# strncasecmp_P.S

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

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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"
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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
POSSIBILITY OF SUCH DAMAGE. */

/* $Id$ */

/*
strncasecmp_P.S
Case insensitive compare

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

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

The strncasecmp_P() function is similar to strcasecmp_P(), except it
only compares the first \p n characters of \p s1.

\param s1 A pointer to a string in the devices SRAM.
\param s2 A pointer to a string in the devices Flash.
\param n The maximum number of bytes to compare.

\returns The strncasecmp_P() function returns an integer less than,
equal to, or greater than zero if \p s1 (or the first \p n bytes
thereof) is found, respectively, to be less than, to match, or be
greater than \p s2. A consequence of the ordering used by
strncasecmp_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 len_hi r21
#define len_lo r20

#define tmp    r22
#define ret_hi r25
#define ret_lo r24

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

1:      subi    len_lo, lo8(1)          ; if (--len == -1) return 0
sbci    len_hi, hi8(1)
brlo    5f

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
4:      sbc     ret_hi, ret_hi          ; sign extension
ret

5:      sub     ret_lo, ret_lo          ; length limit, return 0
rjmp    4b

.size   _U(strncasecmp_P), . - _U(strncasecmp_P)

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */