/* lzo1a_cm.ch -- implementation of the LZO1A compression algorithm This file is part of the LZO real-time data compression library. Copyright (C) 1996-2014 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. Markus F.X.J. Oberhumer http://www.oberhumer.com/opensource/lzo/ */ /* 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 in LZO1 compatible format ************************************************************************/ #define THRESHOLD (M2_MIN_LEN - 1) #define MSIZE LZO_SIZE(M2L_BITS) /*********************************************************************** // ************************************************************************/ #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 short match */ assert(ip <= in_end); /* 2a) compute match parameters */ #if (DD_BITS == 0) assert(pd(ip,m_pos) == m_off); --ip; /* ran one too far, point back to non-match */ m_len = ip - ii; #endif assert(m_len >= M2_MIN_LEN); assert(m_len <= M2_MAX_LEN); assert(m_off >= M2_MIN_OFFSET); assert(m_off <= M2_MAX_OFFSET); assert(ii-m_off == m_pos_sav); assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0); /* 2b) code the match */ m_off -= M2_MIN_OFFSET; /* code short match len + low offset bits */ *op++ = LZO_BYTE(((m_len - THRESHOLD) << M2O_BITS) | (m_off & M2O_MASK)); /* code high offset bits */ *op++ = LZO_BYTE(m_off >> M2O_BITS); 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 long match - see how far we can still go */ const lzo_bytep end; assert(ip <= in_end); assert(ii == ip - (M2_MAX_LEN + 1)); assert(lzo_memcmp(m_pos_sav,ii,(lzo_uint)(ip-ii)) == 0); #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 if (pd(in_end,ip) <= (M3_MAX_LEN - M3_MIN_LEN)) end = in_end; else { end = ip + (M3_MAX_LEN - M3_MIN_LEN); assert(end < in_end); } while (ip < end && *m_pos == *ip) m_pos++, ip++; assert(ip <= in_end); /* 2a) compute match parameters */ m_len = pd(ip, ii); assert(m_len >= M3_MIN_LEN); assert(m_len <= M3_MAX_LEN); 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); assert(pd(ip,m_pos) == m_off); /* 2b) code the match */ m_off -= M3_MIN_OFFSET - M3_EOF_OFFSET; /* code long match flag + low offset bits */ *op++ = LZO_BYTE(((MSIZE - 1) << M3O_BITS) | (m_off & M3O_MASK)); /* code high offset bits */ *op++ = LZO_BYTE(m_off >> M3O_BITS); /* code match len */ *op++ = LZO_BYTE(m_len - M3_MIN_LEN); 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:et */