strcmp.S

/* Copyright (c) 2002, 2007 Marek Michalkiewicz
   All rights reserved.

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   modification, are permitted provided that the following conditions are met:

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     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
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  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 int strcmp(const char *s1, const char *s2)
    \brief Compare two strings.

    The strcmp() function compares the two strings \p s1 and \p s2.

    \returns The strcmp() function returns an integer less than, equal
    to, or greater than zero if \p s1 is found, respectively, to be less
    than, to match, or be greater than \p s2. A consequence of the
    ordering used by strcmp() is that if \p s1 is an initial substring
    of \p s2, then \p s1 is considered to be "less than" \p s2. */

#if !defined(__DOXYGEN__)

#include "macros.inc"

#define s1_hi r25
#define s1_lo r24
#define s2_hi r23
#define s2_lo r22

#define ret_hi r25
#define ret_lo r24

        ASSEMBLY_CLIB_SECTION
        .global _U(strcmp)
        .type   _U(strcmp), @function
_U(strcmp):
        X_movw  ZL, s2_lo
        X_movw  XL, s1_lo
.L_strcmp_loop:
        ld      ret_lo, X+
        ld      __tmp_reg__, Z+
        sub     ret_lo, __tmp_reg__
        cpse    __tmp_reg__, __zero_reg__
        breq    .L_strcmp_loop
; ret_hi = SREG.C ? 0xFF : 0
        sbc     ret_hi, ret_hi
        ret
.L_strcmp_end:
        .size   _U(strcmp), .L_strcmp_end - _U(strcmp)

#endif /* not __DOXYGEN__ */