ref: 65e0e1c3e37c966d0c18178ad8a4c54c0c0fbce9 dir: /sys/src/ape/lib/ap/386/tas.s/
TEXT tas(SB),$0 MOVL $0xdeadead,AX MOVL l+0(FP),BX XCHGL AX,(BX) RET