IVGCVSW-2087 Reference implementation and unit tests for StridedSlice

Change-Id: Ifeacc0adb4547c72537b9ea7a61bf3c4ec3673fa

1 files changed, 158 insertions, 0 deletions

diff --git a/src/backends/reference/workloads/StridedSlice.cpp b/src/backends/reference/workloads/StridedSlice.cpp
new file mode 100644
index 0000000000..71903e421d
--- /dev/null
+++ b/src/backends/reference/workloads/StridedSlice.cpp
@@ -0,0 +1,158 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "StridedSlice.hpp"
+
+#include <boost/assert.hpp>
+#include <boost/numeric/conversion/cast.hpp>
+
+namespace armnn
+{
+
+void PadParams(StridedSliceDescriptor& p, unsigned int dimCount)
+{
+    BOOST_ASSERT_MSG(dimCount <= 4, "Expected input with at most 4 dimensions");
+
+    const unsigned int beginIndicesCount =
+        boost::numeric_cast<unsigned int>(p.m_Begin.size());
+
+    BOOST_ASSERT(dimCount >= beginIndicesCount);
+    const unsigned int padCount = dimCount - beginIndicesCount;
+
+    p.m_Begin.resize(dimCount);
+    p.m_End.resize(dimCount);
+    p.m_Stride.resize(dimCount);
+
+    for (unsigned int i = beginIndicesCount; i > 0; --i)
+    {
+        p.m_Stride[i + padCount - 1] = p.m_Stride[i - 1];
+        p.m_Begin[i + padCount - 1] = p.m_Begin[i - 1];
+        p.m_End[i + padCount - 1] = p.m_End[i - 1];
+    }
+
+    for (unsigned int i = 0; i < padCount; ++i)
+    {
+        p.m_Stride[i] = 1;
+        p.m_Begin[i] = 0;
+        p.m_End[i] = 0;
+    }
+
+    p.m_ShrinkAxisMask <<= padCount;
+    p.m_EllipsisMask <<= padCount;
+    p.m_NewAxisMask <<= padCount;
+    p.m_BeginMask <<= padCount;
+    p.m_EndMask <<= padCount;
+    p.m_BeginMask |= (1 << padCount) - 1;
+    p.m_EndMask |= (1 << padCount) - 1;
+}
+
+bool LoopCondition(int index, int stop, int stride)
+{
+    return stride > 0 ? index >= stop : index <= stop;
+}
+
+TensorShape ExtendShape(const TensorShape& inputShape,
+                        unsigned int newNumDimensions)
+{
+    if (inputShape.GetNumDimensions() >= newNumDimensions)
+    {
+        return inputShape;
+    }
+
+    unsigned int newSizes[newNumDimensions];
+
+    unsigned int diff = newNumDimensions - inputShape.GetNumDimensions();
+
+    for (unsigned int i = 0; i < diff; i++)
+    {
+        newSizes[i] = 1;
+    }
+
+    for (unsigned int i = diff; i < newNumDimensions; i++)
+    {
+        newSizes[i] = inputShape[i - diff];
+    }
+
+    return TensorShape(newNumDimensions, newSizes);
+}
+
+template<typename T>
+void StridedSlice(const TensorInfo& inputInfo,
+                  const TensorInfo& outputInfo,
+                  const StridedSliceDescriptor& params,
+                  const T* inputData,
+                  T* outputData)
+{
+    const TensorShape inputShape =
+        ExtendShape(inputInfo.GetShape(), 4);
+
+    StridedSliceDescriptor paddedParams = params;
+
+    // Pad parameters to 4 dimensions
+    PadParams(paddedParams, 4);
+
+    const int start0 =
+        paddedParams.GetStartForAxis(inputShape, 0);
+    const int stop0 =
+        paddedParams.GetStopForAxis(inputShape, 0, start0);
+
+    const int start1 =
+        paddedParams.GetStartForAxis(inputShape, 1);
+    const int stop1 =
+        paddedParams.GetStopForAxis(inputShape, 1, start1);
+
+    const int start2 =
+        paddedParams.GetStartForAxis(inputShape, 2);
+    const int stop2 =
+        paddedParams.GetStopForAxis(inputShape, 2, start2);
+
+    const int start3 =
+        paddedParams.GetStartForAxis(inputShape, 3);
+    const int stop3 =
+        paddedParams.GetStopForAxis(inputShape, 3, start3);
+
+    T* outPtr = outputData;
+
+    for (int in0 = start0;
+         !LoopCondition(in0, stop0, paddedParams.m_Stride[0]);
+         in0 += paddedParams.m_Stride[0])
+    {
+        for (int in1 = start1;
+             !LoopCondition(in1, stop1, paddedParams.m_Stride[1]);
+             in1 += paddedParams.m_Stride[1])
+        {
+            for (int in2 = start2;
+                 !LoopCondition(in2, stop2, paddedParams.m_Stride[2]);
+                 in2 += paddedParams.m_Stride[2])
+            {
+                for (int in3 = start3;
+                     !LoopCondition(in3, stop3, paddedParams.m_Stride[3]);
+                     in3 += paddedParams.m_Stride[3])
+                {
+                    int dim1 = boost::numeric_cast<int>(inputShape[1]);
+                    int dim2 = boost::numeric_cast<int>(inputShape[2]);
+                    int dim3 = boost::numeric_cast<int>(inputShape[3]);
+
+                    int inputOffset = ((in0 * dim1 + in1) * dim2 + in2) * dim3 + in3;
+                    *(outPtr++) = inputData[inputOffset];
+                }
+            }
+        }
+    }
+}
+
+template void StridedSlice<float>(const TensorInfo& inputInfo,
+                                  const TensorInfo& outputInfo,
+                                  const StridedSliceDescriptor& params,
+                                  const float* inputData,
+                                  float* outData);
+
+template void StridedSlice<uint8_t>(const TensorInfo& inputInfo,
+                                    const TensorInfo& outputInfo,
+                                    const StridedSliceDescriptor& params,
+                                    const uint8_t* inputData,
+                                    uint8_t* outData);
+
+} //namespace armnn