m8.vhd

扩跳频通信在QUARTUS7.0开发环境下的VHDL源程序及总体框图实现

LIBRARY ieee;       
USE ieee.std_logic_1164.all;    
USE ieee.std_logic_arith.all;

ENTITY M8 IS    ----------x8+x4+x3+x2+1 [2 3 4 8]
PORT(clkx1024:IN STD_LOGIC;
	notready:IN STD_LOGIC;
	M_8:OUT STD_LOGIC);
END M8;

ARCHITECTURE generator_archi OF M8 IS 
SIGNAL count:INTEGER RANGE 0 TO 256;
SIGNAL enable:STD_LOGIC;

BEGIN

PROCESS(notready,count,clkx1024)
VARIABLE shift:STD_LOGIC_VECTOR(7 downto 0);
VARIABLE tmp:STD_LOGIC;
BEGIN
IF(notready='1'OR count=256) THEN
  M_8<='0';
  shift:="10000000";  
ELSIF(enable='1') THEN
   IF(clkx1024'event AND clkx1024='1')THEN
     tmp:=shift(0) XOR shift(4) XOR shift(5) XOR shift(6)XOR 
			(NOT shift(7)and not shift(6)and not shift(5)and not shift(4)and not shift(3)and not shift(2)and not shift(1));
     M_8<=tmp;     
     FOR i IN 0 TO 6 LOOP
       shift(i):=shift(i+1);
     END LOOP;
     shift(7):=tmp;
   END IF;
 END IF;
END PROCESS;

PROCESS(notready,clkx1024)
BEGIN
   IF notready='1' THEN
     count<=0;
   ELSIF(clkx1024'event AND clkx1024='1') THEN
    	IF count=256 THEN
			count<=1;
   		ELSE count<=count+1;
  		END IF;
	END IF;
END PROCESS;

PROCESS(count,clkx1024,notready)
BEGIN
	IF notready='1' THEN
 		 enable<='1';
	elsif(clkx1024'event AND clkx1024='0') THEN
		IF(count=255) THEN
		enable<='0';
		ELSIF(count=256) THEN
		enable<='1';
  		END IF;
	END IF;
END PROCESS;
END generator_archi;