#ifndef lint
static char Rcs_Id[] =
    "$Id: hash.c,v 1.2 2001/05/12 16:05:42 thomasf Exp $";
#endif

/*
 * hash.c - a simple hash function for ispell
 *
 * Pace Willisson, 1983
 *
 * Copyright 1992, 1993, Geoff Kuenning, Granada Hills, CA
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All modifications to the source code must be clearly marked as
 *    such.  Binary redistributions based on modified source code
 *    must be clearly marked as modified versions in the documentation
 *    and/or other materials provided with the distribution.
 * 4. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgment:
 *      This product includes software developed by Geoff Kuenning and
 *      other unpaid contributors.
 * 5. The name of Geoff Kuenning may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY GEOFF KUENNING AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL GEOFF KUENNING OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * $Log: hash.c,v $
 * Revision 1.2  2001/05/12 16:05:42  thomasf
 * Big pseudo changes to ispell to make it pass around a structure rather
 * than rely on all sorts of gloabals willy nilly here and there.  Also
 * fixed our spelling class to work with accepting suggestions once more.
 * This code is dirty, gross and ugly (not to mention still not supporting
 * multiple hash sized just yet) but it works on my machine and will no
 * doubt break other machines.
 *
 * Revision 1.1  2001/04/15 16:01:24  tomas_f
 * moving to spell/xp
 *
 * Revision 1.3  1998/12/29 14:55:33  eric
 *
 * I've doctored the ispell code pretty extensively here.  It is now
 * warning-free on Win32.  It also *works* on Win32 now, since I
 * replaced all the I/O calls with ANSI standard ones.
 *
 * Revision 1.2  1998/12/28 23:11:30  eric
 *
 * modified spell code and integration to build on Windows.
 * This is still a hack.
 *
 * Actually, it doesn't yet WORK on Windows.  It just builds.
 * SpellCheckInit is failing for some reason.
 *
 * Revision 1.1  1998/12/28 18:04:43  davet
 * Spell checker code stripped from ispell.  At this point, there are
 * two external routines...  the Init routine, and a check-a-word routine
 * which returns a boolean value, and takes a 16 bit char string.
 * The code resembles the ispell code as much as possible still.
 *
 * Revision 1.20  1994/01/25  07:11:34  geoff
 * Get rid of all old RCS log lines in preparation for the 3.1 release.
 *
 */

#include "ispell.h"

/*
 * The following hash algorithm is due to Ian Dall, with slight modifications
 * by Geoff Kuenning to reflect the results of testing with the English
 * dictionaries actually distributed with ispell.
 */
#define HASHSHIFT   5

#ifdef NO_CAPITALIZATION_SUPPORT
#define HASHUPPER(c)	c
#else /* NO_CAPITALIZATION_SUPPORT */
#define HASHUPPER(c)	mytoupper(DEREF_FIRST_ARG(istate) c)
#endif /* NO_CAPITALIZATION_SUPPORT */

int hash (FIRST_ARG(istate) ichar_t *s, int hashtblsize)
#if 0
    register ichar_t *	s;
    register int	hashtblsize;
#endif
    {
    register long	h = 0;
    register int	i;

#ifdef ICHAR_IS_CHAR
    for (i = 4;  i--  &&  *s != 0;  )
	h = (h << 8) | HASHUPPER (*s++);
#else /* ICHAR_IS_CHAR */
    for (i = 2;  i--  &&  *s != 0;  )
	h = (h << 16) | HASHUPPER (*s++);
#endif /* ICHAR_IS_CHAR */
    while (*s != 0)
	{
	/*
	 * We have to do circular shifts the hard way, since C doesn't
	 * have them even though the hardware probably does.  Oh, well.
	 */
	h = (h << HASHSHIFT)
	  | ((h >> (32 - HASHSHIFT)) & ((1 << HASHSHIFT) - 1));
	h ^= HASHUPPER (*s++);
	}
    return (unsigned long) h % hashtblsize;
    }
