PACKED_FIELD
PACKED_FIELD((lsb) + (width) - 1, (lsb), struct struct_name, struct_field)
PACKED_FIELD(63, 61, struct test_data, field1),
PACKED_FIELD(60, 52, struct test_data, field2),
PACKED_FIELD(51, 28, struct test_data, field3),
PACKED_FIELD(27, 14, struct test_data, field4),
PACKED_FIELD(13, 9, struct test_data, field5),
PACKED_FIELD(8, 0, struct test_data, field6),