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Rev 6 → Rev 7

/cic_core_2/trunk/rtl/verilog/cic_d.sv
1,232 → 1,233
module cic_d
/*********************************************************************************************/
#(
parameter INP_DW = 18, ///< input data width
parameter OUT_DW = 18, ///< output data width
parameter CIC_R = 100, ///< decimation ratio
parameter CIC_N = 7, ///< number of stages
parameter CIC_M = 1, ///< delay in comb
parameter SMALL_FOOTPRINT = 1 ///< reduced registers usage, f_clk / (f_samp/CIC_R) > CIC_N required
)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [INP_DW-1:0] inp_samp_data,
input inp_samp_str,
output wire signed [OUT_DW-1:0] out_samp_data,
output out_samp_str
);
/*********************************************************************************************/
`include "cic_functions.vh"
/*********************************************************************************************/
localparam B_max = clog2_l((CIC_R * CIC_M) ** CIC_N) + INP_DW - 1;
/*********************************************************************************************/
 
genvar i;
generate
for (i = 0; i < CIC_N; i = i + 1) begin : int_stage
localparam B_j = B(i + 1, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW);
localparam B_jm1 = B(i , CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW);
localparam logic [127:0 ] F_sq_j = F_sq(i , CIC_R, CIC_M, CIC_N);
localparam dw_cur = B_max - B_j + 1;
localparam odw_cur = dw_cur;
localparam B_dw_prev = (i != 0) ? B_max - B_jm1 + 1 : 0;
localparam odw_prev = (B_dw_prev > 1) ? B_dw_prev : 2; /// icarus stops with error if in [a -: b] a is <= 0
localparam idw_cur = dw_cur > 0 ? dw_cur : 1;
wire signed [idw_cur - 1 : 0] int_in;
if ( i == 0 ) assign int_in = inp_samp_data;
else assign int_in = int_stage[i - 1].int_out[odw_prev - 1 -: idw_cur];
wire signed [odw_cur - 1 : 0] int_out;
integrator #(
idw_cur,
odw_cur
)
int_inst(
.clk (clk),
.reset_n (reset_n),
.clear (clear) ,
.inp_samp_data (int_in),
.inp_samp_str (inp_samp_str),
.out_samp_data (int_out)
);
initial begin
//$display("i:%d integ dw %d B(%d, %d, %d, %d, %d, %d)=%d, F_sq=%d", i, odw_cur, i + 1, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW, B_j, F_sq_j);
$display("i:%d integ dw %d ", i, odw_cur);
end
end
endgenerate
/*********************************************************************************************/
localparam B_m = B(CIC_N, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW);
localparam ds_dw = B_max - B_m + 1;
wire signed [ds_dw - 1 : 0] ds_out_samp_data;
wire ds_out_samp_str;
/*********************************************************************************************/
initial begin
//$display("i downsamp dw %d , int_stage[%2d].dw_out = %2d", ds_dw, CIC_N - 1, int_stage[CIC_N - 1].odw_cur);
$display("i downsamp dw %d", ds_dw);
end
downsampler #(
.DATA_WIDTH_INP (ds_dw),
.CIC_R (CIC_R)
)
downsampler_inst
(
.clk (clk),
.reset_n (reset_n),
.clear (clear),
.inp_samp_data (int_stage[CIC_N - 1].int_out),
.inp_samp_str (inp_samp_str),
.out_samp_data (ds_out_samp_data),
.out_samp_str (ds_out_samp_str)
);
/*********************************************************************************************/
genvar j;
wire comb_chain_out_str;
reg [CIC_N : 0] comb_inp_str_d;
generate
wire summ_rdy_str;
if (SMALL_FOOTPRINT != 0) begin
always @(negedge reset_n or posedge clk)
if (~reset_n) comb_inp_str_d <= '0;
else if (clear) comb_inp_str_d <= '0;
else comb_inp_str_d <= {comb_inp_str_d[CIC_N - 1 : 0], ds_out_samp_str};
end
if (SMALL_FOOTPRINT == 0) assign summ_rdy_str = '0;
else assign summ_rdy_str = comb_inp_str_d[CIC_N];
 
for (j = 0; j < CIC_N; j = j + 1) begin : comb_stage
localparam j_cic = CIC_N + j + 1;
localparam B_m_j = B( j_cic, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW);
localparam F_sq_j = F_sq( j_cic, CIC_R, CIC_M, CIC_N);
localparam B_m_j_m1 = B( CIC_N + j, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW);
localparam F_sq_2Np1 = F_sq(2 * CIC_N + 1, CIC_R, CIC_M, CIC_N);
localparam idw_cur = B_max - B_m_j + 1;
localparam odw_cur = idw_cur;
localparam odw_prev = (j != 0) ? B_max - B_m_j_m1 + 1 : 0;
wire signed [idw_cur - 1 : 0] comb_in;
wire signed [odw_cur - 1 : 0] comb_out;
wire comb_dv;
if (j == 0) assign comb_in = ds_out_samp_data[ds_dw - 1 -: idw_cur];
else assign comb_in = comb_stage[j - 1].comb_out[odw_prev - 1 -: idw_cur];
comb #(
.SAMP_WIDTH (idw_cur),
.CIC_M (CIC_M),
.SMALL_FOOTPRINT(SMALL_FOOTPRINT)
)
comb_inst(
.clk (clk),
.reset_n (reset_n),
.clear (clear),
.samp_inp_str (ds_out_samp_str),
.samp_inp_data (comb_in),
.summ_rdy_str (summ_rdy_str),
.samp_out_str (comb_dv),
.samp_out_data (comb_out)
);
if (SMALL_FOOTPRINT == 0) assign comb_chain_out_str = comb_stage[CIC_N - 1].comb_dv;
else assign comb_chain_out_str = comb_inp_str_d[CIC_N - 1];
initial begin
//$display("i:%d comb dw %d inp comb_out[%2d -: %2d]; B(%2d, %1d, %1d, %1d, %1d, %1d)=%2d, ln(F_sq)=%4d, F_sq=%8d", j, odw_cur, odw_prev - 1, idw_cur, CIC_N + j + 1, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW, B_m_j, $ln(F_sq_j), F_sq_j);
$display("i:%d comb dw %d", j, odw_cur);
end
end
endgenerate
/*********************************************************************************************/
localparam dw_out = B_max - B(2 * CIC_N, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW) + 1;
reg signed [OUT_DW-1:0] comb_out_samp_data_reg;
reg comb_out_samp_str_reg;
 
