Welcome to the Decaf Home Page

Decaf is a Java class Decompiler written with Ada 95. Version 1.1 provides similar output as the javap program included in the Sun JDK distribution :

Class definition with methods and variables, including private parts
Methods instructions

Version 1.1 includes the following corrections :

Obsolete attribute Safe_Small replaced by Model_Small
ByteCode enumeration type corrections (Aload and Astore misplaced)
ByteCode operands displaying corrections (Sipush)

Decaf implementation uses the following Ada95 features :

Object Oriented Programming
Abstract classes (see CP or Attribute classes)
Child Units combined with subclassing (see CP, Attribute or Field hierarchy)
Enhanced portability (see Basic_Definitions or Byte_Utilities)

Decaf implementation follows stricly the structures defined in The Java Virtual Machine Specification (Release 1.0 Beta - Draft - August 21, 1995). The main program Decaf calls functions and procedures of the Class_File package (which implements the structure class_file presented in the document). All other packages in the Decaf implementation refers to the structures identified in the specification with the corresponding names.

Future versions will allow translation to other languages ( Ada 95 and Smalltalk translations are currently under development). I believe that Decaf is a good basis to develop Java to Ada 95 translation, because a Ada 95 to Java bytecode compiler is currently available (see also the article Programming the Internet in Ada 95 by Tucker Taft). Java bytecode to Smalltalk translation must be feasable too, considering Java and Smalltalk similarities (one could say that Java is Smalltalk with C++ syntax and some Internet Classes).

Decaf is designed to be very portable, and it should be compiled without any problem on any platform with a recent GNAT compiler (I did install it with success with GNAT 3.05 on DOS, AIX and Sun-OS). If you encounter problems with installation on other Ada 95 compilers, please contact me.

Since this tool is developed only during my spare time, planning for these versions is quite difficult and help is really welcome.

Copyright

Decaf has been submitted to the Ada Ressource Association's Ada Lovelace Programming Contest. The rules of this contest require the following Copyright statement to be included in each source file :

   --
   -- Copyright (C) 1996 Ada Resource Association (ARA), Columbus, Ohio.
   -- Author: Gilles Demailly
   --
   --
   -- Permission to use, copy, modify, and distribute this software and its
   -- documentation for any purpose and without fee is hereby granted,
   -- provided that the above copyright and authorship notice appear in all
   -- copies and that both that copyright notice and this permission notice
   -- appear in supporting documentation.
   -- 
   -- The ARA makes no representations about the suitability of this software
   -- for any purpose.  It is provided "as is" without express
   -- or implied warranty.
   --

Acknowledgements

The Decaf Home Page site is provided by friends from TéléObjet, please have a look at their Homepage.

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Gilles Demailly - Last update September 18th, 1996