logisim-evolution with fsm library

This repository is a fork from the official logisim-evolution repository (see official repository for more information) and hosts an early version of logisim with experimental support for editing/analyzing and simulating Finite State Machines plus several other minor features including :

• (incomplete) Support for DE0-CV board from Terasic
• Keypad IO device (currently only for simulation)
• Dual ported register file component for easing the design of MIPS like CPUs

The logisim FSM editor

• The tool menu contains an entry named FSM Tools, with the Finite State Machine component available as a building block.

• By default, the menu instantiates a 4-state example FSM which demonstrates most of the features available in the tool. The FSM transition diagram can be viewed and modified within a graphical editor which is opened by clicking on the Content attribute.

The editor is in advanced beta stage, it supports adding/editing/moving/copying/deleting elements through a context menu (use right click to make it appear). Elements can be selected (left click) and moved to make the diagram more readable.

• Commands (outputs) value are specified using boolean expressions involving bitvector constants ("0101","1"), inputs (with range selection aka A[2:0]), boolean operators (+=OR,.=AND,/=NOT,"1"= true,"0=false ), comparison (==,/=) and concatenation ({A,"0"}). The expression is analyzed for correctness by the editor.

• Transition predicates are also specified using boolean expressions, which must evaluate as a single bit vector. In addition, it is also possible to use a "default" predicate which is evaluated to true when all other transition predicates for a given state are evaluated to false.

In addition to syntactic analysis, the editor also checks that transitions from a given state have all their predicates mutually exclusive to guarantee the the fSM is deterministic. This is achieved using the jdd library, which we use to perform a simple boolean SAT check.

Missing/untested features

• [FIXED] The current version also support VHDL generation although the correctness of generated VHDL was not fully tested yet.

• [MOSTLY FIXED] The editor does not fully supports input/outputs with wordlength greater than one, especially for SAT checks

• [FIXED] Checker does not verify that all states have different binary codes, not that code size (in # bits) is consistent with the number of state on the FSM.

How to install this version of logisim-evolution

You can find the latest version of the tool here. [updated on October 10th, 2018]

To execute it, click on the downloaded file or type in a console

java -jar logisim-evolution.jar

You can also compile it by yourself by cloning the repository on your local machine. Once this is done, enter the directory and execute

ant run

This also creates locally a .jar file, which needs to be fixed due to some library issue. To do so you must run the following command in the project folder containing the jar file.

zip -d logisim-evolution.jar 'META-INF/*.SF' 'META-INF/*.RSA' 'META-INF/*SF'

This jar can be distributed and used on other machines.

Editing logisim-evolution in Eclipse

To import directly logisim-evolution in Eclipse, you can use Eclipse's import wizard:

Import -> git project -> [put the connection details] -> New project -> Java project from Ant

You will, however, encounter a problem when you will try to execute the code. In particular, an exception ExceptionInInitializerError will be thrown. To solve this, execute the eclipse_fix.sh script in the program's directory, or go in the bin/ subdirectory and create links to the following directories available in the program's directory

• boards_model
• javax
• libs
• resources
• doc