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

ENTITY Command_Unit IS
  PORT(
    H: IN std_logic;
    nRST: IN std_logic;
    LinSynchro: IN std_logic;

    octetRecu_EN: OUT std_logic;
    
    n_SELECT: OUT std_logic;
    n_LOAD: OUT std_logic;
    n_EN: OUT std_logic;

    BitNb_SELECT: OUT std_logic;
    BitNb_LOAD: OUT std_logic;
    BitNb_EN: OUT std_logic;

    IdentifierField_EN: OUT std_logic;

    nbData_LOAD: OUT std_logic;
    nbData_EN: OUT std_logic;
    
    n_0: IN std_logic;
    BitNb_0: IN std_logic;
    DataNb_0: IN std_logic;
    
    RecByte_WR: OUT std_logic;
    RecByte_RST: OUT std_logic := '0';
    
    ErrorSet: OUT std_logic_vector(3 downto 1);
    MsgRcv_SET: OUT std_logic
  );
END Command_Unit;

ARCHITECTURE arch of Command_Unit IS
TYPE state IS (waiting, syncBreak0, syncBreak1, syncFieldWait, syncFieldStart, syncFieldData, syncFieldStop, idFieldWait, idFieldStart, idFieldData, idFieldStop, dataFieldWait, dataFieldStart, dataFieldData, dataFieldStop, checksumFieldWait, checksumFieldStart, checksumFieldData, checksumFieldStop);
SIGNAL cState, nState : state;

type errors is record
  ErrorStartBit: std_logic;
  ErrorStopBit: std_logic;
  ErrorSync: std_logic;
end record errors;
SIGNAL errs: errors;

BEGIN

ErrorSet(1) <= errs.ErrorStartBit;
ErrorSet(2) <= errs.ErrorStopBit;
ErrorSet(3) <= errs.ErrorSync;

stateUpd : PROCESS(H, nRST)
BEGIN
  IF(nRST = '0') THEN
    cState <= waiting;
  ELSIF(rising_edge(H)) THEN
    cState <= nState;
  END IF;
END process stateUpd;

nStateUpd : PROCESS(LinSynchro, cState, n_0, BitNb_0)
BEGIN
nState <= cState;
CASE cState IS
  WHEN waiting =>
    if(LinSynchro = '0') THEN
      nState <= syncBreak0;
    END IF;
    
  WHEN syncBreak0 =>
    if(LinSynchro = '1') THEN
      if(BitNb_0 = '1') THEN
        nState <= syncBreak1;
      else
        nState <= waiting;
      END IF;
    END IF;
    
  WHEN syncBreak1 =>
    if(n_0 = '1') THEN
      if(LinSynchro = '1') THEN
        nState <= syncFieldWait;
      else
        nState <= waiting;
      end if;
    END IF;

  WHEN syncFieldWAit =>
    if(LinSynchro = '0') THEN
      nState <= syncFieldStart;
    END IF;

  WHEN syncFieldStart =>
    if(n_0 = '1') THEN
      IF(LinSynchro = '0') THEN
        nState <= syncFieldData;
      else
        nState <= waiting;
      END IF;
    end if;

  WHEN syncFieldData =>
    if(BitNb_0 = '1') THEN
      nState <= syncFieldStop;
    END IF;

  WHEN syncFieldStop =>
    if(n_0 = '1') THEN
      if(LinSynchro = '1') THEN
        nState <= idFieldWait;
      else
        nState <= waiting;
      end if;
    end if;
    
  WHEN idFieldWait =>
    if(LinSynchro = '0') then
      nState <= idFieldStart;
    end if;

  WHEN idFieldStart =>
    if(n_0 = '1') then
      if(LinSynchro = '0') then
        nState <= idFieldData;
      else
        nState <= waiting;
      end if;
    end if;

  WHEN idFieldData =>
    if(BitNb_0 = '1') then
      nState <= idFieldStop;
    end if;

