/* Return the offset of one string within another.
   Copyright (C) 1994,1996,1997,2000,2001,2003 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, [email protected] */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#if defined _LIBC || defined HAVE_STRING_H
# include <string.h>
#endif

typedef unsigned chartype;

#undef strstr

char *
strstr (phaystack, pneedle)
     const char *phaystack;
     const char *pneedle;
{
  const unsigned char *haystack, *needle;
  chartype b;
  const unsigned char *rneedle;

  haystack = (const unsigned char *) phaystack;

  if ((b = *(needle = (const unsigned char *) pneedle)))
    {
      chartype c;
      haystack--;               /* possible ANSI violation */

      {
        chartype a;
        do
          if (!(a = *++haystack))
            goto ret0;
        while (a != b);
      }

      if (!(c = *++needle))
        goto foundneedle;
      ++needle;
      goto jin;

      for (;;)
        {
          {
            chartype a;
            if (0)
            jin:{
                if ((a = *++haystack) == c)
                  goto crest;
              }
            else
              a = *++haystack;
            do
              {
                for (; a != b; a = *++haystack)
                  {
                    if (!a)
                      goto ret0;
                    if ((a = *++haystack) == b)
                      break;
                    if (!a)
                      goto ret0;
                  }
              }
            while ((a = *++haystack) != c);
          }
        crest:
          {
            chartype a;
            {
              const unsigned char *rhaystack;
              if (*(rhaystack = haystack-- + 1) == (a = *(rneedle = needle)))
                do
                  {
                    if (!a)
                      goto foundneedle;
                    if (*++rhaystack != (a = *++needle))
                      break;
                    if (!a)
                      goto foundneedle;
                  }
                while (*++rhaystack == (a = *++needle));
              needle = rneedle; /* took the register-poor aproach */
            }
            if (!a)
              break;
          }
        }
    }
foundneedle:
  return (char *) haystack;
ret0:
  return 0;
}
libc_hidden_builtin_def (strstr)