Sarabjot Singh Khangura
Electrical Engineering Department
University of Southern California
Los Angeles, CA 90007
email:skhangur@usc.edu,khangurasarabjot@gmail.com  

This package includes Simple Regenerating Code applications written using jerasure library. This package also includes some part of jerasure library needed for SRC
implementation. Source files concerning SRC have been released under GNU LGPL v3.0. 
For details on SRC, please refer to "Simple Regenerating Codes: Network Coding for Cloud Storage by D. S. Papailiopoulos, J. Luo, A. G. Dimakis, C. Huang, and J. Li ".
To obtain complete jerasure library,http://web.eecs.utk.edu/~plank/plank/papers/CS-08-627.html. This library is released under GNU LGPL v2.1 license. 

This README provides directions on how to install and run this application. This also includes what is to be expected from the application.  
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HOW TO INSTALL---------------------------------------------------	
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HOW TO INSTALL---------------------------------------------------   
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1. To compile SRC applications, Run 'make' in the parent directory of the Simple-Regenerating-codes. It should compile files without errors but may be with some warnings.   
2. Enter SRC_file directory and run 'make' again. This should again compile files without error but may be with few warnings.

HOW TO RUN---------------------------------------------------------
There are three programs for SRC included in the distribution. One is SRC encoder that encodes any file given as an input. Second one is SRC_decoder that outputs the original 
file that was encoded. Third one is SRC_repair that would repair SRC encoded system.

1. SRC program encodes input file using SRC. 
   Usage:'SRC <name of the file to be encoded> <k> <n> <f> <field size> <buffersize>'. n, k, f are SRC code parameters.
   This would generate 'n' encoded files using SRC and a metafile with all the details needed for repair and decoder applications.

2. This program decodes SRC encoded files when all encoded files are available or when we lose upto (n-k) files.
   a. When there is no encoded file erasure, it simply locates the chunks in the files that have systematic data segments and writes them to file	
   b. if there are encoded file erasures, it would select any 'k' encoded files out of the available encoded files and thereon, uses Decode_by_reed_sol() function to decode.  
   Usage:'SRC_decoder <name of the file that was encoded using SRC>'

3. This program repairs SRC system when upto (n-k) encoded files are lost.
   It has two specialized repair functions:
   a. Repair function when we lose only one encoded file storing the data. It uses xor function from jerasure library to Recover erased encoded file.   
   b. Recover function which is used when lose more than one but upto (n-k) encoded files. It uses decoding function from jerasure libaray as well 
      as xor function.	
   Usage:'SRC_repair <name of the file that was encoded using SRC>'
   
Note: The MDS code used in this implementation of SRC is Vandermonde Reed Solomon Code. However any (n,k) MDS code can be used instead of RS code.
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This package is still under development. Various other versions of SRC will be made available.                 
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This package is still under development. Various other versions of SRC will be made available.                 
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