Subversion Repositories cic_core_2

`timescale 1ns / 1ns

module cic_d_tb

(

);

`include "../../../rtl/verilog/cic_functions.vh"

`define M_PI 3.14159265359      // not all simulators defines PI

/*

// U. Meyer-Baese, Digital Signal Processing with Field Programmable Gate Arrays, 2nd Edition, Spinger, 2004.

// Example 5.5: Three-Stages CIC Decimator II

localparam CIC_R = 32;

localparam SAMP_INP_DW = 8;

localparam SAMP_OUT_DW = 10;

localparam CIC_N = 3;

localparam CIC_M = 2;*/

localparam CIC_R = 100;

localparam SAMP_INP_DW = 18;

localparam SAMP_OUT_DW = 18;

localparam INP_SAMP_WIDTH_TO_SIGNAL_WIDTH = 2;

localparam CIC_N = 7;

localparam CIC_M = 1;

localparam SMALL_FOOTPRINT = 1; ///< set to 1 for less registers usage, but for every sample CIC_N clocks required

/*

//https://www.so-logic.net/documents/trainings/03_so_implementation_of_filters.pdf

localparam CIC_R = 16;

localparam SAMP_INP_DW = 16;

localparam SAMP_OUT_DW = 16;

localparam INP_SAMP_WIDTH_TO_SIGNAL_WIDTH = 1;

localparam CIC_N = 3;

localparam CIC_M = 1;

localparam SMALL_FOOTPRINT = 1;

*/

/*localparam CIC_R = 25;

localparam SAMP_INP_DW = 16;

localparam SAMP_OUT_DW = 16;

localparam CIC_N = 4;

localparam CIC_M = 1;*/

/*localparam R = 8;

localparam SAMP_INP_DW = 12;

localparam SAMP_OUT_DW = 12;

localparam M = 3;

localparam G = 1;*/

/*localparam CIC_R = 100;

localparam SAMP_INP_DW = 17;

localparam SAMP_OUT_DW = 14;

localparam CIC_N = 7;

localparam CIC_M = 1;*/

/*************************************************************/

localparam integer CIC_RM = CIC_R * CIC_M;

localparam real T_clk_ns = 8;//ns

localparam time half_T = T_clk_ns/2;

/// parameters of CIC filter with bits prune

localparam B_max = B_max_calc(CIC_N, CIC_R, CIC_M, SAMP_INP_DW);

localparam B_out = B_out_calc(CIC_N, CIC_R, CIC_M, SAMP_INP_DW, SAMP_OUT_DW);

localparam B_2Np1 = B_max - SAMP_OUT_DW + 1;

localparam delta_f_offs = 200;  /// clock number to start delta-function in simulation

/*************************************************************/

reg                                                                     clk;                                    ///< clock

reg                                                                     reset_n;                                ///< reset, active 0

wire    signed  [SAMP_INP_DW-1:0]       filter_inp_data;                ///< input test data of filter

reg             signed  [SAMP_INP_DW-1:0]       filter_inp_data_d[0:2]; ///< delayed filter_inp_data, for reference model

wire                                            filter_out_str;                 ///< filter output sample ready strobe

reg                                                                     filter_out_str_d;               ///< filter_out_str delayed

wire    signed  [SAMP_OUT_DW-1:0]       filter_out;                             ///< filter output data

reg             signed  [SAMP_OUT_DW-1:0]       filter_out_reg;                 ///<

wire    signed  [SAMP_OUT_DW-1:0]       filter_out_ref_wire;    ///< reference filter output data

reg     signed  [SAMP_OUT_DW-1:0]       filter_out_ref;                 ///<

reg             signed  [SAMP_OUT_DW-1:0]       filter_out_diff;                ///< subtracting tested filter output and reference filter output

integer clk_counter;    ///< counter of clock periods

integer samp_counter;   ///< counter of input samples

real phase_curr;                ///< phase of input signal

real phase_step;                ///< step of input signal phase increment

integer N_t_samp = 2;   ///< period of input samples frequency in clocks

integer samples_period_ctr;     ///< counter for generating input samples period

integer samples_period_val;     ///< period of input samples in clocks

wire    samples_period_rdy;     ///< signal is set at the end of input samples period

real    carry_freq;                     ///< frequency of test sin signal

longint cic_taps[CIC_R * CIC_M * CIC_N];        ///< storage of internal state of reference CIC filter model

integer cic_push_ptr;                                           ///< pointer to the FIFO buffer of reference CIC model

integer cic_model_out_int;                                      ///< output of reference CIC model

integer cic_B_prune;

integer cic_B_prune_last_stage;

longint cic_S_prune;

longint cic_S_prune_last_stage;

