Add activations test

src/kernels/activations.cu

@@ -0,0 +1,48 @@
+#include <functional>
+
+#include "activations.cuh"
+
+__device__ float sigmoid(float a) {
+    return 1.0 / (1.0 + exp(-a));
+}
+
+__device__ float relu(float a) {
+    return a < 0.0 ? 0.0 : a;
+}
+
+__device__ float linear(float a) {
+    return a;
+}
+
+__global__ void sigmoid_kernel(
+    const float* __restrict__ src,
+    float* __restrict__ dst,
+    int len
+) {
+    int stride = gridDim.x * blockDim.x;
+    int tid    = blockDim.x * blockIdx.x + threadIdx.x;
+
+    for (int i = tid; i < len; i += stride) {
+        dst[i] = sigmoid(src[i]);
+    }
+}
+
+__global__ void
+relu_kernel(const float* __restrict__ src, float* __restrict__ dst, int len) {
+    int stride = gridDim.x * blockDim.x;
+    int tid    = blockDim.x * blockIdx.x + threadIdx.x;
+
+    for (int i = tid; i < len; i += stride) {
+        dst[i] = relu(src[i]);
+    }
+}
+
+__global__ void
+linear_kernel(const float* __restrict__ src, float* __restrict__ dst, int len) {
+    int stride = gridDim.x * blockDim.x;
+    int tid    = blockDim.x * blockIdx.x + threadIdx.x;
+
+    for (int i = tid; i < len; i += stride) {
+        dst[i] = linear(src[i]);
+    }
+}