IVGCVSW-4440 : Add HARD_SWISH Support to Activation in CpuRef

* Add a new Activiation type of HardSwish.
* Add CpuRef support and tests.

Signed-off-by: Colm Donelan <Colm.Donelan@arm.com>
Change-Id: I68c3840aa45b7a27d5e416a5d50fe8f99f003ce8

1 files changed, 8 insertions, 0 deletions

diff --git a/src/backends/reference/workloads/Activation.cpp b/src/backends/reference/workloads/Activation.cpp
index 82dd919de9..798c6e48d5 100644
--- a/src/backends/reference/workloads/Activation.cpp
+++ b/src/backends/reference/workloads/Activation.cpp
@@ -9,6 +9,7 @@
 
 namespace armnn
 {
+
 float Activation(float in,
                  ActivationFunction function,
                  float a,
@@ -74,6 +75,13 @@ float Activation(float in,
             output = (in >= 0) ? in : a * (expf(in) - 1);
             break;
         }
+        case ActivationFunction::HardSwish:
+        {
+            // hard_swish(x) = x * relu6(x+3) / 6
+            // relu6(x) = min(max(x,0),6)
+            output = in * (std::min(std::max((in + 3),0.0f),6.0f)) / 6;
+            break;
+        }
         default:
         {
             throw InvalidArgumentException("Unsupported activation function");