/* lzo1b_sm.ch -- implementation of the LZO1B compression algorithm

   This file is part of the LZO real-time data compression library.

   Copyright (C) 2008 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2007 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2006 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer
   All Rights Reserved.

   The LZO library is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version.

   The LZO 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with the LZO library; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

   Markus F.X.J. Oberhumer
   <markus@oberhumer.com>
   http://www.oberhumer.com/opensource/lzo/
 */


/* WARNING: this file should *not* be used by applications. It is
   part of the implementation of the library and is subject
   to change.
 */


/***********************************************************************
// search for a match
************************************************************************/

#if (DD_BITS == 0)

        /* search ip in the dictionary */
        DINDEX1(dindex,ip);
        GINDEX(m_pos,m_off,dict,dindex,in);
        if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
            goto literal;
#if 1
        if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
            goto try_match;
        DINDEX2(dindex,ip);
#endif
        GINDEX(m_pos,m_off,dict,dindex,in);
        if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
            goto literal;
        if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
            goto try_match;
        goto literal;


#else /* (DD_BITS == 0) */


        /* search ip in the deepened dictionary */
        {
            lzo_dict_p d = &dict [ DINDEX(dv,ip) ];
            const lzo_bytep ip_sav;
            unsigned j = DD_SIZE;
            lzo_uint x_len;
            lzo_uint x_off;

            DVAL_ASSERT(dv,ip);

            ip_sav = ip;
            m_len = 0;
            do {
#if !defined(NDEBUG)
                const lzo_bytep z_pos = NULL;
#endif
#if defined(LZO_DICT_USE_PTR)
                m_pos = *d;
                assert((z_pos = m_pos) == *d);
#if defined(LZO_DETERMINISTIC)
                assert(m_pos == NULL || m_pos >= in);
                assert(m_pos == NULL || m_pos < ip);
#endif
#else
                x_off = *d;
#endif
                assert(ip == ip_sav);

                if (LZO_CHECK_MPOS(m_pos,x_off,in,ip,MAX_OFFSET))
#if (CLEVEL == 9)
                    *d = DENTRY(ip,in);
#else
                    ((void)(0));
#endif
                else if (m_pos[m_len] != ip[m_len])
                    ((void)(0));
                else if (*m_pos++ == *ip++ && *m_pos++ == *ip++ && *m_pos++ == *ip++)
                {
#if !defined(LZO_DICT_USE_PTR)
                    assert((z_pos = ip - 3 - x_off) == (m_pos - 3));
#endif
                    /* a match */
                    if (MATCH_M2)
                    {
                        x_len = pd((ip - 1), ip_sav);
                        if (x_len > m_len)
                        {
                            m_len = x_len;
                            m_off = x_off;
                            assert((m_pos_sav = z_pos) != NULL);
                        }
#if (CLEVEL == 9)
                        /* try to find a closer match */
                        else if (x_len == m_len && x_off < m_off)
                        {
                            m_off = x_off;
                            assert((m_pos_sav = z_pos) != NULL);
                        }
#endif
                    }
                    else
                    {
                        assert((ip - ip_sav) == M2_MAX_LEN + 1);
#if (CLEVEL == 9)
#if defined(MATCH_IP_END)
                        {
                            const lzo_bytep end;
                            end = MATCH_IP_END;
                            while (ip < end  &&  *m_pos == *ip)
                                m_pos++, ip++;
                            assert(ip <= in_end);
                            x_len = pd(ip, ip_sav);
                        }
                        if (x_len > m_len)
                        {
                            m_len = x_len;
                            m_off = x_off;
                            assert((m_pos_sav = z_pos) != NULL);
                            if (ip >= MATCH_IP_END)
                            {
                                ip = ip_sav;
#if 0
                                /* not needed - we are at the end */
                                d -= DD_SIZE - j;
                                assert(d == &dict [ DINDEX(dv,ip) ]);
                                UPDATE_P(d,drun,ip,in);
#endif
                                goto match;
                            }
                        }
                        else if (x_len == m_len && x_off < m_off)
                        {
                            m_off = x_off;
                            assert((m_pos_sav = z_pos) != NULL);
                        }
#else
                        /* try to find a closer match */
                        if (m_len < M2_MAX_LEN + 1 || x_off < m_off)
                        {
                            m_len = M2_MAX_LEN + 1;
                            m_off = x_off;
                            assert((m_pos_sav = z_pos) != NULL);
                        }
#endif
#else
                        /* don't search for a longer/closer match */
                        m_len = M2_MAX_LEN + 1;
                        m_off = x_off;
                        assert((m_pos_sav = z_pos) != NULL);
                        ip = ip_sav;
                        d -= DD_SIZE - j;
                        assert(d == &dict [ DINDEX(dv,ip) ]);
                        UPDATE_P(d,drun,ip,in);
                        goto match;
#endif
                    }
                    ip = ip_sav;
                }
                else
                    ip = ip_sav;
                d++;
            } while (--j > 0);
            assert(ip == ip_sav);

            d -= DD_SIZE;
            assert(d == &dict [ DINDEX(dv,ip) ]);
            UPDATE_P(d,drun,ip,in);
        }

#endif /* (DD_BITS == 0) */


/*
vi:ts=4:et
*/