rm_/lib/c-strcasecmp.c

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/* c-strcasecmp.c -- case insensitive string comparator in C locale
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Copyright (C) 1998-1999, 2005-2006, 2009-2022 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
/* Specification. */
#include "c-strcase.h"
#include <limits.h>
#include "c-ctype.h"
int
c_strcasecmp (const char *s1, const char *s2)
{
register const unsigned char *p1 = (const unsigned char *) s1;
register const unsigned char *p2 = (const unsigned char *) s2;
unsigned char c1, c2;
if (p1 == p2)
return 0;
do
{
c1 = c_tolower (*p1);
c2 = c_tolower (*p2);
if (c1 == '\0')
break;
++p1;
++p2;
}
while (c1 == c2);
if (UCHAR_MAX <= INT_MAX)
return c1 - c2;
else
/* On machines where 'char' and 'int' are types of the same size, the
difference of two 'unsigned char' values - including the sign bit -
doesn't fit in an 'int'. */
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return _GL_CMP (c1, c2);
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}