ref: 2c9f4c21ad0b5e66f06a3613f6e21d5fe9f0da6a 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