ref: 8d0d2ec80f06f3d7d8ba44313cd08eaef5d9b5d1 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