always @(negedge reset_n or posedge clk)
begin
if (~reset_n) comb_out_samp_data_reg <= '0;
else if (comb_chain_out_str) comb_out_samp_data_reg <= comb_stage[CIC_N - 1].comb_out[dw_out - 1 -: OUT_DW];
end
 
always @(negedge reset_n or posedge clk)
if (~reset_n) comb_out_samp_str_reg <= '0;
else if (clear) comb_out_samp_str_reg <= '0;
else comb_out_samp_str_reg <= comb_chain_out_str;
 
assign out_samp_data = comb_out_samp_data_reg;
assign out_samp_str = comb_out_samp_str_reg;
/*********************************************************************************************/
task print_parameters_nice;
integer tot_registers;
integer j;
integer B_2Np1;
integer dw_j;
integer B_j;
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;
integer h_f0_x_mul;
integer x_multiplier;
reg [127:0] F_sq_curr;
x_multiplier = 100000;
B_2Np1 = B_max - dw_out + 1;
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_x_mul = x_multiplier * h_f0_pre / 2**(h_f0_divider_exp);
end
else begin
h_f0_x_mul = x_multiplier * h_f0_pre / 2**(B_2Np1 + 1);
end
$display("CIC inp_dw %d", INP_DW);
$display("CIC out_dw %d", OUT_DW);
$display("CIC B_max %d", B_max);
$display("CIC B_2Np1 %d", B_2Np1);
$display("CIC h(f=0) %1d.%1d", h_f0_x_mul / x_multiplier, h_f0_x_mul % x_multiplier);
$display(" clog2_l((r*m)**n) %d", clog2_l((CIC_R*CIC_M)**CIC_N));
tot_registers = 0;
for (j = 1; j < 2 * CIC_N + 2; j = j + 1) begin : check_Bj
F_sq_curr = F_sq(j, CIC_R, CIC_M, CIC_N);
B_j = B(j, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW);
dw_j = B_max - B_j + 1;
tot_registers = tot_registers + dw_j;
end
$display("CIC total registers %2d", tot_registers);
endtask
 
 
generate
initial begin : initial_print_parameters
if (0) begin
print_parameters_nice;
end
end
if (0) begin
for (j = 0; j < CIC_N; j = j + 1) begin : print_int_stage
initial begin
$display("CIC integrator j:%2d B %2d B_ jm1 %2d odw_prev %2d in_dw %3d out_dw %3d data_width_pass %3d", j + 1, int_stage[j].B_j, int_stage[j].B_jm1, int_stage[j].odw_prev, int_stage[j].idw_cur, int_stage[j].odw_cur, 0);
end
end
initial begin
$display("CIC downsampler B %2d ds_dw %3d", B_m, ds_dw);
end
for (j = 0; j < CIC_N; j = j + 1) begin : print_comb_stage
initial begin
$display("CIC comb j:%2d B %2d B_mjm1 %2d in_dw %3d out_dw %3d", j, comb_stage[j].B_m_j, comb_stage[j].B_m_j_m1, comb_stage[j].idw_cur, comb_stage[j].odw_cur);
end
end
initial begin
$display("CIC out odw %3d", OUT_DW);
end
end
endgenerate
endmodule
module cic_d
/*********************************************************************************************/
#(
parameter INP_DW = 18, ///< input data width
parameter OUT_DW = 18, ///< output data width
parameter CIC_R = 100, ///< decimation ratio
parameter CIC_N = 7, ///< number of stages
parameter CIC_M = 1, ///< delay in comb
parameter SMALL_FOOTPRINT = 1 ///< reduced registers usage, f_clk / (f_samp/CIC_R) > CIC_N required
)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [INP_DW-1:0] inp_samp_data,
input inp_samp_str,
output wire signed [OUT_DW-1:0] out_samp_data,
output out_samp_str
);
/*********************************************************************************************/
`include "cic_functions.vh"
/*********************************************************************************************/
localparam B_max = clog2_l((CIC_R * CIC_M) ** CIC_N) + INP_DW - 1;
/*********************************************************************************************/
 
