From 772f20abb0a3a0979c440114bf3a1cff5b3cef03 Mon Sep 17 00:00:00 2001 From: cvpcs Date: Wed, 2 Jun 2010 11:02:31 -0500 Subject: initial import of bash 4.1 --- lib/sh/strstr.c | 125 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 125 insertions(+) create mode 100644 lib/sh/strstr.c (limited to 'lib/sh/strstr.c') diff --git a/lib/sh/strstr.c b/lib/sh/strstr.c new file mode 100644 index 0000000..c43b05e --- /dev/null +++ b/lib/sh/strstr.c @@ -0,0 +1,125 @@ +/* strstr - find a substring within a string */ + +/* Copyright (C) 1994, 1999 Free Software Foundation, Inc. + + This file is part of GNU Bash, the Bourne Again SHell. + + Bash is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + Bash 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with Bash. If not, see . +*/ + +/* + * 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 +#endif + +#if defined _LIBC || defined HAVE_STRING_H +# include +#endif +#include + +typedef unsigned chartype; + +#undef strstr + +char * +strstr (const char *phaystack, const char *pneedle) +{ + register const unsigned char *haystack, *needle; + register chartype b, c; + + haystack = (const unsigned char *) phaystack; + needle = (const unsigned char *) pneedle; + + b = *needle; + if (b != '\0') + { + haystack--; /* possible ANSI violation */ + do + { + c = *++haystack; + if (c == '\0') + goto ret0; + } + while (c != b); + + c = *++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 (a == b) + break; + a = *++haystack; + if (a == '\0') + goto ret0; +shloop:; } + while (a != b); + +jin: a = *++haystack; + if (a == '\0') + goto ret0; + + if (a != c) + goto shloop; + + rhaystack = haystack-- + 1; + rneedle = needle; + a = *rneedle; + + if (*rhaystack == a) + do + { + if (a == '\0') + goto foundneedle; + ++rhaystack; + a = *++needle; + if (*rhaystack != a) + break; + if (a == '\0') + goto foundneedle; + ++rhaystack; + a = *++needle; + } + while (*rhaystack == a); + + needle = rneedle; /* took the register-poor approach */ + + if (a == '\0') + break; + } + } +foundneedle: + return (char*) haystack; +ret0: + return 0; +} -- cgit v1.1