  WHEN idFieldStop =>
    if(n_0 = '1') then
      if(LinSYnchro = '1') then
        nState <= dataFieldWait;
      else
        nState <= waiting;
      end if;
    end if;

  WHEN dataFieldWait =>
    if(LinSynchro = '0') then
      nState <= dataFieldStart;
    end if;

  WHEN dataFieldStart =>
    if(n_0 = '1') then
      if(LinSynchro = '0') then
        nState <= dataFieldData;
      else
        nState <= waiting;
      end if;
    end if;

  WHEN dataFieldData =>
    if(BitNb_0 = '1') then
      nState <= dataFieldStop;
    end if;

  WHEN dataFieldStop =>
    if(n_0 = '1') then
      if(LinSynchro = '1') then
        if(DataNb_0 = '1') then
          nState <= checksumFieldWait;
        else
          nState <= dataFieldWait;
        end if;
      else
        nState <= waiting;
      end if;
    end if;

  WHEN checksumFieldWait =>
    if(LinSynchro = '0') then
      nState <= checksumFieldStart;
    end if;

  WHEN checksumFieldStart =>
    if(n_0 = '1') then
      if(LinSynchro = '0') then
        nState <= checksumFieldData;
      else
        nState <= waiting;
      end if;
    end if;

  WHEN checksumFieldData =>
    if(BitNb_0 = '1') then
      nState <= checksumFieldStop;
    end if;

  WHEN checksumFieldStop =>
    if(n_0 = '1') then
      nState <= waiting;
    end if;

  end CASE;
END PROCESS nStateUpd;

RCS : PROCESS(cState, LinSynchro, n_0)
BEGIN
  BitNb_EN <= '0';
  nbData_EN <= '0';
  RecByte_WR <= '0';
  MsgRcv_SET <= '0';
  errs <= (others => '0');
  
  CASE cState IS
    WHEN waiting =>
      if(LinSynchro = '0') THEN
        n_LOAD <= '1';
        BitNb_EN <= '1';
        n_SELECT <= '1';
        BitNb_LOAD <= '1';
        BitNb_SELECT <= '0';
      end IF;
      
    WHEN syncBreak0 =>
      if(LinSynchro = '1') then
        if(BitNb_0 = '1') then
          n_LOAD <= '1';
          n_SELECT <= '0';
        else
          errs.ErrorSync <= '1';
        end if;
      else
        if(n_0 = '1' AND BitNb_0 = '0') then
          n_select <= '0';
          n_LOAD <= '1';
          BitNb_EN <= '1';
        else
          n_LOAD <= '0';
          BitNb_EN <= '0';
        end if;
        n_EN <= '1';
        BitNb_LOAD <= '0';
      end if;
      
    WHEN syncBreak1 =>
      if(n_0 = '1') then
        if(LinSynchro = '0') then
          errs.ErrorStopBit <= '1';
        end if;
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;
      
    WHEN syncFieldWait =>
      if(LinSynchro = '0') then
          n_LOAD <= '1';
          n_SELECT <= '1';
      end if;
      
    WHEN syncFieldStart =>
      if(n_0 = '1') then
        if(LinSynchro = '0') then
          n_SELECT <= '0';
          n_LOAD <= '1';
          BitNb_SELECT <= '1';
          BitNb_LOAD <= '1';
          BitNb_EN <= '1';
        else
          errs.ErrorStartBit <= '1';
        end if;
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;
      
    WHEN syncFieldData =>
      if(BitNb_0 = '1') then
        n_SELECT <= '0';
        n_LOAD <= '1';
        octetRecu_EN <= '0';
      else
        if(n_0 = '1') then
          n_LOAD <= '1';
          n_SELECT <= '0';
          BitNb_EN <= '1';
          octetRecu_EN <= '1';
        else
          n_LOAD <= '0';
          BitNb_EN <= '0';
          octetRecu_EN <= '0';
        end if;
        BitNb_LOAD <= '0';
      end if;
      
