ref: 2d4a2c5c2065a32b6b5bd6a0e887af1574a8dfec dir: /sys/src/ape/lib/ap/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