strcasecmp_PF.S

/* Copyright (c) 2006, Carlos Lamas

based on libc/pmstring/strcasecmp_P.S which is

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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
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/* $Id$ */

#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 ret_b1 r25
#define ret_b0 r24

#define tmp s2_b1       /* copied to Z pointer */
#define cht s2_b0

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

The strcasecmp_PF() function compares the two strings \e s1 and \e s2, ignoring
the case of the characters

\param s1 A pointer to the first string in SRAM
\param s2 A far pointer to the second string in Flash

\returns The strcasecmp_PF() function returns an integer less than, equal
to, or greater than zero if \e s1 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(strcasecmp_PF)
.type   _U(strcasecmp_PF), @function

_U(strcasecmp_PF):

X_movw  ZL, s2_b0
LPM_R0_ZPLUS_INIT s2_b2
X_movw  XL, s1_b0

.L_strcasecmp_PF_loop:

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 tmp lower case
cpi     cht, 'a'                ; test on [a .. z]
brlt    .L_strcasecmp_PF_tst
cpi     cht, 'z'+1
brge    .L_strcasecmp_PF_tst
ori     tmp, 0x20               ; we got an aplpha in s2
ori     ret_b0, 0x20

.L_strcasecmp_PF_tst:                   ; compare

sub     ret_b0, tmp
brne    .L_strcasecmp_PF_done
tst     r0                      ; end of s2?
brne    .L_strcasecmp_PF_loop

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

sbc     ret_b1, ret_b1
LPM_R0_ZPLUS_FINI s2_b2
ret

.L_strcasecmp_PF_end:

.size   _U(strcasecmp_PF), .L_strcasecmp_PF_end - _U(strcasecmp_PF)

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */