ddr2_model.v

DDR2 SDRAM仿真模型

                                    end
                                    // DLL Reset
                                    dll_reset = addr[8];
                                    if (!dll_reset) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d DLL Reset = Normal", $time, cmd_string[cmd], bank);
                                    end else if (dll_reset) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d DLL Reset = Reset DLL", $time, cmd_string[cmd], bank);
                                        dll_locked = 0;
                                        ck_dll_reset <= ck_cntr;
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal DLL Reset = %d", $time, cmd_string[cmd], bank, dll_reset);
                                    end
                                    // Write Recovery
                                    write_recovery  = addr[11:9] + 1;
                                    if ((write_recovery >= WR_MIN) && (write_recovery <= WR_MAX)) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Write Recovery = %d", $time, cmd_string[cmd], bank, write_recovery);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal Write Recovery = %d", $time, cmd_string[cmd], bank, write_recovery);
                                    end
                                    // Power Down Mode
                                    low_power = addr[12];
                                    if (!low_power) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Power Down Mode = Fast Exit", $time, cmd_string[cmd], bank);
                                    end else if (low_power) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Power Down Mode = Slow Exit", $time, cmd_string[cmd], bank);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal Power Down Mode = %d", $time, cmd_string[cmd], bank, low_power);
                                    end
                                end
                                1 : begin
                                    // DLL Enable
                                    dll_en = !addr[0];
                                    if (!dll_en) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d DLL Enable = Disabled", $time, cmd_string[cmd], bank);
                                    end else if (dll_en) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d DLL Enable = Enabled", $time, cmd_string[cmd], bank);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal DLL Enable = %d", $time, cmd_string[cmd], bank, dll_en);
                                    end
                                    // Output Drive Strength
                                    if (!addr[1]) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Output Drive Strength = Full", $time, cmd_string[cmd], bank);
                                    end else if (addr[1]) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Output Drive Strength = Reduced", $time, cmd_string[cmd], bank);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal Output Drive Strength = %d", $time, cmd_string[cmd], bank, addr[1]);
                                    end
                                    // ODT Rtt
                                    odt_rtt = {addr[6], addr[2]};
                                    if (odt_rtt == 2'b00) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d ODT Rtt = Disabled", $time, cmd_string[cmd], bank);
                                        odt_en = 0;
                                    end else if (odt_rtt == 2'b01) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d ODT Rtt = 75 Ohm", $time, cmd_string[cmd], bank);
                                        odt_en = 1;
                                        tm_odt_en <= $time;
                                    end else if (odt_rtt == 2'b10) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d ODT Rtt = 150 Ohm", $time, cmd_string[cmd], bank);
                                        odt_en = 1;
                                        tm_odt_en <= $time;
                                    end else if (odt_rtt == 2'b11) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d ODT Rtt = 50 Ohm", $time, cmd_string[cmd], bank);
                                        odt_en = 1;
                                        tm_odt_en <= $time;
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal ODT Rtt = %d", $time, cmd_string[cmd], bank, odt_rtt);
                                        odt_en = 0;
                                    end
                                    // Additive Latency
                                    additive_latency = addr[5:3];
                                    read_latency = cas_latency + additive_latency;
                                    write_latency = read_latency - 1;
                                    if ((additive_latency >= AL_MIN) && (additive_latency <= AL_MAX)) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Additive Latency = %d", $time, cmd_string[cmd], bank, additive_latency);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal Additive Latency = %d", $time, cmd_string[cmd], bank, additive_latency);
                                    end
                                    // OCD Program
                                    ocd = addr[9:7];
                                    if (ocd == 3'b000) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d OCD Program = OCD Exit", $time, cmd_string[cmd], bank);
                                    end else if (ocd == 3'b111) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d OCD Program = OCD Default", $time, cmd_string[cmd], bank);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal OCD Program = %b", $time, cmd_string[cmd], bank, ocd);
                                    end

                                    // DQS_N Enable
                                    dqs_n_en = !addr[10];
                                    if (!dqs_n_en) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d DQS_N Enable = Disabled", $time, cmd_string[cmd], bank);
                                    end else if (dqs_n_en) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d DQS_N Enable = Enabled", $time, cmd_string[cmd], bank);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal DQS_N Enable = %d", $time, cmd_string[cmd], bank, dqs_n_en);
                                    end 
                                    // RDQS Enable
                                    rdqs_en = addr[11];
                                    if (!rdqs_en) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d RDQS Enable = Disabled", $time, cmd_string[cmd], bank);
                                    end else if (rdqs_en) begin
`ifdef x8
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d RDQS Enable = Enabled", $time, cmd_string[cmd], bank);
`else
                                        $display ("%m: at time %t WARNING: %s %d Illegal RDQS Enable.  RDQS only exists on a x8 part", $time, cmd_string[cmd], bank);
                                        rdqs_en = 0;
`endif
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal RDQS Enable = %d", $time, cmd_string[cmd], bank, rdqs_en);
                                    end 
                                    // Output Enable
                                    out_en = !addr[12];
                                    if (!out_en) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Output Enable = Disabled", $time, cmd_string[cmd], bank);
                                    end else if (out_en) begin
                                        if (DEBUG) $display ("%m: at time %t INFO: %s %d Output Enable = Enabled", $time, cmd_string[cmd], bank);
                                    end else begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal Output Enable = %d", $time, cmd_string[cmd], bank, out_en);
                                    end 
                                end
                                2, 3 : begin
                                    if (addr !== 0) begin
                                        $display ("%m: at time %t ERROR: %s %d Illegal value.  Reserved bits must be programmed to zero", $time, cmd_string[cmd], bank);
                                    end
                                end
                            endcase
                            init_mode_reg[bank] = 1;
                            ck_load_mode <= ck_cntr;
                        end
                    end
                    REFRESH : begin
                        if (|active_bank) begin
                            $display ("%m: at time %t ERROR: %s Failure.  All banks must be Precharged.", $time, cmd_string[cmd]);
                            if (STOP_ON_ERROR) $stop(0);
                        end else begin
                            if (DEBUG) $display ("%m: at time %t INFO: %s", $time, cmd_string[cmd]);
                            er_trfc_max = 0;
                            ref_cntr = ref_cntr + 1;
                            tm_refresh <= $time;
                        end
                    end
                    PRECHARGE : begin
                        // tRPA timing applies when the PRECHARGE (ALL) command is issued, regardless of
                        // the number of banks already open or closed.
                        if (addr[AP] && (`BANKS == 8)) begin
                            if (DEBUG) $display ("%m: at time %t INFO: %s All", $time, cmd_string[cmd]);
                            precharge_all = 1'b1;
                        end
                        // PRECHARGE command will be treated as a NOP if there is no open row in that bank (idle state), 
                        // or if the previously open row is already in the process of precharging
                        if (|active_bank) begin
                            for (i=0; i<`BANKS; i=i+1) begin
                                if (active_bank[i]) begin
                                    if (addr[AP] || (i == bank)) begin

