init`` | ||
allow to specify an access mode to be used by algorithms for accessing the buffer. | ||
The mode serves as a hint, and can be overridden depending on semantics of the algorithm. | ||
When invoking an algorithm, the same access mode arguments should be used | ||
for ``begin`` and ``end``. Otherwise, the behavior is undefined. | ||
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.. code:: cpp | ||
using namespace oneapi; | ||
auto buf_begin = dpl::begin(buf, sycl::write_only); | ||
auto buf_end_1 = dpl::end(buf, sycl::write_only); | ||
auto buf_end_2 = dpl::end(buf, sycl::write_only, sycl::no_init); | ||
dpl::fill(dpl::execution::dpcpp_default, buf_begin, buf_end_1, 42); // allowed | ||
dpl::fill(dpl::execution::dpcpp_default, buf_begin, buf_end_2, 42); // not allowed | ||
.. _`SYCL`: https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html |