It is sometimes easier to write the code and have the documentation generated from that. Sometimes you inherit legacy code without documentation, in these situations especially if new to a language tools to help visualise what is happening can be quite useful.
With cadence tools you can run your code with 'code coverage' then imc can load the coverage data and run FSM Analysis.
I have included a simple FSM below and show the generated state diagram.
module simple_fsm();
//Inputs to FSM
logic clk;
logic rst_n;
logic [1:0] state ;
logic [1:0] nextstate;
logic turn_on ;
logic turn_off ;
localparam S_OFF = 2'b00;
localparam S_GO_ON = 2'b01;
localparam S_ON = 2'b10;
localparam S_GO_OFF = 2'b11;
// State FlipFlop
always @(posedge clk or negedge rst_n) begin
if (~rst_n) begin
state <= 2'b0;
end
else begin
state <= nextstate;
end
end
//Nextstate Logic
always @* begin
case (state)
2'd0 : if (turn_on) begin
nextstate = S_GO_ON;
end
2'd1 : nextstate = S_ON;
2'd2 : if (turn_off) begin
nextstate = S_GO_OFF ;
end
2'd3 : nextstate = S_OFF;
endcase
end
//TB clk
initial begin
#1ns;
clk = 0;
forever begin
#20ns;
clk = ~clk;
end
end
//The Test
initial begin
rst_n = 1'b0;
turn_on = 1'b0;
turn_off = 1'b0;
@(posedge clk);
@(posedge clk);
rst_n = 1'b1 ;
@(posedge clk);
turn_on = 1'b1;
@(posedge clk);
turn_on = 1'b0;
@(posedge clk);
@(posedge clk);
#100ms;
$finish();
end
endmodule
Execute with :
$ irun simple_fsm.sv -coverage all -covdut simple_fsm
$ imc &
Load cov_work (folder created by above simulation) in imc, select simple_fsm and choose FSM Analysis.
imc also helps to visualise your test coverage as well. Arcs and states that have not been hit are shown in red.
We have seen that there are some tools which can visualise the FSM, another part of the question is; is the syntax of the purposed FSM suitable for these tools.
@vermaete has reported that Modelsim SE can not see the FSM. From imc I get :
Which does not seem to cover the complexity of the code, and is shown as only having 2 reachable states, IDLE and BUSY. I would recommend if OP is going down the route of using tools to visualise, adopt a simpler (syntax) FSM structure so that the tools can parse it better.