    WHEN syncFieldStop =>
      if(n_0 = '1') then
        if(LinSynchro = '1') then
          RecByte_WR <= '1';
        else
          errs.ErrorStopBit <= '1';
        end if;
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;
      
    WHEN idFieldWait =>
      if(LinSynchro = '0') then
        n_SELECT <= '1';
        n_LOAD <= '1';
      end if;

    WHEN idFieldStart =>
      if(n_0 = '1') then
        n_SELECT <= '0';
        n_LOAD <= '1';
        BitNb_SELECT <= '1';
        BitNb_LOAD <= '1';
        BitNb_EN <= '1';
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN idFieldData =>
      if(BitNb_0 = '1') then
        n_SELECT <= '0';
        n_LOAD <= '1';
        octetRecu_EN <= '0';
      else
        if(n_0 = '1') then
          n_LOAD <= '1';
          n_SELECT <= '0';
          BitNb_EN <= '1';
          octetRecu_EN <= '1';
        else
          n_LOAD <= '0';
          BitNb_EN <= '0';
          octetRecu_EN <= '0';
        end if;
        BitNb_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN idFieldStop =>
      if(n_0 = '1') then
        if(LinSynchro = '1') then
          nbData_LOAD <= '1';
          nbData_EN <= '1';
          IdentifierField_EN <= '1';
          RecByte_WR <= '1';
        else
          errs.ErrorStopBit <= '1';
        end if;
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN dataFieldWait =>
      if(LinSynchro = '0') then
        n_SELECT <= '1';
        n_LOAD <= '1';
      else
        nbData_EN <= '0';
        nbData_LOAD <= '0';
        IdentifierField_EN <= '0';
      end if;

    WHEN dataFieldStart =>
      if(n_0 = '1') then
        n_SELECT <= '0';
        n_LOAD <= '1';
        BitNb_SELECT <= '1';
        BitNb_LOAD <= '1';
        BitNb_EN <= '1';
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN dataFieldData =>
      if(BitNb_0 = '1') then
        n_SELECT <= '0';
        n_LOAD <= '1';
        octetRecu_EN <= '0';
      else
        if(n_0 = '1') then
          n_LOAD <= '1';
          n_SELECT <= '0';
          BitNb_EN <= '1';
          octetRecu_EN <= '1';
        else
          n_LOAD <= '0';
          BitNb_EN <= '0';
          octetRecu_EN <= '0';
        end if;
        BitNb_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN dataFieldStop =>
      if(n_0 = '1') then
        if(LinSynchro = '1') then
          nbData_EN <= '1';
          RecByte_WR <= '1';
        else
          errs.ErrorStopBit <= '1';
        end if;
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN checksumFieldWait =>
      if(LinSynchro = '0') then
        n_SELECT <= '1';
        n_LOAD <= '1';
      end if;

    WHEN checksumFieldStart =>
      if(n_0 = '1') then
        n_SELECT <= '0';
        n_LOAD <= '1';
        BitNb_SELECT <= '1';
        BitNb_LOAD <= '1';
        BitNb_EN <= '1';
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN checksumFieldData =>
      if(BitNb_0 = '1') then
        n_SELECT <= '0';
        n_LOAD <= '1';
        octetRecu_EN <= '0';
      else
        if(n_0 = '1') then
          n_LOAD <= '1';
          n_SELECT <= '0';
          BitNb_EN <= '1';
          octetRecu_EN <= '1';
        else
          n_LOAD <= '0';
          BitNb_EN <= '0';
          octetRecu_EN <= '0';
        end if;
        BitNb_LOAD <= '0';
        n_EN <= '1';
      end if;

    WHEN checksumFieldStop =>
      if(n_0 = '1') then
        if(LinSynchro = '1') then
          RecByte_WR <= '1';
          MsgRcv_SET <= '1';
        else
          errs.ErrorStopBit <= '1';
        end if;
      else
        n_LOAD <= '0';
        n_EN <= '1';
      end if;
    
      
  end CASE;
END PROCESS RCS;

END ARCHITECTURE arch;