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Viewing changes to claw/impl/lzw_encoder.tpp

  • Committer: Bazaar Package Importer
  • Author(s): Julien Jorge
  • Date: 2008-05-17 15:36:57 UTC
  • Revision ID: james.westby@ubuntu.com-20080517153657-0b1204j754ykoz48
Tags: upstream-1.5.2b
Import upstream version 1.5.2b

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claw/impl/lzw_encoder.tpp
 
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/**
 
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 * \file lzw_encoder.tpp
 
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 * \brief Implementation of the claw::lzw_encoder class.
 
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 * \author Julien Jorge
 
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 */
 
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#include <map>
 
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/*----------------------------------------------------------------------------*/
 
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/**
 
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 * \brief Encode a sequence of datas.
 
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 * \param input Where we read the uncompressed data.
 
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 * \param output Where we write compressed data.
 
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 */
 
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template<typename InputBuffer, typename OutputBuffer>
 
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void claw::lzw_encoder<InputBuffer, OutputBuffer>::encode
 
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( input_buffer_type& input, output_buffer_type& output ) const
 
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{
 
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  typedef std::pair<unsigned int, unsigned int> word;
 
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  if ( !input.end_of_data() )
 
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    {
 
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      std::map<word, unsigned int> table;
 
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      unsigned int symbol = input.get_next();
 
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      unsigned int prefix_code = symbol;
 
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      unsigned int next_code = input.symbols_count();
 
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      while ( !input.end_of_data() && (next_code != output.max_code()) )
 
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        {
 
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          symbol = input.get_next();
 
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          word new_word(prefix_code, symbol);
 
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          if ( table.find(new_word) != table.end() )
 
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            prefix_code = table[new_word];
 
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          else
 
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            {
 
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              output.write(prefix_code);
 
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              output.new_code(next_code);
 
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              table[new_word] = next_code;
 
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              prefix_code = symbol;
 
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              ++next_code;
 
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            }
 
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        }
 
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      output.write(prefix_code);
 
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    }
 
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} // lzw_encoder::encode()