lzo1a_de.h

lzo-1.08-src.zip 高效的压缩解压代码

/* lzo1a_de.h -- definitions for the the LZO1A 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]>
 */


/* WARNING: this file should *not* be used by applications. It is
   part of the implementation of the LZO package and is subject
   to change.
 */


#ifndef __LZO_DEFS_H
#define __LZO_DEFS_H

#ifdef __cplusplus
extern "C" {
#endif


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

/*
	 Format of the marker byte


	 76543210
	 --------
	 00000000	a long literal run ('R0' run) - there are short and long R0 runs
	 000rrrrr	a short literal run with len r
	 mmmooooo	a short match (len = 2+m, o = offset low bits)
	 111ooooo	a long match (o = offset low bits)
*/


#define RSIZE	(1 << RBITS)
#define RMASK	(RSIZE - 1)

#define MBITS	(8 - OBITS)
#define MSIZE	(1 << MBITS)
#define MMASK	(MSIZE - 1)

#define OBITS	RBITS				/* offset and run-length use same bits */
#define OSIZE	(1 << OBITS)
#define OMASK	(OSIZE - 1)


/* additional bits for coding the length in a long match */
#define LBITS	8
#define LSIZE	(1 << LBITS)
#define LMASK	(LSIZE - 1)


/***********************************************************************
// some macros to improve readability
************************************************************************/

/* Minimum len of a match */
#define	MIN_MATCH			3
#define	THRESHOLD			(MIN_MATCH - 1)

/* Min-/Maximum len of a match coded in 2 bytes */
#define	MIN_MATCH_SHORT		(MIN_MATCH)
#define	MAX_MATCH_SHORT		(MIN_MATCH_SHORT + (MSIZE - 2) - 1)
/* why (MSIZE - 2) ? because 0 is used to mark runs,
 *                   and MSIZE-1 is used to mark a long match */

/* Min-/Maximum len of a match coded in 3 bytes */
#define	MIN_MATCH_LONG		(MAX_MATCH_SHORT + 1)
#define	MAX_MATCH_LONG		(MIN_MATCH_LONG + LSIZE - 1)

/* Min-/Maximum offset of a match */
#define	MIN_OFFSET			1
#define	MAX_OFFSET			(1 << (CHAR_BIT + OBITS))


/* R0 literal run (a long run) */

#define	R0MIN	(RSIZE)				/* Minimum len of R0 run of literals */
#define	R0MAX	(R0MIN + 255)		/* Maximum len of R0 run of literals */
#define	R0FAST	(R0MAX & ~7)		/* R0MAX aligned to 8 byte boundary */

#if (R0MAX - R0FAST != 7) || ((R0FAST & 7) != 0)
#  error "something went wrong"
#endif

/* 7 special codes from R0FAST+1 .. R0MAX
 * these codes mean long R0 runs with lengths
 * 512, 1024, 2048, 4096, 8192, 16384, 32768 */


/*

RBITS | MBITS  MIN  THR.  MSIZE  MAXS  MINL  MAXL   MAXO  R0MAX R0FAST
======+===============================================================
  3   |   5      3    2     32    32    33    288   2048    263   256
  4   |   4      3    2     16    16    17    272   4096    271   264
  5   |   3      3    2      8     8     9    264   8192    287   280

 */


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

#define DBITS		13
#include "lzo_dict.h"
#define DVAL_LEN	DVAL_LOOKAHEAD



#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* already included */

/*
vi:ts=4:et
*/