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这是一个基于c++的算术编码源代码

% Arithmetic Coding
% Reference : 
% [1] Arithmetic Coding For Data Compression 
%                   Ian H.Witten , Radford M.Neal, John G.Cleary
% [2] Embedded Image Coding Using Zerotrees of wavelet coefficients
%                   Jerome M.Shapiro
% The program is just a conversion from C program given in [1] to MATLAB program.
% ************** THIS CODE IS NOT OPTIMIZED **************
% Although contains some changes, but effectively it is the same program as in [1]
% i.e The input is taken from a file named text.txt

% Almost all the variables in the program are GLOBAL, this makes the program easier
% to understand and few are static to the program and will be specified using PERSISTENT.
% All the variables and function names are same as used in [1].
% Comments have been added to make things easier, in any case user is reffered to [1].

% Please Contact the author for any Criticism or Appreciation :
%             Ravi Lakkundi, M.Tech (Digital Electronics)
%             SDM College of Engineering and Technology
%             Dhavalgiri,Dharwad - 580002
%             Karnataka, INDIA  
%             Ph: 0091-0836-2223037  
%             E-mail : [e-mail]
% Author : I will be really glad to hear from you a word, just put a mail across.

% This program was written to test Embedded Image Coding [2], although EZW using Arithmetic coding
% will be dealt later.

%     FUNCTION NAMES FOR ENCODING    
% ******************** Functions for encoding ******************** 
% 1.  main_encode               :   Main program for encoding
% 2.  start_model_fixed         :   Initializes variables, arrays etc for the use of fixed model
% 2a. start_model_adaptive      :   Initializes variables, arrays etc for the use of adaptive model
% 3.  start_outputting_bits     :   Outputs the bits after encoding
% 4.  start_encoding            :   Initializes encoding function
% 5.  encode_symbol             :   Encodes the given symbol
% 6.  update_model_fixed        :   Updates the model ( NULL )
% 6a. update_model_adaptive     :   Updates the model 
% 7.  done_encoding             :   Assigns the last two bits
% 8.  done_outputting_bits      :   Refer [1]
% 9.  bit_plus_follow           :   Bits in Range between [1/4,3/4], Refer [1]
% 10. output_bit                :   Output byte ! (yes), bits in groups of 8 ,to a file compressed.txt

% If user is using fixed models use 'start_model_fixed' with 'update_model_fixed'
% else if adaptive use 'start_model_adaptive' with 'update_model_adaptive'
% In the program enter CHOICE 1 and 2, for fixed and adaptive respectively

%     FUNCTION NAME FOR DECODING
% ******************** Functions for decoding ********************
% 1.  main_decode               :   main program for decode
% 2.  start_model_fixed         :   Same as above
% 2a. start_model_adaptive      :   Same as above
% 3.  start_inputting_bits      :   Gets the initial bits for decoding
% 4.  start_decoding            :   Initializes decoding function
% 5.  decode_symbol             :   Decodes the given bit
% 6.  update_model_fixed        :   Updates the model ( NULL ) 
% 6b. update_model_adaptive     :   Updates the model 
% 7.  input_bit                 :   Get bits in order

% Please report for any BUGS