/*
Copyright 2002, QNX Software Systems Ltd. Unpublished Work All Rights
Reserved.

 
This source code contains confidential information of QNX Software Systems
Ltd. (QSSL). Any use, reproduction, modification, disclosure, distribution
or transfer of this software, or any software which includes or is based
upon any of this code, is only permitted under the terms of the QNX
Confidential Source License version 1.0 (see licensing.qnx.com for details)
or as otherwise expressly authorized by a written license agreement from
QSSL. For more information, please email licensing@qnx.com.
*/
/* lzo1b_cm.ch -- implementation of the LZO1B compression algorithm

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

   Copyright (C) 1996-1999 Markus Franz Xaver Johannes Oberhumer

   Markus F.X.J. Oberhumer
   markus.oberhumer@jk.uni-linz.ac.at
 */


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



/***********************************************************************
// code the match
************************************************************************/

#if (DD_BITS == 0)

		/* we already matched M2_MIN_LEN bytes,
		 * m_pos also already advanced M2_MIN_LEN bytes */
		ip += M2_MIN_LEN;
		assert(m_pos < ip);

		/* try to match another M2_MAX_LEN + 1 - M2_MIN_LEN bytes
		 * to see if we get more than a M2 match */
#define M2_OR_M3	(MATCH_M2)

#else /* (DD_BITS == 0) */

		/* we already matched m_len bytes */
		assert(m_len >= M2_MIN_LEN);
		ip += m_len;
		assert(ip <= in_end);

#define M2_OR_M3	(m_len <= M2_MAX_LEN)

#endif /* (DD_BITS == 0) */



		if (M2_OR_M3)
		{
		/* we've found a M2 or M3 match */
			assert(ip <= in_end);

		/* 2a) compute match parameters */
#if (DD_BITS == 0)
			assert((lzo_moff_t)(ip-m_pos) == m_off);
			--ip;	/* ran one too far, point back to non-match */
			m_len = ip - ii;
#endif

		/* 2a2) verify match parameters */
			assert(m_len >= M2_MIN_LEN);
			assert(m_len <= M2_MAX_LEN);
			assert(m_len <= M3_MAX_LEN);

			assert(m_off >= M2_MIN_OFFSET);
			assert(m_off >= M3_MIN_OFFSET);
			assert(m_off <= M3_MAX_OFFSET);
			assert(ii-m_off == m_pos_sav);
			assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);

		/* 2b) code the match */
#if (_M2_MAX_OFFSET != _M3_MAX_OFFSET)
			if (m_off <= M2_MAX_OFFSET)
			{
#else
				assert(m_off <= M2_MAX_OFFSET);
#endif
				m_off -= M2_MIN_OFFSET;
				/* code match len + low offset bits */
				*op++ = LZO_BYTE(((m_len - (M2_MIN_LEN - 2)) << M2O_BITS) |
				                  (m_off & M2O_MASK));
				/* code high offset bits */
				*op++ = LZO_BYTE(m_off >> M2O_BITS);
				LZO_STATS(lzo_stats->m2_matches++);
				LZO_STATS(lzo_stats->m2_match[m_len]++);
#if (_M2_MAX_OFFSET != _M3_MAX_OFFSET)
			}
			else
			{
#if defined(LZO_HAVE_R1)
#if (M3_MIN_LEN == M2_MIN_LEN)
				r1 = ip_end;	/* invalidate R1 pointer */
#endif
#endif
				assert(m_len >= M3_MIN_LEN);
				m_off -= M3_MIN_OFFSET - M3_EOF_OFFSET;
				/* code match len */
				*op++ = LZO_BYTE(M3_MARKER | (m_len - (M3_MIN_LEN - 1)));
				/* code low offset bits */
				*op++ = LZO_BYTE(m_off & M3O_MASK);
				/* code high offset bits */
				*op++ = LZO_BYTE(m_off >> M3O_BITS);
				LZO_STATS(lzo_stats->m3_matches++);
				LZO_STATS(lzo_stats->m3_match[m_len]++);
#if defined(LZO_HAVE_M3)
				m3 = op;		/* set M3 pointer */
#endif
			}
#endif /* (_M2_MAX_OFFSET != _M3_MAX_OFFSET) */


