strcmp_P.S

/* Copyright (c) 2002, 2005, 2006, 2007 Marek Michalkiewicz

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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_pgmspace
\fn int strcmp_P(const char *s1, PGM_P s2)

The strcmp_P() function is similar to strcmp() except that \p s2 is
pointer to a string in program space.

\returns The strcmp_P() 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_P() 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(__AVR_TINY__)

#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_P)
.type   _U(strcmp_P), @function
_U(strcmp_P):
X_movw  ZL, s2_lo
X_movw  XL, s1_lo
.L_strcmp_P_loop:
ld      ret_lo, X+
X_lpm   r0, Z+
sub     ret_lo, r0
cpse    r0, __zero_reg__
breq    .L_strcmp_P_loop
; ret_hi = SREG.C ? 0xFF : 0
sbc     ret_hi, ret_hi
ret
.L_strcmp_P_end:
.size   _U(strcmp_P), .L_strcmp_P_end - _U(strcmp_P)

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */