diff options
Diffstat (limited to 'encoder.cc')
| -rw-r--r-- | encoder.cc | 42 |
1 files changed, 20 insertions, 22 deletions
@@ -1,18 +1,18 @@ -/* Lzip - LZMA lossless data compressor - Copyright (C) 2008-2019 Antonio Diaz Diaz. +/* Lzip - LZMA lossless data compressor + Copyright (C) 2008-2021 Antonio Diaz Diaz. - This program 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. + This program 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. - This program 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. + This program 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 this program. If not, see <http://www.gnu.org/licenses/>. + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ #define _FILE_OFFSET_BITS 64 @@ -42,9 +42,8 @@ int LZ_encoder::get_match_pairs( Pair * pairs ) if( len_limit < 4 ) return 0; } - int maxlen = 0; + int maxlen = 3; // only used if pairs != 0 int num_pairs = 0; - const int pos1 = pos + 1; const int min_pos = ( pos > dictionary_size ) ? pos - dictionary_size : 0; const uint8_t * const data = ptr_to_current_pos(); @@ -57,32 +56,31 @@ int LZ_encoder::get_match_pairs( Pair * pairs ) if( pairs ) { - int np2 = prev_positions[key2]; - int np3 = prev_positions[key3]; + const int np2 = prev_positions[key2]; + const int np3 = prev_positions[key3]; if( np2 > min_pos && buffer[np2-1] == data[0] ) { pairs[0].dis = pos - np2; - pairs[0].len = maxlen = 2; + pairs[0].len = maxlen = 2 + ( np2 == np3 ); num_pairs = 1; } if( np2 != np3 && np3 > min_pos && buffer[np3-1] == data[0] ) { maxlen = 3; - np2 = np3; - pairs[num_pairs].dis = pos - np2; - ++num_pairs; + pairs[num_pairs++].dis = pos - np3; } if( num_pairs > 0 ) { - const int delta = pos1 - np2; + const int delta = pairs[num_pairs-1].dis + 1; while( maxlen < len_limit && data[maxlen-delta] == data[maxlen] ) ++maxlen; pairs[num_pairs-1].len = maxlen; + if( maxlen < 3 ) maxlen = 3; if( maxlen >= len_limit ) pairs = 0; // done. now just skip } - if( maxlen < 3 ) maxlen = 3; } + const int pos1 = pos + 1; prev_positions[key2] = pos1; prev_positions[key3] = pos1; int newpos1 = prev_positions[key4]; |