# strncasecmp_PF.S

/* Copyright (c) 2006, Carlos Lamas

based on libc/pmstring/strncasecmp_P.S which is

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* Neither the name of the copyright holders nor the names of
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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. */

/* $Id$ */

#if !defined(__AVR_TINY__)

#include "macros.inc"

#define s1_b1 r25
#define s1_b0 r24
#define s2_b3 r23
#define s2_b2 r22
#define s2_b1 r21
#define s2_b0 r20
#define len_b1 r19
#define len_b0 r18

#define cht s2_b1
#define tmp s2_b0

#define ret_b1 r25
#define ret_b0 r24

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

The strncasecmp_PF() function is similar to strcasecmp_PF(), except it
only compares the first \e n characters of \e s1 and the string in flash is

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

\returns The strncasecmp_PF() function returns an integer less than, equal
to, or greater than zero if \e s1 (or the first \e n bytes thereof) is found,
respectively, to be less than, to match, or be greater than \e s2. The
contents of RAMPZ SFR are undefined when the function returns  */

#if !defined(__DOXYGEN__)

.text
.global _U(strncasecmp_PF)
.type   _U(strncasecmp_PF), @function

_U(strncasecmp_PF):

X_movw  ZL, s2_b0
LPM_R0_ZPLUS_INIT s2_b2
X_movw  XL, s1_b0

.L_strncasecmp_PF_loop:

subi    len_b0, lo8(1)
sbci    len_b1, hi8(1)
brcs    .L_strncasecmp_PF_equal
ld      ret_b0, X+              ; load *s1
mov     tmp, r0                 ; copy of *s2 to tmp
mov     cht, r0                 ; copy of *s2 to cht
ori     cht, 0x20               ; make it lower case
cpi     cht, 'a'                ; test on [a .. z]
brlt    .L_strncasecmp_PF_tst
cpi     cht, 'z'+1
brge    .L_strncasecmp_PF_tst
ori     tmp, 0x20               ; we got an alpha in s2
ori     ret_b0, 0x20            ; make *s1, *s2 lower case

.L_strncasecmp_PF_tst:

sub     ret_b0, tmp
brne    .L_strncasecmp_PF_done
tst     r0
brne    .L_strncasecmp_PF_loop

.L_strncasecmp_PF_equal:

sub     ret_b0, ret_b0

.L_strncasecmp_PF_done:
; ret_hi = SREG.C ? 0xFF : 0

sbc     ret_b1, ret_b1
LPM_R0_ZPLUS_FINI s2_b2
ret

.L_strncasecmp_PF_end:

.size   _U(strncasecmp_PF), .L_strncasecmp_PF_end - _U(strncasecmp_PF)

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */