SimpleProcessorCore/src/Steuerwerk.vhd

-------------------------------------------------------
--! @file 
--! @brief the control unit of the IIB2 Akkumulator machine
--! @author Dominik Meyer
--! @email dmeyer@hsu-hh.de
--! @date 2010-11-19
-------------------------------------------------------


library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

library work;
use work.cpupkg.all;

entity Steuerwerk is
    port  (
        iClk 			:	in 	std_logic;	--! iClk signal
        iReset			:	in		std_logic;	--! iReset signal
        icOpCode		:	in		optype;		--! icOpCode bus
        idCarry		:	in		std_logic;	--! carry from register file
        idZero			:	in		std_logic;	--! zero flag from register file
        ocRnotWRam	:	out	std_logic;	--! r_notw to RAM
        ocLoadEn		:	out	std_logic;	--! safe result of alu
        ocEnableRAM	:	out	std_logic;	--! put akku on databus
        ocLoadInstr	:	out	std_logic;	--! load instruction control signal
        ocNextPC		:	out	std_logic;	--! increment pc
        ocAddrSel		:	out	std_logic;	--! pc on addressbus
        ocJump			:	out	std_logic	--! do a ocJump
    );
end Steuerwerk;

architecture arch of Steuerwerk is

type STATES	is (load, decode, exshl, exshr, exsto, exloa, exadd, exsub, exaddc, exsubc, 
					exopor, exopand, exopxor, exopnot, exjpz, exjpc, exjmp, exhlt);

signal sState, sState_next	:	STATES;

begin

-- switch sStates if needed
sState_change: process(iClk,iReset)
begin
	if (iReset = '1') then
		sState	<= load;
		
	elsif (rising_edge(iClk)) then
		sState <= sState_next;
	end if;
end process;


calc_sState_next: process(sState, icOpCode, idCarry, idZero)
begin
	
	case sState is
		when load	=>
						sState_next	<= decode; 
		when decode	=>
						case icOpCode is
							when shl	=>		sState_next <= exshl;
							when shr	=>		sState_next <= exshr;
							when sto	=>  	sState_next <= exsto;
							when loa	=>		sState_next <= exloa;
							when add	=>  	sState_next <= exadd;
							when sub	=>  	sState_next <= exsub;
							when addc =>  	sState_next <= exaddc;
							when subc =>  	sState_next <= exsubc;
							when opand	=> sState_next <= exopand;
							when opor	=> sState_next <= exopor;
							when opxor	=> sState_next <= exopxor;
							when opnot	=> sState_next <= exopnot;
							when jpz		=> if (idZero = '1') then
													sState_next <= exjpz;
												else
													sState_next <= load;
												end if;
							when jpc		=> if (idCarry = '1') then
													sState_next <= exjpc;
												else
													sState_next <= load;
												end if;
							when jmp	=>  	sState_next <= exjmp;
							
							when hlt	=>  	sState_next <= exhlt;	
						end case;						
		when exhlt	=> sState_next <= exhlt;		
		when others => sState_next <= load;
	end case;

end process;



--! calculate the  output in each sState
calc_output: process(sState)
begin
	
	case sState is
		
		when load 	=>
						ocRnotWRam 		<= '1';	-- read from RAM
						ocLoadEn			<= '0';	-- do not save result
						ocEnableRAM		<= '1';	-- do not put akku on databus
						ocLoadInstr 	<= '0'; -- load instruction
						ocNextPC			<= '0';	-- do not increment pc
						ocAddrSel		<= '1';	-- pc on addressbus
						ocJump			<= '0';	-- no ocJump
						
		when decode	=>
						ocRnotWRam 		<= '1';	-- read from RAM
						ocLoadEn			<= '0';	-- do not save result
						ocEnableRAM		<= '1';	-- do not put akku on databus
						ocLoadInstr 	<= '1'; -- load instruction
						ocNextPC			<= '1';	-- do not increment pc
						ocAddrSel		<= '0';	-- pc on addressbus
						ocJump			<= '0';	-- no ocJump
						
		when exshl	=>
						ocRnotWRam 		<= '1';	-- read from RAM
						ocLoadEn			<= '1';	-- save result
						ocEnableRAM		<= '0';	-- do not put akku on databus
						ocLoadInstr 	<= '0'; -- do not load instruction
						ocNextPC			<= '0';	-- increment pc
						ocAddrSel		<= '0';	-- no pc on addressbus
						ocJump			<= '0';	-- no ocJump
						
		when exshr	=>
						ocRnotWRam 		<= '1';	-- read from RAM
						ocLoadEn			<= '1';	-- save result
						ocEnableRAM		<= '0';	-- do not put akku on databus
						ocLoadInstr 	<= '0'; -- do not load instruction
						ocNextPC			<= '0';	-- increment pc
						ocAddrSel		<= '0';	-- no pc on addressbus
						ocJump			<= '0';	-- no ocJump
		
		when exsto	=>
						ocRnotWRam 	<= '0';	-- write to RAM
						ocLoadEn		<= '0';	-- do not save result
						ocEnableRAM	<= '1';	-- put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump 
		
		when exloa	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump 
									
		when exadd	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump
				
		when exsub	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump
						
		when exaddc	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump
				
		when exsubc	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump
		
		when exopor	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump
		
		when exopand => 
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump						 
		
		when exopxor => 
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump	
						
		when exopnot => 
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '1';	-- save result
						ocEnableRAM	<= '1';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump
						
		when exjpz	 =>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '0';	-- save result
						ocEnableRAM	<= '0';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '1';	-- ocJump
						
		when exjpc	 =>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '0';	-- save result
						ocEnableRAM	<= '0';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '1';	-- ocJump
		
		when exjmp	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '0';	-- save result
						ocEnableRAM	<= '0';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '1';	-- ocJump
		when exhlt	=>
						ocRnotWRam 	<= '1';	-- read from RAM
						ocLoadEn		<= '0';	-- save result
						ocEnableRAM	<= '0';	-- do not put akku on databus
						ocLoadInstr <= '0'; -- do not load instruction
						ocNextPC		<= '0';	-- increment pc
						ocAddrSel	<= '0';	-- no pc on addressbus
						ocJump		<= '0';	-- no ocJump
		
		when others => 
						ocRnotWRam 	<= '-';	-- read from RAM
						ocLoadEn		<= '-';	-- save result
						ocEnableRAM	<= '-';	-- do not put akku on databus
						ocLoadInstr <= '-'; -- do not load instruction
						ocNextPC		<= '-';	-- increment pc
						ocAddrSel	<= '-';	-- no pc on addressbus
						ocJump		<= '-';	-- no ocJump
	end case;

end process;


end arch;