strlcpy.S

/*
   AVR LIBC
   strlcpy()

   Copyright (c) 2003, 2007 Eric B. Weddington, R. Patommel
   Copyright (c) 2009  Dmitry Xmelkov
   All rights reserved.

   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
     notice, this list of conditions and the following disclaimer in
     the documentation and/or other materials provided with the
     distribution.
   * Neither the name of the copyright holders nor the names of
     contributors may be used to endorse or promote products derived
     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
  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  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
  POSSIBILITY OF SUCH DAMAGE.

*/

/* $Id$ */

/** \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__) */