VHDL4*4键盘按键循环显示

LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_UNSIGNED.ALL; ENTITY SCAN_LED IS port(A0,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11,A12,A13,A14,A15:IN STD_LOGIC; CLK : IN STD_LOGIC; SG : OUT STD_LOGIC_VECTOR(6 DOWNTO 0); Q1,Q2,Q3,Q4:OUT STD_LOGIC_VECTOR(3 DOWNTO 0)); END; ARCHITECTURE ONE OF SCAN_LED IS SIGNAL A:INTEGER RANGE 0 TO 15; BEGIN P1:PROCESS(CLK,A0,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11,A12,A13,A14,A15) VARIABLE P:STD_LOGIC_VECTOR(15 DOWNTO 0); VARIABLE S:INTEGER RANGE 0 TO 4; VARIABLE T:STD_LOGIC_VECTOR(3 DOWNTO 0); VARIABLE W:STD_LOGIC_VECTOR(3 DOWNTO 0); VARIABLE M1,M2,M3: STD_LOGIC_VECTOR(3 DOWNTO 0); BEGIN IF CLK'EVENT AND CLK='1'THEN P:=A0&A1&A2&A3&A4&A5&A6&A7&A8&A9&A10&A11&A12&A13&A14&A15; IF P>0 THEN S:=S+1; IF S>4 THEN S:=1; END IF; CASE S IS WHEN 0 =>W:="0000"; WHEN 1 =>W:="0001"; WHEN 2 =>W:="0011"; WHEN 3 =>W:="0111"; WHEN 4 =>W:="1111"; END CASE; CASE P IS WHEN "0000000000000001"=>T:="1111"; A<=15; WHEN "0000000000000010"=>T:="1110"; A<=14; WHEN "0000000000000100"=>T:="1101"; A<=13; WHEN "0000000000001000"=>T:="1100"; A<=12; WHEN "0000000000010000"=>T:="1011"; A<=11; WHEN "0000000000100000"=>T:="1010"; A<=10; WHEN "0000000001000000"=>T:="1001"; A<=9; WHEN "0000000010000000"=>T:="1000"; A<=8; WHEN "0000000100000000"=>T:="0111"; A<=7; WHEN "0000001000000000"=>T:="0110"; A<=6; WHEN "0000010000000000"=>T:="0101"; A<=5; WHEN "0000100000000000"=>T:="0100"; A<=4; WHEN "0001000000000000"=>T:="0011"; A<=3; WHEN "0010000000000000"=>T:="0010"; A<=2; WHEN "0100000000000000"=>T:="0001"; A<=1; WHEN "1000000000000000"=>T:="0000"; A<=0; WHEN OTHERS =>NULL; END CASE; IF W="0001" THEN Q4<=M3;Q3<=M2;Q2<=M1;Q1<=t; M3:=M2;M2:=M1;M1:=t; ELSIF W="0011" THEN Q4<=M3;Q3<=M2;Q2<=M1;Q1<=t; M3:=M2;M2:=M1;M1:=t; ELSIF W="0111" THEN Q4<=M3;Q3<=M2;Q2<=M1;Q1<=t; M3:=M2;M2:=M1;M1:=t; ELSIF W="1111" THEN Q4<=M3;Q3<=M2;Q2<=M1;Q1<=t; M3:=M2;M2:=M1;M1:=t; END IF; END IF; END IF; END PROCESS P1; P2:PROCESS(A) BEGIN CASE A IS WHEN 0 => SG <= "0111111"; WHEN 1 => SG <= "0000110"; WHEN 2 => SG <= "1011011"; WHEN 3 => SG <= "1001111"; WHEN 4 => SG <= "1100110"; WHEN 5 => SG <= "1101101"; WHEN 6 => SG <= "1111101"; WHEN 7 => SG <= "0000111"; WHEN 8 => SG <= "1111111"; WHEN 9 => SG <= "1101111"; WHEN 10 => SG <= "1110111"; WHEN 11 => SG <= "1111100"; WHEN 12 => SG <= "0111001"; WHEN 13 => SG <= "1011110"; WHEN 14 => SG <= "1111001"; WHEN 15 => SG <= "1110001"; WHEN OTHERS => NULL; END CASE; END PROCESS P2; END;