Abstract activation and implement softmax

include/layers/activation.cuh

@@ -0,0 +1,55 @@
+#ifndef CUDANET_ACTIVATION_H
+#define CUDANET_ACTIVATION_H
+
+namespace CUDANet::Layers {
+
+/**
+ * @brief Activation functions
+ * 
+ * SIGMOID: Sigmoid
+ * RELU: Rectified Linear Unit
+ * SOFTMAX: Softmax
+ *
+ */
+enum ActivationType { SIGMOID, RELU, SOFTMAX, NONE };
+
+class Activation {
+  public:
+
+    Activation() = default;
+
+    /**
+     * @brief Construct a new Activation object
+     * 
+     * @param activation Type of activation
+     * @param length     Length of the input
+     */
+    Activation(ActivationType activation, const unsigned int length);
+
+    /**
+     * @brief Destroy the Activation object
+     * 
+     */
+    ~Activation();
+
+    /**
+     * @brief Run the activation function on the input
+     * 
+     * @param d_input Pointer to the input vector on the device
+     */
+    void activate(float* d_input);
+
+
+  private:
+    ActivationType activationType;
+    unsigned int length;
+    unsigned int gridSize;
+
+    float* d_softmax_sum;
+
+};
+
+
+}  // namespace CUDANet::Layers
+
+#endif  // CUDANET_ACTIVATION_H