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Operations

Moving and modifying data in a heterogenous memory system can be annoying. You have to keep track of the source and destination, and often use vendor-specific APIs to perform the modifications. In Umpire, all data modification and movement is wrapped up in a concept we call operations. Full documentation for all of these is available here. The full code listing for each example is include at the bottom of the page.

Copy

Let's start by looking at how we copy data around. The :class:`umpire::ResourceManager` provides an interface to copy that handles figuring out where the source and destination pointers were allocated, and selects the correct implementation to copy the data:

.. literalinclude:: ../../../examples/tutorial/tut_copy.cpp
   :start-after: _sphinx_tag_tut_copy_start
   :end-before: _sphinx_tag_tut_copy_end
   :language: C++

This example allocates the destination data using any valid Allocator.

Move

If you want to move data to a new Allocator and deallocate the old copy, Umpire provides a :func:`umpire::ResourceManager::move` operation.

.. literalinclude:: ../../../examples/tutorial/tut_move.cpp
   :start-after: _sphinx_tag_tut_move_start
   :end-before: _sphinx_tag_tut_move_end
   :language: C++

The move operation combines an allocation, a copy, and a deallocate into one function call, allowing you to move data without having to have the destination data allocated. As always, this operation will work with any valid destination Allocator.

Memset

Setting a whole block of memory to a value (like 0) is a common operation, that most people know as a memset. Umpire provides a :func:`umpire::ResourceManager::memset` implementation that can be applied to any allocation, regardless of where it came from:

.. literalinclude:: ../../../examples/tutorial/tut_memset.cpp
   :start-after: _sphinx_tag_tut_memset_start
   :end-before: _sphinx_tag_tut_memset_end
   :language: C++

Reallocate

Reallocating CPU memory is easy, there is a function designed specifically to do it: realloc. When the original allocation was made in a different memory however, you can be out of luck. Umpire provides a :func:`umpire::ResourceManager::reallocate` operation:

.. literalinclude:: ../../../examples/tutorial/tut_reallocate.cpp
   :start-after: _sphinx_tag_tut_realloc_start
   :end-before: _sphinx_tag_tut_realloc_end
   :language: C++

This method returns a pointer to the reallocated data. Like all operations, this can be used regardless of the Allocator used for the source data.

Listings

Copy Example Listing

.. literalinclude:: ../../../examples/tutorial/tut_copy.cpp

Move Example Listing

.. literalinclude:: ../../../examples/tutorial/tut_move.cpp

Memset Example Listing

.. literalinclude:: ../../../examples/tutorial/tut_memset.cpp

Reallocate Example Listing

.. literalinclude:: ../../../examples/tutorial/tut_reallocate.cpp