library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
  
entity RAM9X8_HWPBusMaster is	
	generic(
		HWP_CMD_2_LOWER : integer := 46;
		HWP_CMD_2_UPPER : integer := 47;
		HWP_CMD_1_LOWER : integer := 48;
		HWP_CMD_1_UPPER : integer := 49;
		HWP_DATA_2_LOWER : integer := 50;
		HWP_DATA_2_UPPER : integer := 51;
		HWP_DATA_1_LOWER : integer := 52;
		HWP_DATA_1_UPPER : integer := 53;
		
		DATA_BUS_WIDTH : integer := 8;
		ADDRESS_BUS_WIDTH : integer := 9
	);
	
	port(
		clk : in std_logic;
		
		data : inout std_logic_vector(DATA_BUS_WIDTH - 1 downto 0);
		address : in std_logic_vector(ADDRESS_BUS_WIDTH - 1 downto 0);
		we : in std_logic;
		oe : in std_logic;
		ce : in std_logic;	
	
		hwpdataout : out std_logic;
		hwpclk : out std_logic;
		hwpdatain : in std_logic_vector(1 downto 0)
	); 
end entity;

architecture behavorial of RAM9X8_HWPBusMaster is

signal cmdBuf : std_logic_vector(31 downto 0) := (others => '0');
signal dataBuf : std_logic_vector(31 downto 0) := (others => '0');
signal tempBuf : std_logic_vector(31 downto 0) := (others => '0');
signal dataToSend : std_logic_vector(33 downto 0) := (others => '0');
signal cmdBuf_0_prev : std_logic := '0';
signal done : std_logic := '1';

type   HWPSt is (Waiting, SendingData, ReceivingData, Checking);  
signal HWPState  : HWPSt := Waiting;

begin	

	process (we, oe, ce)
		variable addr : integer range 0 to 2**ADDRESS_BUS_WIDTH - 1 := 0;
	begin
		if (ce = '0') then  -- Если микросхема выбрана
			addr := conv_integer(address);
			if (addr = HWP_CMD_2_UPPER or addr = HWP_CMD_2_LOWER or addr = HWP_CMD_1_UPPER or addr = HWP_CMD_1_LOWER
				or addr = HWP_DATA_2_UPPER or addr = HWP_DATA_2_LOWER or addr = HWP_DATA_1_UPPER or addr = HWP_DATA_1_LOWER) then
				if (oe = '0' and we = '1') then  -- Если сигнал чтения активен, а записи нет	
					case addr is
						when HWP_CMD_2_UPPER =>
							data <= cmdBuf(31 downto 24);
						when HWP_CMD_2_LOWER =>
							data <= cmdBuf(23 downto 16);
						when HWP_CMD_1_UPPER =>
							data <= cmdBuf(15 downto 8);
						when HWP_CMD_1_LOWER =>
							data(7 downto 1) <= cmdBuf(7 downto 1);
							data(0) <= done;
						when HWP_DATA_2_UPPER =>
							data <= tempBuf(29 downto 22);
						when HWP_DATA_2_LOWER =>
							data <= tempBuf(21 downto 14);
						when HWP_DATA_1_UPPER =>
							data <= tempBuf(13 downto 6);
						when HWP_DATA_1_LOWER =>
							data(7 downto 2) <= tempBuf(5 downto 0);	
							data(1 downto 0) <= (others => '0');
						when others => 
							data <= (others => 'Z');  -- Запретить запись на шину
					end case;				
				elsif (oe = '1' and we = '0') then  -- Если сигнал записи активен, а чтения нет
					case addr is
						when HWP_CMD_2_UPPER =>
							cmdBuf(31 downto 24) <= data;
						when HWP_CMD_2_LOWER =>
							cmdBuf(23 downto 16) <= data;
						when HWP_CMD_1_UPPER =>
							cmdBuf(15 downto 8) <= data;
						when HWP_CMD_1_LOWER =>
							cmdBuf(7 downto 0) <= data;
						when HWP_DATA_2_UPPER =>
							dataBuf(31 downto 24) <= data;
						when HWP_DATA_2_LOWER =>
							dataBuf(23 downto 16) <= data;
						when HWP_DATA_1_UPPER =>
							dataBuf(15 downto 8) <= data;
						when HWP_DATA_1_LOWER =>
							dataBuf(7 downto 0) <= data;								
						when others =>
							data <= (others => 'Z');  -- Запретить запись на шину
					end case;
				else
					data <= (others => 'Z');  -- Запретить запись на шину
				end if;				
			else 
				data <= (others => 'Z');  -- Запретить запись на шину
			end if;	
		else
			data <= (others => 'Z');  -- Запретить запись на шину
		end if;
	end process;
	
	process(clk) is
		variable count : integer range 0 to 511 := 0;
		variable state : integer range 0 to 1 := 0;
		variable countBit : integer range 0 to 32 := 0;
	begin
		if rising_edge(clk) then
			case HWPState is
				when Waiting =>
					if cmdBuf(0) = '1' and cmdBuf_0_prev = '0' then
						done <= '1';
						if cmdBuf(14) = '0' then
							if cmdBuf(13) = '0' then
								dataToSend(33 downto 22) <= (others => '0');
								dataToSend(21 downto 16) <= cmdBuf(15 downto 10);
								dataToSend(15 downto 0) <= cmdBuf(31 downto 16);
								countBit := 21;
							else 	
								dataToSend(33) <= '0';
								dataToSend(32 downto 30) <= cmdBuf(15 downto 13);
								dataToSend(29 downto 0) <= dataBuf(31 downto 2);
								countBit := 32;
							end if;
						else
							dataToSend(33) <= '1';
							dataToSend(32 downto 2) <= (others => '0');
							dataToSend(1 downto 0) <= cmdBuf(15 downto 14);
							countBit := 1;							
						end if;
						HWPState <= SendingData;
						count := 0;
						state := 0;
					end if;	
				when SendingData =>
					if count < 511 and state = 0 then
						if count = 0 then
							hwpdataout <= dataToSend(countBit);
						end if;
						count := count + 1;
					elsif count = 511 and state = 0 then
						hwpclk <= '0';
						count := 0;
						state := 1;
					elsif count < 511 and state = 1 then
						count := count + 1;
					elsif count = 511 and state = 1 then
						hwpclk <= '1';
						count := 0;
						state := 0;
						if countBit > 0 then
							countBit := countBit - 1;
						else
							if dataToSend(33) = '1' then
								HWPState <= ReceivingData;
								countBit := 29;
							else
								HWPState <= Checking;
							end if;	
						end if;
					end if;	
				when ReceivingData =>
					if count < 511 and state = 0 then
						count := count + 1;
					elsif count = 511 and state = 0 then
						hwpclk <= '0';
						count := 0;
						state := 1;
						if dataToSend(1) = '0' then
							tempBuf(countBit) <= hwpdatain(0);
							hwpdataout <= hwpdatain(0);
						else 
							tempBuf(countBit) <= hwpdatain(1);
							hwpdataout <= hwpdatain(1);
						end if;	
 					elsif count < 511 and state = 1 then
						count := count + 1;
					elsif count = 511 and state = 1 then
						hwpclk <= '1';
						count := 0;
						state := 0;
						if countBit > 0 then
							countBit := countBit - 1;
						else
							HWPState <= Checking;	
						end if;
					end if;
				when Checking =>
					done <= '0';
					HWPState <= Waiting;
				when others =>
					HWPState <= Waiting;
			end case;
			cmdBuf_0_prev <= cmdBuf(0);
		end if;	
	end process;
	
end behavorial;