1 /* Return the offset of one string within another.
2 Copyright (C) 1994, 1996, 1997 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
21 * My personal strstr() implementation that beats most other algorithms.
22 * Until someone tells me otherwise, I assume that this is the
23 * fastest implementation of strstr() in C.
24 * I deliberately chose not to comment it. You should have at least
25 * as much fun trying to understand it, as I had to write it :-).
27 * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de */
31 typedef unsigned chartype;
36 strstr (phaystack, pneedle)
37 const char *phaystack;
40 register const unsigned char *haystack, *needle;
41 register chartype b, c;
43 haystack = (const unsigned char *) phaystack;
44 needle = (const unsigned char *) pneedle;
49 haystack--; /* possible ANSI violation */
67 register const unsigned char *rhaystack, *rneedle;
90 rhaystack = haystack-- + 1;
108 while (*rhaystack == a);
110 needle = rneedle; /* took the register-poor approach */
117 return (char*) haystack;