// AN9238 virtual ADC model (1 port)

module virtual_adc_model #(
    parameter int unsigned ADC_DATA_WIDTH = 12,

    // Bipolar input range: +/- VOLTAGE_RANGE
    parameter real VOLTAGE_RANGE = 1.0,

    // Analog input correction
    parameter real VOLTAGE_GAIN  = 0.2,
    parameter real GROUND_BIAS   = 0.0,

    // ADC timing parameters
    parameter time CONVERSION_DELAY = 150ps
)(
    input  logic                         clk_i,
    input  real                          voltage_i,

    output logic                         otr_o,
    output logic [ADC_DATA_WIDTH-1:0]    data_o
);

    localparam int unsigned ZERO_CODE = (1 << (ADC_DATA_WIDTH - 1));
    localparam real VOLTAGE_STEP = VOLTAGE_RANGE / real'(ZERO_CODE);

    //------------------------------------------------------------
    // Convert analog voltage to ADC code TODO: add OTR check
    //------------------------------------------------------------
    function automatic real code_to_voltage(
        input logic [ADC_DATA_WIDTH-1:0] code
    );
        return (int'(code) - int'(ZERO_CODE)) * VOLTAGE_STEP;
    endfunction

    //------------------------------------------------------------
    // Initial state
    //------------------------------------------------------------
    initial begin
        data_o = ZERO_CODE; // 0V
        otr_o  = 0;
    end

    //------------------------------------------------------------
    // Update analog output
    //------------------------------------------------------------
    always @(posedge clk_i) begin
        #(CONVERSION_DELAY);
        data_o = ;
        otr_o = ;
        
    end

endmodule