genvar i;
generate
for (i = 0; i < CIC_N; i = i + 1) begin : int_stage
localparam B_jm1 = B_calc(i , CIC_N, CIC_R, CIC_M, INP_DW, OUT_DW);
localparam B_j = B_calc(i + 1, CIC_N, CIC_R, CIC_M, INP_DW, OUT_DW);
localparam F_sq_j = 0;
localparam idw_cur = B_max - B_jm1 + 1;
localparam odw_cur = B_max - B_j + 1;
localparam B_dw_prev = (i != 0) ? B_max - B_jm1 + 1 : 0;
wire signed [idw_cur - 1 : 0] int_in;
if ( i == 0 ) assign int_in = inp_samp_data;
else assign int_in = int_stage[i - 1].int_out;
wire signed [idw_cur - 1 : 0] int_inst_out;
wire signed [odw_cur - 1 : 0] int_out;
assign int_out = int_inst_out[idw_cur - 1 -: odw_cur];
integrator #(
idw_cur,
idw_cur
)
int_inst(
.clk (clk),
.reset_n (reset_n),
.clear (clear) ,
.inp_samp_data (int_in),
.inp_samp_str (inp_samp_str),
.out_samp_data (int_inst_out)
);
initial begin
//$display("i:%d integ idw=%2d odw=%2d B(%2d, %3d, %2d, %2d, %2d, %2d)=%2d, Bj-1=%2d, F_sq=%8d", i, idw_cur, odw_cur, i + 1, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW, B_j, B_jm1, F_sq_j);
$display("i:%d integ idw=%d ", i, idw_cur);
end
end
endgenerate
/*********************************************************************************************/
localparam B_m = B_calc(CIC_N, CIC_N, CIC_R, CIC_M, INP_DW, OUT_DW);
localparam ds_dw = B_max - B_m + 1;
wire signed [ds_dw - 1 : 0] ds_out_samp_data;
wire ds_out_samp_str;
/*********************************************************************************************/
initial begin
//$display("i downsamp dw %d , int_stage[%2d].dw_out = %2d", ds_dw, CIC_N - 1, int_stage[CIC_N - 1].odw_cur);
$display("i downsamp dw %d", ds_dw);
end
downsampler #(
.DATA_WIDTH_INP (ds_dw),
.CIC_R (CIC_R)
)
downsampler_inst
(
.clk (clk),
.reset_n (reset_n),
.clear (clear),
.inp_samp_data (int_stage[CIC_N - 1].int_out),
.inp_samp_str (inp_samp_str),
.out_samp_data (ds_out_samp_data),
.out_samp_str (ds_out_samp_str)
);
/*********************************************************************************************/
genvar j;
wire comb_chain_out_str;
reg [CIC_N : 0] comb_inp_str_d;
generate
wire summ_rdy_str;
if (SMALL_FOOTPRINT != 0) begin
always @(negedge reset_n or posedge clk)
if (~reset_n) comb_inp_str_d <= '0;
else if (clear) comb_inp_str_d <= '0;
else comb_inp_str_d <= {comb_inp_str_d[CIC_N - 1 : 0], ds_out_samp_str};
end
if (SMALL_FOOTPRINT == 0) assign summ_rdy_str = '0;
else assign summ_rdy_str = comb_inp_str_d[CIC_N];
 
for (j = 0; j < CIC_N; j = j + 1) begin : comb_stage
localparam B_m_j_m1 = B_calc(CIC_N + j , CIC_N, CIC_R, CIC_M, INP_DW, OUT_DW);
localparam B_m_j = B_calc(CIC_N + j + 1, CIC_N, CIC_R, CIC_M, INP_DW, OUT_DW);
localparam F_sq_j = 1;
localparam idw_cur = B_max - B_m_j_m1 + 1;
localparam odw_cur = B_max - B_m_j + 1;
wire signed [idw_cur - 1 : 0] comb_in;
wire signed [idw_cur - 1 : 0] comb_inst_out;
wire signed [odw_cur - 1 : 0] comb_out;
wire comb_dv;
if (j == 0) assign comb_in = ds_out_samp_data;
else assign comb_in = comb_stage[j - 1].comb_out;
assign comb_out = comb_inst_out[idw_cur - 1 -: odw_cur];
comb #(
.SAMP_WIDTH (idw_cur),
.CIC_M (CIC_M),
.SMALL_FOOTPRINT(SMALL_FOOTPRINT)
)
comb_inst(
.clk (clk),
.reset_n (reset_n),
.clear (clear),
.samp_inp_str (ds_out_samp_str),
.samp_inp_data (comb_in),
.summ_rdy_str (summ_rdy_str),
.samp_out_str (comb_dv),
.samp_out_data (comb_inst_out)
);
if (SMALL_FOOTPRINT == 0) assign comb_chain_out_str = comb_stage[CIC_N - 1].comb_dv;
else assign comb_chain_out_str = comb_inp_str_d[CIC_N - 1];
initial begin
//$display("i:%d comb idw=%2d odw=%2d B(%2d, %3d, %2d, %2d, %2d, %2d)=%2d, ln(F_sq)=%4d, F_sq=%8d", j, idw_cur, odw_cur, CIC_N + j + 1, CIC_R, CIC_M, CIC_N, INP_DW, OUT_DW, B_m_j, $ln(F_sq_j), F_sq_j);
//if (j != 0) $display("odw_prev=%2d, comb_stage[j - 1].odw_cur=%2d", odw_prev, comb_stage[j - 1].odw_cur);
$display("i:%d comb idw=%d", j, idw_cur);
end
end
endgenerate
/*********************************************************************************************/
localparam dw_out = B_max - B_calc(2 * CIC_N, CIC_N, CIC_R, CIC_M, INP_DW, OUT_DW) + 1;
reg signed [OUT_DW-1:0] comb_out_samp_data_reg;
reg comb_out_samp_str_reg;
 
always @(negedge reset_n or posedge clk)
begin
if (~reset_n) comb_out_samp_data_reg <= '0;
else if (comb_chain_out_str) comb_out_samp_data_reg <= comb_stage[CIC_N - 1].comb_out[dw_out - 1 -: OUT_DW];
end
 
always @(negedge reset_n or posedge clk)
if (~reset_n) comb_out_samp_str_reg <= '0;
else if (clear) comb_out_samp_str_reg <= '0;
else comb_out_samp_str_reg <= comb_chain_out_str;
 
assign out_samp_data = comb_out_samp_data_reg;
assign out_samp_str = comb_out_samp_str_reg;
/*********************************************************************************************/
task print_parameters_nice;
integer tot_registers;
integer j;
integer B_2Np1;
integer dw_j;
integer B_j;
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;
integer h_f0_x_mul;
integer x_multiplier;
reg [127:0] F_sq_curr;
x_multiplier = 100000;
B_2Np1 = B_max - dw_out + 1;
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_x_mul = x_multiplier * h_f0_pre / 2**(h_f0_divider_exp);
end
else begin
h_f0_x_mul = x_multiplier * h_f0_pre / 2**(B_2Np1 + 1);
end
$display("CIC inp_dw %d", INP_DW);
$display("CIC out_dw %d", OUT_DW);
$display("CIC B_max %d", B_max);
$display("CIC B_out %d", dw_out);
$display("CIC B_2Np1 %d", B_2Np1);
$display("CIC h(f=0) %1d.%1d", h_f0_x_mul / x_multiplier, h_f0_x_mul % x_multiplier);
$display(" clog2_l((r*m)**n) %d", clog2_l((CIC_R*CIC_M)**CIC_N));
tot_registers = 0;
for (j = 1; j < 2 * CIC_N + 2; j = j + 1) begin : check_Bj
F_sq_curr = F_sq_calc(j, CIC_N, CIC_R, CIC_M);
B_j = B_calc(j, CIC_N, CIC_R, CIC_M, INP_DW, OUT_DW);
dw_j = B_max - B_j + 1;
tot_registers = tot_registers + dw_j;
end
$display("CIC total registers %2d", tot_registers);
endtask
 
