82 lines
3.0 KiB
ReStructuredText
82 lines
3.0 KiB
ReStructuredText
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.. _cccl-runtime-algorithm:
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Algorithm
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==========
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The ``runtime`` part of the ``cuda/algorithm`` header provides stream-ordered, byte-wise primitives that operate on
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:cpp:class:`cuda::std::span` and :cpp:class:`cuda::std::mdspan`-compatible types. They require a
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:cpp:class:`cuda::stream_ref` to enqueue work.
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:cpp:func:`cuda::copy_bytes`
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-------------------------------
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.. _cccl-runtime-algorithm-copy_bytes:
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Launch a byte-wise copy from source to destination on the provided stream.
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- Signature: :cpp:func:`cuda::copy_bytes`
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- Overloads accept :cpp:class:`cuda::std::span`-convertible contiguous ranges or
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:cpp:class:`cuda::std::mdspan`-convertible multi-dimensional views.
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- Elements must be trivially copyable
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- :cpp:class:`cuda::std::mdspan`-convertible types must convert to an mdspan that is exhaustive
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- The optional ``config`` argument is a :cpp:struct:`cuda::copy_configuration` that controls source access order and
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managed-memory location hints
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Availability: CCCL 3.1.0 / CUDA 13.1
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.. code:: cpp
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#include <cuda/algorithm>
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#include <cuda/stream>
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#include <cuda/std/algorithm>
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#include <cuda/std/span>
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void copy_example(cuda::stream_ref s, cuda::std::span<const int> src, cuda::std::span<int> dst) {
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// copy_bytes copies up to src.size_bytes(); dst can be larger.
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auto n = cuda::std::min(src.size(), dst.size());
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auto src_prefix = src.first(n / 2);
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auto dst_prefix = dst.first(n / 2);
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auto src_suffix = src.subspan(n / 2);
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auto dst_suffix = dst.subspan(n / 2);
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// Default behavior: enqueue a stream-ordered byte-wise copy on stream s.
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cuda::copy_bytes(s, src_prefix, dst_prefix);
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// Advanced behavior: customize source access order for this copy.
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auto config = cuda::copy_configuration{
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.src_access_order = cuda::source_access_order::during_api_call,
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};
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cuda::copy_bytes(s, src_suffix, dst_suffix, config);
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}
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:cpp:func:`cuda::fill_bytes`
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-------------------------------
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.. _cccl-runtime-algorithm-fill_bytes:
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Launch a byte-wise fill of the destination on the provided stream.
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- Overloads accept :cpp:class:`cuda::std::span`-convertible or :cpp:class:`cuda::std::mdspan`-convertible destinations.
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- Elements must be trivially copyable
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- :cpp:class:`cuda::std::mdspan`-convertible types must convert to an mdspan that is exhaustive
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Availability: CCCL 3.1.0 / CUDA 13.1
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.. code:: cpp
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#include <cuda/algorithm>
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#include <cuda/stream>
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#include <cuda/std/algorithm>
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#include <cuda/std/span>
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void fill_example(cuda::stream_ref s, cuda::std::span<unsigned char> dst) {
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// Reserve 16-byte red zones at both ends and clear the payload in between.
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auto guard = cuda::std::min(static_cast<decltype(dst.size())>(16), dst.size() / 2);
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auto head = dst.first(guard);
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auto body = dst.subspan(guard, dst.size() - 2 * guard);
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auto tail = dst.last(guard);
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cuda::fill_bytes(s, head, 0xCD); // debug guard pattern
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cuda::fill_bytes(s, body, 0x00); // initialize payload
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cuda::fill_bytes(s, tail, 0xCD); // debug guard pattern
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}
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