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Alchemy on passing functional pointers to kernel in CUDA programming. https://leimao.github.io/blog/Pass-Function-Pointers-to-Kernels-CUDA/
#include <iostream>
// Since C++ 11
template<typename T>
using func_t = T (*) (T, T);
template <typename T>
__device__ T add_func (T x, T y)
{
return x + y;
}
template <typename T>
__device__ T mul_func (T x, T y)
{
return x * y;
}
// Required for functional pointer argument in kernel function
// Static pointers to device functions
template <typename T>
__device__ func_t<T> p_add_func = add_func<T>;
template <typename T>
__device__ func_t<T> p_mul_func = mul_func<T>;
template <typename T>
__global__ void kernel(func_t<T> op, T * d_x, T * d_y, T * result)
{
*result = (*op)(*d_x, *d_y);
}
template <typename T>
void test(T x, T y)
{
func_t<T> h_add_func;
func_t<T> h_mul_func;
T * d_x, * d_y;
cudaMalloc(&d_x, sizeof(T));
cudaMalloc(&d_y, sizeof(T));
cudaMemcpy(d_x, &x, sizeof(T), cudaMemcpyHostToDevice);
cudaMemcpy(d_y, &y, sizeof(T), cudaMemcpyHostToDevice);
T result;
T * d_result, * h_result;
cudaMalloc(&d_result, sizeof(T));
h_result = &result;
// Copy device function pointer to host side
cudaMemcpyFromSymbol(&h_add_func, p_add_func<T>, sizeof(func_t<T>));
cudaMemcpyFromSymbol(&h_mul_func, p_mul_func<T>, sizeof(func_t<T>));
kernel<T><<<1,1>>>(h_add_func, d_x, d_y, d_result);
cudaDeviceSynchronize();
cudaMemcpy(h_result, d_result, sizeof(T), cudaMemcpyDeviceToHost);
std::cout << "Sum: " << result << std::endl;
kernel<T><<<1,1>>>(h_mul_func, d_x, d_y, d_result);
cudaDeviceSynchronize();
cudaMemcpy(h_result, d_result, sizeof(T), cudaMemcpyDeviceToHost);
std::cout << "Product: " << result << std::endl;
}
int main()
{
std::cout << "Test int for type int ..." << std::endl;
test<int>(2.05, 10.00);
std::cout << "Test float for type float ..." << std::endl;
test<float>(2.05, 10.00);
std::cout << "Test double for type double ..." << std::endl;
test<double>(2.05, 10.00);
}
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