/// the reference model of a CIC filter

task cic_model_reset;   ///< set filter to the initial state

        integer i_s;

        integer i_t;

        for(i_s = CIC_N - 1; i_s >= 0; i_s = i_s - 1)

                for(i_t = 0; i_t < CIC_RM; i_t = i_t + 1)

                        cic_taps[i_t + i_s * CIC_RM] = 0;

        cic_push_ptr = 0;

endtask

task cic_model_push(longint inp_samp);  ///< add input sample

        integer i_s;

        for (i_s = CIC_N - 1; i_s >= 1; i_s = i_s - 1)

                cic_taps[cic_push_ptr + i_s * CIC_RM] = cic_model_stage_get_out(i_s - 1);

        cic_taps[cic_push_ptr] = inp_samp;

        if (cic_push_ptr < CIC_RM - 1)          cic_push_ptr = cic_push_ptr + 1;

        else                                                            cic_push_ptr = 0;

endtask

function longint cic_model_stage_get_out(integer stage);        ///< get output of stage

        integer i_t;

        cic_model_stage_get_out = 0;

        for(i_t = 0; i_t < CIC_RM; i_t = i_t + 1)

                cic_model_stage_get_out = cic_model_stage_get_out + cic_taps[i_t + stage * CIC_RM];

        cic_model_stage_get_out = cic_model_stage_get_out / cic_S_prune;

        if (stage == CIC_N - 1)

                cic_model_stage_get_out = cic_model_stage_get_out / cic_S_prune_last_stage;

endfunction

/*************************************************************/

initial begin : clk_gen

        clk = 1'b0;

        clk_counter = 0;

        carry_freq = 10000;

        samples_period_val = 6;

        samples_period_ctr = 0;

        phase_curr <= 0;

        phase_step = T_clk_ns * samples_period_val * 2 * carry_freq * `M_PI * 0.000000001;

        cic_model_reset();

        samp_counter <= 0;

        #half_T forever #half_T clk = ~clk;

end

/*************************************************************/

initial begin

        $dumpfile("../out/cic_d_tb.vcd");

        $dumpvars(4, cic_d_tb);

end

initial begin : reset_gen

        reg [127:0] h_f0_pre;

        integer log2_h_f0_pre;

        integer h_f0_pre_limit_prec;

        integer h_f0_pre_divider;

        integer h_f0_divider_exp;

        real    h_f0;

        integer B_max;

        integer B_out;

        integer B_2Np1;

        $display("tb CIC INP_DW      %d", SAMP_INP_DW);

        $display("tb CIC OUT_DW      %d", SAMP_OUT_DW);

        $display("tb CIC R        %d", CIC_R);

        $display("tb CIC N        %d", CIC_N);

        $display("tb CIC M        %d", CIC_M);

        B_max = B_max_calc(CIC_N, CIC_R, CIC_M, SAMP_INP_DW);

        B_out = B_out_calc(CIC_N, CIC_R, CIC_M, SAMP_INP_DW, SAMP_OUT_DW);

        B_2Np1 = B_max - B_out + 1;

        $display("B_max= %2d, B_out = %2d, B_2N+1 = %2d", B_max, B_out, B_2Np1);

        h_f0_pre = (CIC_R*CIC_M)**CIC_N;

        h_f0_divider_exp = (B_2Np1 + 1);

        h_f0_pre_limit_prec = 30;

        log2_h_f0_pre = clog2_l(h_f0_pre);

        if (log2_h_f0_pre > h_f0_pre_limit_prec) begin

                $display(" log2_h_f0_pre = %2d, lim %2d", log2_h_f0_pre, h_f0_pre_limit_prec);

                h_f0_pre_divider = log2_h_f0_pre - h_f0_pre_limit_prec;

