CUDA c++ Class Making

Accelerated Computing CUDA CUDA Programming and Performance
1

I’m trying CUDA Class in c++.
However, I cannot use global in my class.
How can I use global in my class?
Here is my class code and global function.

class CUDA_TVM
{
public:
global void init(float* xbar, float* xn, float* y1, float* y2, float* img, int w, int h, int nc);
}

global
void CUDA_TVM::init(float* xbar, float* xn, float* y1, float* y2, float* img, int w, int h, int nc)
{

int x = threadIdx.x + blockDim.x * blockIdx.x;

int y = threadIdx.y + blockDim.y * blockIdx.y;

if (x < w && y < h) {

	int i;

	float val;

	for (int z = 0; z < nc; z++) {

		i = x + w * y + w * h * z;

		val = img[i];

		xbar[i] = val;

		xn[i] = val;

		y1[i] = 0.f;

		y2[i] = 0.f;
	}
}

}