LIBRARY ieee;
USE ieee.std_logic_1164.all; 

ENTITY Interf IS

	-- {{ALTERA_IO_BEGIN}} DO NOT REMOVE THIS LINE!
	PORT
	(
		CLK : IN STD_LOGIC;
		DATA_GEN : IN STD_LOGIC_VECTOR(7 downto 0);
		FRAMEn : IN STD_LOGIC;
		IRDYn : IN STD_LOGIC;
		CBEn : IN STD_LOGIC_VECTOR(3 downto 0);
		IDSEL : IN STD_LOGIC;
		RSTn : IN STD_LOGIC;
		RST : OUT STD_LOGIC;
		GEN : OUT STD_LOGIC;
		DEVSELn : OUT STD_LOGIC;
		TRDYn : OUT STD_LOGIC;
		STOPn : OUT STD_LOGIC;
		OUT1 : OUT STD_LOGIC_VECTOR(31 downto 0);
		OUT2 : OUT STD_LOGIC_VECTOR(3 downto 0);
		AD1 : INOUT STD_LOGIC_VECTOR(31 downto 0);
		PAR : INOUT STD_LOGIC
	);
	-- {{ALTERA_IO_END}} DO NOT REMOVE THIS LINE!

END Interf;

ARCHITECTURE Interf_architecture OF Interf IS

--Функция проверки чётности. Возвращает "1", если количество 1 не чётное и "0", если чётное.

function PARITY (X : std_logic_vector) return std_ulogic is
 variable TMP : std_logic := '0';
begin
  for J in X'range loop
	 TMP := TMP xor X(J);
  end loop; 
 return TMP;
end PARITY;

--++++++++

--Функция декодирования адреса 32-разрядного регистра в пространстве конфигурации 

function DECODER (X : std_logic_vector(5 downto 0)) return natural is      
begin
	case X is
			when "000000" => return 0; 
			when "000001" => return 1; 
			when "000010" => return 2;  
			when "000011" => return 3;  
			when "000100" => return 4;  
			when "000101" => return 5;  
			when "000110" => return 6;
			when "000111" => return 7; 
			when "001000" => return 8; 
			when "001001" => return 9;
			when "001010" => return 10;
			when "001011" => return 11;
			when "001100" => return 12;
			when "001101" => return 13;
			when "001110" => return 14;
			when "001111" => return 15;
			when "010000" => return 16;
			when others => return 17;  
	end case; 
end DECODER;

--+++++++++     

CONSTANT ZST	       : std_logic_vector (31 downto 0) := "ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ";
CONSTANT NUL	       : std_logic_vector (31 downto 0) := "00000000000000000000000000000000";

--Пространство конфигурации

type DWORD is array (0 to 17) of std_logic_vector(31 downto 0);

CONSTANT Vendor_ID       : std_logic_vector (15 downto 0) :="0000000000011010";
CONSTANT Device_ID       : std_logic_vector (15 downto 0) :="1111000000011010";
SHARED VARIABLE STATUS   : std_logic_vector (15 downto 0) :="0000000000000000";
CONSTANT COMAND          : std_logic_vector (15 downto 0) :="0000000000000001";
CONSTANT Class_code      : std_logic_vector (23 downto 0) :="111111110000000000000000";
CONSTANT Revision_ID     : std_logic_vector (7 downto 0) :="00000000";
CONSTANT BIST            : std_logic_vector (7 downto 0) :="00000000";
CONSTANT Header_type     : std_logic_vector (7 downto 0) :="00000000";
CONSTANT Latency_timer   : std_logic_vector (7 downto 0) :="00000000";
CONSTANT Cache_line_Size : std_logic_vector (7 downto 0) :="00000000";
SHARED VARIABLE BAR      : std_logic_vector (31 downto 0) := "00000000000000000000000000001001";