                $display(" h_f0_pre_divider = %2d", h_f0_pre_divider);

                h_f0_pre = h_f0_pre >> h_f0_pre_divider;

                h_f0_divider_exp = h_f0_divider_exp - h_f0_pre_divider;

                $display(" log2_h_f0_pre limited = %2d, divider_exp limited %2d", log2_h_f0_pre, h_f0_divider_exp);

                h_f0 = 1.0 * h_f0_pre / 2**(h_f0_divider_exp);

        end

        else begin

                h_f0 = h_f0 / 2**(B_2Np1 + 1);

        end

        $display("tb CIC h fwd    %2.8f", h_f0);

        // to avoid overflow in reference model, use cic_B_prune to

        //cic_B_prune = B_2Np1 / CIC_N;

        cic_B_prune = 0;

        cic_S_prune = 1 << cic_B_prune;

        cic_B_prune_last_stage = B_2Np1 + 1 - cic_B_prune * CIC_N;

        cic_S_prune_last_stage = 1 << cic_B_prune_last_stage;

        $display("cic_B_prune = %2d, cic_B_prune_last = %2d, ", cic_B_prune, cic_B_prune_last_stage);

        $display($time, " << Starting the Simulation >>");

        reset_n = 1'b0;

        repeat (2) @(negedge clk);

        $display($time, " << Coming out of reset >>");

        reset_n = 1'b1;

        repeat (40000) @(posedge clk);

        @(posedge clk);

        $display($time, " << Simulation done >>");

        $finish;

end

always @(posedge clk) if (~clk) clk_counter <= clk_counter + 1;

/*************************************************************/

assign samples_period_rdy = samples_period_ctr >= (samples_period_val - 1);

always @(posedge clk)

        if (samples_period_rdy) samples_period_ctr <= 0;

        else                            samples_period_ctr <= samples_period_ctr + 1;

always @(posedge clk)

begin

        if (samples_period_rdy == 1'b1) begin

                for (int i1 = 2; i1 >= 1; i1 = i1 - 1) filter_inp_data_d[i1] <= filter_inp_data_d[i1 - 1];

                filter_inp_data_d[0] <= filter_inp_data;

                cic_model_push(filter_inp_data_d[1]);

                samp_counter <= samp_counter + 1;

                phase_curr <= phase_curr + phase_step;

        end

end

/*************************************************************/

assign filter_inp_data = $rtoi((2**(SAMP_INP_DW - INP_SAMP_WIDTH_TO_SIGNAL_WIDTH - 1) - 1)*($sin(phase_curr)));

//assign filter_inp_data = samp_counter == delta_f_offs ? 10000 : 0;    ///< delta function

//assign filter_inp_data = samp_counter >= delta_f_offs && samp_counter < delta_f_offs + CIC_N ? 10000 : 0;

//assign filter_inp_data = samp_counter >= delta_f_offs ? 10000 : 0;    ///< Hamming function

/*************************************************************/

cic_d #(

        .INP_DW                         (SAMP_INP_DW),

        .OUT_DW                         (SAMP_OUT_DW),

        .CIC_R                          (CIC_R),

        .CIC_N                          (CIC_N),

        .CIC_M                          (CIC_M),

        .SMALL_FOOTPRINT        (SMALL_FOOTPRINT)

)

dut1

(

    .clk                        (clk),

    .reset_n            (reset_n),

    .clear                      (1'b0),

    .inp_samp_data      (filter_inp_data),

    .inp_samp_str       (samples_period_rdy),

    .out_samp_data      (filter_out),

    .out_samp_str       (filter_out_str)

);

always @(posedge clk)

        filter_out_str_d <= filter_out_str;

always @(posedge clk)

begin

        if (filter_out_str == 1'b1) begin

                filter_out_reg  <= filter_out;

                filter_out_ref  <= cic_model_stage_get_out(CIC_N - 1);

        end

end

always @(posedge clk)

begin

        if (filter_out_str_d == 1'b1) begin

                filter_out_diff <= filter_out - filter_out_ref;

        end

end

/*************************************************************/

endmodule