ref: 2dea7c2f8e55b4de0c79448c3ce03351a8f75e3b dir: /sys/src/libc/68000/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