IVGCVSW-1898 : Ref backend folder structure

* Reference backend is renamed to backends/reference as per
  https://confluence.arm.com/display/MLENG/Pluggable+backends

Change-Id: I27a13c274eb60995dfb459e3c49c0e2f60bcd32c

1 files changed, 49 insertions, 0 deletions

diff --git a/src/backends/reference/workloads/Softmax.cpp b/src/backends/reference/workloads/Softmax.cpp
new file mode 100644
index 0000000000..4f1016e86c
--- /dev/null
+++ b/src/backends/reference/workloads/Softmax.cpp
@@ -0,0 +1,49 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "Softmax.hpp"
+
+#include <cmath>
+#include <vector>
+
+namespace armnn
+{
+
+/// Computes the softmax function on some inputs, into outputs, with a shape given by tensorInfo.
+void Softmax(const float* in, float* out, const TensorInfo& tensorInfo, float beta)
+{
+    unsigned int numChannels = tensorInfo.GetShape()[1];
+    for (unsigned int n = 0; n < tensorInfo.GetShape()[0]; n++)
+    {
+        // Find maximum channel.
+        float max = in[n * numChannels];
+        for (unsigned int c = 1; c < numChannels; c++)
+        {
+            float val = in[n * numChannels + c];
+            if (val > max)
+            {
+                max = val;
+            }
+        }
+
+        // Exponentiate all values and sum.
+        std::vector<float> exponentials(numChannels);
+        float              sum = 0.0f;
+        for (unsigned int c = 0; c < numChannels; c++)
+        {
+            float val       = in[n * numChannels + c];
+            exponentials[c] = expf((val - max) * beta);
+            sum += exponentials[c];
+        }
+
+        // Divide exponentials by sum to give outputs.
+        for (unsigned int c = 0; c < numChannels; c++)
+        {
+            out[n * numChannels + c] = exponentials[c] / sum;
+        }
+    }
+}
+
+} //namespace armnn