mt48lc8m8.vhd

vhdl cod for ram.For sp3e

            WHEN pwron =>
                IF (PoweredUp = false) THEN
                    ASSERT (command = nop)
                        REPORT InstancePath & partID & BankString
                               &": Only NOPs allowed"
                               & " during power up."
                        SEVERITY SeverityMode;
                    DataDrive := (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  -- IF cur_bank = bank THEN
                    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;
                    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
                    IF rising_edge(CLKIn) THEN
                        ASSERT false
                            REPORT InstancePath & partID & BankString &
                               ": Illegal command "
                               & "received in write state."
                            SEVERITY SeverityMode;
                    END IF;
                ELSIF (command = read) THEN
                    IF cur_bank = bank THEN

                        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;
                    ELSE
                        statebank(bank) <= bank_act;
                    END IF;
                ELSIF (command = writ) THEN
                    IF (Burst_Cnt(bank) = Burst_Length) THEN
                        statebank(bank) <= bank_act;
                        Burst_Cnt(bank) := 0;
                        ras_in(bank) <= '1';
                        Burst_Inc(bank) := 0;
                    ELSE
                        IF cur_bank = bank THEN

                            FixColumnAddress(bank);

                            ASSERT ((AddressIn(10) = '0') OR
                                    (AddressIn(10) = '1'))
                                REPORT InstancePath & partID & BankString &
                                  ": AddressIn(10) = X"
                                  & " during write command. Next state unknown."
                                SEVERITY SeverityMode;
                            IF (AddressIn(10) = '0') THEN
                                statebank(bank) <= write;
                            ELSIF (AddressIn(10) = '1') THEN
                                statebank(bank) <= write_auto_pre;
                            END IF;

                            WriteToMem(bank);

                            Burst_Cnt(bank) := 1;
                            written := true;
                        ELSE
                            statebank(bank)<=bank_act;
                        END IF;
                    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 (DQM_nwv = '1')
                       REPORT InstancePath & partID & BankString &
                          ": DQM 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 (Burst_Cnt(bank) = Burst_Length OR WB = single) THEN
                         statebank(bank) <= bank_act;
                         Burst_Cnt(bank) := 0;
                         ras_in(bank) <= '1';
                         Burst_Inc(bank) := 0;
                    ELSE
                         statebank(bank) <= write;
                         BurstCtrl(bank);

                         WriteToMem(bank);

                    END IF;
                ELSIF cur_bank = bank THEN
                    ASSERT false
                        REPORT InstancePath & partID & ": Illegal command"
                               & " received in write state."
                        SEVERITY SeverityMode;
                END IF;

            WHEN read =>
                IF (command = bst) THEN
                    statebank(bank) <= bank_act;
                    Burst_Cnt(bank) := 0;
                    Burst_Inc(bank) := 0;
                ELSIF (command = read) THEN