__pbs_rs
#define bus_space_read_1(t, h, o) __pbs_rs(1,u_int8_t,(t),(h),(o))
#define bus_space_read_2(t, h, o) __pbs_rs(2,u_int16_t,(t),(h),(o))
#define bus_space_read_4(t, h, o) __pbs_rs(4,u_int32_t,(t),(h),(o))
#define bus_space_read_8(t, h, o) __pbs_rs(8,u_int64_t,(t),(h),(o))