lzo1a.c

lzo-1.08-src.zip 高效的压缩解压代码

/* lzo1a.c -- implementation of 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]>
 */


#include <lzo1a.h>
#include "lzo_conf.h"


/***********************************************************************
// The next two defines can be changed to customize LZO1A.
// The default version is LZO1A-5/1.
************************************************************************/

/* run bits (3 - 5) - the compressor and the decompressor
 * must use the same value. */
#if !defined(RBITS)
#  define RBITS		5
#endif

/* compression level (1 - 9) - this only affects the compressor.
 * 1 is fastest, 9 is best compression ratio
 */
#if !defined(CLEVEL)
#  define CLEVEL	1			/* fastest by default */
#endif


/* Collect statistics */
#if 0 && !defined(LZO_COLLECT_STATS)
#  define LZO_COLLECT_STATS
#endif


/***********************************************************************
// You should not have to change anything below this line.
************************************************************************/

/* check configuration */
#if (RBITS < 3 || RBITS > 5)
#  error "invalid RBITS"
#endif
#if (CLEVEL < 1 || CLEVEL > 9)
#  error "invalid CLEVEL"
#endif


/***********************************************************************
// internal configuration
// all of these affect compression only
************************************************************************/

/* return -1 instead of copying if the data cannot be compressed */
#undef LZO_RETURN_IF_NOT_COMPRESSIBLE


/* choose the hashing strategy */
#ifndef LZO_HASH
#define LZO_HASH	LZO_HASH_LZO_INCREMENTAL_A
#endif
#define D_INDEX1(d,p)		d = DM((0x21*DX2(p,5,5)) >> 5)
#define D_INDEX2(d,p)		d = d ^ D_MASK

#include "lzo1a_de.h"
#include "stats1a.h"
#include "lzo_util.h"


/* check other constants */
#if (LBITS < 5 || LBITS > 8)
#  error "invalid LBITS"
#endif


#if defined(LZO_COLLECT_STATS)
   static lzo1a_stats_t lzo_statistics;
   lzo1a_stats_t *lzo1a_stats = &lzo_statistics;
#  define lzo_stats lzo1a_stats
#endif


/***********************************************************************
// get algorithm info, return memory required for compression
************************************************************************/

LZO_EXTERN(lzo_uint) lzo1a_info ( int *rbits, int *clevel );

LZO_PUBLIC(lzo_uint)
lzo1a_info ( int *rbits, int *clevel )
{
	if (rbits)
		*rbits = RBITS;
	if (clevel)
		*clevel = CLEVEL;
	return D_SIZE * lzo_sizeof(lzo_byte *);
}


/***********************************************************************
// LZO1A decompress a block of data.
//
// Could be easily translated into assembly code.
************************************************************************/

LZO_PUBLIC(int)
lzo1a_decompress ( const lzo_byte *in , lzo_uint  in_len,
                         lzo_byte *out, lzo_uintp out_len,
                         lzo_voidp wrkmem )
{
#if defined(LZO_OPTIMIZE_GNUC_i386)
	register lzo_byte *op __asm__("%edi");
	register const lzo_byte *ip __asm__("%esi");
	register lzo_uint t __asm__("%ecx");
	register const lzo_byte *m_pos __asm__("%ebx");
#else
	register lzo_byte *op;
	register const lzo_byte *ip;
	register lzo_uint t;
	register const lzo_byte *m_pos;
#endif
	const lzo_byte * const ip_end = in + in_len;

	LZO_UNUSED(wrkmem);

#if defined(__LZO_QUERY_DECOMPRESS)
	if (__LZO_IS_DECOMPRESS_QUERY(in,in_len,out,out_len,wrkmem))
		return __LZO_QUERY_DECOMPRESS(in,in_len,out,out_len,wrkmem,0,0);
#endif

	op = out;
	ip = in;
	while (ip < ip_end)
	{
		t = *ip++;		/* get marker */
		LZO_STATS(lzo_stats->marker[t]++);

		if (t == 0)				/* a R0 literal run */
		{
			t = *ip++;
			if (t >= R0FAST - R0MIN)			/* a long R0 run */
			{
				t -= R0FAST - R0MIN;
				if (t == 0)
					t = R0FAST;
				else
				{
#if 0
					t = 256u << ((unsigned) t);
#else
					/* help the optimizer */
					lzo_uint tt = 256;
					do tt <<= 1; while (--t > 0);
					t = tt;
#endif
				}
				MEMCPY8_DS(op,ip,t);
				continue;
			}
			t += R0MIN;
			goto literal;
		}
		else if (t < R0MIN)		/* a short literal run */
		{
literal:
			MEMCPY_DS(op,ip,t);

