ref: 896a1657a35e8eaa4e135e564ba05221b32d14dc 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