pluto_hdl_adi/library/axi_adc_decimate/fir_decim.v

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// ***************************************************************************
// ***************************************************************************
// Copyright (C) 2017-2023 Analog Devices, Inc. All rights reserved.
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//
// In this HDL repository, there are many different and unique modules, consisting
// of various HDL (Verilog or VHDL) components. The individual modules are
// developed independently, and may be accompanied by separate and unique license
// terms.
//
// The user should read each of these license terms, and understand the
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// freedoms and responsibilities that he or she has by using this source/core.
//
// This core is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE.
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//
// Redistribution and use of source or resulting binaries, with or without modification
// of this file, are permitted under one of the following two license terms:
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//
// 1. The GNU General Public License version 2 as published by the
// Free Software Foundation, which can be found in the top level directory
// of this repository (LICENSE_GPL2), and also online at:
// <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
//
// OR
//
// 2. An ADI specific BSD license, which can be found in the top level directory
// of this repository (LICENSE_ADIBSD), and also on-line at:
// https://github.com/analogdevicesinc/hdl/blob/master/LICENSE_ADIBSD
// This will allow to generate bit files and not release the source code,
// as long as it attaches to an ADI device.
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//
// ***************************************************************************
// ***************************************************************************
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`timescale 1 ns / 1 ns
module fir_decim #(
parameter USE_DSP48E = 1
) (
input clk,
input clk_enable,
input reset,
input signed [11:0] filter_in,
output reg signed [25:0] filter_out,
output reg ce_out
);
localparam signed [11:0] coeffphase1_1 = 12'b000011010101; //sfix12_En11
localparam signed [11:0] coeffphase1_2 = 12'b011011110010; //sfix12_En11
localparam signed [11:0] coeffphase1_3 = 12'b110000111110; //sfix12_En11
// We know that clk_enable is asserted at most every 5th clock cycle and the
// output is decimated by two. So we have 10 clock cycles to compute the
// result. That's plenty of time considering that there are only 6
// coefficients.
reg active = 1'b0;
reg active_d1 = 1'b0;
reg active_d2 = 1'b0;
reg [1:0] count = 2'b00;
reg phase = 1'b1;
reg ready = 1'b0;
reg [3:0] storage0[0:11];
reg [3:0] storage1[0:11];
reg signed [11:0] data0;
reg signed [11:0] data1;
reg signed [11:0] coeff;
wire signed [25:0] sum;
integer j;
initial begin
for (j = 0; j < 12; j = j + 1) begin
storage0[j] <= 'h00;
storage1[j] <= 'h00;
end
end
always @(posedge clk) begin
if (reset == 1'b1) begin
phase <= 1'b1;
end else begin
if (clk_enable == 1'b1) begin
phase <= phase + 1'b1;
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end
end
end
always @(posedge clk) begin
if (clk_enable == 1'b1 && phase == 1'b1) begin
active <= 1'b1;
end else if (count == 'h2) begin
active <= 1'b0;
end
active_d1 <= active;
active_d2 <= active_d1;
end
always @(posedge clk) begin
if (active == 1'b1) begin
case (count)
'h2: count <= 'h0;
default: count <= count + 1'b1;
endcase
end
end
always @(posedge clk) begin
if (active_d1 == 1'b0 && active_d2 == 1'b1) begin
ready <= 1'b1;
end else begin
ready <= 1'b0;
end
end
generate
genvar i;
for (i = 0; i < 12; i = i + 1) begin
always @(posedge clk) begin
if (clk_enable == 1'b1) begin
if (phase == 1'b0) begin
storage0[i] <= {storage0[i][2:0],filter_in[i]};
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end
if (phase == 1'b1) begin
storage1[i] <= {storage1[i][2:0],filter_in[i]};
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end
end
end
always @(*) begin
data0[i] <= storage0[i][2-count];
data1[i] <= storage1[i][count];
end
end
endgenerate
always @(*) begin
case (count)
'h0: coeff <= coeffphase1_1;
'h1: coeff <= coeffphase1_2;
'h2: coeff <= coeffphase1_3;
default: coeff <= 'h00;
endcase
end
generate if (USE_DSP48E) begin
wire [47:0] _sum;
wire [6:0] opmode = {1'b0,active_d2,5'b00101};
// Can't exceed 26 bit.
