eigen/Eigen/src/Core/AssignEvaluator.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2011 Benoit Jacob <jacob.benoit.1@gmail.com>
// Copyright (C) 2011 Gael Guennebaud <gael.guennebaud@inria.fr>
// Copyright (C) 2011 Jitse Niesen <jitse@maths.leeds.ac.uk>
//
// Eigen is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// Alternatively, you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of
// the License, or (at your option) any later version.
//
// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License and a copy of the GNU General Public License along with
// Eigen. If not, see <http://www.gnu.org/licenses/>.

#ifndef EIGEN_ASSIGN_EVALUATOR_H
#define EIGEN_ASSIGN_EVALUATOR_H

// This implementation is based on Assign.h

// copy_using_evaluator_traits is based on assign_traits

namespace internal {
  
template <typename Derived, typename OtherDerived>
struct copy_using_evaluator_traits
{
public:
  enum {
    DstIsAligned = Derived::Flags & AlignedBit,
    DstHasDirectAccess = Derived::Flags & DirectAccessBit,
    SrcIsAligned = OtherDerived::Flags & AlignedBit,
    JointAlignment = bool(DstIsAligned) && bool(SrcIsAligned) ? Aligned : Unaligned
  };

private:
  enum {
    InnerSize = int(Derived::IsVectorAtCompileTime) ? int(Derived::SizeAtCompileTime)
              : int(Derived::Flags)&RowMajorBit ? int(Derived::ColsAtCompileTime)
              : int(Derived::RowsAtCompileTime),
    InnerMaxSize = int(Derived::IsVectorAtCompileTime) ? int(Derived::MaxSizeAtCompileTime)
              : int(Derived::Flags)&RowMajorBit ? int(Derived::MaxColsAtCompileTime)
              : int(Derived::MaxRowsAtCompileTime),
    MaxSizeAtCompileTime = Derived::SizeAtCompileTime,
    PacketSize = packet_traits<typename Derived::Scalar>::size
  };

  enum {
    StorageOrdersAgree = (int(Derived::IsRowMajor) == int(OtherDerived::IsRowMajor)),
    MightVectorize = StorageOrdersAgree
                  && (int(Derived::Flags) & int(OtherDerived::Flags) & ActualPacketAccessBit),
    MayInnerVectorize  = MightVectorize && int(InnerSize)!=Dynamic && int(InnerSize)%int(PacketSize)==0
                       && int(DstIsAligned) && int(SrcIsAligned),
    MayLinearize = StorageOrdersAgree && (int(Derived::Flags) & int(OtherDerived::Flags) & LinearAccessBit),
    MayLinearVectorize = MightVectorize && MayLinearize && DstHasDirectAccess
                       && (DstIsAligned || MaxSizeAtCompileTime == Dynamic),
      /* If the destination isn't aligned, we have to do runtime checks and we don't unroll,
         so it's only good for large enough sizes. */
    MaySliceVectorize  = MightVectorize && DstHasDirectAccess
                       && (int(InnerMaxSize)==Dynamic || int(InnerMaxSize)>=3*PacketSize)
      /* slice vectorization can be slow, so we only want it if the slices are big, which is
         indicated by InnerMaxSize rather than InnerSize, think of the case of a dynamic block
         in a fixed-size matrix */
  };

public:
  enum {
    Traversal = int(MayInnerVectorize)  ? int(DefaultTraversal)  // int(InnerVectorizedTraversal)
              : int(MayLinearVectorize) ? int(DefaultTraversal)  // int(LinearVectorizedTraversal)
              : int(MaySliceVectorize)  ? int(DefaultTraversal)  // int(SliceVectorizedTraversal)
              : int(MayLinearize)       ? int(DefaultTraversal)  // int(LinearTraversal)
                                        : int(DefaultTraversal),
    Vectorized = int(Traversal) == InnerVectorizedTraversal
              || int(Traversal) == LinearVectorizedTraversal
              || int(Traversal) == SliceVectorizedTraversal
  };

