ref: 74241e31aaaebb55883c96c6d1e2681930c44245 dir: /sys/src/libc/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