100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
/* Copyright (C) 1995-2013 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, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/*
|
|
* The original strstr() file contains the following comment:
|
|
*
|
|
* 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 */
|
|
|
|
#include <wchar.h>
|
|
|
|
wchar_t *
|
|
wcsstr (haystack, needle)
|
|
const wchar_t *haystack;
|
|
const wchar_t *needle;
|
|
{
|
|
wchar_t b, c;
|
|
|
|
if ((b = *needle) != L'\0')
|
|
{
|
|
haystack--; /* possible ANSI violation */
|
|
do
|
|
if ((c = *++haystack) == L'\0')
|
|
goto ret0;
|
|
while (c != b);
|
|
|
|
if (!(c = *++needle))
|
|
goto foundneedle;
|
|
++needle;
|
|
goto jin;
|
|
|
|
for (;;)
|
|
{
|
|
wchar_t a;
|
|
const wchar_t *rhaystack, *rneedle;
|
|
|
|
do
|
|
{
|
|
if (!(a = *++haystack))
|
|
goto ret0;
|
|
if (a == b)
|
|
break;
|
|
if ((a = *++haystack) == L'\0')
|
|
goto ret0;
|
|
shloop: ;
|
|
}
|
|
while (a != b);
|
|
|
|
jin: if (!(a = *++haystack))
|
|
goto ret0;
|
|
|
|
if (a != c)
|
|
goto shloop;
|
|
|
|
if (*(rhaystack = haystack-- + 1) == (a = *(rneedle = needle)))
|
|
do
|
|
{
|
|
if (a == L'\0')
|
|
goto foundneedle;
|
|
if (*++rhaystack != (a = *++needle))
|
|
break;
|
|
if (a == L'\0')
|
|
goto foundneedle;
|
|
}
|
|
while (*++rhaystack == (a = *++needle));
|
|
|
|
needle = rneedle; /* took the register-poor approach */
|
|
|
|
if (a == L'\0')
|
|
break;
|
|
}
|
|
}
|
|
foundneedle:
|
|
return (wchar_t*) haystack;
|
|
ret0:
|
|
return NULL;
|
|
}
|
|
/* This alias is for backward compatibility with drafts of the ISO C
|
|
standard. Unfortunately the Unix(TM) standard requires this name. */
|
|
weak_alias (wcsstr, wcswcs)
|