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#include "macros.inc"
#define dest_hi r25
#define dest_lo r24
#define src_hi r23
#define src_lo r22
#define len_hi r21
#define len_lo r20
; char *strncat(char *dest, const char *src, size_t len)
.text
.global _U(strncat)
.type _U(strncat), @function
_U(strncat):
LOAD_Z(src_lo, src_hi)
LOAD_X(dest_lo, dest_hi)
.strncat_skip:
ld __tmp_reg__, X+
tst __tmp_reg__
brne .strncat_skip
sbiw XL, 1 ; undo post-increment (point the the NUL)
.strncat_loop:
subi len_lo, lo8(1)
sbci len_hi, hi8(1)
brcs .strncat_done
ld __tmp_reg__, Z+
tst __tmp_reg__
st X+, __tmp_reg__
brne .strncat_loop
; return dest (unchanged)
ret
.strncat_done:
st X, __zero_reg__
; return dest (unchanged)
ret
.strncat_end:
.size _U(strncat), .strncat_end - _U(strncat)
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