libatalk/util/strcasestr.c

   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.
   4
   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.
   9
  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.
  14
  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.  */
  19
  20 /*
  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 :-).
  26  *
  27  * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de */
  28 /* added strcasestr support, davidm@lineo.com */
  29
  30 #if HAVE_CONFIG_H
  31 # include <config.h>
  32 #endif
  33
  34 #ifndef HAVE_STRCASESTR
  35
  36 #if  defined HAVE_STRING_H
  37 # include <string.h>
  38 #endif
  39
  40 typedef unsigned chartype;
  41
  42 #include <ctype.h>
  43 #define VAL(x)  tolower(x)
  44 #define FUNC strcasestr
  45 #undef strcasestr
  46
  47 char * FUNC ( const char *phaystack, const char *pneedle)
  48 {
  49         register const unsigned char *haystack, *needle;
  50         register chartype b, c;
  51
  52         haystack = (const unsigned char *) phaystack;
  53         needle = (const unsigned char *) pneedle;
  54
  55         b = *needle;
  56         if (b != '\0') {
  57                 haystack--;                             /* possible ANSI violation */
  58                 do {
  59                         c = *++haystack;
  60                         if (c == '\0')
  61                                 goto ret0;
  62                 }
  63                 while (VAL(c) != VAL(b));
  64
  65                 c = *++needle;
  66                 if (c == '\0')
  67                         goto foundneedle;
  68                 ++needle;
  69                 goto jin;
  70
  71                 for (;;) {
  72                         register chartype a;
  73                         register const unsigned char *rhaystack, *rneedle;
  74
  75                         do {
  76                                 a = *++haystack;
  77                                 if (a == '\0')
  78                                         goto ret0;
  79                                 if (VAL(a) == VAL(b))
  80                                         break;
  81                                 a = *++haystack;
  82                                 if (a == '\0')
  83                                         goto ret0;
  84                   shloop:}
  85                         while (VAL(a) != VAL(b));
  86
  87                   jin:a = *++haystack;
  88                         if (a == '\0')
  89                                 goto ret0;
  90
  91                         if (VAL(a) != VAL(c))
  92                                 goto shloop;
  93
  94                         rhaystack = haystack-- + 1;
  95                         rneedle = needle;
  96                         a = *rneedle;
  97
  98                         if (VAL(*rhaystack) == VAL(a))
  99                                 do {
 100                                         if (a == '\0')
 101                                                 goto foundneedle;
 102                                         ++rhaystack;
 103                                         a = *++needle;
 104                                         if (VAL(*rhaystack) != VAL(a))
 105                                                 break;
 106                                         if (a == '\0')
 107                                                 goto foundneedle;
 108                                         ++rhaystack;
 109                                         a = *++needle;
 110                                 }
 111                                 while (VAL(*rhaystack) == VAL(a));
 112
 113                         needle = rneedle;       /* took the register-poor approach */
 114
 115                         if (a == '\0')
 116                                 break;
 117                 }
 118         }
 119   foundneedle:
 120         return (char *) haystack;
 121   ret0:
 122         return 0;
 123 }
 124 #endif