Migrate Dense layer

src/backends/cuda/kernels/pooling.cu

@@ -1,5 +1,5 @@
 #include "cuda_helper.cuh"
-#include "layer.cuh"
+#include "layer.hpp"
 #include "pooling.cuh"
 
 using namespace CUDANet;

src/backends/cuda/layers/dense.cu

@@ -0,0 +1,69 @@
+#include <cuda_runtime.h>
+
+#include <cstdio>
+#include <cstdlib>
+#include <functional>
+#include <iostream>
+
+#include "vector.cuh"
+#include "activation.hpp"
+#include "cuda_helper.cuh"
+#include "dense.hpp"
+#include "matmul.cuh"
+
+using namespace CUDANet::Layers;
+
+void Dense::initCUDA() {
+    d_output = nullptr;
+
+    CUDA_CHECK(cudaMalloc((void**)&d_output, sizeof(float) * outputSize));
+
+    d_weights = nullptr;
+    d_biases  = nullptr;
+
+    // Allocate GPU memory for weights and biases
+    CUDA_CHECK(
+        cudaMalloc((void**)&d_weights, sizeof(float) * inputSize * outputSize)
+    );
+    CUDA_CHECK(cudaMalloc((void**)&d_biases, sizeof(float) * outputSize));
+    toCuda();
+
+    // Calculate block and grid sizes
+    forwardGridSize =
+        (std::max(inputSize, outputSize) + BLOCK_SIZE - 1) / BLOCK_SIZE;
+    biasGridSize = (outputSize + BLOCK_SIZE - 1) / BLOCK_SIZE;
+}
+
+void Dense::delCUDA() {
+    cudaFree(d_output);
+    cudaFree(d_weights);
+    cudaFree(d_biases);
+}
+
+void Dense::toCuda() {
+    CUDA_CHECK(cudaMemcpy(
+        d_weights, weights.data(), sizeof(float) * inputSize * outputSize,
+        cudaMemcpyHostToDevice
+    ));
+    CUDA_CHECK(cudaMemcpy(
+        d_biases, biases.data(), sizeof(float) * outputSize,
+        cudaMemcpyHostToDevice
+    ));
+}
+
+float* Dense::forwardCUDA(const float* d_input) {
+    Kernels::mat_vec_mul<<<forwardGridSize, BLOCK_SIZE>>>(
+        d_weights, d_input, d_output, inputSize, outputSize
+    );
+    CUDA_CHECK(cudaGetLastError());
+
+    Kernels::vec_vec_add<<<biasGridSize, BLOCK_SIZE>>>(
+        d_biases, d_output, d_output, outputSize
+    );
+    CUDA_CHECK(cudaGetLastError());
+
+    activation->activate(d_output);
+    CUDA_CHECK(cudaDeviceSynchronize());
+
+    return d_output;
+}