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Diffstat (limited to 'string/strcasestr.c')
| -rw-r--r-- | string/strcasestr.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/string/strcasestr.c b/string/strcasestr.c new file mode 100644 index 0000000000..1dde43c606 --- /dev/null +++ b/string/strcasestr.c @@ -0,0 +1,142 @@ +/* Return the offset of one string within another. + Copyright (C) 1994, 1996-2000, 2004 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 */ + +#if HAVE_CONFIG_H +# include <config.h> +#endif + +#include <ctype.h> + +#if defined _LIBC || defined HAVE_STRING_H +# include <string.h> +#endif + +#ifdef _LIBC +# include <locale/localeinfo.h> +# define TOLOWER(c) __tolower_l ((unsigned char) c, loc) +#else +# define TOLOWER(c) _tolower (c) +#endif + +typedef unsigned chartype; + +#undef strcasestr +#undef __strcasestr + +char * +__strcasestr (phaystack, pneedle) + const char *phaystack; + const char *pneedle; +{ + register const unsigned char *haystack, *needle; + register chartype b, c; +#ifdef _LIBC + __locale_t loc = _NL_CURRENT_LOCALE; +#endif + + haystack = (const unsigned char *) phaystack; + needle = (const unsigned char *) pneedle; + + b = TOLOWER (*needle); + if (b != '\0') + { + haystack--; /* possible ANSI violation */ + do + { + c = *++haystack; + if (c == '\0') + goto ret0; + } + while (TOLOWER (c) != (int) b); + + c = TOLOWER (*++needle); + if (c == '\0') + goto foundneedle; + ++needle; + goto jin; + + for (;;) + { + register chartype a; + register const unsigned char *rhaystack, *rneedle; + + do + { + a = *++haystack; + if (a == '\0') + goto ret0; + if (TOLOWER (a) == (int) b) + break; + a = *++haystack; + if (a == '\0') + goto ret0; +shloop: + ; + } + while (TOLOWER (a) != (int) b); + +jin: a = *++haystack; + if (a == '\0') + goto ret0; + + if (TOLOWER (a) != (int) c) + 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; +} + +weak_alias (__strcasestr, strcasestr) |