From b85547024490d4c89538dcebfb0a2730e18a6d8d Mon Sep 17 00:00:00 2001
From: David Monahan <david.monahan@arm.com>
Date: Thu, 25 Apr 2019 16:03:38 +0100
Subject: IVGCVSW-2657: Fix to force correct quantisation parameters for
 QASYMM8 Softmax Signed-off-by: David Monahan <david.monahan@arm.com>

Change-Id: I0989ea843714ba1d5da756bb87ddefa3706b07eb
---
 include/armnn/INetwork.hpp |  2 ++
 src/armnn/Network.cpp      | 18 ++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/armnn/INetwork.hpp b/include/armnn/INetwork.hpp
index a15ceb1c15..7141770298 100644
--- a/include/armnn/INetwork.hpp
+++ b/include/armnn/INetwork.hpp
@@ -219,6 +219,8 @@ public:
         const char* name = nullptr) = 0;
 
     /// Adds a softmax layer to the network.
+    /// If the data type is QAsymm8, then the output quantization parameters
+    /// must have a scale of 1/256 and an offset of 0
     /// @param softmaxDescriptor - SoftmaxDescriptor to configure the softmax.
     /// @param name - Optional name for the layer.
     /// @return - Interface for configuring the layer.
diff --git a/src/armnn/Network.cpp b/src/armnn/Network.cpp
index 0bd8d4b69b..a38bcf1910 100644
--- a/src/armnn/Network.cpp
+++ b/src/armnn/Network.cpp
@@ -114,8 +114,8 @@ bool CheckScaleSetOnQuantizedType(Layer* layer, Optional<std::vector<std::string
     bool noErrors = true;
     unsigned int numOutputs = layer->GetNumOutputSlots();
     for (unsigned int i = 0; i < numOutputs; i++) {
-        const OutputSlot &outputSlot = layer->GetOutputSlot(i);
-        const TensorInfo &info = outputSlot.GetTensorInfo();
+        OutputSlot& outputSlot = layer->GetOutputSlot(i);
+        TensorInfo info = outputSlot.GetTensorInfo();
         if (DataType::QuantisedAsymm8 == info.GetDataType()) {
             if (0.f == info.GetQuantizationScale()) {
                 noErrors = false;
@@ -125,6 +125,20 @@ bool CheckScaleSetOnQuantizedType(Layer* layer, Optional<std::vector<std::string
                    << " Quantized 8 bit but its scale parameter has not been set";
                 ReportError(ss.str(), errMessages);
             }
+            // Softmax under QuantisedAsymm8 must always be scale (1.0f/256.0f) and offset 0
+            if ((info.GetQuantizationScale() != (1.0f / 256.0f) ||
+                 info.GetQuantizationOffset() != 0) &&
+                 layer->GetType() == armnn::LayerType::Softmax)
+            {
+                std::stringstream ss;
+                ss << "Quantization parameters for Softmax layer (Scale: " <<
+                info.GetQuantizationScale() << " and Offset: " << info.GetQuantizationOffset() <<
+                ") are incorrect and have been updated to Scale: 0.00390625 and Offset: 0";
+                BOOST_LOG_TRIVIAL(warning) << ss.str();
+                info.SetQuantizationScale((1.0f /256.0f));
+                info.SetQuantizationOffset(0);
+                outputSlot.SetTensorInfo(info);
+            }
         }
     }
     return noErrors;
-- 
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