347 lines
9.7 KiB
C++
347 lines
9.7 KiB
C++
/* 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 Range_decoder
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{
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enum { buffer_size = 16384 };
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unsigned long long partial_member_pos;
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uint8_t * const buffer; // input buffer
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int pos; // current pos in buffer
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int stream_pos; // when reached, a new block must be read
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uint32_t code;
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uint32_t range;
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const int infd; // input file descriptor
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bool at_stream_end;
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bool read_block();
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Range_decoder( const Range_decoder & ); // declared as private
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void operator=( const Range_decoder & ); // declared as private
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public:
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explicit Range_decoder( const int ifd )
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:
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partial_member_pos( 0 ),
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buffer( new uint8_t[buffer_size] ),
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pos( 0 ),
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stream_pos( 0 ),
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code( 0 ),
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range( 0xFFFFFFFFU ),
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infd( ifd ),
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at_stream_end( false )
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{}
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~Range_decoder() { delete[] buffer; }
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bool finished() { return pos >= stream_pos && !read_block(); }
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unsigned long long member_position() const
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{ return partial_member_pos + pos; }
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void reset_member_position()
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{ partial_member_pos = 0; partial_member_pos -= pos; }
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uint8_t get_byte()
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{
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// 0xFF avoids decoder error if member is truncated at EOS marker
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if( finished() ) return 0xFF;
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return buffer[pos++];
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}
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int read_data( uint8_t * const outbuf, const int size )
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{
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int sz = 0;
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while( sz < size && !finished() )
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{
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const int rd = std::min( size - sz, stream_pos - pos );
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std::memcpy( outbuf + sz, buffer + pos, rd );
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pos += rd;
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sz += rd;
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}
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return sz;
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}
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bool load( const bool ignore_marking = true )
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{
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code = 0;
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range = 0xFFFFFFFFU;
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// check and discard first byte of the LZMA stream
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if( get_byte() != 0 && !ignore_marking ) return false;
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for( int i = 0; i < 4; ++i ) code = ( code << 8 ) | get_byte();
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return true;
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}
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void normalize()
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{
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if( range <= 0x00FFFFFFU )
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{ range <<= 8; code = ( code << 8 ) | get_byte(); }
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}
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unsigned decode( const int num_bits )
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{
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unsigned symbol = 0;
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for( int i = num_bits; i > 0; --i )
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{
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normalize();
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range >>= 1;
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// symbol <<= 1;
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// if( code >= range ) { code -= range; symbol |= 1; }
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const bool bit = ( code >= range );
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symbol <<= 1; symbol += bit;
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code -= range & ( 0U - bit );
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}
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return symbol;
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}
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bool decode_bit( Bit_model & bm )
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{
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normalize();
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const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability;
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if( code < bound )
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{
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range = bound;
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bm.probability +=
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( bit_model_total - bm.probability ) >> bit_model_move_bits;
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return 0;
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}
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else
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{
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code -= bound;
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range -= bound;
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bm.probability -= bm.probability >> bit_model_move_bits;
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return 1;
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}
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}
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void decode_symbol_bit( Bit_model & bm, unsigned & symbol )
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{
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normalize();
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symbol <<= 1;
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const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability;
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if( code < bound )
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{
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range = bound;
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bm.probability +=
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( bit_model_total - bm.probability ) >> bit_model_move_bits;
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}
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else
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{
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code -= bound;
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range -= bound;
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bm.probability -= bm.probability >> bit_model_move_bits;
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symbol |= 1;
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}
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}
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void decode_symbol_bit_reversed( Bit_model & bm, unsigned & model,
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unsigned & symbol, const int i )
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{
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normalize();
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model <<= 1;
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const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability;
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if( code < bound )
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{
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range = bound;
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bm.probability +=
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( bit_model_total - bm.probability ) >> bit_model_move_bits;
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}
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else
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{
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code -= bound;
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range -= bound;
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bm.probability -= bm.probability >> bit_model_move_bits;
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model |= 1;
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symbol |= 1 << i;
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}
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}
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unsigned decode_tree6( Bit_model bm[] )
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{
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unsigned symbol = 1;
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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return symbol & 0x3F;
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}
