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.file "memchr.S"
.section .text
.global _memchr
.type _memchr,@function
_memchr:
;; R1: string pointer
;; R2: byte sought
;; R3: max number to scan
#ifdef __RX_DISALLOW_STRING_INSNS__
mov.b r2, r2 ; The mov.b below sign extends as it loads, so make sure that r2 is sign-extended as well.
2: cmp #0, r3
beq 1f
sub #1, r3
mov.b [r1+], r5
cmp r5, r2
bne 2b
sub #1, r1 ; We have found a match, bit now R1 points to the byte after the match.
1: rts
#else
cmp #0, r3 ; If r3 is 0 suntil.b will do nothing and not set any flags...
stz #1, r1 ; ...so store 1 into r1. It will be decremented by the SUB later.
suntil.b ; Search until *r1 == r2 or r3 bytes have been examined.
stnz #1, r1 ; If no match was found return NULL.
sub #1, r1 ; suntil.b leaves r1 pointing at the address *after* the match.
rts
#endif
.size _memchr, . - _memchr
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