Circular-convolution without using cconv(x,y,n)

It is used to convolve two Discrete Fourier transform sequences.It is faster for long sequences than linear convolution.

Enter x(n):
[1 2 2 1]
Enter h(n):
[1 2 3 1]
x(n) is:
1 2 2 1

h(n) is:
1 2 3 1

Y(n) is:
11 9 10 12