 
generate
initial begin : initial_print_parameters
if (1) begin
print_parameters_nice;
end
end
if (0) begin
for (j = 0; j < CIC_N; j = j + 1) begin : print_int_stage
initial begin
$display("CIC integrator j:%2d B %2d B_ jm1 %2d odw_prev %2d in_dw %3d out_dw %3d data_width_pass %3d", j + 1, int_stage[j].B_j, int_stage[j].B_jm1, int_stage[j].odw_prev, int_stage[j].idw_cur, int_stage[j].odw_cur, 0);
end
end
initial begin
$display("CIC downsampler B %2d ds_dw %3d", B_m, ds_dw);
end
for (j = 0; j < CIC_N; j = j + 1) begin : print_comb_stage
initial begin
$display("CIC comb j:%2d B %2d B_mjm1 %2d in_dw %3d out_dw %3d", j, comb_stage[j].B_m_j, comb_stage[j].B_m_j_m1, comb_stage[j].idw_cur, comb_stage[j].odw_cur);
end
end
initial begin
$display("CIC out odw %3d", OUT_DW);
end
end
endgenerate
endmodule
/cic_core_2/trunk/rtl/verilog/cic_functions.vh
1,157 → 1,163
/**
* Library: cic_functions
*
* library with functions for calculating parameters for CIC filter and Hogenauer pruning
*/
`ifndef _CIC_FUNCTIONS_VH_
`define _CIC_FUNCTIONS_VH_
`define M_PI 3.14159265359 // not all simulator defines PI
/*********************************************************************************************/
function reg unsigned [127 : 0] nchoosek; ///< Binomial coefficient
input integer n;
input integer k;
reg unsigned [127:0] tmp;
integer i;
begin
tmp = 1.0;
for (i = 1; i <= (n - k); i = i + 1)
tmp = tmp * (k + i) / i;
nchoosek = tmp;
end
endfunction
/*********************************************************************************************/
function integer clog2_l;
input reg unsigned [127:0] depth;
reg unsigned [127:0] i;
begin
clog2_l = 0;
if (depth > 0) begin
i = depth - 1; // with "- 1" clog2(2^N) will be N, not N + 1
for(clog2_l = 0; i > 0; clog2_l = clog2_l + 1)
i = i >> 1;
end else
clog2_l = -1;
end
endfunction
/*********************************************************************************************/
function integer B_max_calc;
input integer N;
input integer R;
input integer M;
input integer INP_DW;
reg unsigned [127:0] RMpN;
begin
RMpN = (R * M) ** N;
B_max_calc = clog2_l(RMpN) + INP_DW - 1;
end
endfunction
/*********************************************************************************************/
function integer B_out_calc;
input integer N;
input integer R;
input integer M;
input integer INP_DW;
input integer OUT_DW;
begin
B_out_calc = B_max_calc(N, R, M, OUT_DW) - B(2 * N, R, M, N, INP_DW, OUT_DW) + 1;
end
endfunction
/*********************************************************************************************/
function integer flog2_l;
input reg unsigned [127:0] depth;
reg unsigned [127:0] i;
begin
i = depth;
for(flog2_l = 0; i > 1; flog2_l = flog2_l + 1)
i = i >> 1;
end
endfunction
/*********************************************************************************************/
function reg signed [127:0] h;
input integer j;
input integer k;
input integer R;
input integer M;
input integer N;
integer c_stop;
integer i;
reg signed [127:0] tmp;
reg signed [127:0] prod_1;
reg signed [127:0] prod_2;
reg signed [127:0] summ;
begin
c_stop = k / (R * M);
if ((j >= 1)&&( j<=N )) begin
tmp = 0;
for (i = 0; i <= c_stop; i = i + 1) begin
prod_1 = nchoosek(N, i);
prod_2 = nchoosek(N - j + k - R * M * i, k - R * M * i);
summ = prod_1 * prod_2;
if (i % 2) summ = -summ;
tmp = tmp + summ;
end
end
else begin
tmp = nchoosek(2 * N + 1 - j, k);
if (k % 2) tmp = -tmp;
end
h = tmp;
end
endfunction
/*********************************************************************************************/
function reg signed [127:0] F_sq; ///< F()**2
input integer j;
input integer R;
input integer M;
input integer N;
integer c_stop;
reg signed [127:0] tmp;
integer i;
reg signed [127:0] h_jk;
begin
tmp = 0;
if (j <= N)
c_stop = (((R * M -1 ) * N) + j - 1);
else
c_stop = 2 * N + 1 - j;
for (i = 0;i <= c_stop; i = i + 1) begin
h_jk = h(j, i, R, M, N);
tmp = tmp + h_jk ** 2;
end
F_sq = tmp;
end
endfunction
/*********************************************************************************************/
function integer B;
input integer j;
input integer R;
input integer M;
input integer N;
input integer dw_in;
input integer dw_out;
integer B_max;
reg signed [127:0] sigma_T_2Np1_sq;
reg signed [127:0] B_2Np1;
reg signed [127:0] B_exp_real;
integer B_out;
reg signed [127:0] F_sq_j;
reg signed [127:0] F_sq_2Np1;
begin
B_max = B_max_calc(N, R, M, dw_in);
if (j == 2 * N + 1) begin
B = B_max - dw_out + 1;
end else begin
B_2Np1 = B_max - dw_out + 1;
F_sq_j = F_sq(j, R, M, N);
F_sq_2Np1 = F_sq(2 * N + 1, R, M, N);
sigma_T_2Np1_sq = (128'b1 << (2 * B_2Np1)) * F_sq_2Np1 / 12;
B_exp_real = (sigma_T_2Np1_sq / F_sq_j * 6 / N);
B_out = flog2_l(B_exp_real) / 2;
B = B_out;
end
end
endfunction
/*********************************************************************************************/
 
