ref: b5ab8a5cebc607a77a049bef64767766538d9698 dir: /sys/src/libc/68000/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