/***************************************************************************
                          StaticFor.h  -  description
                             -------------------
    begin                : Jul 16, 2019
    copyright            : (C) 2019 by Tomas Oberhuber
    email                : tomas.oberhuber@fjfi.cvut.cz
 ***************************************************************************/

/* See Copyright Notice in tnl/Copyright */

#pragma once

#include <TNL/Cuda/CudaCallable.h>

namespace TNL {
namespace Algorithms {

// Manual unrolling does not make sense for loops with a large iterations
// count. For a very large iterations count it would trigger the compiler's
// limit on recursive template instantiation. Also note that the compiler
// will (at least partially) unroll loops with static bounds anyway.
template< int Begin, int End, bool unrolled = (End - Begin <= 8) >
struct StaticFor;

template< int Begin, int End >
struct StaticFor< Begin, End, true >
{
   static_assert( Begin < End, "Wrong index interval for StaticFor. Begin must be less than end." );

   template< typename Function, typename... Args >
   __cuda_callable__
   static void exec( const Function& f, Args&&... args )
   {
      f( Begin, args... );
      StaticFor< Begin + 1, End >::exec( f, std::forward< Args >( args )... );
   }
};

template< int End >
struct StaticFor< End, End, true >
{
   template< typename Function, typename... Args >
   __cuda_callable__
   static void exec( const Function& f, Args&&... args ) {}
};

template< int Begin, int End >
struct StaticFor< Begin, End, false >
{
   static_assert( Begin <= End, "Wrong index interval for StaticFor. Begin must be less than or equal to end." );

   template< typename Function, typename... Args >
   __cuda_callable__
   static void exec( const Function& f, Args&&... args )
   {
      for( int i = Begin; i < End; i++ )
         f( i, std::forward< Args >( args )... );
   }
};

} // namespace Algorithms
} // namespace TNL
