# strlcpy.S

/*
AVR LIBC
strlcpy()

Copyright (c) 2003, 2007 Eric B. Weddington, R. Patommel

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
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* Neither the name of the copyright holders nor the names of
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from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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*/

/* $Id$ */

/** \file */

/** \ingroup avr_string
\fn size_t strlcpy (char *dst, const char *src, size_t siz)
\brief Copy a string.

Copy \p src to string \p dst of size \p siz.  At most \p siz-1
characters will be copied.  Always NULL terminates (unless \p siz == 0).

\returns The strlcpy() function returns strlen(src). If retval >= siz,
truncation occurred.  */

#if !defined(__AVR_TINY__)

#if !defined(__DOXYGEN__)

#include "asmdef.h"

#define dst_lo          r24
#define src_hi          r23
#define src_lo          r22
#define siz_hi          r21
#define siz_lo          r20
#define rslt_lo         r24

ENTRY strlcpy
X_movw  XL, dst_lo              ; X = dst
X_movw  ZL, src_lo              ; Z = src

; copy loop
1:      subi    siz_lo, lo8(1)
sbci    siz_hi, hi8(1)
brcs    4f                      ; is possible with siz == 0
breq    3f                      ; --> siz chars copied
ld      __tmp_reg__, Z+
st      X+, __tmp_reg__
tst     __tmp_reg__
brne    1b

; calculate result (Z - 1 - src) and return
2:      sub     ZL, src_lo
sbc     ZH, src_hi
sbiw    ZL, 1
X_movw  rslt_lo, ZL
ret

; terminate dst
3:      st      X, __zero_reg__

; find src end
4:      ld      __tmp_reg__, Z+
tst     __tmp_reg__
brne    4b
rjmp    2b

ENDFUNC

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */