vivado FIR Filters
Vivado合成直接从RTL中推导出乘加级联来组成FIR滤波器。这种滤波器有几种可能的实现方式；一个例子是收缩滤波器在7系列DSP48E1 Slice用户指南（UG479）中进行了描述，并在8抽头偶数中显示对称收缩FIR（Verilog）。从编码示例下载编码示例文件。
8-Tap Even Symmetric Systolic FIR (Verilog)
Filename: sfir_even_symetric_systolic_top.v
// sfir_even_symmetric_systolic_top.v
// FIR Symmetric Systolic Filter, Top module is
sfir_even_symmetric_systolic_top
// sfir_shifter - sub module which is used in top level
(* dont_touch = "yes" *)
module sfir_shifter #(parameter dsize = 16, nbtap = 4)
(input clk, [dsize-1:0] datain, output [dsize-1:0] dataout);
(* srl_style = "srl_register" *) reg [dsize-1:0] tmp [0:2*nbtap-1];
integer i;
always @(posedge clk)
begin
tmp[0] <= datain;
for (i=0; i<=2*nbtap-2; i=i+1)
tmp[i+1] <= tmp[i];
end
assign dataout = tmp[2*nbtap-1];
endmodule
// sfir_even_symmetric_systolic_element - sub module which is used in top
module sfir_even_symmetric_systolic_element #(parameter dsize = 16)
(input clk, input signed [dsize-1:0] coeffin, datain, datazin, input signed
[2*dsize-1:0] cascin,
output signed [dsize-1:0] cascdata, output reg signed [2*dsize-1:0]
cascout);
reg signed [dsize-1:0] coeff;
reg signed [dsize-1:0] data;
reg signed [dsize-1:0] dataz;
reg signed [dsize-1:0] datatwo;
reg signed [dsize:0] preadd;
reg signed [2*dsize-1:0] product;
assign cascdata = datatwo;
always @(posedge clk)
begin
coeff <= coeffin;
data <= datain;
datatwo <= data;
dataz <= datazin;
preadd <= datatwo + dataz;
product <= preadd * coeff;
cascout <= product + cascin;
end
endmodule
module sfir_even_symmetric_systolic_top #(parameter nbtap = 4, dsize = 16,
psize = 2*dsize)
(input clk, input signed [dsize-1:0] datain, output signed [2*dsize-1:0]
firout);
wire signed [dsize-1:0] h [nbtap-1:0];
wire signed [dsize-1:0] arraydata [nbtap-1:0];
wire signed [psize-1:0] arrayprod [nbtap-1:0];
wire signed [dsize-1:0] shifterout;
reg signed [dsize-1:0] dataz [nbtap-1:0];
assign h[0] = 7;
assign h[1] = 14;
assign h[2] = -138;
assign h[3] = 129;
assign firout = arrayprod[nbtap-1]; // Connect last product to output
sfir_shifter #(dsize, nbtap) shifter_inst0 (clk, datain, shifterout);
generate
genvar I;
for (I=0; I<nbtap; I=I+1)
if (I==0)
sfir_even_symmetric_systolic_element #(dsize) fte_inst0 (clk, h[I], datain,
shifterout, {32{1'b0}}, arraydata[I], arrayprod[I]);
else
sfir_even_symmetric_systolic_element #(dsize) fte_inst (clk, h[I],
arraydata[I-1], shifterout, arrayprod[I-1], arraydata[I], arrayprod[I]);
endgenerate
endmodule // sfir_even_symmetric_systolic_top
8-Tap Even Symmetric Systolic FIR (VHDL)
Filename: sfir_even_symetric_systolic_top.vhd
--
-- FIR filter top
-- File: sfir_even_symmetric_systolic_top.vhd
-- FIR filter shifter
-- submodule used in top (sfir_even_symmetric_systolic_top)
library ieee;
use ieee.std_logic_1164.all;
entity sfir_shifter is
generic(
DSIZE : natural := 16;
NBTAP : natural := 4
);
port(
clk : in std_logic;
datain : in std_logic_vector(DSIZE - 1 downto 0);
dataout : out std_logic_vector(DSIZE - 1 downto 0)
);
end sfir_shifter;
architecture rtl of sfir_shifter is
-- Declare signals
--
type CHAIN is array (0 to 2 * NBTAP - 1) of std_logic_vector(DSIZE - 1
downto 0);
signal tmp : CHAIN;
begin
process(clk)
begin
if rising_edge(clk) then
