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/* Return the offset of one string within another.
Copyright (C) 1994,1996,1997,1998,1999,2000 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/*
* My personal strstr() implementation that beats most other algorithms.
* Until someone tells me otherwise, I assume that this is the
* fastest implementation of strstr() in C.
* I deliberately chose not to comment it. You should have at least
* as much fun trying to understand it, as I had to write it :-).
*
* Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de*/
/* Faster looping by precalculating bl, bu, cl, cu before looping.
* 2004 Apr 08 Jose Da Silva, digital@joescat@com */
#include <string.h>
#include <ctype.h>
typedef unsigned chartype;
char* strcasestr (const char* phaystack, const char* pneedle)
{
const unsigned char *haystack, *needle;
chartype bl, bu, cl, cu;
haystack = (const unsigned char *) phaystack;
needle = (const unsigned char *) pneedle;
bl = tolower (*needle);
if (bl != '\0')
{
bu = toupper (bl);
haystack--;/* possible ANSI violation */
do
{
cl = *++haystack;
if (cl == '\0')
goto ret0;
}
while ((cl != bl) && (cl != bu));
cl = tolower (*++needle);
if (cl == '\0')
goto foundneedle;
cu = toupper (cl);
++needle;
goto jin;
for (;;)
{
chartype a;
const unsigned char *rhaystack, *rneedle;
do
{
a = *++haystack;
if (a == '\0')
goto ret0;
if ((a == bl) || (a == bu))
break;
a = *++haystack;
if (a == '\0')
goto ret0;
shloop:
;
}
while ((a != bl) && (a != bu));
jin: a = *++haystack;
if (a == '\0')
goto ret0;
if ((a != cl) && (a != cu))
goto shloop;
rhaystack = haystack-- + 1;
rneedle = needle;
a = tolower (*rneedle);
if (tolower (*rhaystack) == (int) a)
do
{
if (a == '\0')
goto foundneedle;
++rhaystack;
a = tolower (*++needle);
if (tolower (*rhaystack) != (int) a)
break;
if (a == '\0')
goto foundneedle;
++rhaystack;
a = tolower (*++needle);
}
while (tolower (*rhaystack) == (int) a);
needle = rneedle;/* took the register-poor approach */
if (a == '\0')
break;
}
}
foundneedle:
return (char*) haystack;
ret0:
return 0;
}
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