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/* lzo1b_sm.ch -- implementation of the LZO1B compression algorithm
This file is part of the LZO real-time data compression library.
Copyright (C) 1996-2017 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_DEFINE_UNINITIALIZED_VAR(lzo_uint, x_off, 0);
DVAL_ASSERT(dv,ip);
ip_sav = ip;
m_len = 0;
do {
#if !defined(NDEBUG)
const lzo_bytep z_pos = NULL;
#endif
#if (LZO_DICT_USE_PTR)
m_pos = *d;
assert((z_pos = m_pos) == *d);
#if (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 !(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) */
/* vim:set ts=4 sw=4 et: */
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