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Diffstat (limited to 'decoder.cc')
| -rw-r--r-- | decoder.cc | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/decoder.cc b/decoder.cc new file mode 100644 index 0000000..aa394de --- /dev/null +++ b/decoder.cc @@ -0,0 +1,207 @@ +/* Lzlib - A compression library for lzip files + Copyright (C) 2009 Antonio Diaz Diaz. + + This 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 3 of the License, or + (at your option) any later version. + + This 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 this program. If not, see <http://www.gnu.org/licenses/>. + + As a special exception, you may use this file as part of a free + software library without restriction. Specifically, if other files + instantiate templates or use macros or inline functions from this + file, or you compile this file and link it with other files to + produce an executable, this file does not by itself cause the + resulting executable to be covered by the GNU General Public + License. This exception does not however invalidate any other + reasons why the executable file might be covered by the GNU General + Public License. +*/ + +#define _FILE_OFFSET_BITS 64 + +#include <algorithm> +#include <cerrno> +#include <cstdlib> +#include <cstring> +#include <string> +#include <vector> +#include <stdint.h> + +#include "lzlib.h" +#include "lzip.h" +#include "decoder.h" + + +const CRC32 crc32; + + +int Circular_buffer::read_data( uint8_t * const out_buffer, const int out_size ) throw() + { + int size = 0; + if( get > put ) + { + size = std::min( buffer_size - get, out_size ); + if( size > 0 ) + { + std::memmove( out_buffer, buffer + get, size ); + get += size; + if( get >= buffer_size ) get = 0; + } + } + if( get < put ) + { + const int size2 = std::min( put - get, out_size - size ); + if( size2 > 0 ) + { + std::memmove( out_buffer + size, buffer + get, size2 ); + get += size2; + size += size2; + } + } + return size; + } + + +int Circular_buffer::write_data( uint8_t * const in_buffer, const int in_size ) throw() + { + int size = 0; + if( put >= get ) + { + size = std::min( buffer_size - put - (get == 0), in_size ); + if( size > 0 ) + { + std::memmove( buffer + put, in_buffer, size ); + put += size; + if( put >= buffer_size ) put = 0; + } + } + if( put < get ) + { + const int size2 = std::min( get - put - 1, in_size - size ); + if( size2 > 0 ) + { + std::memmove( buffer + put, in_buffer + size, size2 ); + put += size2; + size += size2; + } + } + return size; + } + + +bool LZ_decoder::verify_trailer() + { + bool error = false; + File_trailer trailer; + const int trailer_size = trailer.size( format_version ); + for( int i = 0; i < trailer_size && !error; ++i ) + { + if( range_decoder.finished() ) error = true; + ((uint8_t *)&trailer)[i] = range_decoder.get_byte(); + } + if( format_version == 0 ) trailer.member_size( member_position() ); + if( trailer.data_crc() != crc() ) error = true; + if( trailer.data_size() != data_position() ) error = true; + if( trailer.member_size() != member_position() ) error = true; + return !error; + } + + + // Return value: 0 = OK, 1 = decoder error, 2 = unexpected EOF, + // 3 = trailer error, 4 = unknown marker found. +int LZ_decoder::decode_member() + { + if( member_finished_ ) return 0; + while( true ) + { + if( range_decoder.available_bytes() <= 0 || + ( !range_decoder.at_stream_end() && + range_decoder.available_bytes() < min_available_bytes ) ) + return 0; // need more data + if( free_bytes() < max_match_len ) return 0; + if( range_decoder.finished() ) return 2; + const int pos_state = data_position() & pos_state_mask; + if( range_decoder.decode_bit( bm_match[state()][pos_state] ) == 0 ) + { + if( state.is_char() ) + prev_byte = literal_decoder.decode( range_decoder, prev_byte ); + else + prev_byte = literal_decoder.decode_matched( range_decoder, prev_byte, + get_byte( rep0 ) ); + put_byte( prev_byte ); + state.set_char(); + } + else + { + int len; + if( range_decoder.decode_bit( bm_rep[state()] ) == 1 ) + { + len = 0; + if( range_decoder.decode_bit( bm_rep0[state()] ) == 0 ) + { + if( range_decoder.decode_bit( bm_len[state()][pos_state] ) == 0 ) + { len = 1; state.set_short_rep(); } + } + else + { + unsigned int distance; + if( range_decoder.decode_bit( bm_rep1[state()] ) == 0 ) + distance = rep1; + else + { + if( range_decoder.decode_bit( bm_rep2[state()] ) == 0 ) + distance = rep2; + else { distance = rep3; rep3 = rep2; } + rep2 = rep1; + } + rep1 = rep0; + rep0 = distance; + } + if( len == 0 ) + { + len = min_match_len + rep_match_len_decoder.decode( range_decoder, pos_state ); + state.set_rep(); + } + } + else + { + rep3 = rep2; rep2 = rep1; rep1 = rep0; + len = min_match_len + len_decoder.decode( range_decoder, pos_state ); + state.set_match(); + const int dis_slot = range_decoder.decode_tree( bm_dis_slot[get_dis_state(len)], dis_slot_bits ); + if( dis_slot < start_dis_model ) rep0 = dis_slot; + else + { + const int direct_bits = ( dis_slot >> 1 ) - 1; + rep0 = ( 2 | ( dis_slot & 1 ) ) << direct_bits; + if( dis_slot < end_dis_model ) + rep0 += range_decoder.decode_tree_reversed( bm_dis + rep0 - dis_slot, direct_bits ); + else + { + rep0 += range_decoder.decode( direct_bits - dis_align_bits ) << dis_align_bits; + rep0 += range_decoder.decode_tree_reversed( bm_align, dis_align_bits ); + if( rep0 == 0xFFFFFFFF ) // Marker found + { + if( len == min_match_len ) // End Of Stream marker + { + member_finished_ = true; + if( verify_trailer() ) return 0; else return 3; + } + return 4; + } + } + } + } + if( !copy_block( rep0, len ) ) return 1; + prev_byte = get_byte( 0 ); + } + } + } |