		/* after a literal a match must follow */
			while (ip < ip_end)
			{
				t = *ip++;			/* get R1 marker */
				if (t >= R0MIN)
					goto match;

			/* R1 match - a context sensitive 3 byte match + 1 byte literal */
				assert((t & OMASK) == t);
				m_pos = op - MIN_OFFSET;
				m_pos -= t | (((lzo_uint) *ip++) << OBITS);
				assert(m_pos >= out); assert(m_pos < op);
				*op++ = *m_pos++;
				*op++ = *m_pos++;
				*op++ = *m_pos++;
				*op++ = *ip++;
			}
		}
		else					/* a match */
		{
match:
			/* get match offset */
			m_pos = op - MIN_OFFSET;
			m_pos -= (t & OMASK) | (((lzo_uint) *ip++) << OBITS);
			assert(m_pos >= out); assert(m_pos < op);

			/* get match len */
			if (t < ((MSIZE - 1) << OBITS))			/* a short match */
			{
				t >>= OBITS;
				*op++ = *m_pos++;
				*op++ = *m_pos++;
				MEMMOVE_DS(op,m_pos,t);
			}
			else									 /* a long match */
			{
#if (LBITS < 8)
				t = (MIN_MATCH_LONG - THRESHOLD) + ((lzo_uint)(*ip++) & LMASK);
#else
				t = (MIN_MATCH_LONG - THRESHOLD) + (lzo_uint)(*ip++);
#endif
				*op++ = *m_pos++;
				*op++ = *m_pos++;
				MEMMOVE_DS(op,m_pos,t);
#if (LBITS < 8)
				/* a very short literal following a long match */
				t = ip[-1] >> LBITS;
				if (t) do
					*op++ = *ip++;
				while (--t);
#endif
			}
		}
	}

	*out_len = op - out;

	/* the next line is the only check in the decompressor */
	return (ip == ip_end ? LZO_E_OK :
	       (ip < ip_end  ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
}



/***********************************************************************
// LZO1A compress a block of data.
//
// I apologize for the spaghetti code, but it really helps the optimizer.
************************************************************************/

#include "lzo1a_cr.ch"

static int
do_compress    ( const lzo_byte *in , lzo_uint  in_len,
                       lzo_byte *out, lzo_uintp out_len,
                       lzo_voidp wrkmem )
{
#if defined(LZO_OPTIMIZE_GNUC_i386)
	register const lzo_byte *ip __asm__("%esi");
#else
	register const lzo_byte *ip;
#endif
#if defined(__LZO_HASH_INCREMENTAL)
	lzo_uint32 dv;
#endif
	const lzo_byte *m_pos;
	lzo_byte *op;
	const lzo_byte * const ip_end = in+in_len - DVAL_LEN - MIN_MATCH_LONG;
	const lzo_byte * const in_end = in+in_len - DVAL_LEN;
	const lzo_byte *ii;
	lzo_dict_p const dict = (lzo_dict_p) wrkmem;
	const lzo_byte *r1 = ip_end;	/* pointer for R1 match (none yet) */
#if (LBITS < 8)
	const lzo_byte *im = ip_end;	/* pointer to last match start */
#endif

#if !defined(NDEBUG)
	const lzo_byte *m_pos_sav;
#endif

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

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

	DVAL_FIRST(dv,ip); UPDATE_D(dict,0,dv,ip,in); ip++;
	DVAL_NEXT(dv,ip);

	do {
		lzo_moff_t m_off;
		lzo_uint dindex;

		DINDEX1(dindex,ip);
		GINDEX(m_pos,m_off,dict,dindex,in);
		if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,MAX_OFFSET))
			goto literal;
		if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2])
			goto match;
		DINDEX2(dindex,ip);
		GINDEX(m_pos,m_off,dict,dindex,in);
		if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,MAX_OFFSET))
			goto literal;
		if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2])
			goto match;
		goto literal;

literal:
		UPDATE_I(dict,0,dindex,ip,in);
		if (++ip >= ip_end)
			break;
		continue;

match:
		UPDATE_I(dict,0,dindex,ip,in);
#if !defined(NDEBUG) && defined(LZO_DICT_USE_PTR)
		assert(m_pos == NULL || m_pos >= in);
		m_pos_sav = m_pos;
#endif
		m_pos += 3;
		{
	/* we have found a match (of at least length 3) */

#if !defined(NDEBUG) && !defined(LZO_DICT_USE_PTR)
			assert((m_pos_sav = ip - m_off) == (m_pos - 3));
#endif