assign sum = _sum[43:18];
// MAC with pre-adder
DSP48E1 #(
.ACASCREG (0),
.ADREG (1),
.ALUMODEREG (0),
.AREG (0),
.AUTORESET_PATDET ("NO_RESET"),
.A_INPUT ("DIRECT"),
.BCASCREG (1),
.BREG (1),
.B_INPUT ("DIRECT"),
.CARRYINREG (0),
.CARRYINSELREG (0),
.CREG (0),
.DREG (0),
.INMODEREG (0),
.MASK (48'h3fffffffffff),
.MREG (1),
.OPMODEREG (1),
.PATTERN (48'h000000000000),
.PREG (1),
.SEL_MASK ("MASK"),
.SEL_PATTERN ("PATTERN"),
.USE_DPORT ("TRUE"),
.USE_MULT ("MULTIPLY"),
.USE_PATTERN_DETECT ("NO_PATDET"),
.USE_SIMD ("ONE48"))
i_dsp_mac (
.CLK (clk),
.A ({5'h0,data0[11],data0,12'h0}), // MSB aligned to 24-bit, 25th bit signed extended
.B ({coeff,6'b0}),
.C (48'h00),
.D ({data1[11],data1,12'h0}),
.MULTSIGNIN (1'b0),
.CARRYIN (1'b0),
.CARRYCASCIN (1'b0),
.ACIN (30'h0),
.BCIN (18'h0),
.PCIN (48'h0),
.P (_sum),
.MULTSIGNOUT (),
.CARRYOUT (),
.CARRYCASCOUT (),
.ACOUT (),
.BCOUT (),
.PCOUT (),
.ALUMODE (4'b0000),
.CARRYINSEL (3'h0),
.INMODE (5'b00100),
.OPMODE (opmode),
.PATTERNBDETECT (),
.PATTERNDETECT (),
.OVERFLOW (),
.UNDERFLOW (),
.CEA1 (1'b0),
.CEA2 (1'b0),
.CEAD (active),
.CEALUMODE (1'b0),
.CEB1 (1'b0),
.CEB2 (active),
.CEC (1'b0),
.CECARRYIN (1'b0),
.CECTRL (active),
.CED (1'b0),
.CEINMODE (1'b0),
.CEM (active_d1),
.CEP (active_d2),
.RSTA (1'b0),
.RSTALLCARRYIN (1'b0),
.RSTALUMODE (1'b0),
.RSTB (1'b0),
.RSTC (1'b0),
.RSTCTRL (1'b0),
.RSTD (1'b0),
.RSTINMODE (1'b0),
.RSTM (1'b0),
.RSTP (1'b0)
);
end else begin
reg signed [25:0] _sum = 'h00;
reg signed [12:0] pre_adder;
reg signed [11:0] coeff_d1;
reg signed [23:0] product = 'h00;
assign sum = _sum;
always @(posedge clk) begin
if (active == 1'b1) begin
pre_adder <= data0 + data1;
coeff_d1 <= coeff;
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end
if (active_d1 == 1'b1) begin
product <= coeff_d1 * pre_adder;
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end
if (reset == 1'b1 || ready == 1'b1) begin
_sum <= 'h00;
end else if (active_d2 == 1'b1) begin
_sum <= _sum + product;
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end
end
end
endgenerate
always @(posedge clk) begin
if (reset == 1'b1) begin
ce_out <= 1'b0;
end else begin
ce_out <= ready;
end
end
always @(posedge clk) begin
if (ready == 1'b1) begin
filter_out <= sum;
end
end
endmodule