ref: 20bca0c2029c53de3d4149d957240b17d44684a8 dir: /sys/src/libc/68020/strlen.s/
TEXT strlen(SB), $0 MOVL s+0(FP), A1 TSTB (A1)+ BEQ null MOVL A1, A2 l1: TSTB (A1)+ BNE l1 SUBL A2, A1 MOVL A1, R0 RTS null: MOVL $0, R0 RTS