From f697df723798779bc29d9f7299bb5398767d5db0 Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Wed, 14 Jan 2015 15:38:48 -0800
Subject: Improved support for RowMajor tensors Misc fixes and API cleanups.

---
 unsupported/Eigen/CXX11/src/Tensor/TensorPatch.h | 46 +++++++++++++++++++++---
 1 file changed, 41 insertions(+), 5 deletions(-)

(limited to 'unsupported/Eigen/CXX11/src/Tensor/TensorPatch.h')

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorPatch.h b/unsupported/Eigen/CXX11/src/Tensor/TensorPatch.h
index e2fe32d67..1c03d202f 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorPatch.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorPatch.h
@@ -24,11 +24,14 @@ template<typename PatchDim, typename XprType>
 struct traits<TensorPatchOp<PatchDim, XprType> > : public traits<XprType>
 {
   typedef typename XprType::Scalar Scalar;
-  typedef typename internal::packet_traits<Scalar>::type Packet;
-  typedef typename traits<XprType>::StorageKind StorageKind;
-  typedef typename traits<XprType>::Index Index;
+  typedef traits<XprType> XprTraits;
+  typedef typename packet_traits<Scalar>::type Packet;
+  typedef typename XprTraits::StorageKind StorageKind;
+  typedef typename XprTraits::Index Index;
   typedef typename XprType::Nested Nested;
   typedef typename remove_reference<Nested>::type _Nested;
+  static const int NumDimensions = XprTraits::NumDimensions + 1;
+  static const int Layout = XprTraits::Layout;
 };
 
 template<typename PatchDim, typename XprType>
@@ -89,11 +92,16 @@ struct TensorEvaluator<const TensorPatchOp<PatchDim, ArgType>, Device>
   enum {
     IsAligned = false,
     PacketAccess = TensorEvaluator<ArgType, Device>::PacketAccess,
-  };
+    Layout = TensorEvaluator<ArgType, Device>::Layout,
+    CoordAccess = true,
+ };
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorEvaluator(const XprType& op, const Device& device)
       : m_impl(op.expression(), device)
   {
+   // Only column major tensors are supported for now.
+    EIGEN_STATIC_ASSERT((Layout == ColMajor), YOU_MADE_A_PROGRAMMING_MISTAKE);
+
     Index num_patches = 1;
     const typename TensorEvaluator<ArgType, Device>::Dimensions& input_dims = m_impl.dimensions();
     const PatchDim& patch_dims = op.patch_dims();
@@ -195,6 +203,35 @@ struct TensorEvaluator<const TensorPatchOp<PatchDim, ArgType>, Device>
     }
   }
 
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType coeff(const array<Index, NumDims>& coords) const
+  {
+    // Location of the first element of the patch.
+    const Index patchIndex = coords[NumDims - 1];
+
+    if (TensorEvaluator<ArgType, Device>::CoordAccess) {
+      array<Index, NumDims-1> inputCoords;
+      for (int i = NumDims - 2; i > 0; --i) {
+        const Index patchIdx = patchIndex / m_patchStrides[i];
+        patchIndex -= patchIdx * m_patchStrides[i];
+        const Index offsetIdx = coords[i];
+        inputCoords[i] = coords[i] + patchIdx;
+      }
+      inputCoords[0] = (patchIndex + coords[0]);
+      return m_impl.coeff(inputCoords);
+    }
+    else {
+      Index inputIndex = 0;
+      for (int i = NumDims - 2; i > 0; --i) {
+        const Index patchIdx = patchIndex / m_patchStrides[i];
+        patchIndex -= patchIdx * m_patchStrides[i];
+        const Index offsetIdx = coords[i];
+        inputIndex += (patchIdx + offsetIdx) * m_inputStrides[i];
+      }
+      inputIndex += (patchIndex + coords[0]);
+      return m_impl.coeff(inputIndex);
+    }
+  }
+
   Scalar* data() const { return NULL; }
 
  protected:
@@ -206,7 +243,6 @@ struct TensorEvaluator<const TensorPatchOp<PatchDim, ArgType>, Device>
   TensorEvaluator<ArgType, Device> m_impl;
 };
 
-
 } // end namespace Eigen
 
 #endif // EIGEN_CXX11_TENSOR_TENSOR_PATCH_H
-- 
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