CONSTANT MAX_LAT         : std_logic_vector (7 downto 0) :="00000000";
CONSTANT MIN_GNT         : std_logic_vector (7 downto 0) :="00000000";
CONSTANT Interrupt_Pin   : std_logic_vector (7 downto 0) :="00000000";
CONSTANT Interrupt_Line  : std_logic_vector (7 downto 0) :="11111111";

CONSTANT ELSE_REG        : std_logic_vector (31 downto 0) :=NUL;

signal CNF : DWORD:= (
						0  => (Vendor_ID & Device_ID),
						1  => (STATUS & COMAND),
						2  => (Class_code & Revision_ID),
						3  => (BIST & Header_type & Latency_timer & Cache_line_size),
						4  =>  BAR,
						16 => (MAX_LAT & MIN_GNT & Interrupt_Pin & Interrupt_Line),
						others => ELSE_REG
					  );				
--+++++++++ 


type state	is	(IDLE,B_BUSY,S_DATA,BACKOFF,CONF_WR,CONF_RD);
signal 	STAT      : STATE:=IDLE;
signal 	nxt_stat  : STATE:=IDLE;

signal RD_TX      :STD_LOGIC:='0';  --Read transaction signal
signal CNF_RD     :STD_LOGIC:='0';  --Configuration read transaction signal
signal CNF_WR     :STD_LOGIC:='0';  --Configuration write transaction signal
signal NOT_WE     :STD_LOGIC:='0';  --Other divace address signal
signal DONE       :STD_LOGIC:='1';  --Transaction done signal
signal OTHER_CMD  :STD_LOGIC:='0';  


signal ADDR       : STD_LOGIC_VECTOR(5 downto 0):="000000"; --Адрес 32-разрядного регистра в пространстве конфигурации

--signal DATA_G     : std_logic_vector (7 downto 0):="00110011";
--shared variable G : BIT:='1';

shared variable CMD   : std_logic_vector(3 downto 0):="0000";
shared variable ADR   : std_logic_vector(31 downto 0):=BAR;

BEGIN

--**********************
--*NEXT_STATE_GENERATOR*
--**********************

Process(CLK,RSTn)
 begin
   if ( RSTn = '0' ) then
     STAT<=IDLE;
     RST<='1';
   elsif(CLK'event and CLK='1') then
     STAT<=nxt_stat;
     RST<='0';
   end if;
 end process;
 
--**************************
--*STATE_mashine_controller*
--**************************

process(NOT_WE,CNF_WR,CNF_RD,DONE,OTHER_CMD)
 begin    
  case STAT is       
       when IDLE => 
          if    (NOT_WE='0') then  if CBEn="0010" then nxt_stat<=S_DATA; 
					          else nxt_stat<=BACKOFF; end if;
          elsif (CNF_RD='1')     then nxt_stat<=CONF_RD;
          elsif (CNF_WR='1')     then nxt_stat<=CONF_WR;
          elsif (OTHER_CMD='1')  then nxt_stat<=BACKOFF;
          elsif (DONE='0')       then nxt_stat<=B_BUSY;
                                 else nxt_stat<=IDLE; end if;
       --READ
       when S_DATA =>
          if (DONE='1') then nxt_stat<=IDLE;
                        else nxt_stat<=S_DATA; end if;
                        
       --Configuration Read
       when CONF_RD =>
          if (DONE='1') then nxt_stat<=IDLE;
                        else nxt_stat<=CONF_RD; end if;
                                               
       --Configuration write
       when CONF_WR =>
          if (DONE='1') then nxt_stat<=IDLE;
                        else nxt_stat<=CONF_WR; end if;                       
       --Bus busy
       when B_BUSY =>
          if (DONE='1') then nxt_stat<=IDLE;
                        else nxt_stat<=B_BUSY; end if;
                        
       --Not supported comand
       when BACKOFF =>
          if (DONE='1') then nxt_stat<=IDLE;
                        else nxt_stat<=BACKOFF; end if;
        
       when OTHERS => nxt_stat<=IDLE;
  end case;
end process;

