1 files changed, 91 insertions, 0 deletions
diff --git a/src/backends/reference/workloads/LogSoftmax.cpp b/src/backends/reference/workloads/LogSoftmax.cpp
new file mode 100644
index 0000000000..3fa3dc0d8c
--- /dev/null
+++ b/src/backends/reference/workloads/LogSoftmax.cpp
@@ -0,0 +1,91 @@
+//
+// Copyright © 2019 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "LogSoftmax.hpp"
+
+#include <TensorUtils.hpp>
+
+#include <cmath>
+
+#include <boost/assert.hpp>
+#include <boost/core/ignore_unused.hpp>
+#include <boost/numeric/conversion/cast.hpp>
+
+namespace
+{
+
+inline bool ValidateAxis(int axis, unsigned int numDimensions)
+{
+    const int sNumDimensions = boost::numeric_cast<int>(numDimensions);
+    return axis < sNumDimensions && axis >= -sNumDimensions;
+}
+
+} // anonymous namespace
+
+namespace armnn
+{
+
+void LogSoftmax(Decoder<float>& input,
+                Encoder<float>& output,
+                const TensorInfo& inputInfo,
+                const LogSoftmaxDescriptor& descriptor)
+{
+    const unsigned int numDimensions = inputInfo.GetNumDimensions();
+
+    bool axisIsValid = ValidateAxis(descriptor.m_Axis, numDimensions);
+    BOOST_ASSERT_MSG(axisIsValid,
+        "Axis index is not in range [-numDimensions, numDimensions).");
+    boost::ignore_unused(axisIsValid);
+
+    unsigned int uAxis = descriptor.m_Axis < 0  ?
+        numDimensions - boost::numeric_cast<unsigned int>(std::abs(descriptor.m_Axis)) :
+        boost::numeric_cast<unsigned int>(descriptor.m_Axis);
+
+    const TensorShape& inputShape = inputInfo.GetShape();
+    const unsigned int outerSize  = armnnUtils::GetNumElementsBetween(inputShape, 0, uAxis);
+    const unsigned int axisSize   = inputShape[uAxis];
+    const unsigned int innerSize  = armnnUtils::GetNumElementsBetween(inputShape,
+                                                                      uAxis + 1,
+                                                                      inputShape.GetNumDimensions());
+
+    for (unsigned int outer = 0; outer < outerSize; ++outer)
+    {
+        for (unsigned int inner = 0; inner < innerSize; ++inner)
+        {
+            // Find max
+            input[outer * axisSize * innerSize + inner];
+            float maxValue = input.Get();
+            for (unsigned int i = 1u; i < axisSize; ++i)
+            {
+                input[(outer * axisSize + i) * innerSize + inner];
+                maxValue = std::max(maxValue, input.Get());
+            }
+
+            // Compute sum
+            float sum = 0.0f;
+            for (unsigned int i = 0u; i < axisSize; ++i)
+            {
+                input[(outer * axisSize + i) * innerSize + inner];
+                sum += std::exp((input.Get() - maxValue) * descriptor.m_Beta);
+            }
+
+            // Compute log sum
+            const float logSum = std::log(sum);
+
+            // Compute result
+            for (unsigned int i = 0u; i < axisSize; ++i)
+            {
+                const unsigned int index = (outer * axisSize + i) * innerSize + inner;
+
+                input [index];
+                output[index];
+
+                output.Set((input.Get() - maxValue) * descriptor.m_Beta - logSum);
+            }
+        }
+    }
+}
+
+} // namespace armnn