Claw
1.7.3
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00001 /* 00002 CLAW - a C++ Library Absolutely Wonderful 00003 00004 CLAW is a free library without any particular aim but being useful to 00005 anyone. 00006 00007 Copyright (C) 2005-2011 Julien Jorge 00008 00009 This library is free software; you can redistribute it and/or 00010 modify it under the terms of the GNU Lesser General Public 00011 License as published by the Free Software Foundation; either 00012 version 2.1 of the License, or (at your option) any later version. 00013 00014 This library is distributed in the hope that it will be useful, 00015 but WITHOUT ANY WARRANTY; without even the implied warranty of 00016 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00017 Lesser General Public License for more details. 00018 00019 You should have received a copy of the GNU Lesser General Public 00020 License along with this library; if not, write to the Free Software 00021 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 00022 00023 contact: julien.jorge@gamned.org 00024 */ 00030 #include <list> 00031 00032 /*----------------------------------------------------------------------------*/ 00038 template<typename InputBuffer, typename OutputBuffer> 00039 void claw::lzw_decoder<InputBuffer, OutputBuffer>::decode 00040 ( input_buffer_type& input, output_buffer_type& output ) 00041 { 00042 const unsigned int symbols_count = input.symbols_count(); 00043 00044 table_type table; 00045 unsigned int table_size = 0; 00046 00047 unsigned int prefix = input.get_next(); 00048 00049 if ( !input.end_of_data() ) 00050 { 00051 while ( !input.end_of_data() ) 00052 { 00053 unsigned int suffix = input.get_next(); 00054 00055 if (!input.end_of_data() ) 00056 { 00057 unsigned int new_suffix; 00058 00059 if ( suffix < table_size + symbols_count ) 00060 new_suffix = get_first_symbol(table, suffix, symbols_count); 00061 else 00062 new_suffix = get_first_symbol(table, prefix, symbols_count); 00063 00064 table.push_back( word_type(prefix, new_suffix) ); 00065 ++table_size; 00066 input.new_code(table_size + symbols_count); 00067 00068 decompose( table, prefix, symbols_count, output ); 00069 prefix = suffix; 00070 } 00071 } 00072 00073 decompose( table, prefix, symbols_count, output ); 00074 } 00075 } // lzw_decoder::decode() 00076 00077 /*----------------------------------------------------------------------------*/ 00084 template<typename InputBuffer, typename OutputBuffer> 00085 unsigned int claw::lzw_decoder<InputBuffer, OutputBuffer>::get_first_symbol 00086 ( const table_type& table, const unsigned int code, 00087 const unsigned int symbols_count ) const 00088 { 00089 unsigned int result = code; 00090 00091 while ( result >= symbols_count ) 00092 result = table[result - symbols_count].first; 00093 00094 return result; 00095 } // lzw_decoder::get_first_symbol() 00096 00097 /*----------------------------------------------------------------------------*/ 00105 template<typename InputBuffer, typename OutputBuffer> 00106 void claw::lzw_decoder<InputBuffer, OutputBuffer>::decompose 00107 ( const table_type& table, unsigned int code, 00108 const unsigned int symbols_count, output_buffer_type& output ) const 00109 { 00110 std::list<unsigned int> result; 00111 00112 while ( code >= symbols_count ) 00113 { 00114 result.push_front( table[code - symbols_count].second ); 00115 code = table[code - symbols_count].first; 00116 } 00117 00118 result.push_front(code); 00119 00120 std::list<unsigned int>::const_iterator it; 00121 00122 for (it=result.begin(); it!=result.end(); ++it) 00123 output.write( *it ); 00124 00125 } // lzw_decoder::decompose()