mt48lc4m16.vhd

vhdl cod for ram.For sp3e

        IF (NOT(PoweredUp) AND command /= nop) THEN
            ASSERT false
                REPORT InstancePath & partID & ": Incorrect power up. Command"
                        & " issued before power up complete."
                SEVERITY SeverityMode;
        END IF;

        -- Bank Decode
        CASE BAIn IS
            WHEN "00" => cur_bank := 0; BankString := " Bank-0 ";
            WHEN "01" => cur_bank := 1; BankString := " Bank-1 ";
            WHEN "10" => cur_bank := 2; BankString := " Bank-2 ";
            WHEN "11" => cur_bank := 3; BankString := " Bank-3 ";
            WHEN others =>
                ASSERT false
                    REPORT InstancePath & partID & ": Could not decode bank"
                        & " selection - results may be incorrect."
                    SEVERITY SeverityMode;
        END CASE;
    END IF;

    -- The Big State Machine
    IF (rising_edge(CLKIn) AND CKEreg = '1') THEN

        ASSERT (not(Is_X(CSNegIn)))
            REPORT InstancePath & partID & ": Unusable value for CSNeg"
            SEVERITY SeverityMode;

        IF (CSNegIn = '1') THEN
            command := nop;
        END IF;

        -- DQM pipeline
        DQM0_reg2 := DQM0_reg1;
        DQM0_reg1 := DQM0_reg0;
        DQM0_reg0 := DQM0In;
        DQM1_reg2 := DQM1_reg1;
        DQM1_reg1 := DQM1_reg0;
        DQM1_reg0 := DQM1In;

        -- by default data drive is Z, might get over written in one
        -- of the passes below
        DataDrive := (OTHERS => 'Z');

        banks : FOR bank IN 0 TO hi_bank LOOP
        CASE statebank(bank) IS
        WHEN pwron =>
            IF (PoweredUp = false) THEN
                ASSERT (command = nop)
                    REPORT InstancePath & partID & BankString
                        &": Only NOPs allowed"
                        & " during power up."
                    SEVERITY SeverityMode;
                DataDrive := "ZZZZZZZZZZZZZZZZ";
            ELSIF (command = pre) AND ((cur_bank = bank) OR
                    (AddressIn(10) = '1')) THEN
                statebank(bank) <= precharge, idle AFTER tdevice_TRP;
            END IF;

        WHEN precharge =>
            IF cur_bank = bank THEN
                -- It is only an error if this bank is selected
                ASSERT (command = nop OR command = pre)
                    REPORT InstancePath & partID & BankString
                            &": Illegal command received"
                            & " during precharge."
                    SEVERITY SeverityMode;
            END IF;

        WHEN idle =>
            IF (command = nop OR command = bst OR command = pre) OR
                (cur_bank /= bank) THEN
                null;
            ELSIF (command = mrs) THEN
                IF (statebank = idle & idle & idle & idle) THEN
                    ModeReg := AddressIn;
                    statebank <= mode_set & mode_set & mode_set & mode_set;
                END IF;
            ELSIF (command = ref) THEN
                IF (statebank = idle & idle & idle & idle) THEN
                    IF (CKEIn = '1') THEN
                        statebank(bank) <= auto_refresh, idle  AFTER
                            tdevice_TRCAR;
                    ELSE
                        statebank <= self_refresh & self_refresh
                                & self_refresh & self_refresh;
                    END IF;
                END IF;
            ELSIF (command = act) THEN
                statebank(bank) <= bank_act;
                ras_in(bank)  <= '1', '0' AFTER 70 ns;
                rct_in  <= '1', '0' AFTER 1 ns;
                rcdt_in(bank) <= '1', '0' AFTER 1 ns;
                MemAddr(bank)(19 downto 8) := AddressIn;  -- latch row addr
            ELSE
                ASSERT false
                    REPORT InstancePath & partID & ": Illegal command"
                            & " received in idle state."
                    SEVERITY SeverityMode;
            END IF;

