lzo1b_cr.ch

来自「lzo-1.08-src.zip 高效的压缩解压代码」· CH 代码 · 共 114 行

/* lzo1b_cr.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]>
 */


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



/***********************************************************************
// store the current literal run
************************************************************************/

		assert(ip < ip_end);
		if (pd(ip,ii) > 0)
		{
			lzo_uint t = pd(ip,ii);

#if defined(LZO_HAVE_R1)
			if (ip == r1)
			{
				/* Code a context sensitive R1 match. */
				LZO_STATS(lzo_stats->literals += t);
				LZO_STATS(lzo_stats->r1_matches++);
				assert(t == 1);
				/* modify marker byte */
				assert((op[-2] >> M2O_BITS) == (M2_MARKER >> M2O_BITS));
				op[-2] &= M2O_MASK;
				assert((op[-2] >> M2O_BITS) == 0);
				/* copy 1 literal */
				*op++ = *ii++;
				r1 = ip + (M2_MIN_LEN + 1);		/* set new R1 pointer */
			}
			else
#endif
			if (t < R0MIN)
			{
				/* inline the copying of a short run */
				LZO_STATS(lzo_stats->literals += t);
				LZO_STATS(lzo_stats->lit_runs++);
				LZO_STATS(lzo_stats->lit_run[t]++);
#if defined(LZO_HAVE_M3)
				if (t < LZO_SIZE(8-M3O_BITS) && op == m3)
				{
				/* Code a very short literal run into the low offset bits
				 * of the previous M3/M4 match.
				 */
					LZO_STATS(lzo_stats->lit_runs_after_m3_match++);
					LZO_STATS(lzo_stats->lit_run_after_m3_match[t]++);
					assert((m3[-2] >> M3O_BITS) == 0);
					m3[-2] |= LZO_BYTE(t << M3O_BITS);
				}
				else
#endif
				{
					*op++ = LZO_BYTE(t);
				}
				MEMCPY_DS(op, ii, t);
#if defined(LZO_HAVE_R1)
				r1 = ip + (M2_MIN_LEN + 1);		/* set new R1 pointer */
#endif
			}
			else if (t < R0FAST)
			{
				/* inline the copying of a short R0 run */
				LZO_STATS(lzo_stats->literals += t);
				LZO_STATS(lzo_stats->r0short_runs++);
				*op++ = 0; *op++ = LZO_BYTE(t - R0MIN);
				MEMCPY_DS(op, ii, t);
#if defined(LZO_HAVE_R1)
				r1 = ip + (M2_MIN_LEN + 1);		/* set new R1 pointer */
#endif
			}
			else
			{
				op = STORE_RUN(op,ii,t);
				ii = ip;
			}
		}


		/* ii now points to the start of the current match */
		assert(ii == ip);


/*
vi:ts=4:et
*/