.file "strlen.S" .section .text .global _strlen .type _strlen,@function _strlen: #ifdef __RX_DISALLOW_STRING_INSNS__ mov r1, r4 1: mov.b [r1+], r5 cmp #0, r5 bne 1b sub #1, r1 sub r4, r1 rts #else add #0, r1, r4 ; Save a copy of the string start address and set the condition flags. beq null_string ; Test for a NULL pointer. mov #-1, r3 ; Set a limit on the number of bytes examined. mov #0, r2 ; Stop searching when we find a NUL byte. suntil.b ; Search until *r1 == r2 sub #1, r1 ; suntil.b leaves r1 pointing to the byte beyond the match. null_string: sub r4, r1 ; Compute the length. rts #endif .size _strlen, . - _strlen