        WHEN mode_set =>
            statebank <= idle & idle & idle & idle;
            ASSERT (ModeReg(7) = '0' AND ModeReg(8) ='0')
                REPORT InstancePath & partID & BankString
                        &": Illegal operating mode set."
                SEVERITY SeverityMode;
            ASSERT command = nop
                REPORT InstancePath & partID & BankString
                        & ": Illegal command received during mode_set."
                SEVERITY SeverityMode;
            -- read burst length
            IF (ModeReg(2 downto 0) = "000") THEN
                BurstLen := 1;
                Burst_Bits := 0;
            ELSIF (ModeReg(2 downto 0) = "001") THEN
                BurstLen := 2;
                Burst_Bits := 1;
            ELSIF (ModeReg(2 downto 0) = "010") THEN
                BurstLen := 4;
                Burst_Bits := 2;
            ELSIF (ModeReg(2 downto 0) = "011") THEN
                BurstLen := 8;
                Burst_Bits := 3;
            ELSIF (ModeReg(2 downto 0) = "111") THEN
                BurstLen := 256;
                Burst_Bits := 7;
            ELSE
                ASSERT false
                    REPORT InstancePath & partID & BankString
                            &": Invalid burst length specified."
                    SEVERITY SeverityMode;
            END IF;
            -- read burst type
            IF (ModeReg(3) = '0') THEN
                Burst := sequential;
            ELSIF (ModeReg(3) = '1') THEN
                Burst := interleave;
            ELSE
                ASSERT false
                    REPORT InstancePath & partID & BankString
                            &": Invalid burst type specified."
                    SEVERITY SeverityMode;
            END IF;
            -- read CAS latency
            IF (ModeReg(6 downto 4) = "010") THEN
                CAS_Lat <= 2;
            ELSIF (ModeReg(6 downto 4) = "011") THEN
                CAS_Lat <= 3;
            ELSE
                ASSERT false
                REPORT InstancePath & partID & BankString &
                    ": CAS Latency set incorrecty "
                SEVERITY SeverityMode;
            END IF;
            -- read write burst mode
            IF (ModeReg(9) = '0') THEN
                WB := programmed;
            ELSIF (ModeReg(9) = '1') THEN
                WB := single;
            ELSE
                ASSERT false
                    REPORT InstancePath & partID & BankString &
                            ": Invalid burst type specified."
                    SEVERITY SeverityMode;
            END IF;

        WHEN auto_refresh =>
            IF (Ref_Cnt < 8192) THEN
                Ref_Cnt := Ref_Cnt + 1;
            END IF;
            ASSERT command = nop
                REPORT InstancePath & partID & BankString &
                        ": Illegal command received during auto_refresh."
                SEVERITY SeverityMode;

        WHEN bank_act =>
            IF (command = pre) AND ((cur_bank = bank) OR (AddressIn(10) = '1'))
                THEN
                ASSERT ras_out(bank) = '1'
                    REPORT InstancePath & partID & BankString &
                            ": precharge command"
                            & " does not meet tRAS time."
                    SEVERITY SeverityMode;
                statebank(bank) <= precharge, idle AFTER tdevice_TRP;
            ELSIF (command = nop OR command = bst) OR (cur_bank /= bank) THEN
                null;
            ELSIF (command = read) THEN
                ASSERT rcdt_out(bank) = '0'
                    REPORT InstancePath & partID & BankString &
                            ": read command received too soon after active."
                    SEVERITY SeverityMode;
                ASSERT ((AddressIn(10) = '0') OR (AddressIn(10) = '1'))
                    REPORT InstancePath & partID & BankString &
                            ": AddressIn(10) = X"
                            & " during read command. Next state unknown."
                    SEVERITY SeverityMode;
                MemAddr(bank)(7 downto 0) := (others => '0'); -- clr old addr

                BurstIncProc(Bank);

                MemAddr(bank)(7 downto Burst_Bits) :=
                            AddressIn(7 downto Burst_Bits); --latch col addr
                StartAddr(bank) := BurstInc(bank) mod 8;
                BaseLoc(bank) := to_nat(MemAddr(bank));
                Loc := 2*(BaseLoc(bank) + BurstInc(bank));

                generate_out(Bank);

