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JHDL Advantages

Overall, JHDL is

Free
Open Source
Easy to set-up and configure
Easily customized

Module Generation

Generally complex module generators consist of two major parts: a front-end that performs data processing to determine the structural circuit details based on some user specification, and a back-end that performs circuit generation and emits the corresponding net-list.

Except in cases where the module generator is extremely simple, the software for the front-end is much better suited to a general-purpose language than a Hardware Description Language (HDL) such as VHDL. Front-end processing ususally interprets user input and this often requires the sort of processing normally associated with a general-purpose language: parsing of input, error detection, construction and processing of dynamic data structures such as linked lists and file I/O, etc.

Moreover, software development is much easier when done with standard compilers and debuggers than with VHDL synthesizers and simulators.

The only way to overcome this problem with VHDL is to take a combined strategy that uses a general-purpose language such as C++ for front-end processing and a VHDL synthesis tool as the back-end for circuit generation. However this approach is unsatisfactory for several reasons:

It requires the designer of the module generator to have experience in both C++ and VHDL.
It complicates the design and debugging of the module generator, because the designer will have to debug both the C++ and VHDL code.
It requires the end-user to install and maintain an expensive systhesis tool that in many cases only serves as a net-list translator because the front end usually generates a structural description from the user input.
It requires the end-user to understand how to use the VHDL synthesizer because the front-end will occasionally generate incompatible VHDL code due to bugs in either the front-end or the synthesizer, or due to versioning problems.

JHDL overcomes the basic problems listed above because it is based on a general-purpose language (Java.) Moreover, this general-purpose language heritage also makes it straightforward to add new functionality to the JHDL suite. The schematic viewer, simulator, and various browser windows have been developed in modular fashion and can be extended or modified to ease debugging and verification on a per application basis.

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JHDL 0.3.45