fsmconverter

A toml to verilog fsm converter

Introduction

The goal of this project is to simplify the tedious work of creating a finite state machine (FSM) in Verilog code by using the TOML configuration file format. It also generates a [Graphviz](https://www.graphviz.org/] .gv dot file. This is useful to get a visual overview of the state transitions.

Install process

As this project is written in Go the Go development kit needs to installed on your system. How to do this depends on your OS or distribution. For Fedora there is a helpful article on how to get started. It should be useful for users of other distributions as well. Once you have the GOPATH variable set and GOPATH/bin in your PATH as described in the above article, simply execute

cd $GOPATH
go get -u -v github.com/kinnarr/fsmconverter/
cd src/github.com/kinnarr/fsmconverter
go install

Typing 'fsmconverter' should now show you the help screen of fsmconverter:

Usage:
  fsmconverter [command]

Available Commands:
  generatedot     Generates dot file for graphviz from the fsm config
  generateverilog Generates verilog from the fsm config
  help            Help about any command
  prettyprint     Print the fsm config in a pretty stil
  printstate      Prints the given fsm state
  validate        Validates the fsm config

Flags:
      --debug                   debugging output
      --fsm-config-dir string   search here for fsm config (default "fsm")
  -h, --help                    help for fsmconverter
      --ignore-unknown-states   ignores unknown states in validation
      --optimize                optimize state of fsm

Usage

The states and their respective inputs, outputs and transitions are specified in one or several .toml files. These files are placed in one folder with an arbitrary sub-folder structure. Fsm converter reads in this directory(specified with the '--fsm-config-dir' flag) and either validates('fsmconverter validate') or prints the found states in an orderly way('fsmconverter prettyprint').

File structure

List states

[state.EXAMPLE]

Conditions for state transition

[[state.EXAMPLE1.next.Example2.and.condition]]
condition1=3        #decimal works
condition2=0b00011  #so does binary
condition3=0o3      #octal
condition4=0x3      #and hexadecimal notation

Else/Default Transition

Sometimes you want to define a default transition that is taken only when the conditions of the other possible transitions are not met.

[state.EXAMPLE1.else.Example3]

Output of state

[state.EXAMPLE1.output]

Inputs

Every condition needs to be defined in one of the toml files used, e.g. 'inputs.toml' Same as in the outputs, the binary length of these variables has to be defined

[inputs]
condition1=2		#2'b00
condition2=5		#5'b00000
condition3=3		#3'b000
condition4=4		#4'b0000

Outputs

Outputs need to be defined similarly to the inputs; for every output variable a default value needs to be specified.

[outputs]
output1=3		#3'b000
output2=4		#4'b0000

[defaults.outputs]
output1=0		#3'b000
output2=15		#4'b1111

A default state (usually the reset state) needs to be provided:

[defaults]
state="RESET"