private:
  enum {
    UnrollingLimit      = EIGEN_UNROLLING_LIMIT * (Vectorized ? int(PacketSize) : 1),
    MayUnrollCompletely = int(Derived::SizeAtCompileTime) != Dynamic
                       && int(OtherDerived::CoeffReadCost) != Dynamic
                       && int(Derived::SizeAtCompileTime) * int(OtherDerived::CoeffReadCost) <= int(UnrollingLimit),
    MayUnrollInner      = int(InnerSize) != Dynamic
                       && int(OtherDerived::CoeffReadCost) != Dynamic
                       && int(InnerSize) * int(OtherDerived::CoeffReadCost) <= int(UnrollingLimit)
  };

public:
  enum {
    Unrolling = (int(Traversal) == int(InnerVectorizedTraversal) || int(Traversal) == int(DefaultTraversal))
                ? (
 		    int(MayUnrollCompletely) ? int(NoUnrolling)    // int(CompleteUnrolling)
                  : int(MayUnrollInner)      ? int(NoUnrolling)    // int(InnerUnrolling)
                                             : int(NoUnrolling)
                  )
              : int(Traversal) == int(LinearVectorizedTraversal)
                ? ( bool(MayUnrollCompletely) && bool(DstIsAligned) ? int(NoUnrolling)   // int(CompleteUnrolling) 
                                                                    : int(NoUnrolling) )
              : int(Traversal) == int(LinearTraversal)
                ? ( bool(MayUnrollCompletely) ? int(NoUnrolling)   // int(CompleteUnrolling) 
                                              : int(NoUnrolling) )
              : int(NoUnrolling)
  };

#ifdef EIGEN_DEBUG_ASSIGN
  static void debug()
  {
    EIGEN_DEBUG_VAR(DstIsAligned)
    EIGEN_DEBUG_VAR(SrcIsAligned)
    EIGEN_DEBUG_VAR(JointAlignment)
    EIGEN_DEBUG_VAR(InnerSize)
    EIGEN_DEBUG_VAR(InnerMaxSize)
    EIGEN_DEBUG_VAR(PacketSize)
    EIGEN_DEBUG_VAR(StorageOrdersAgree)
    EIGEN_DEBUG_VAR(MightVectorize)
    EIGEN_DEBUG_VAR(MayLinearize)
    EIGEN_DEBUG_VAR(MayInnerVectorize)
    EIGEN_DEBUG_VAR(MayLinearVectorize)
    EIGEN_DEBUG_VAR(MaySliceVectorize)
    EIGEN_DEBUG_VAR(Traversal)
    EIGEN_DEBUG_VAR(UnrollingLimit)
    EIGEN_DEBUG_VAR(MayUnrollCompletely)
    EIGEN_DEBUG_VAR(MayUnrollInner)
    EIGEN_DEBUG_VAR(Unrolling)
  }
#endif
};

// copy_using_evaluator_impl is based on assign_impl

template<typename LhsXprType, typename RhsXprType,
         int Traversal = copy_using_evaluator_traits<LhsXprType, RhsXprType>::Traversal,
         int Unrolling = copy_using_evaluator_traits<LhsXprType, RhsXprType>::Unrolling>
struct copy_using_evaluator_impl;

template<typename LhsXprType, typename RhsXprType>
struct copy_using_evaluator_impl<LhsXprType, RhsXprType, DefaultTraversal, NoUnrolling>
{
  static void run(const LhsXprType& lhs, const RhsXprType& rhs)
  {
    typedef typename evaluator<LhsXprType>::type LhsEvaluatorType;
    typedef typename evaluator<RhsXprType>::type RhsEvaluatorType;
    typedef typename LhsXprType::Index Index;

    LhsEvaluatorType lhsEvaluator(lhs.const_cast_derived());
    RhsEvaluatorType rhsEvaluator(rhs);

    for(Index outer = 0; outer < lhs.outerSize(); ++outer) {
      for(Index inner = 0; inner < lhs.innerSize(); ++inner) {
	Index row = lhs.rowIndexByOuterInner(outer, inner);
	Index col = lhs.colIndexByOuterInner(outer, inner);
	lhsEvaluator.coeffRef(row, col) = rhsEvaluator.coeff(row, col);
      }
    }
  }
};

// Based on DenseBase::LazyAssign()

template<typename LhsXprType, typename RhsXprType>
void copy_using_evaluator(const LhsXprType& lhs, const RhsXprType& rhs)
{
  copy_using_evaluator_impl<LhsXprType, RhsXprType>::run(lhs, rhs);
}

} // namespace internal

#endif // EIGEN_ASSIGN_EVALUATOR_H