mt48lc4m16.vhd

来自「VHDL的ram和fifo model code 包含众多的厂家」· VHDL 代码 · 共 1,475 行 · 第 1/5 页

                Violation := Pviol_CLK OR
                             Tviol_BA_CLK OR
                             Tviol_DQML_CLK OR
                             Tviol_DQMH_CLK OR
                             Tviol_CKE_CLK OR
                             Tviol_Address_CLK OR
                             Tviol_WENeg_CLK OR
                             Tviol_RASNeg_CLK OR
                             Tviol_CSNeg_CLK OR
                             Tviol_CASNeg_CLK;

                ASSERT Violation = '0'
                    REPORT InstancePath & partID & ": simulation may be" &
                           " inaccurate due to timing violations"
                    SEVERITY SeverityMode;

            END IF; -- Timing Check Section

    --------------------------------------------------------------------
    -- Functional Section
    --------------------------------------------------------------------

    IF (rising_edge(CLKIn)) THEN
        CKEreg <= CKE_nwv;
        IF (NOW > Next_Ref AND PoweredUp AND Ref_Cnt > 0) THEN
            Ref_Cnt := Ref_Cnt - 1;
            Next_Ref := NOW + tdevice_REF;
        END IF;
        IF CKEreg = '1' THEN
            IF CSNegIn = '0' THEN
                chip_en := true;
            ELSE
                chip_en := false;
            END IF;
        END IF;
    END IF;

    IF (rising_edge(CLKIn) AND CKEreg = '1' AND to_X01(CSNegIn) = '1') THEN
        command := nop;
    ELSIF (rising_edge(CLKIn) AND CKEreg = '1' AND to_X01(CSNegIn) = '0') THEN
        ASSERT (not(Is_X(WENegIn)))
            REPORT InstancePath & partID & ": Unusable value for WENeg"
            SEVERITY SeverityMode;
        ASSERT (not(Is_X(RASNegIn)))
            REPORT InstancePath & partID & ": Unusable value for RASNeg"
            SEVERITY SeverityMode;
        ASSERT (not(Is_X(CASNegIn)))
            REPORT InstancePath & partID & ": Unusable value for CASNeg"
            SEVERITY SeverityMode;

        -- Command Decode
        IF ((RASNegIn = '1') AND (CASNegIn = '1') AND (WENegIn = '1')) THEN
            command := nop;
        ELSIF ((RASNegIn = '0') AND (CASNegIn = '1') AND (WENegIn = '1')) THEN
            command := act;
        ELSIF ((RASNegIn = '1') AND (CASNegIn = '0') AND (WENegIn = '1')) THEN
            command := read;
        ELSIF ((RASNegIn = '1') AND (CASNegIn = '0') AND (WENegIn = '0')) THEN
            command := writ;
        ELSIF ((RASNegIn = '1') AND (CASNegIn = '1') AND (WENegIn = '0')) THEN
            command := bst;
        ELSIF ((RASNegIn = '0') AND (CASNegIn = '1') AND (WENegIn = '0')) THEN
            command := pre;
        ELSIF ((RASNegIn = '0') AND (CASNegIn = '0') AND (WENegIn = '1')) THEN
            command := ref;
        ELSIF ((RASNegIn = '0') AND (CASNegIn = '0') AND (WENegIn = '0')) THEN
            command := mrs;
        END IF;

        -- PowerUp Check
        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;

    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;

        -- by default data drive is Z, might get over written in one
        -- of the passes below
        DataDriveL := (OTHERS => 'Z');
        DataDriveH := (OTHERS => 'Z');
    -- The Big State Machine
        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;
                    DataDriveL := (OTHERS => 'Z');
                    DataDriveH := (OTHERS => 'Z');
                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_TRFC;
                        ELSE
                            statebank(bank) <= 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 10 ps;
                    rcdt_in(bank) <= '1', '0' AFTER 10 ps;
                    MemAddr(bank)(HiAddrBit+HiColBit+1 downto HiColBit +1) :=
                                                  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
                    Burst_Length := 1;
                    Burst_Bits := 0;
                ELSIF (ModeReg(2 downto 0) = "001") THEN
                    Burst_Length := 2;
                    Burst_Bits := 1;
                ELSIF (ModeReg(2 downto 0) = "010") THEN
                    Burst_Length := 4;
                    Burst_Bits := 2;
                ELSIF (ModeReg(2 downto 0) = "011") THEN
                    Burst_Length := 8;
                    Burst_Bits := 3;
                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;
                    ASSERT TimingModel(16) /= '6'
                        REPORT "CAS Latency 2 is NOT allowed for this "&
                        "TimingModel"
                        SEVERITY warning;
                ELSIF (ModeReg(6 downto 4) = "110") 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;
                    FixColumnAddress(bank);

                    ReadFromMem(bank);

                    Burst_Cnt(bank) := 1;
                    IF (AddressIn(10) = '0') THEN
                        statebank(bank) <= read;
                    ELSIF (AddressIn(10) = '1') THEN
                        statebank(bank) <= read_auto_pre;
                    END IF;
                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;

                    FixColumnAddress(bank);

                    WriteToMem(bank);

                    Burst_Cnt(bank) := 1;
                    IF (AddressIn(10) = '0') THEN
                        statebank(bank) <= write;
                    ELSIF (AddressIn(10) = '1') THEN
                        statebank(bank) <= write_auto_pre;
                    END IF;