Improve softmax numerical stability

include/kernels/matmul.cuh

@@ -35,6 +35,33 @@ __global__ void vec_vec_add(
     const unsigned int w
 );
 
+/**
+ * @brief Max reduction kernel
+ *
+ * @param d_vector Device pointer to vector
+ * @param d_output Device pointer to output vector
+ */
+__global__ void max_reduce(
+    const float* __restrict__ d_vector,
+    float* __restrict__ d_output
+);
+
+/**
+ * @brief Add scalar to each element of the vector
+ * 
+ * @param d_vector 
+ * @param d_scalar 
+ * @param d_output 
+ * @param w 
+ * @return __global__ 
+ */
+__global__ void vec_scalar_sub(
+    const float* __restrict__ d_vector,
+    const float* __restrict__ d_scalar,
+    float* __restrict__ d_output,
+    const unsigned int w
+);
+
 }  // namespace CUDANet::Kernels
 
 #endif  // CUDANET_MATMUL_H