# strcasecmp_P.S

/* Copyright (c) 2002, 2005, 2006, 2007 Reiner Patommel

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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE. */

/* $Id$ */

/*
strcasecmp_P.S
Case insensitive compare

Contributors:
Created by Reiner Patommel
*/
/** \file */

/** \ingroup avr_pgmspace
\fn int strcasecmp_P(const char *s1, PGM_P s2)
\brief Compare two strings ignoring case.

The strcasecmp_P() function compares the two strings \p s1 and \p s2,
ignoring the case of the characters.

\param s1 A pointer to a string in the devices SRAM.
\param s2 A pointer to a string in the devices Flash.

\returns The strcasecmp_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 strcasecmp_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

#define tmp r22

ASSEMBLY_CLIB_SECTION
.global _U(strcasecmp_P)
.type   _U(strcasecmp_P), @function
_U(strcasecmp_P):
X_movw  ZL, s2_lo
X_movw  XL, s1_lo

1:      ld      ret_lo, X+              ; *s1++
cpi     ret_lo, 'A'             ; if in [A-Z] then tolower()
brlt    2f
cpi     ret_lo, 'Z'+1
brge    2f
subi    ret_lo, 'A'-'a'

2:      X_lpm   tmp, Z+                 ; *s2++
cpi     tmp, 'A'                ; if in [A-Z] then tolower()
brlt    3f
cpi     tmp, 'Z'+1
brge    3f
subi    tmp, 'A'-'a'

3:      sub     ret_lo, tmp             ; compare
cpse    tmp, __zero_reg__       ; break, if end of string
breq    1b

sbc     ret_hi, ret_hi          ; sign extension
ret

.size   _U(strcasecmp_P), . - _U(strcasecmp_P)

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */