/* Return the offset of one string within another.
   Copyright (C) 1994, 1996-2000, 2004 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, berg@pool.informatik.rwth-aachen.de */

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

#include <ctype.h>

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

#ifdef _LIBC
# include <locale/localeinfo.h>
# define TOLOWER(c) __tolower_l ((unsigned char) c, loc)
#else
# define TOLOWER(c) _tolower (c)
#endif

typedef unsigned chartype;

#undef strcasestr
#undef __strcasestr

char *
psStrcasestr(const char *phaystack,
	     const char *pneedle)
{
    register const unsigned char *haystack, *needle;
    register chartype b, c;
    #ifdef _LIBC

    __locale_t loc = _NL_CURRENT_LOCALE;
    #endif

    haystack = (const unsigned char *) phaystack;
    needle = (const unsigned char *) pneedle;

    b = TOLOWER (*needle);
    if (b != '\0') {
        haystack--;    /* possible ANSI violation */
        do {
            c = *++haystack;
            if (c == '\0')
                goto ret0;
        } while (TOLOWER (c) != (int) b);

        c = TOLOWER (*++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 (TOLOWER (a) == (int) b)
                    break;
                a = *++haystack;
                if (a == '\0')
                    goto ret0;
shloop:
                ;
            } while (TOLOWER (a) != (int) b);

jin:
            a = *++haystack;
            if (a == '\0')
                goto ret0;

            if (TOLOWER (a) != (int) c)
                goto shloop;

            rhaystack = haystack-- + 1;
            rneedle = needle;
            a = TOLOWER (*rneedle);

            if (TOLOWER (*rhaystack) == (int) a)
                do {
                    if (a == '\0')
                        goto foundneedle;
                    ++rhaystack;
                    a = TOLOWER (*++needle);
                    if (TOLOWER (*rhaystack) != (int) a)
                        break;
                    if (a == '\0')
                        goto foundneedle;
                    ++rhaystack;
                    a = TOLOWER (*++needle);
                } while (TOLOWER (*rhaystack) == (int) a);

            needle = rneedle;  /* took the register-poor approach */

            if (a == '\0')
                break;
        }
    }
foundneedle:
    return (char*) haystack;
ret0:
    return 0;
}
