Algorithm

The runtime part of the cuda/algorithm header provides stream-ordered, byte-wise primitives that operate on cuda::std::span and cuda::std::mdspan-compatible types. They require a cuda::stream_ref to enqueue work.

cuda::copy_bytes

Launch a byte-wise copy from source to destination on the provided stream.

• Signature: copy_bytes(stream, src, dst, config = {})

• Overloads accept cuda::std::span-convertible contiguous ranges or cuda::std::mdspan-convertible multi-dimensional views.

• Elements must be trivially copyable

• cuda::std::mdspan-convertible types must convert to an mdspan that is exhaustive

• The optional config argument is a cuda::copy_configuration that controls source access order and managed-memory location hints

Availability: CCCL 3.1.0 / CUDA 13.1

#include <cuda/algorithm>
#include <cuda/stream>
#include <cuda/std/algorithm>
#include <cuda/std/span>

void copy_example(cuda::stream_ref s, cuda::std::span<const int> src, cuda::std::span<int> dst) {
  // copy_bytes copies up to src.size_bytes(); dst can be larger.
  auto n = cuda::std::min(src.size(), dst.size());
  auto src_prefix = src.first(n / 2);
  auto dst_prefix = dst.first(n / 2);
  auto src_suffix = src.subspan(n / 2);
  auto dst_suffix = dst.subspan(n / 2);

  // Default behavior: enqueue a stream-ordered byte-wise copy on stream s.
  cuda::copy_bytes(s, src_prefix, dst_prefix);

  // Advanced behavior: customize source access order for this copy.
  auto config = cuda::copy_configuration{
    .src_access_order = cuda::source_access_order::during_api_call,
  };
  cuda::copy_bytes(s, src_suffix, dst_suffix, config);
}

cuda::fill_bytes

Launch a byte-wise fill of the destination on the provided stream.

• Overloads accept cuda::std::span-convertible or cuda::std::mdspan-convertible destinations.

• Elements must be trivially copyable

• cuda::std::mdspan-convertible types must convert to an mdspan that is exhaustive

Availability: CCCL 3.1.0 / CUDA 13.1

#include <cuda/algorithm>
#include <cuda/stream>
#include <cuda/std/algorithm>
#include <cuda/std/span>

void fill_example(cuda::stream_ref s, cuda::std::span<unsigned char> dst) {
  // Reserve 16-byte red zones at both ends and clear the payload in between.
  auto guard = cuda::std::min(static_cast<decltype(dst.size())>(16), dst.size() / 2);
  auto head  = dst.first(guard);
  auto body  = dst.subspan(guard, dst.size() - 2 * guard);
  auto tail  = dst.last(guard);

  cuda::fill_bytes(s, head, 0xCD); // debug guard pattern
  cuda::fill_bytes(s, body, 0x00); // initialize payload
  cuda::fill_bytes(s, tail, 0xCD); // debug guard pattern
}