`endif
 
/**
* Library: cic_functions
*
* library with functions for calculating parameters for CIC filter and Hogenauer pruning
*/
`ifndef _CIC_FUNCTIONS_VH_
`define _CIC_FUNCTIONS_VH_
`define M_PI 3.14159265359 // not all simulator defines PI
 
function reg unsigned [127 : 0] nchoosek; ///< Binomial coefficient
input integer n;
input integer k;
reg unsigned [127:0] tmp;
integer i;
begin
tmp = 1.0;
for (i = 1; i <= (n - k); i = i + 1)
tmp = tmp * (k + i) / i;
nchoosek = tmp;
end
endfunction
 
function integer clog2_l;
input reg unsigned [127:0] depth;
reg unsigned [127:0] i;
begin
clog2_l = 0;
if (depth > 0) begin
i = depth - 1; // with "- 1" clog2(2^N) will be N, not N + 1
for(clog2_l = 0; i > 0; clog2_l = clog2_l + 1)
i = i >> 1;
end else
clog2_l = -1;
end
endfunction
 
function integer B_max_calc;
input integer N;
input integer R;
input integer M;
input integer INP_DW;
reg unsigned [127:0] RMpN;
begin
RMpN = (R * M) ** N;
B_max_calc = clog2_l(RMpN) + INP_DW - 1;
//$display("B_max_calc: N=%2d, R=%2d, M=%2d, ret=%2d", N, R, M, B_max_calc);
end
endfunction
 
function integer B_out_calc;
input integer N;
input integer R;
input integer M;
input integer INP_DW;
input integer OUT_DW;
begin
B_out_calc = B_max_calc(N, R, M, OUT_DW) - B_calc(2 * N, N, R, M, INP_DW, OUT_DW) + 1;
end
endfunction
 
 
function integer flog2_l;
input reg unsigned [127:0] depth;
reg unsigned [127:0] i;
begin
i = depth;
for(flog2_l = 0; i > 1; flog2_l = flog2_l + 1)
i = i >> 1;
end
endfunction
 
 
function reg signed [127:0] h_calc;
input integer j;
input integer k;
input integer N;
input integer R;
input integer M;
integer c_stop;
integer i;
reg signed [127:0] tmp;
reg signed [127:0] prod_1;
reg signed [127:0] prod_2;
reg signed [127:0] summ;
begin
c_stop = k / (R * M);
if ((j >= 1)&&( j<=N )) begin
tmp = 0;
for (i = 0; i <= c_stop; i = i + 1) begin
prod_1 = nchoosek(N, i);
prod_2 = nchoosek(N - j + k - R * M * i, k - R * M * i);
summ = prod_1 * prod_2;
if (i % 2) summ = -summ;
tmp = tmp + summ;
end
end
else begin
tmp = nchoosek(2 * N + 1 - j, k);
if (k % 2) tmp = -tmp;
end
h_calc = tmp;
end
endfunction
 
function reg signed [127:0] F_sq_calc; ///< F()**2
input integer j;
input integer N;
input integer R;
input integer M;
integer c_stop;
reg signed [127:0] tmp;
integer i;
reg signed [127:0] h_jk;
begin
tmp = 0;
if (j <= N)
c_stop = (((R * M -1 ) * N) + j - 1);
else
c_stop = 2 * N + 1 - j;
for (i = 0;i <= c_stop; i = i + 1) begin
h_jk = h_calc(j, i, N, R, M);
tmp = tmp + h_jk ** 2;
end
F_sq_calc = tmp;
end
endfunction
 
function integer B_calc;
input integer j;
input integer N;
input integer R;
input integer M;
input integer dw_in;
input integer dw_out;
integer B_max;
reg signed [127:0] sigma_T_2Np1_sq;
reg signed [127:0] B_2Np1;
reg signed [127:0] B_exp_real;
integer B_out;
reg signed [127:0] F_sq_j;
reg signed [127:0] F_sq_2Np1;
begin
if (j <= 0) begin
B_calc = 0;
end else begin
B_max = B_max_calc(N, R, M, dw_in);
if (j == 2 * N + 1) begin
B_calc = B_max - dw_out + 1;
end else begin
B_2Np1 = B_max - dw_out + 1;
F_sq_j = F_sq_calc(j, N, R, M);
F_sq_2Np1 = F_sq_calc(2 * N + 1, N, R, M);
sigma_T_2Np1_sq = (128'b1 << (2 * B_2Np1)) * F_sq_2Np1 / 12;
B_exp_real = (sigma_T_2Np1_sq / F_sq_j * 6 / N);
B_out = flog2_l(B_exp_real) / 2;
B_calc = B_out;
end
end
end
endfunction
 
