Library usage

Each compression method can be used by running the following command:

$ ./app -m COMPRESSION_FUNCTION_NAME -i dataIn -o dataOut

List of available parameters can be obtained by running the following command:

$ ./app -m COMPRESSION_FUNCTION_NAME -p ?

Note: Detailed notes for the compression methods can be found in the following papers:

• Fiala, M.: Implementation of DCA Compression Method. Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, May 2007. Master thesis.
• Šimek, F.: Data compression library. Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, May 2009. Master thesis.
• Řezníček, J.: Corpus for comparing compression methods and an extension of a ExCom library. Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, May 2010. Master thesis.
• Baier, J.: Music Sheet Compression. Faculty of Information Technology, Czech Technical University in Prague, Prague, January 2012. Master thesis.

New compression method

This part contains the main information necessary to implement new compression method. However, some information may not be stated here, so please refer to the following publications:

• Řezníček, J.: Corpus for comparing compression methods and an extension of a ExCom library. Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, May 2010. Master thesis.
• Baier, J.: Music Sheet Compression. Faculty of Information Technology, Czech Technical University in Prague, Prague, January 2012. Master thesis.

Adding implementations of new compression methods to the ExCom library is currently not very straightforward. Suppose we want to add new compression method called XYZ. Here is a list of actions that need to be performed.

• Create directory lib/method/xyz. Implement the main class CompXYZ, derived from CompModule, and store the source code in this directory. The directory should also contain other files related to the implementation, like its license or a Readme file.
• Include name of the author in the AUTHORS file.
• Add method/xyz/libmetxyz.la to the libexcom_la_LIBADD variable in the template file lib/Makefile.am.
• Add xyz to the SUBDIRS variable in lib/method/Makefile.am.
• Create the lib/method/xyz/Makefile.am template file. It should be similar to other
• Add lib/method/xyz/Makefile into the AC_CONFIG_FILES in the configure.ac file.
methods' Makefile.am files.
• Define a new named constant EXCOM_MET_XYZ in the excom_method_e enum in excom.h. Also, at the end of this file, add enumerations of named constants of the method's parameters.
• Include the module's header file (the one where CompXYZ is declared, if the module has multiple header files) in lib/main.cpp. If this header file is called xyz.hpp, the inclusion will look like this:
  

  #include "method/xyz/xyz.hpp"

• Create a separate else if branch in the implementation of the exc_compModule function in lib/main.cpp.
  

  #ifdef METHOD_XYZ
    else if (method == EXCOM_MET_XYZ) {
      comp = new CompXYZ(handle);
    }
  #endif
  

• Add conditional variable for the method in configure.ac (so that the method can be disabled by the configure script).
  

  AC_ARG_ENABLE([xyz],
    [ --disable-xyz turn off XYZ compression method],
    [case "${enableval}" in
      yes) xyz=true;;
      no) xyz=false;;
      *) AC_MSG_ERROR([bad value ${enableval} for --disable-xyz]);;
    esac],
    [xyz=true])
  AM_CONDITIONAL([METHOD_XYZ], [test x$xyz = xtrue])
  

• Add the following to the objects_LDADD variable in src/unittest/Makefile.am (so that the objects unit test builds without errors).
  

  $(REL)/method/xyz/libmetxyz.la

• Optionally create a unit test for the XYZ method.