diff options
Diffstat (limited to 'src/lzo1a_cm.ch')
| -rw-r--r-- | src/lzo1a_cm.ch | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/src/lzo1a_cm.ch b/src/lzo1a_cm.ch new file mode 100644 index 0000000..d86b891 --- /dev/null +++ b/src/lzo1a_cm.ch @@ -0,0 +1,245 @@ +/* lzo1a_cm.ch -- implementation of the LZO1A compression algorithm + + This file is part of the LZO real-time data compression library. + + Copyright (C) 2011 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2010 Markus Franz Xaver Johannes Oberhumer + Copyright (C) 2009 Markus Franz Xaver Johannes Oberhumer + 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. + */ + + + +/*********************************************************************** +// code the match in LZO1 compatible format +************************************************************************/ + +#define THRESHOLD (M2_MIN_LEN - 1) +#define MSIZE LZO_SIZE(M2L_BITS) + + +/*********************************************************************** +// +************************************************************************/ + +#if (DD_BITS == 0) + + /* we already matched M2_MIN_LEN bytes, + * m_pos also already advanced M2_MIN_LEN bytes */ + ip += M2_MIN_LEN; + assert(m_pos < ip); + + /* try to match another M2_MAX_LEN + 1 - M2_MIN_LEN bytes + * to see if we get more than a M2 match */ +#define M2_OR_M3 (MATCH_M2) + +#else /* (DD_BITS == 0) */ + + /* we already matched m_len bytes */ + assert(m_len >= M2_MIN_LEN); + ip += m_len; + assert(ip <= in_end); + +#define M2_OR_M3 (m_len <= M2_MAX_LEN) + +#endif /* (DD_BITS == 0) */ + + + if (M2_OR_M3) + { + /* we've found a short match */ + assert(ip <= in_end); + + /* 2a) compute match parameters */ +#if (DD_BITS == 0) + assert(pd(ip,m_pos) == m_off); + --ip; /* ran one too far, point back to non-match */ + m_len = ip - ii; +#endif + assert(m_len >= M2_MIN_LEN); + assert(m_len <= M2_MAX_LEN); + + assert(m_off >= M2_MIN_OFFSET); + assert(m_off <= M2_MAX_OFFSET); + assert(ii-m_off == m_pos_sav); + assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0); + + /* 2b) code the match */ + m_off -= M2_MIN_OFFSET; + /* code short match len + low offset bits */ + *op++ = LZO_BYTE(((m_len - THRESHOLD) << M2O_BITS) | + (m_off & M2O_MASK)); + /* code high offset bits */ + *op++ = LZO_BYTE(m_off >> M2O_BITS); + + + if (ip >= ip_end) + { + ii = ip; + break; + } + + + /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */ + +#if (CLEVEL == 9) || (CLEVEL >= 7 && M2L_BITS <= 4) || (CLEVEL >= 5 && M2L_BITS <= 3) + /* Insert the whole match (ii+1)..(ip-1) into dictionary. */ + ++ii; + do { + DVAL_NEXT(dv,ii); +#if 0 + UPDATE_D(dict,drun,dv,ii,in); +#else + dict[ DINDEX(dv,ii) ] = DENTRY(ii,in); +#endif + MI + } while (++ii < ip); + DVAL_NEXT(dv,ii); + assert(ii == ip); + DVAL_ASSERT(dv,ip); +#elif (CLEVEL >= 3) + SI DI DI XI +#elif (CLEVEL >= 2) + SI DI XI +#else + XI +#endif + } + + else + + { + /* we've found a long match - see how far we can still go */ + const lzo_bytep end; + + assert(ip <= in_end); + assert(ii == ip - (M2_MAX_LEN + 1)); + assert(lzo_memcmp(m_pos_sav,ii,(lzo_uint)(ip-ii)) == 0); + +#if (DD_BITS > 0) + assert(m_len == (lzo_uint)(ip-ii)); + m_pos = ip - m_off; + assert(m_pos == m_pos_sav + m_len); +#endif + + if (pd(in_end,ip) <= (M3_MAX_LEN - M3_MIN_LEN)) + end = in_end; + else + { + end = ip + (M3_MAX_LEN - M3_MIN_LEN); + assert(end < in_end); + } + + while (ip < end && *m_pos == *ip) + m_pos++, ip++; + assert(ip <= in_end); + + /* 2a) compute match parameters */ + m_len = pd(ip, ii); + assert(m_len >= M3_MIN_LEN); + assert(m_len <= M3_MAX_LEN); + + assert(m_off >= M3_MIN_OFFSET); + assert(m_off <= M3_MAX_OFFSET); + assert(ii-m_off == m_pos_sav); + assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0); + assert(pd(ip,m_pos) == m_off); + + /* 2b) code the match */ + m_off -= M3_MIN_OFFSET - M3_EOF_OFFSET; + /* code long match flag + low offset bits */ + *op++ = LZO_BYTE(((MSIZE - 1) << M3O_BITS) | (m_off & M3O_MASK)); + /* code high offset bits */ + *op++ = LZO_BYTE(m_off >> M3O_BITS); + /* code match len */ + *op++ = LZO_BYTE(m_len - M3_MIN_LEN); + + + if (ip >= ip_end) + { + ii = ip; + break; + } + + + /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */ +#if (CLEVEL == 9) + /* Insert the whole match (ii+1)..(ip-1) into dictionary. */ + /* This is not recommended because it can be slow. */ + ++ii; + do { + DVAL_NEXT(dv,ii); +#if 0 + UPDATE_D(dict,drun,dv,ii,in); +#else + dict[ DINDEX(dv,ii) ] = DENTRY(ii,in); +#endif + MI + } while (++ii < ip); + DVAL_NEXT(dv,ii); + assert(ii == ip); + DVAL_ASSERT(dv,ip); +#elif (CLEVEL >= 8) + SI DI DI DI DI DI DI DI DI XI +#elif (CLEVEL >= 7) + SI DI DI DI DI DI DI DI XI +#elif (CLEVEL >= 6) + SI DI DI DI DI DI DI XI +#elif (CLEVEL >= 5) + SI DI DI DI DI XI +#elif (CLEVEL >= 4) + SI DI DI DI XI +#elif (CLEVEL >= 3) + SI DI DI XI +#elif (CLEVEL >= 2) + SI DI XI +#else + XI +#endif + } + + /* ii now points to the start of the next literal run */ + assert(ii == ip); + + +/* +vi:ts=4:et +*/ |