lzo1c_cc.c

lzo-1.08-src.zip 高效的压缩解压代码

/* lzo1c_cc.c -- LZO1C compression internal entry point

   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]>
 */


#define LZO_NEED_DICT_H
#include "config1c.h"


/***********************************************************************
// compression internal entry point.
************************************************************************/

int _lzo1c_do_compress   ( const lzo_byte *in,  lzo_uint  in_len,
								 lzo_byte *out, lzo_uintp out_len,
								 lzo_voidp wrkmem,
								 lzo_compress_t func )
{
	int r;
#if defined(LZO_TEST_COMPRESS_OVERRUN)
	lzo_uint avail_out = *out_len;
#endif


#if defined(LZO_COLLECT_STATS)
	_lzo1c_stats_init(lzo_stats);
	lzo_stats->in_len = in_len;
#endif


	/* don't try to compress a block that's too short */
	if (in_len <= 0)
	{
		*out_len = 0;
		r = LZO_E_OK;
	}
	else if (in_len <= MIN_LOOKAHEAD + 1)
	{
#if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE)
		*out_len = 0;
		r = LZO_E_NOT_COMPRESSIBLE;
#else
		*out_len = STORE_RUN(out,in,in_len) - out;
		r = (*out_len > in_len) ? LZO_E_OK : LZO_E_ERROR;
#endif
	}
	else
		r = func(in,in_len,out,out_len,wrkmem);


#if defined(LZO_EOF_CODE)
#if defined(LZO_TEST_COMPRESS_OVERRUN)
	if (r == LZO_E_OK && avail_out - *out_len < 3)
		r = LZO_E_COMPRESS_OVERRUN;
#endif
	if (r == LZO_E_OK)
	{
		lzo_byte *op = out + *out_len;
		*op++ = M3_MARKER | 1;
		*op++ = 0;
		*op++ = 0;
		*out_len += 3;
	}
#endif


#if defined(LZO_COLLECT_STATS)
	lzo_stats->out_len = *out_len;
	lzo_stats->match_bytes =
	   1 * lzo_stats->m1_matches + 2 * lzo_stats->m2_matches +
	   3 * lzo_stats->m3_matches + 4 * lzo_stats->m4_matches;
	_lzo1c_stats_calc(lzo_stats);
#endif

	return r;
}


/***********************************************************************
// note: this is not thread safe, but as it is used for finetuning only
//       we don't care
************************************************************************/

#undef lzo_stats
/* lzo_stats_t is still defined */


#if defined(LZO_COLLECT_STATS)

static lzo_stats_t lzo_statistics;
lzo_stats_t * const lzo1c_stats = &lzo_statistics;


void _lzo1c_stats_init(lzo_stats_t *lzo_stats)
{
	memset(lzo_stats,0,sizeof(*lzo_stats));
}


void _lzo1c_stats_calc(lzo_stats_t *lzo_stats)
{
	lzo_stats->matches =
	   lzo_stats->m1_matches + lzo_stats->m2_matches +
	   lzo_stats->m3_matches + lzo_stats->m4_matches;

	lzo_stats->literal_overhead = lzo_stats->lit_runs +
	   2 * (lzo_stats->r0short_runs + lzo_stats->r0fast_runs +
	        lzo_stats->r0long_runs);
	lzo_stats->literal_bytes = lzo_stats->literals +
	   lzo_stats->literal_overhead;

#if 0
	assert(lzo_stats->match_bytes + lzo_stats->literal_bytes ==
	   lzo_stats->out_len);
#endif

	lzo_stats->m2_matches -= lzo_stats->r1_matches;
	lzo_stats->m2_match[M2_MIN_LEN] -= lzo_stats->r1_matches;

	if (lzo_stats->literals > 0)
		lzo_stats->literal_overhead_percent =
		   100.0 * lzo_stats->literal_overhead / lzo_stats->literals;
}


#endif


/*
vi:ts=4:et
*/