serial_implementation.vhdl

VHDL 实现 有限冲击响应滤波器的设计（串行式）

LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.numeric_std.ALL;

ENTITY serial_implementation IS
   GENERIC (WIDTH:INTEGER:=8;
            N:INTEGER:=4);
   PORT (reset,start,clk:STD_LOGIC;
         x:IN STD_LOGIC_VECTOR(WIDTH-1 DOWNTO 0);
         y:OUT STD_LOGIC_VECTOR(2*WIDTH-1 DOWNTO 0);
         finished:OUT STD_LOGIC);
END serial_implementation;

ARCHITECTURE arch_serial_implementation OF serial_implementation IS
TYPE array_type IS ARRAY(0 TO N-1) OF
              STD_LOGIC_VECTOR(WIDTH-1 DOWNTO 0);

--CONSTANT const_array:array_type:=("11011000",
--                                 "00011101",
--                                 "00011101",
--                                 "11011000");
CONSTANT const_array:array_type:=("00000001",
                                        "00000001",
                                        "00000001",
                                        "00000001");
SIGNAL sample_array:array_type;
SIGNAL y_signal:SIGNED(2*WIDTH-1 DOWNTO 0);
SIGNAL count:INTEGER RANGE 0 TO N;

BEGIN
   FIR_process:
   PROCESS(reset,clk,start)
   BEGIN
      IF (reset='1') THEN
         y_signal<=(OTHERS=>'0');
         sample_array(1)<="00001111";
         sample_array(2)<="00111100";
         sample_array(3)<="00011100";
--         sample_array(1)<="00000001";
--         sample_array(2)<="00000001";
--         sample_array(3)<="00000001";
      ELSIF (clk'EVENT AND clk='1') THEN
         IF (start='1') THEN
            count<=0;
            finished<='0';
            sample_array(0)<=x;
            y_signal<=(OTHERS=>'0');
         ELSIF (count<N) THEN
            y_signal<=y_signal+SIGNED(sample_array(count))*
                               SIGNED(const_array(count));
            IF (count=N-1)THEN
               FOR i IN sample_array'HIGH DOWNTO 2 LOOP
                  sample_array(i)<=sample_array(i-1);
               END LOOP;
               sample_array(1)<=x;
               finished<='1';
            END IF;
            count<=count+1;
       END IF;
      END IF;
   END PROCESS FIR_process;
   y<=STD_LOGIC_VECTOR(y_signal);
END arch_serial_implementation;