yosys/tests/various/fsm-arst.ys

read_verilog << EOT
module non_self_rs_fsm (
    input  wire clk,
    input  wire reset,
    output wire s1
);
    localparam [7:0] RST = 8'b10010010;
    localparam [7:0] S1 = 8'b01001000;
    localparam [7:0] S2 = 8'b11000111;

    reg [7:0] current_state, next_state;
    always @(posedge clk or posedge reset) begin
        if (reset) begin
            current_state <= RST;
        end else begin
            current_state <= next_state;
        end
    end

    always @(*) begin
        next_state = current_state;

        case (current_state)
            RST: next_state = S1;
            S1: next_state = S2;
            S2: next_state = S1;
            default: next_state = RST;
        endcase
    end

    assign s1 = next_state == S1;
endmodule

module semi_self_rs_fsm (
    input  wire clk,
    input wire test,
    output wire s1
);
    localparam [7:0] RST = 8'b10010010;
    localparam [7:0] S1 = 8'b01001000;
    localparam [7:0] S2 = 8'b11000111;

    reg [7:0] current_state, next_state;
    reg [1:0] reset_test;

    wire reset = (test || (reset_test == 2));

    always @(posedge clk or posedge reset) begin
        if (reset) begin
            current_state <= RST;
            reset_test <= 0;
        end else begin
            current_state <= next_state;
            if (current_state == S2)
                reset_test = reset_test + 1;
        end
    end
    

    always @(*) begin
        next_state = current_state;

        case (current_state)
            RST: next_state = S1;
            S2: next_state = S1;
            S1: next_state = S2;

            default: next_state = RST;
        endcase
    end

    assign s1 = next_state == S1;
endmodule

module self_rs_fsm (
    input  wire clk,
    output wire s1
);
    localparam [7:0] RST = 8'b10010010;
    localparam [7:0] S1 = 8'b01001000;
    localparam [7:0] S2 = 8'b11000111;

    reg [7:0] next_state;
    wire reset = next_state == S1;

    always @(posedge clk or posedge reset) begin
        if (reset) begin
            next_state <= RST;
        end else begin
            case (next_state)
                RST: next_state = S1;
                S1: next_state = S2;
                S2: next_state = S1;
                default: next_state = RST;
            endcase
        end
    end


    assign s1 = next_state == S1;
endmodule

EOT

proc
opt_expr
opt_clean
check
opt -nodffe -nosdff

fsm_detect 
fsm_extract

cd non_self_rs_fsm
select -assert-count 1 t:$fsm

cd semi_self_rs_fsm
select -assert-count 1 t:$fsm

cd self_rs_fsm
select -assert-none t:$fsm