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.. Copyright (c) 2016, Johan Mabille, Sylvain Corlay
Distributed under the terms of the BSD 3-Clause License.
The full license is in the file LICENSE, distributed with this software.
.. raw:: html
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.. _Arch Dispatching:
Arch Dispatching
================
`xsimd` provides a generic way to dispatch a function call based on the architecture the code was compiled for and the architectures available at runtime.
The :cpp:func:`xsimd::dispatch` function takes a functor whose call operator takes an architecture parameter as first operand, followed by any number of arguments ``Args...`` and turn it into a
dispatching functor that takes ``Args...`` as arguments.
.. doxygenfunction:: xsimd::dispatch
:project: xsimd
Following code showcases a usage of the :cpp:func:`xsimd::dispatch` function:
.. code-block:: c++
#include "sum.hpp"
// Create the dispatching function, specifying the architecture we want to
// target.
auto dispatched = xsimd::dispatch<xsimd::arch_list<xsimd::avx2, xsimd::sse2>>(sum{});
// Call the appropriate implementation based on runtime information.
float res = dispatched(data, 17);
This code does *not* require any architecture-specific flags. The architecture
specific details follow.
The ``sum.hpp`` header contains the function being actually called, in an
architecture-agnostic description:
.. literalinclude:: ../../../test/doc/sum.hpp
The SSE2 and AVX2 version needs to be provided in other compilation units, compiled with the appropriate flags, for instance:
.. literalinclude:: ../../../test/doc/sum_avx2.cpp
.. literalinclude:: ../../../test/doc/sum_sse2.cpp
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