62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
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/* Lzip - LZMA lossless data compressor
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Copyright (C) 2008-2024 Antonio Diaz Diaz.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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class FLZ_encoder : public LZ_encoder_base
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{
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unsigned key4; // key made from latest 4 bytes
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void reset_key4()
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{
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key4 = 0;
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for( int i = 0; i < 3 && i < available_bytes(); ++i )
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key4 = ( key4 << 4 ) ^ buffer[i];
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}
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int longest_match_len( int * const distance );
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void update_and_move( int n )
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{
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while( --n >= 0 )
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{
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if( available_bytes() >= 4 )
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{
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key4 = ( ( key4 << 4 ) ^ buffer[pos+3] ) & key4_mask;
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pos_array[cyclic_pos] = prev_positions[key4];
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prev_positions[key4] = pos + 1;
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}
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move_pos();
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}
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}
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enum { before_size = 0,
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dict_size = 65536,
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// bytes to keep in buffer after pos
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after_size = max_match_len,
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dict_factor = 16,
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num_prev_positions23 = 0,
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pos_array_factor = 1 };
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public:
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FLZ_encoder( const int ifd, const int outfd )
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:
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LZ_encoder_base( before_size, dict_size, after_size, dict_factor,
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num_prev_positions23, pos_array_factor, ifd, outfd )
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{}
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bool encode_member( const unsigned long long member_size );
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};
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