/src/lzo-2.10/src/lzo1b_c.ch

Source
/* lzo1b_c.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/
 */



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

#if !defined(LZO_HAVE_R1) && !defined(LZO_NO_R1)
#  define LZO_HAVE_R1 1
#endif

#if !defined(LZO_HAVE_M3) && !defined(LZO_NO_M3)
#  if (M3O_BITS < 8)
#    define LZO_HAVE_M3 1
#  endif
#endif


#define MI      /*empty*/
#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.
************************************************************************/

#ifdef __cplusplus
extern "C" {
#endif
LZO_PRIVATE(int)
do_compress    ( const lzo_bytep in , lzo_uint  in_len,
                       lzo_bytep out, lzo_uintp out_len,
                       lzo_voidp wrkmem )
{
    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 (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_PP_MACRO_EXPAND(COMPRESS_ID);
#endif

    /* init dictionary */
#if (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_DEFINE_UNINITIALIZED_VAR(lzo_uint, m_off, 0);
#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 (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 */
}
#ifdef __cplusplus
} /* extern "C" */
#endif


/* vim:set ts=4 sw=4 et: */

Coverage Report

Created: 2026-06-10 06:40