# strcmp.S

/* Copyright (c) 2002, 2007 Marek Michalkiewicz

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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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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 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__ */