BWT encoder and decoder

I have implemented BWT transformation.The current implementation works for text file.It can be enhanced to transform images also. The files are bwtenc and bwtdec. future works include doing image compression using current bwt module+Mive to front and either Huffman or Arithmetic Coding.
Pls send me suggestions and Coding Bugs.

% type bwtenc at the command prompt and
% a user interface is dispalyed.
% currently,its just text file.u can select just text files
% for now.
%the BWT transformed file is written as bwt.cmp in the
%current directory

%bwtdec is a BWT decoder
% type bwtdec at the command prompt
% this particular function reads the transformed(BWT)
% file bwt.txt and then geets the original file back
% as orig_text
% BE SURE that the transformed file BWT.TXT is in the
% current directory