Consider an array of 16-bit numbers A(i,j), where i = 0 through n - 1 is the row index and j = 0 through m - 1 is the column index. The array is stored in the memory of a 68000 computer one row after another, with elements of each row occupying m successive word locations. Write a 68000 subroutine for adding column x to column y, element by element, leaving the sum elements in column y. The indices x and y are passed to the subroutine in registers D1 and D2. The parameters n and m are passed to the subroutine in registers D3 and D4, and the address of element A(0,0) is passed in register AO. Any of the addressing modes in Table 3.2 can be used.