`endif
 
/cic_core_2/trunk/rtl/verilog/cic_i.sv
1,53 → 1,53
module cic_i
/*********************************************************************************************/
#(parameter dw = 8, r = 4, m = 4, g = 1)
/*********************************************************************************************/
//m - CIC order (comb chain length, integrator chain length)
//r - interpolation ratio
//dw - input data width
//g - differential delay in combs
/*********************************************************************************************/
(
input clk,
input reset_n,
input in_dv,
input signed [dw-1:0] data_in,
output signed [dw+$clog2((r**(m))/r)-1:0] data_out
);
/*********************************************************************************************/
wire signed [dw+m-2:0] upsample;
/*********************************************************************************************/
genvar i;
generate
for (i = 0; i < m; i++) begin:comb_stage
wire signed [dw+i-1:0] comb_in;
localparam odw = (i == m - 1) ? dw+i : dw+i+1;
if (i!=0)
assign comb_in = comb_stage[i-1].comb_out;
else
assign comb_in = data_in;
wire signed [odw-1:0] comb_out;
comb #(dw+i, odw, g) comb_inst(.clk(clk) , .reset_n(reset_n) , .in_dv(in_dv) , .data_in(comb_in) , .data_out(comb_out));
end
endgenerate
/*********************************************************************************************/
assign upsample = (in_dv) ? comb_stage[m-1].comb_out : 0;
/*********************************************************************************************/
genvar j;
generate
for (j = 0; j < m; j++) begin:int_stage
localparam idw = (j == 0) ? dw+m-1 : dw+$clog2(((2**(m-j))*(r**(j)))/r);
localparam odw = dw+$clog2(((2**(m-j-1))*(r**(j+1)))/r);
wire signed [idw-1:0] int_in;
if (j==0)
assign int_in = upsample;
else
assign int_in = int_stage[j-1].int_out;
wire signed [odw-1:0] int_out;
integrator #(idw, odw) int_inst(.clk(clk) , .reset_n(reset_n) , .data_in(int_in) , .data_out(int_out));
end
endgenerate
/*********************************************************************************************/
assign data_out = int_stage[m-1].int_out;
/*********************************************************************************************/
endmodule
module cic_i
/*********************************************************************************************/
#(parameter dw = 8, r = 4, m = 4, g = 1)
/*********************************************************************************************/
//m - CIC order (comb chain length, integrator chain length)
//r - interpolation ratio
//dw - input data width
//g - differential delay in combs
/*********************************************************************************************/
(
input clk,
input reset_n,
input in_dv,
input signed [dw-1:0] data_in,
output signed [dw+$clog2((r**(m))/r)-1:0] data_out
);
/*********************************************************************************************/
wire signed [dw+m-2:0] upsample;
/*********************************************************************************************/
genvar i;
generate
for (i = 0; i < m; i++) begin:comb_stage
wire signed [dw+i-1:0] comb_in;
localparam odw = (i == m - 1) ? dw+i : dw+i+1;
if (i!=0)
assign comb_in = comb_stage[i-1].comb_out;
else
assign comb_in = data_in;
wire signed [odw-1:0] comb_out;
comb #(dw+i, odw, g) comb_inst(.clk(clk) , .reset_n(reset_n) , .in_dv(in_dv) , .data_in(comb_in) , .data_out(comb_out));
end
endgenerate
/*********************************************************************************************/
assign upsample = (in_dv) ? comb_stage[m-1].comb_out : 0;
/*********************************************************************************************/
genvar j;
generate
for (j = 0; j < m; j++) begin:int_stage
localparam idw = (j == 0) ? dw+m-1 : dw+$clog2(((2**(m-j))*(r**(j)))/r);
localparam odw = dw+$clog2(((2**(m-j-1))*(r**(j+1)))/r);
wire signed [idw-1:0] int_in;
if (j==0)
assign int_in = upsample;
else
assign int_in = int_stage[j-1].int_out;
wire signed [odw-1:0] int_out;
integrator #(idw, odw) int_inst(.clk(clk) , .reset_n(reset_n) , .data_in(int_in) , .data_out(int_out));
end
endgenerate
/*********************************************************************************************/
assign data_out = int_stage[m-1].int_out;
/*********************************************************************************************/
endmodule
/cic_core_2/trunk/rtl/verilog/comb.sv
1,83 → 1,83
`timescale 1ns / 1ns
/**
* Module: comb
*
* Comb stage for CIC filter
* There is two variants of realisation.
* Ordinary (SMALL_FOOTPRINT = 0).
* For every stage in the output extra register added for isolation combinatorial logic outside own adder.
* Small footprint (SMALL_FOOTPRINT = 1)
* No additional register, adders are in the chain of CIC_N cells.
* Output sample generated after CIC_N clocks, f_clk / f_comb_samp > CIC_N required.
*
*/
module comb
/*********************************************************************************************/
#(
parameter SAMP_WIDTH = 8,
parameter CIC_M = 1,
//parameter CIC_N = 1,
parameter SMALL_FOOTPRINT = 0 ///< set to 1 for less registers usage, but for every sample CIC_N clocks required
)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [SAMP_WIDTH - 1:0] samp_inp_data,
input samp_inp_str,
input summ_rdy_str, ///< for SMALL_FOOTPRINT set 1 after CIC_N cycles from inp_str to load FIFO registers with new sample
///< output data must be latched before summ_rdy_str is set, read output data at CIC_N - 1 clock after inp_str
output wire signed [SAMP_WIDTH - 1:0] samp_out_data,
output wire samp_out_str
);
/*********************************************************************************************/
integer i;
reg signed [SAMP_WIDTH - 1 : 0] data_reg[CIC_M - 1 : 0]; ///< the storage for the FIFO register
wire data_reg_push_str; ///< strobe to push data into data_reg FIFO
/*********************************************************************************************/
 
 
generate
if (SMALL_FOOTPRINT == 0) begin
reg samp_out_str_reg;
reg signed [SAMP_WIDTH - 1 : 0] data_out_reg;
assign data_reg_push_str = samp_inp_str;
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) data_out_reg <= '0;
else if (clear) data_out_reg <= '0;
else if (samp_inp_str) data_out_reg <= samp_inp_data - data_reg[CIC_M - 1];
end
assign samp_out_data = data_out_reg;
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) samp_out_str_reg <= '0;
else if (clear) samp_out_str_reg <= '0;
else samp_out_str_reg <= samp_inp_str;
end
assign samp_out_str = samp_out_str_reg;
end else begin
assign data_reg_push_str = summ_rdy_str;
assign #4 samp_out_data = samp_inp_data - data_reg[CIC_M - 1]; // delay for 18x18 multiplier of Cyclone V SE is 3.4 ns
assign samp_out_str = summ_rdy_str;
end
endgenerate
 
