hash.cpp

/* enchant
 * Copyright (C) 2003 Dom Lachowicz
 *
 * This 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.
 *
 * This 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 this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 * In addition, as a special exception, Dom Lachowicz
 * gives permission to link the code of this program with
 * non-LGPL Spelling Provider libraries (eg: a MSFT Office
 * spell checker backend) and distribute linked combinations including
 * the two.  You must obey the GNU Lesser General Public License in all
 * respects for all of the code used other than said providers.  If you modify
 * this file, you may extend this exception to your version of the
 * file, but you are not obligated to do so.  If you do not wish to
 * do so, delete this exception statement from your version.
 */
 
/*
 * 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.
 */
 
/*
 * $Log$
 * Revision 1.1  2004/01/31 16:44:12  zrusin
 * ISpell plugin.
 *
 * Revision 1.4  2003/08/14 17:51:27  dom
 * update license - exception clause should be Lesser GPL
 *
 * Revision 1.3  2003/07/28 20:40:26  dom
 * fix up the license clause, further win32-registry proof some directory getting functions
 *
 * Revision 1.2  2003/07/16 22:52:39  dom
 * LGPL + exception license
 *
 * Revision 1.1  2003/07/15 01:15:05  dom
 * ispell enchant backend
 *
 * Revision 1.2  2003/01/29 05:50:11  hippietrail
 *
 * Fixed my mess in EncodingManager.
 * Changed many C casts to C++ casts.
 *
 * Revision 1.1  2003/01/24 05:52:33  hippietrail
 *
 * Refactored ispell code. Old ispell global variables had been put into
 * an allocated structure, a pointer to which was passed to many functions.
 * I have now made all such functions and variables private members of the
 * ISpellChecker class. It was C OO, now it's C++ OO.
 *
 * I've fixed the makefiles and tested compilation but am unable to test
 * operation. Please back out my changes if they cause problems which
 * are not obvious or easy to fix.
 *
 * Revision 1.5  2002/09/19 05:31:15  hippietrail
 *
 * More Ispell cleanup.  Conditional globals and DEREF macros are removed.
 * K&R function declarations removed, converted to Doxygen style comments
 * where possible.  No code has been changed (I hope).  Compiles for me but
 * unable to test.
 *
 * Revision 1.4  2002/09/17 03:03:29  hippietrail
 *
 * After seeking permission on the developer list I've reformatted all the
 * spelling source which seemed to have parts which used 2, 3, 4, and 8
 * spaces for tabs.  It should all look good with our standard 4-space
 * tabs now.
 * I've concentrated just on indentation in the actual code.  More prettying
 * could be done.
 * * NO code changes were made *
 *
 * Revision 1.3  2002/09/13 17:20:13  mpritchett
 * Fix more warnings for Linux build
 *
 * 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_checker.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(c)
#endif /* NO_CAPITALIZATION_SUPPORT */
 
/*
 * \param s
 * \param hashtblsize
 */
int ISpellChecker::hash (ichar_t *s, int hashtblsize)
{
    long    h = 0;
    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 static_cast<unsigned long>(h) % hashtblsize;
}