lzo-2.03/src/lzo1b_c.ch

/* lzo1b_c.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/
 */



/***********************************************************************
//
************************************************************************/

#if !defined(LZO_HAVE_R1) && !defined(LZO_NO_R1)
#  define LZO_HAVE_R1
#endif

#if !defined(LZO_HAVE_M3) && !defined(LZO_NO_M3)
#  if (M3O_BITS < 8)
#    define LZO_HAVE_M3
#  endif
#endif


#define MI
#define SI      MI
#if (DD_BITS > 0)
#define DI      ++ii; DVAL_NEXT(dv,ii); UPDATE_D(dict,drun,dv,ii,in); MI
#define XI      assert(ii < ip); ii = ip; DVAL_FIRST(dv,(ip));
#else
#define DI      ++ii; DINDEX1(dindex,ii); UPDATE_I(dict,0,dindex,ii,in); MI
#define XI      assert(ii < ip); ii = ip;
#endif


/***********************************************************************
// compress a block of data.
//
// I really apologize for this spaghetti code.
************************************************************************/

LZO_PRIVATE(int)
do_compress    ( const lzo_bytep in , lzo_uint  in_len,
                       lzo_bytep out, lzo_uintp out_len,
                       lzo_voidp wrkmem )
{
    register const lzo_bytep ip;
#if (DD_BITS > 0)
#if defined(__LZO_HASH_INCREMENTAL)
    lzo_xint dv;
#endif
    unsigned drun = 0;
#endif
    lzo_bytep op;
    const lzo_bytep const in_end = in + in_len;
    const lzo_bytep const ip_end = in + in_len - MIN_LOOKAHEAD;
    const lzo_bytep ii;
#if defined(LZO_HAVE_R1)
    const lzo_bytep r1 = ip_end;    /* pointer for R1 match (none yet) */
#endif
#if defined(LZO_HAVE_M3)
    lzo_bytep m3 = out + 1;         /* pointer after last m3/m4 match */
#endif

    lzo_dict_p const dict = (lzo_dict_p) wrkmem;


#if defined(LZO_COLLECT_STATS)
    lzo_stats->r_bits   = R_BITS;
    lzo_stats->m3o_bits = M3O_BITS;
    lzo_stats->dd_bits  = DD_BITS;
    lzo_stats->clevel   = CLEVEL;
    lzo_stats->d_bits   = D_BITS;
    lzo_stats->min_lookahead  = MIN_LOOKAHEAD;
    lzo_stats->max_lookbehind = MAX_LOOKBEHIND;
    lzo_stats->compress_id    = LZO_CPP_MACRO_EXPAND(COMPRESS_ID);
#endif

    /* init dictionary */
#if defined(LZO_DETERMINISTIC)
    BZERO8_PTR(wrkmem,sizeof(lzo_dict_t),D_SIZE);
#endif


    op = out;
    ip = in;
    ii = ip;            /* point to start of current literal run */


#if (DD_BITS > 0)
    DVAL_FIRST(dv,ip);
    UPDATE_D(dict,drun,dv,ip,in);
    ip++;
    DVAL_NEXT(dv,ip);
#else
    ip++;
#endif

    assert(ip < ip_end);
    for (;;)
    {
        const lzo_bytep m_pos;
#if !defined(NDEBUG)
        const lzo_bytep m_pos_sav = NULL;
#endif
        lzo_uint m_off;
#if (DD_BITS == 0)
        lzo_uint dindex;
#endif
        lzo_uint m_len;


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

#if !defined(LZO_SEARCH_MATCH_INCLUDE_FILE)
#  define LZO_SEARCH_MATCH_INCLUDE_FILE     "lzo1b_sm.ch"
#endif

#include LZO_SEARCH_MATCH_INCLUDE_FILE


#if !defined(LZO_TEST_MATCH_INCLUDE_FILE)
#  define LZO_TEST_MATCH_INCLUDE_FILE       "lzo1b_tm.ch"
#endif

#include LZO_TEST_MATCH_INCLUDE_FILE



/***********************************************************************
// found a literal
************************************************************************/


    /* a literal */
literal:
#if (DD_BITS == 0)
        UPDATE_I(dict,0,dindex,ip,in);
#endif
        if (++ip >= ip_end)
            break;
#if (DD_BITS > 0)
        DVAL_NEXT(dv,ip);
#endif
        continue;



/***********************************************************************
// found a match
************************************************************************/

match:
#if (DD_BITS == 0)
        UPDATE_I(dict,0,dindex,ip,in);
#endif
        /* we have found a match of at least M2_MIN_LEN */


#if !defined(LZO_CODE_RUN_INCLUDE_FILE)
#  define LZO_CODE_RUN_INCLUDE_FILE     "lzo1b_cr.ch"
#endif

#include LZO_CODE_RUN_INCLUDE_FILE


        /* ii now points to the start of the current match */
        assert(ii == ip);


/***********************************************************************
// code the match
************************************************************************/

#if !defined(LZO_CODE_MATCH_INCLUDE_FILE)
#  define LZO_CODE_MATCH_INCLUDE_FILE   "lzo1b_cm.ch"
#endif

#include LZO_CODE_MATCH_INCLUDE_FILE


        /* ii now points to the start of the next literal run */
        assert(ii == ip);

    }


/***********************************************************************
// end of block
************************************************************************/

    assert(ip <= in_end);

#if defined(LZO_COLLECT_STATS)
    {
        lzo_uint i;
        const lzo_bytep p;

        for (i = 0; i < D_SIZE; i++)
        {
            p = dict[i];
            if (BOUNDS_CHECKING_OFF_IN_EXPR(p == NULL || p < in || p > in_end))
                lzo_stats->unused_dict_entries++;
        }
        lzo_stats->unused_dict_entries_percent =
            100.0 * lzo_stats->unused_dict_entries / D_SIZE;
    }
#endif


#if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE)
    /* return if op == out to indicate that we
     * couldn't compress and didn't copy anything.
     */
    if (op == out)
    {
        *out_len = 0;
        return LZO_E_NOT_COMPRESSIBLE;
    }
#endif

    /* store the final literal run */
    if (pd(in_end,ii) > 0)
    {
        lzo_uint t = pd(in_end,ii);
        op = STORE_RUN(op,ii,t);
    }

    *out_len = pd(op, out);
    return LZO_E_OK;                /* compression went ok */
}


/*
vi:ts=4:et
*/