/* Copyright (c) 2002, 2007 Reiner Patommel
   Copyright (c) 2007  Dmitry Xmelkov
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   * Redistributions of source code must retain the above copyright
     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
  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  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: strncasecmp.S 1944 2009-04-01 23:12:20Z arcanum $ */

/*
   strncasecmp.S
   Case insensitive compare

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

/** \ingroup avr_string
    \fn int strncasecmp(const char *s1, const char *s2, size_t len)
    \brief Compare two strings ignoring case.

    The strncasecmp() function is similar to strcasecmp(), except it
    only compares the first \p len characters of \p s1.

    \returns The strncasecmp() function returns an integer less than,
    equal to, or greater than zero if \p s1 (or the first \p len 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() 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 len_hi	r21
#define len_lo	r20

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

	ASSEMBLY_CLIB_SECTION
	.global	_U(strncasecmp)
	.type	_U(strncasecmp), @function
	
_U(strncasecmp):
	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:	ld	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), . - _U(strncasecmp)

#endif /* not __DOXYGEN__ */
