MD5_SHIFT_11
FF(a, b, c, d, x_0, MD5_SHIFT_11, MD5_CONST_e(0)); /* 1 */
FF(a, b, c, d, x_4, MD5_SHIFT_11, MD5_CONST_e(4)); /* 5 */
FF(a, b, c, d, x_8, MD5_SHIFT_11, MD5_CONST_e(8)); /* 9 */
FF(a, b, c, d, x_12, MD5_SHIFT_11, MD5_CONST_e(12)); /* 13 */