 
/*********************************************************************************************/
// FIFO register with reset and clear
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) for (i = 0; i < CIC_M; i = i + 1) data_reg[i] <= '0;
else if (clear) for (i = 0; i < CIC_M; i = i + 1) data_reg[i] <= '0;
else if (data_reg_push_str) begin
data_reg[0] <= samp_inp_data;
for (i = 1; i < CIC_M; i = i + 1) data_reg[i] <= data_reg[i - 1];
end
end
 
/*********************************************************************************************/
endmodule
`timescale 1ns / 1ns
/**
* Module: comb
*
* Comb stage for CIC filter
* There is two variants of realisation.
* Ordinary (SMALL_FOOTPRINT = 0).
* For every stage in the output extra register added for isolation combinatorial logic outside own adder.
* Small footprint (SMALL_FOOTPRINT = 1)
* No additional register, adders are in the chain of CIC_N cells.
* Output sample generated after CIC_N clocks, f_clk / f_comb_samp > CIC_N required.
*
*/
module comb
/*********************************************************************************************/
#(
parameter SAMP_WIDTH = 8,
parameter CIC_M = 1,
//parameter CIC_N = 1,
parameter SMALL_FOOTPRINT = 0 ///< set to 1 for less registers usage, but for every sample CIC_N clocks required
)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [SAMP_WIDTH - 1:0] samp_inp_data,
input samp_inp_str,
input summ_rdy_str, ///< for SMALL_FOOTPRINT set 1 after CIC_N cycles from inp_str to load FIFO registers with new sample
///< output data must be latched before summ_rdy_str is set, read output data at CIC_N - 1 clock after inp_str
output wire signed [SAMP_WIDTH - 1:0] samp_out_data,
output wire samp_out_str
);
/*********************************************************************************************/
integer i;
reg signed [SAMP_WIDTH - 1 : 0] data_reg[CIC_M - 1 : 0]; ///< the storage for the FIFO register
wire data_reg_push_str; ///< strobe to push data into data_reg FIFO
/*********************************************************************************************/
 
 
generate
if (SMALL_FOOTPRINT == 0) begin
reg samp_out_str_reg;
reg signed [SAMP_WIDTH - 1 : 0] data_out_reg;
assign data_reg_push_str = samp_inp_str;
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) data_out_reg <= '0;
else if (clear) data_out_reg <= '0;
else if (samp_inp_str) data_out_reg <= samp_inp_data - data_reg[CIC_M - 1];
end
assign samp_out_data = data_out_reg;
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) samp_out_str_reg <= '0;
else if (clear) samp_out_str_reg <= '0;
else samp_out_str_reg <= samp_inp_str;
end
assign samp_out_str = samp_out_str_reg;
end else begin
assign data_reg_push_str = summ_rdy_str;
assign #4 samp_out_data = samp_inp_data - data_reg[CIC_M - 1]; // delay for 18x18 multiplier of Cyclone V SE is 3.4 ns
assign samp_out_str = summ_rdy_str;
end
endgenerate
 
 
/*********************************************************************************************/
// FIFO register with reset and clear
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) for (i = 0; i < CIC_M; i = i + 1) data_reg[i] <= '0;
else if (clear) for (i = 0; i < CIC_M; i = i + 1) data_reg[i] <= '0;
else if (data_reg_push_str) begin
data_reg[0] <= samp_inp_data;
for (i = 1; i < CIC_M; i = i + 1) data_reg[i] <= data_reg[i - 1];
end
end
 
