ref: aa2b5bc0e721fb6c9d0c99e488c6ee93b72067a4 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