Move cuda source to separate directory

src/cuda/layers/concat.cu

@@ -0,0 +1,37 @@
+#include "concat.cuh"
+#include "cuda_helper.cuh"
+
+using namespace CUDANet::Layers;
+
+
+Concat::Concat(const int inputASize, const int inputBSize)
+    : inputASize(inputASize), inputBSize(inputBSize) {
+
+    d_output = nullptr;
+    CUDA_CHECK(cudaMalloc(
+        (void**)&d_output, sizeof(float) * (inputASize + inputBSize)
+    ));
+}
+
+Concat::~Concat() {
+    cudaFree(d_output);
+}
+
+float* Concat::forward(const float* d_input_A, const float* d_input_B) {
+    CUDA_CHECK(cudaMemcpy(
+        d_output, d_input_A, sizeof(float) * inputASize, cudaMemcpyDeviceToDevice
+    ));
+
+    CUDA_CHECK(cudaMemcpy(
+        d_output + inputASize, d_input_B,
+        sizeof(float) * inputBSize, cudaMemcpyDeviceToDevice
+    ));
+
+    CUDA_CHECK(cudaDeviceSynchronize());
+
+    return d_output;
+}
+
+int Concat::getOutputSize() {
+    return inputASize + inputBSize;
+};