ref: aab7b5ae8b18b4f097efcc59ea4a59093d0d6962 dir: /sys/src/ape/lib/ap/68020/tas.s/
TEXT tas(SB), $0 MOVL $0, R0 MOVL a+0(FP), A0 TAS (A0) BEQ tas_1 MOVL $1, R0 tas_1: RTS