diff options
author | Karl Berry <karl@freefriends.org> | 2006-01-17 21:41:51 +0000 |
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committer | Karl Berry <karl@freefriends.org> | 2006-01-17 21:41:51 +0000 |
commit | 487ca4806cc046076293cf6cc5fbba0db282bac7 (patch) | |
tree | 847b412ab5158dd7bdd7ed7e5a4cc3fbca94be32 /Build/source/texk/kpathsea/strstr.c | |
parent | a3d3111bfe26b8e5f5bc6049dfb2a4ca2edc7881 (diff) |
texk 1
git-svn-id: svn://tug.org/texlive/trunk@1485 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Build/source/texk/kpathsea/strstr.c')
-rw-r--r-- | Build/source/texk/kpathsea/strstr.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/Build/source/texk/kpathsea/strstr.c b/Build/source/texk/kpathsea/strstr.c new file mode 100644 index 00000000000..5080a9e1e63 --- /dev/null +++ b/Build/source/texk/kpathsea/strstr.c @@ -0,0 +1,125 @@ +/* strstr.c - search for a substring in string. + + Copyright (C) 1994, 95 Free Software Foundation, Inc. + This file was part of the GNU C Library. Modified by kb@mail.tug.org. + + This 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. + + This 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 this library; if not, write to the Free Software + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 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 !defined (__STDC__) || !__STDC__ +/* This is a separate conditional since some stdc systems + reject `defined (const)'. */ +#ifndef const +#define const +#endif +#endif + +typedef unsigned chartype; + +char * +strstr (phaystack, pneedle) + 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 aproach */ + + if (a == '\0') + break; + } + } +foundneedle: + return (char*) haystack; +ret0: + return 0; +} |