tmp(0) <= datain;
looptmp : for i in 0 to 2 * NBTAP - 2 loop
tmp(i + 1) <= tmp(i);
end loop;
end if;
end process;
dataout <= tmp(2 * NBTAP - 1);
end rtl;
--
-- FIR filter engine (multiply with pre-add and post-add)
-- submodule used in top (sfir_even_symmetric_systolic_top)
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity sfir_even_symmetric_systolic_element is
generic(DSIZE : natural := 16);
port(clk : in std_logic;
coeffin, datain, datazin : in std_logic_vector(DSIZE - 1 downto 0);
cascin : in std_logic_vector(2 * DSIZE downto 0);
cascdata : out std_logic_vector(DSIZE - 1 downto 0);
cascout : out std_logic_vector(2 * DSIZE downto 0));
end sfir_even_symmetric_systolic_element;
architecture rtl of sfir_even_symmetric_systolic_element is
-- Declare signals
--
signal coeff, data, dataz, datatwo : signed(DSIZE - 1 downto 0);
signal preadd : signed(DSIZE downto 0);
signal product, cascouttmp : signed(2 * DSIZE downto 0);
begin
process(clk)
begin
if rising_edge(clk) then
coeff <= signed(coeffin);
data <= signed(datain);
datatwo <= data;
dataz <= signed(datazin);
preadd <= resize(datatwo, DSIZE + 1) + resize(dataz, DSIZE + 1);
product <= preadd * coeff;
cascouttmp <= product + signed(cascin);
end if;
end process;
-- Type conversion for output
--
cascout <= std_logic_vector(cascouttmp);
cascdata <= std_logic_vector(datatwo);
end rtl;
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity sfir_even_symmetric_systolic_top is
generic(NBTAP : natural := 4;
DSIZE : natural := 16;
PSIZE : natural := 33);
port(clk : in std_logic;
datain : in std_logic_vector(DSIZE - 1 downto 0);
firout : out std_logic_vector(PSIZE - 1 downto 0));
end sfir_even_symmetric_systolic_top;
architecture rtl of sfir_even_symmetric_systolic_top is
-- Declare signals
--
type DTAB is array (0 to NBTAP - 1) of std_logic_vector(DSIZE - 1 downto 0);
type HTAB is array (0 to NBTAP - 1) of std_logic_vector(0 to DSIZE - 1);
type PTAB is array (0 to NBTAP - 1) of std_logic_vector(PSIZE - 1 downto 0);
signal arraydata, dataz : DTAB;
signal arrayprod : PTAB;
signal shifterout : std_logic_vector(DSIZE - 1 downto 0);
-- Initialize coefficients and a "zero" for the first filter element
--
constant h : HTAB := ((std_logic_vector(TO_SIGNED(63, DSIZE))),
(std_logic_vector(TO_SIGNED(18, DSIZE))),
(std_logic_vector(TO_SIGNED(-100, DSIZE))),
(std_logic_vector(TO_SIGNED(1, DSIZE))));
constant zero_psize : std_logic_vector(PSIZE - 1 downto 0) := (others =>
'0');
begin
-- Connect last product to output
--
firout <= arrayprod(nbtap - 1);
-- Shifter
--
shift_u0 : entity work.sfir_shifter
generic map(DSIZE, NBTAP)
port map(clk, datain, shifterout);
-- Connect the arithmetic building blocks of the FIR
--
gen : for I in 0 to NBTAP - 1 generate
begin
g0 : if I = 0 generate
element_u0 : entity work.sfir_even_symmetric_systolic_element
generic map(DSIZE)
port map(clk, h(I), datain, shifterout, zero_psize, arraydata(I),
arrayprod(I));
end generate g0;
gi : if I /= 0 generate
element_ui : entity work.sfir_even_symmetric_systolic_element
generic map(DSIZE)
port map(clk, h(I), arraydata(I - 1), shifterout, arrayprod(I - 1),
arraydata(I), arrayprod(I));
end generate gi;
end generate gen;
end rtl;