--*********
--*SIGNALS*
--*********

NOT_WE    <= '0' when (FRAMEn='0' and AD1=ADR ) else '1' when (DONE='0') else 'Z';   --Не распознан адрес
RD_TX     <= '1' when (FRAMEn='0' and CNF(4)=AD1) else '0';                          --Транзакция чтения данных  and CBEn="0010"
CNF_RD    <= '1' when (FRAMEn='0' and IDSEL='1' and CBEn="1010") else '0';           --Транзакция чтения конфигурации
CNF_WR    <= '1' when (FRAMEn='0' and IDSEL='1' and CBEn="1011") else '0';           --Транзакция записи конфигурации
DONE      <= '1' when (FRAMEn='1' and IRDYn='1') else '0';                           --Транзакция Закончена

GEN  <= '1' when (nxt_stat=S_DATA) else '0'; --Запрос генератору на ПСП

--Сохранение адреса читаемого регистра в пространстве конфигурации
Process(CNF_RD)  
 begin
  if (CNF_RD'event and CNF_RD='1') then ADDR <= AD1(7 downto 2); end if;  
 end process; 
 
--Сохранение адреса устройства в регистр адреса в пространстве конфигурации 
Process(CNF_WR)
 begin
  if (CNF_WR'event and CNF_WR='0') then ADR:= AD1(31 downto 2)&"01" ; end if;  
 end process;
 
OUT1<=ADR;

OUT2(0)<=NOT_WE;
OUT2(1)<=RD_TX;  ---NEED!!
OUT2(2)<=CNF_RD; ---NEED!!
OUT2(3)<=CNF_WR;

MAIN:PROCESS(STAT)

--************
--*PROCEDURES*
--************

--Чтение данных

Procedure DATA_READ is

  begin 
     DEVSELn <='0';
     STOPn   <='1';
     TRDYn   <='0';
     PAR     <= PARITY(DATA_GEN) XOR PARITY(CBEn);
     
     AD1(7 downto 0)  <= DATA_GEN;
     AD1(31 downto 8) <="000000000000000000000000";
              
 end DATA_READ;
 
--Состояние ожидания

Procedure IDLE_PRC is

  begin 
     DEVSELn <='Z';
     STOPn   <='Z';
     TRDYn   <='Z';
     PAR     <='Z';         
     AD1     <=ZST;
 end IDLE_PRC;
  

--Неспособность обработать данную команду
 
Procedure BACKOFF_PRC is

  begin 
     DEVSELn <='1';
     STOPn   <='0';
     TRDYn   <='1';
     PAR     <='Z';         
     AD1     <=ZST;
 end BACKOFF_PRC;
 
--Чтение пространства конфигурации

Procedure CONF_READ is

  begin 
     DEVSELn <='0';
     STOPn   <='1';
     TRDYn   <='0';
     
     if (DECODER(ADDR)=4) then PAR <= PARITY(ADR) XOR PARITY(CBEn);
                               AD1 <= ADR;
                          else PAR <= PARITY(CNF(DECODER(ADDR))) XOR PARITY(CBEn);     
			       AD1 <= CNF(DECODER(ADDR)); end if;							   
              
 end CONF_READ;

--Запись в пространство конфигурации (BAR)

Procedure CONF_WRITE is

  begin     
     DEVSELn <='0';
     STOPn   <='1';
     TRDYn   <='0';
     PAR     <='Z';
                   
 end CONF_WRITE;
 
 
--**************
--*MAIN_PROCESS*
--**************
 
begin   
   case STAT is
    when S_DATA  => DATA_READ;
    when IDLE    => IDLE_PRC;
    when CONF_WR => CONF_WRITE;
    when CONF_RD => CONF_READ;
    when BACKOFF => BACKOFF_PRC;
    when others => IDLE_PRC;
   end case;   
end process MAIN;


END Interf_architecture;