			if (ip >= ip_end)
			{
				ii = ip;
				break;
			}


		/* 2c) Insert phrases (beginning with ii+1) into the dictionary. */

#if (CLEVEL == 9) || (CLEVEL >= 7 && M2L_BITS <= 4) || (CLEVEL >= 5 && M2L_BITS <= 3)
		/* Insert the whole match (ii+1)..(ip-1) into dictionary.  */
			++ii;
			do {
				DVAL_NEXT(dv,ii);
#if 0
				UPDATE_D(dict,drun,dv,ii,in);
#else
				dict[ DINDEX(dv,ii) ] = DENTRY(ii,in);
#endif
				MI
			} while (++ii < ip);
			DVAL_NEXT(dv,ii);
			assert(ii == ip);
			DVAL_ASSERT(dv,ip);
#elif (CLEVEL >= 3)
			SI   DI DI   XI
#elif (CLEVEL >= 2)
			SI   DI      XI
#else
			             XI
#endif
		}

		else

		{
		/* we've found a M3 or M4 match - see how far we can still go */
			assert(ip <= in_end);
			assert(lzo_memcmp(m_pos_sav,ii,(lzo_uint)(ip-ii)) == 0);

		/* 2a) compute match parameters */
#if !defined(MATCH_IP_END)
			assert(ii == ip - (M2_MAX_LEN + 1));
#if (DD_BITS > 0)
			assert(m_len == (lzo_uint)(ip-ii));
			m_pos = ip - m_off;
			assert(m_pos == m_pos_sav + m_len);
#endif
			{
				const lzo_byte *end;
				end = in_end;
				while (ip < end  &&  *m_pos == *ip)
					m_pos++, ip++;
				assert(ip <= in_end);
				m_len = (ip - ii);
			}
			assert((lzo_moff_t)(ip-m_pos) == m_off);
#endif

		/* 2a2) verify match parameters */
			assert(m_len >= M3_MIN_LEN);

			assert(m_off >= M3_MIN_OFFSET);
			assert(m_off >= M4_MIN_OFFSET);
			assert(m_off <= M3_MAX_OFFSET);
			assert(m_off <= M4_MAX_OFFSET);
			assert(ii-m_off == m_pos_sav);
			assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);

		/* 2b) code the match */
			if (m_len <= M3_MAX_LEN)
			{
				/* code match len */
				*op++ = LZO_BYTE(M3_MARKER | (m_len - (M3_MIN_LEN - 1)));
				LZO_STATS(lzo_stats->m3_matches++);
				LZO_STATS(lzo_stats->m3_match[m_len]++);
			}
			else
			{
				assert(m_len >= M4_MIN_LEN);
				/* code M4 match len flag */
				*op++ = M4_MARKER;
				/* code match len */
				m_len -= M4_MIN_LEN - 1;
				while (m_len > 255)
				{
					m_len -= 255;
					*op++ = 0;
				}
				assert(m_len > 0);
				*op++ = LZO_BYTE(m_len);
				LZO_STATS(lzo_stats->m4_matches++);
			}

			m_off -= M3_MIN_OFFSET - M3_EOF_OFFSET;
			/* code low offset bits */
			*op++ = LZO_BYTE(m_off & M3O_MASK);
			/* code high offset bits */
			*op++ = LZO_BYTE(m_off >> M3O_BITS);

#if defined(LZO_HAVE_M3)
			m3 = op;		/* set M3 pointer */
#endif


			if (ip >= ip_end)
			{
				ii = ip;
				break;
			}


		/* 2c) Insert phrases (beginning with ii+1) into the dictionary. */
#if (CLEVEL == 9)
		/* Insert the whole match (ii+1)..(ip-1) into dictionary.  */
		/* This is not recommended because it can be slow. */
			++ii;
			do {
				DVAL_NEXT(dv,ii);
#if 0
				UPDATE_D(dict,drun,dv,ii,in);
#else
				dict[ DINDEX(dv,ii) ] = DENTRY(ii,in);
#endif
				MI
			} while (++ii < ip);
			DVAL_NEXT(dv,ii);
			assert(ii == ip);
			DVAL_ASSERT(dv,ip);
#elif (CLEVEL >= 8)
			SI   DI DI DI DI DI DI DI DI   XI
#elif (CLEVEL >= 7)
			SI   DI DI DI DI DI DI DI      XI
#elif (CLEVEL >= 6)
			SI   DI DI DI DI DI DI         XI
#elif (CLEVEL >= 5)
			SI   DI DI DI DI               XI
#elif (CLEVEL >= 4)
			SI   DI DI DI                  XI
#elif (CLEVEL >= 3)
			SI   DI DI                     XI
#elif (CLEVEL >= 2)
			SI   DI                        XI
#else
			                               XI
#endif
		}

		/* ii now points to the start of the next literal run */
		assert(ii == ip);


/*
vi:ts=4
*/