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unsigned decode_tree8( Bit_model bm[] )
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{
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unsigned symbol = 1;
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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return symbol & 0xFF;
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}
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unsigned decode_tree_reversed( Bit_model bm[], const int num_bits )
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{
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unsigned model = 1;
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unsigned symbol = 0;
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for( int i = 0; i < num_bits; ++i )
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decode_symbol_bit_reversed( bm[model], model, symbol, i );
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return symbol;
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}
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unsigned decode_tree_reversed4( Bit_model bm[] )
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{
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unsigned model = 1;
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unsigned symbol = 0;
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decode_symbol_bit_reversed( bm[model], model, symbol, 0 );
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decode_symbol_bit_reversed( bm[model], model, symbol, 1 );
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decode_symbol_bit_reversed( bm[model], model, symbol, 2 );
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decode_symbol_bit_reversed( bm[model], model, symbol, 3 );
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return symbol;
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}
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unsigned decode_matched( Bit_model bm[], unsigned match_byte )
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{
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Bit_model * const bm1 = bm + 0x100;
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unsigned symbol = 1;
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while( symbol < 0x100 )
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{
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const unsigned match_bit = ( match_byte <<= 1 ) & 0x100;
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const bool bit = decode_bit( bm1[symbol+match_bit] );
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symbol <<= 1; symbol |= bit;
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if( match_bit >> 8 != bit )
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{
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while( symbol < 0x100 ) decode_symbol_bit( bm[symbol], symbol );
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break;
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}
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}
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return symbol & 0xFF;
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}
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unsigned decode_len( Len_model & lm, const int pos_state )
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{
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Bit_model * bm;
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unsigned mask, offset, symbol = 1;
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if( decode_bit( lm.choice1 ) == 0 )
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{ bm = lm.bm_low[pos_state]; mask = 7; offset = 0; goto len3; }
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if( decode_bit( lm.choice2 ) == 0 )
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{ bm = lm.bm_mid[pos_state]; mask = 7; offset = len_low_symbols; goto len3; }
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bm = lm.bm_high; mask = 0xFF; offset = len_low_symbols + len_mid_symbols;
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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len3:
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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decode_symbol_bit( bm[symbol], symbol );
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return ( symbol & mask ) + min_match_len + offset;
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}
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};
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class LZ_decoder
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{
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unsigned long long partial_data_pos;
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Range_decoder & rdec;
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const unsigned dictionary_size;
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uint8_t * const buffer; // output buffer
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unsigned pos; // current pos in buffer
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unsigned stream_pos; // first byte not yet written to file
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uint32_t crc_;
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const int outfd; // output file descriptor
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bool pos_wrapped;
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void flush_data();
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int check_trailer( const Pretty_print & pp, const bool ignore_empty ) const;
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uint8_t peek_prev() const
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{ return buffer[((pos > 0) ? pos : dictionary_size)-1]; }
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uint8_t peek( const unsigned distance ) const
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{
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const unsigned i = ( ( pos > distance ) ? 0 : dictionary_size ) +
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pos - distance - 1;
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return buffer[i];
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}
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void put_byte( const uint8_t b )
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{
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buffer[pos] = b;
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if( ++pos >= dictionary_size ) flush_data();
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}
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void copy_block( const unsigned distance, unsigned len )
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{
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unsigned lpos = pos, i = lpos - distance - 1;
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bool fast, fast2;
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if( lpos > distance )
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{
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fast = ( len < dictionary_size - lpos );
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fast2 = ( fast && len <= lpos - i );
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}
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else
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{
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i += dictionary_size;
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fast = ( len < dictionary_size - i ); // (i == pos) may happen
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fast2 = ( fast && len <= i - lpos );
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}
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if( fast ) // no wrap
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{
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pos += len;
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if( fast2 ) // no wrap, no overlap
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std::memcpy( buffer + lpos, buffer + i, len );
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else
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for( ; len > 0; --len ) buffer[lpos++] = buffer[i++];
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}
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else for( ; len > 0; --len )
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{
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buffer[pos] = buffer[i];
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if( ++pos >= dictionary_size ) flush_data();
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if( ++i >= dictionary_size ) i = 0;
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}
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}
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LZ_decoder( const LZ_decoder & ); // declared as private
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void operator=( const LZ_decoder & ); // declared as private
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public:
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LZ_decoder( Range_decoder & rde, const unsigned dict_size, const int ofd )
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:
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partial_data_pos( 0 ),
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rdec( rde ),
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dictionary_size( dict_size ),
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buffer( new uint8_t[dictionary_size] ),
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pos( 0 ),
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stream_pos( 0 ),
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crc_( 0xFFFFFFFFU ),
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outfd( ofd ),
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pos_wrapped( false )
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// prev_byte of first byte; also for peek( 0 ) on corrupt file
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{ buffer[dictionary_size-1] = 0; }
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~LZ_decoder() { delete[] buffer; }
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unsigned crc() const { return crc_ ^ 0xFFFFFFFFU; }
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unsigned long long data_position() const { return partial_data_pos + pos; }
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int decode_member( const Cl_options & cl_opts, const Pretty_print & pp );
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};
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