                                        for (j=0; j<NOP; j=j+1) begin
                                            chk_err(1'b0, i, j, cmd);
                                            chk_err(1'b1, i, j, cmd);
                                        end
                                        chk_err(1'b0, i, PWR_DOWN, cmd);
                                        chk_err(1'b0, i, SELF_REF, cmd);

                                        if (auto_precharge_bank[i]) begin
                                            $display ("%m: at time %t ERROR: %s Failure.  Auto Precharge is scheduled to bank %d.", $time, cmd_string[cmd], i);
                                            if (STOP_ON_ERROR) $stop(0);
                                        end else begin
                                            if (DEBUG) $display ("%m: at time %t INFO: %s bank %d", $time, cmd_string[cmd], i);
                                            active_bank[i] = 1'b0;
                                            tm_bank_precharge[i] <= $time;
                                            tm_precharge <= $time;
                                        end
                                    end
                                end
                            end
                        end
                    end
                    ACTIVATE : begin
                        if (`BANKS == 8) begin
                            tfaw_cntr = 0;
                            for (i=0; i<`BANKS; i=i+1) begin
                                if ($time - tm_bank_activate[i] < TFAW) begin
                                    tfaw_cntr = tfaw_cntr + 1;
                                end
                            end
                            if (tfaw_cntr > 3) begin
                                $display ("%m: at time %t ERROR:  tFAW violation during %s to bank %d", $time, cmd_string[cmd], bank);
                            end
                        end

                        if (!init_done) begin
                            $display ("%m: at time %t ERROR: %s Failure.  Initialization sequence is not complete.", $time, cmd_string[cmd]);
                            if (STOP_ON_ERROR) $stop(0);
                        end else if (active_bank[bank]) begin
                            $display ("%m: at time %t ERROR: %s Failure.  Bank %d must be Precharged.", $time, cmd_string[cmd], bank);
                            if (STOP_ON_ERROR) $stop(0);
                        end else begin
                            if (addr >= 1<<ROW_BITS) begin
                                $display ("%m: at time %t WARNING: row = %h does not exist.  Maximum row = %h", $time, addr, (1<<ROW_BITS)-1);
                            end
                            if (DEBUG) $display ("%m: at time %t INFO: %s bank %d row %h", $time, cmd_string[cmd], bank, addr);
                            active_bank[bank] = 1'b1;
                            active_row[bank] = addr;
                            tm_bank_activate[bank] <= $time;
                            tm_activate <= $time;
                        end
                        
                    end
                    WRITE : begin
                        if (!init_done) begin
                            $display ("%m: at time %t ERROR: %s Failure.  Initialization sequence is not complete.", $time, cmd_string[cmd]);
                            if (STOP_ON_ERROR) $stop(0);
                        end else if (!active_bank[bank]) begin
                            $display ("%m: at time %t ERROR: %s Failure.  Bank %d must be Activated.", $time, cmd_string[cmd], bank);
                            if (STOP_ON_ERROR) $stop(0);
                        end else if (auto_precharge_bank[bank]) begin
                            $display ("%m: at time %t ERROR: %s Failure.  Auto Precharge is scheduled to bank %d.", $time, cmd_string[cmd], bank);
                            if (STOP_ON_ERROR) $stop(0);
                        end else if ((ck_cntr - ck_write < burst_length/2) && (ck_cntr - ck_write)%2) begin
                            $display ("%m: at time %t ERROR: %s Failure.  Illegal burst interruption.", $time, cmd_string[cmd]);
                            if (STOP_ON_ERROR) $stop(0);
                        end else begin
                            if (addr[AP]) begin
                                auto_precharge_bank[bank] = 1'b1;
                                write_precharge_bank[bank] = 1'b1;
                            end
                            col = ((addr>>1) & -1*(1<<AP)) | (addr & {AP{1'b1}});
                            if (col >= 1<<COL_BITS) begin
                                $display ("%m: at time %t WARNING: col = %h does not exist.  Maximum col = %h", $time, col, (1<<COL_BITS)-1);
                            end
                            if (DEBUG) $display ("%m: at time %t INFO: %s bank %d col %h, auto precharge %d", $time, cmd_string[cmd], bank, col, addr[AP]);
                            wr_pipeline[2*write_latency + 1]  = 1;
                            ba_pipeline[2*write_latency + 1]  = bank;