lzo1b_c.ch

lzo-1.08-src.zip 高效的压缩解压代码

/* lzo1b_c.ch -- implementation of the LZO1B compression algorithm

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

   Copyright (C) 1996-2002 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.,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Markus F.X.J. Oberhumer
   <[e-mail]>
 */



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

#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_byte *in , lzo_uint  in_len,
                       lzo_byte *out, lzo_uintp out_len,
                       lzo_voidp wrkmem )
{
/* this seems to work with buggy gcc */
/* #if defined(LZO_OPTIMIZE_GNUC_i386) */
#if 0 && defined(__GNUC__) && defined(__i386__)
	register const lzo_byte *ip __asm__("%esi");
#else
	register const lzo_byte *ip;
#endif
#if (DD_BITS > 0)
#if defined(__LZO_HASH_INCREMENTAL)
	lzo_uint32 dv;
#endif
	unsigned drun = 0;
#endif
	lzo_byte *op;
	const lzo_byte * const in_end = in + in_len;
	const lzo_byte * const ip_end = in + in_len - MIN_LOOKAHEAD;
	const lzo_byte *ii;
#if defined(LZO_HAVE_R1)
	const lzo_byte *r1 = ip_end;	/* pointer for R1 match (none yet) */
#endif
#if defined(LZO_HAVE_M3)
	lzo_byte *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_MEXPAND(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_byte *m_pos;
#if !defined(NDEBUG)
		const lzo_byte *m_pos_sav = NULL;
#endif
		lzo_moff_t 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_byte *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 = op - out;
	return LZO_E_OK;				/* compression went ok */
}


/*
vi:ts=4:et
*/