/*********************************************************************************************/
endmodule
/cic_core_2/trunk/rtl/verilog/downsampler.sv
1,46 → 1,46
module downsampler
/*********************************************************************************************/
#(
parameter DATA_WIDTH_INP = 8,
parameter CIC_R = 4
)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [DATA_WIDTH_INP - 1:0] inp_samp_data,
input inp_samp_str,
output reg signed [DATA_WIDTH_INP - 1:0] out_samp_data,
output reg out_samp_str
);
/*********************************************************************************************/
localparam DECIM_COUNTER_WIDTH = $clog2(CIC_R);
reg [DECIM_COUNTER_WIDTH - 1 : 0] counter;
/*********************************************************************************************/
// decimation counter
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) counter <= '0;
else if (clear) counter <= '0;
else if (inp_samp_str) counter <= (counter < CIC_R - 1) ? counter + {{(DECIM_COUNTER_WIDTH - 1){1'b0}}, 1'b1} : '0;
end
/*********************************************************************************************/
// output register
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) out_samp_data <= '0;
else if (clear) out_samp_data <= '0;
else if (inp_samp_str) out_samp_data <= (counter < CIC_R - 1) ? out_samp_data : inp_samp_data;
end
/*********************************************************************************************/
// data valid register
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) out_samp_str <= 1'b0;
else if (clear) out_samp_str <= 1'b0;
else if (inp_samp_str) out_samp_str <= (counter == CIC_R - 1);
else out_samp_str <= 1'b0;
end
/*********************************************************************************************/
endmodule
module downsampler
/*********************************************************************************************/
#(
parameter DATA_WIDTH_INP = 8,
parameter CIC_R = 4
)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [DATA_WIDTH_INP - 1:0] inp_samp_data,
input inp_samp_str,
output reg signed [DATA_WIDTH_INP - 1:0] out_samp_data,
output reg out_samp_str
);
/*********************************************************************************************/
localparam DECIM_COUNTER_WIDTH = $clog2(CIC_R);
reg [DECIM_COUNTER_WIDTH - 1 : 0] counter;
/*********************************************************************************************/
// decimation counter
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) counter <= '0;
else if (clear) counter <= '0;
else if (inp_samp_str) counter <= (counter < CIC_R - 1) ? counter + {{(DECIM_COUNTER_WIDTH - 1){1'b0}}, 1'b1} : '0;
end
/*********************************************************************************************/
// output register
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) out_samp_data <= '0;
else if (clear) out_samp_data <= '0;
else if (inp_samp_str) out_samp_data <= (counter < CIC_R - 1) ? out_samp_data : inp_samp_data;
end
/*********************************************************************************************/
// data valid register
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) out_samp_str <= 1'b0;
else if (clear) out_samp_str <= 1'b0;
else if (inp_samp_str) out_samp_str <= (counter == CIC_R - 1);
else out_samp_str <= 1'b0;
end
/*********************************************************************************************/
endmodule
/cic_core_2/trunk/rtl/verilog/integrator.sv
1,24 → 1,24
`timescale 1ns / 1ns
module integrator
/*********************************************************************************************/
#(parameter DATA_WIDTH_INP = 8 , DATA_WIDTH_OUT = 9)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [DATA_WIDTH_INP - 1:0] inp_samp_data,
input inp_samp_str,
output reg signed [DATA_WIDTH_OUT - 1:0] out_samp_data
);
/*********************************************************************************************/
wire signed [DATA_WIDTH_OUT - 1:0] sum;
assign #4 sum = out_samp_data + inp_samp_data; // delay for 18x18 multiplier of Cyclone V SE is 3.4 ns
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) out_samp_data <= '0;
else if (clear) out_samp_data <= '0;
else if (inp_samp_str) out_samp_data <= sum;
end
/*********************************************************************************************/
endmodule
`timescale 1ns / 1ns
module integrator
/*********************************************************************************************/
#(parameter DATA_WIDTH_INP = 8 , DATA_WIDTH_OUT = 9)
/*********************************************************************************************/
(
input clk,
input reset_n,
input clear,
input wire signed [DATA_WIDTH_INP - 1:0] inp_samp_data,
input inp_samp_str,
output reg signed [DATA_WIDTH_OUT - 1:0] out_samp_data
);
/*********************************************************************************************/
wire signed [DATA_WIDTH_OUT - 1:0] sum;
assign #4 sum = out_samp_data + inp_samp_data; // delay for 18x18 multiplier of Cyclone V SE is 3.4 ns
always @(posedge clk or negedge reset_n)
begin
if (!reset_n) out_samp_data <= '0;
else if (clear) out_samp_data <= '0;
else if (inp_samp_str) out_samp_data <= sum;
end
/*********************************************************************************************/
endmodule
/cic_core_2/trunk/rtl_sim/run/cic_d_gtkwave_run.sh
1,3 → 1,3
#!/bin/sh
gtkwave ../out/cic_d_tb.vcd ./cic_d_tb.gtkw
#shmidcat ../out/cic_d_tb.vcd | gtkwave -v -I ./cic_d_tb.gtkw
#!/bin/sh
gtkwave ../out/cic_d_tb.vcd ./cic_d_tb.gtkw
#shmidcat ../out/cic_d_tb.vcd | gtkwave -v -I ./cic_d_tb.gtkw
/cic_core_2/trunk/rtl_sim/run/cic_d_sim_run.sh
1,6 → 1,7
#!/bin/sh
PATH_CIC=../../../rtl/verilog
iverilog -g2005-sv -g2012 -o ../out/cic_d.out -I $PATH_CIC/ $PATH_CIC/cic_functions.vh $PATH_CIC/cic_d.sv $PATH_CIC/integrator.sv $PATH_CIC/comb.sv $PATH_CIC/downsampler.sv ../src/cic_d_tb.sv || exit # if error then stop
echo "iverilog ready, run vvp"
vvp ../out/cic_d.out
echo "vvp ready"
#!/bin/sh
PATH_CIC=../../rtl/verilog
mkdir -p ../out
iverilog -g2005-sv -g2012 -o ../out/cic_d.out -I $PATH_CIC/ $PATH_CIC/cic_functions.vh $PATH_CIC/cic_d.sv $PATH_CIC/integrator.sv $PATH_CIC/comb.sv $PATH_CIC/downsampler.sv ../src/cic_d_tb.sv || exit # if error then stop
echo "iverilog ready, run vvp"
vvp ../out/cic_d.out
echo "vvp ready"
/cic_core_2/trunk/rtl_sim/src/cic_d_tb.sv
1,252 → 1,275
`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
`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 INP_SAMP_WIDTH_TO_SIGNAL_WIDTH = 2;
localparam CIC_N = 3;
localparam CIC_M = 2;
localparam SMALL_FOOTPRINT = 1;
*/
/*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;
*/
/*
// Eugene B. Hogenauer paper
// B: 1, 6, 9, 13, 14, 15, 16, 17
localparam CIC_R = 25;
localparam SAMP_INP_DW = 16;
localparam SAMP_OUT_DW = 16;
localparam CIC_N = 4;
localparam CIC_M = 1;
localparam SMALL_FOOTPRINT = 1;
localparam INP_SAMP_WIDTH_TO_SIGNAL_WIDTH = 0;
*/
/*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 SMALL_FOOTPRINT = 1;
localparam INP_SAMP_WIDTH_TO_SIGNAL_WIDTH = 0;
 
/*************************************************************/
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_scale_out;
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;
B_2Np1 = B_calc(CIC_N * 2, CIC_N, CIC_R, CIC_M, SAMP_INP_DW, SAMP_OUT_DW);
$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);
$display(" log2_h_f0_pre = %2d, lim %2d", log2_h_f0_pre, h_f0_pre_limit_prec);
if (log2_h_f0_pre > h_f0_pre_limit_prec) begin
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_pre / 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_scale_out = B_max + 1 - SAMP_OUT_DW;
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_B_prune_last_stage = cic_B_scale_out - cic_B_prune * CIC_N;
cic_S_prune_last_stage = 1 << cic_B_prune_last_stage;
$display("model:");
$display(" B_max=%2d; B_out=%2d; cic_B_scale_out=%2d", B_max, B_out, cic_B_scale_out);
$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);
//$finish;
$display($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 ? 1 << (SAMP_INP_DW / 2) : 0; ///< Hamming function
//assign filter_inp_data = samp_counter >= delta_f_offs ? 1 << (SAMP_INP_DW - INP_SAMP_WIDTH_TO_SIGNAL_WIDTH -1 ) : 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

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