                BurstCnt(bank) := 1;
                NextStateAuto(Bank,read);
            ELSIF (command = writ) THEN
                ASSERT rcdt_out(bank) = '0'
                    REPORT InstancePath & partID & BankString &
                            ": write command"
                            & " received too soon after active."
                    SEVERITY SeverityMode;
                ASSERT ((AddressIn(10) = '0') OR (AddressIn(10) = '1'))
                    REPORT InstancePath & partID & BankString &
                            ": AddressIn(10) = X"
                            & " during write command. Next state unknown."
                    SEVERITY SeverityMode;
                MemAddr(bank)(7 downto 0) := (others => '0'); -- clr old addr

                BurstIncProc(Bank);

                MemAddr(bank)(7 downto Burst_Bits) :=
                            AddressIn(7 downto Burst_Bits); --latch col addr

                StartAddr(bank) := BurstInc(bank) mod 8;
                BaseLoc(bank) := to_nat(MemAddr(bank));
                Loc := 2*(BaseLoc(bank) + BurstInc(bank));
                MemWrite(Bank);
                BurstCnt(bank) := 1;
                NextStateAuto(Bank,write);
                written := true;

            ELSIF (cur_bank = bank) OR (command = mrs) THEN
                ASSERT false
                    REPORT InstancePath & partID & BankString &
                            ": Illegal command "
                            & "received in active state."
                    SEVERITY SeverityMode;
            END IF;

        WHEN write =>
            IF (command = bst) THEN
                statebank(bank) <= bank_act;
                BurstCnt(bank) := 0;
            ELSIF (command = read) THEN
                IF (bank = cur_bank) THEN
                    MemAddr(bank)(7 downto 0):= (others => '0');-- clr old addr

                    BurstIncProc(Bank);

                    MemAddr(bank)(7 downto Burst_Bits) :=
                            AddressIn(7 downto Burst_Bits); --latch col addr

                    StartAddr(bank) := BurstInc(bank) mod 8;
                    BaseLoc(bank) := to_nat(MemAddr(bank));
                    Loc := 2*(BaseLoc(bank) + BurstInc(bank));

                    generate_out(Bank);

                    BurstCnt(bank) := 1;
                    NextStateAuto(Bank,read);
                ELSE
                    statebank(bank) <= bank_act;
                END IF;
            ELSIF (command = writ) THEN
                IF cur_bank = bank THEN
                    MemAddr(bank)(7 downto 0):=(others => '0');-- clr old addr

                    BurstIncProc(Bank);

                    MemAddr(bank)(7 downto Burst_Bits) :=
                            AddressIn(7 downto Burst_Bits); --latch col addr

                    StartAddr(bank) := BurstInc(bank) mod 8;
                    BaseLoc(bank) := to_nat(MemAddr(bank));
                    Loc := 2*(BaseLoc(bank) + BurstInc(bank));
                    MemWrite(Bank);
                    BurstCnt(bank) := 1;
                    IF (AddressIn(10) = '1') THEN
                        statebank(bank) <= write_auto_pre;
                    END IF;
                ELSE
                    statebank(bank) <= bank_act;
                END IF;
            ELSIF (command = pre) AND ((cur_bank = bank) OR
                                (AddressIn(10) = '1')) THEN
                ASSERT ras_out(bank) = '1'
                    REPORT InstancePath & partID & BankString &
                            ": precharge command"
                            & " does not meet tRAS time."
                    SEVERITY SeverityMode;
                ASSERT (DQML_nwv = '1')
                    REPORT InstancePath & partID & BankString &
                            ": DQML should be"
                            & " held high, data is lost."
                    SEVERITY SeverityMode;
                ASSERT (DQMH_nwv = '1')
                    REPORT InstancePath & partID & BankString &
                            ": DQMH should be"
                            & " held high, data is lost."
                    SEVERITY SeverityMode;
                    statebank(bank) <= precharge, idle AFTER tdevice_TRP;
            ELSIF (command = nop) OR (cur_bank /= bank) THEN
                IF (BurstCnt(bank) = BurstLen OR WB = single) THEN
                    statebank(bank) <= bank_act;
                    BurstCnt(bank) := 0;
                    ras_in(bank) <= '1';
                ELSE