ref: 1d0b9d7088f61fd3e28dada8e8e97abf3eac69f9 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