Big[A0_, m0_, a0_, b0_, c0_, d0_] :=

 Module[{A = A0, m = m0, a = a0, b = b0, c = c0, d = d0},

  For[i = 1, i <= 64, i = i + 4,
   For[j = 1, j <= 64, j = j + 4,
    A[[i ;; i + 3, j ;; j + 3]] =
     DiagonalMatrix[(m + 1)*
        Diagonal[A[[i ;; i + 3, j ;; j + 3]]] + {a, b, c, d}*
        RotateLeft[Diagonal[A[[i ;; i + 3, j ;; j + 3]]], 1]]
    ]
   ];
  A]