mig_7series_v1_9_arb_select.v

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//*****************************************************************************
//   ____  ____
//  /   /\/   /
// /___/  \  /    Vendor                : Xilinx
// \   \   \/     Version               : %version
//  \   \         Application           : MIG
//  /   /         Filename              : arb_select.v
// /___/   /\     Date Last Modified    : $date$
// \   \  /  \    Date Created          : Tue Jun 30 2009
//  \___\/\___\
//
//Device            : 7-Series
//Design Name       : DDR3 SDRAM
//Purpose           :
//Reference         :
//Revision History  :
//*****************************************************************************

// Based on granta_r and grantc_r, this module selects a
// row and column command from the request information
// provided by the bank machines.
//
// Depending on address mode configuration, nCL and nCWL, a column
// command pipeline of up to three states will be created.

`timescale 1 ps / 1 ps

module mig_7series_v1_9_arb_select #
  (
    parameter TCQ = 100,
    parameter EVEN_CWL_2T_MODE         = "OFF",
    parameter ADDR_CMD_MODE            = "1T",
    parameter BANK_VECT_INDX           = 11,
    parameter BANK_WIDTH               = 3,
    parameter BURST_MODE               = "8",
    parameter CS_WIDTH                 = 4,
    parameter CL                       = 5,
    parameter CWL                      = 5,
    parameter DATA_BUF_ADDR_VECT_INDX  = 31,
    parameter DATA_BUF_ADDR_WIDTH      = 8,
    parameter DRAM_TYPE                = "DDR3",
    parameter EARLY_WR_DATA_ADDR       = "OFF",
    parameter ECC                      = "OFF",
    parameter nBANK_MACHS              = 4,
    parameter nCK_PER_CLK              = 2,
    parameter nCS_PER_RANK             = 1,
    parameter CKE_ODT_AUX              = "FALSE",
    parameter nSLOTS                   = 2,
    parameter RANKS                    = 1,
    parameter RANK_VECT_INDX           = 15,
    parameter RANK_WIDTH               = 2,
    parameter ROW_VECT_INDX            = 63,
    parameter ROW_WIDTH                = 16,
    parameter RTT_NOM                  = "40",
    parameter RTT_WR                   = "120",
    parameter SLOT_0_CONFIG            = 8'b0000_0101,
    parameter SLOT_1_CONFIG            = 8'b0000_1010
  )
  (

    // Outputs

    output wire col_periodic_rd,
    output wire [RANK_WIDTH-1:0] col_ra,
    output wire [BANK_WIDTH-1:0] col_ba,
    output wire [ROW_WIDTH-1:0] col_a,
    output wire col_rmw,
    output wire col_rd_wr,
    output wire col_size,
    output wire [ROW_WIDTH-1:0] col_row,
    output wire [DATA_BUF_ADDR_WIDTH-1:0]     col_data_buf_addr,
    output wire [DATA_BUF_ADDR_WIDTH-1:0]     col_wr_data_buf_addr,

    output wire [nCK_PER_CLK-1:0]             mc_ras_n,
    output wire [nCK_PER_CLK-1:0]             mc_cas_n,
    output wire [nCK_PER_CLK-1:0]             mc_we_n,
    output wire [nCK_PER_CLK*ROW_WIDTH-1:0]   mc_address,
    output wire [nCK_PER_CLK*BANK_WIDTH-1:0]  mc_bank,
    output wire [CS_WIDTH*nCS_PER_RANK*nCK_PER_CLK-1:0] mc_cs_n,
    output wire [1:0]                         mc_odt,
    output wire [nCK_PER_CLK-1:0]             mc_cke,
    output wire [3:0]                         mc_aux_out0,
    output wire [3:0]                         mc_aux_out1,
    output      [2:0]                         mc_cmd,
    output wire [5:0]                         mc_data_offset,
    output wire [5:0]                         mc_data_offset_1,
    output wire [5:0]                         mc_data_offset_2,
    output wire [1:0]                         mc_cas_slot,
    
    output wire [RANK_WIDTH-1:0] rnk_config,

    // Inputs

    input clk,
    input rst,
    input init_calib_complete,

    input [RANK_VECT_INDX:0] req_rank_r,
    input [BANK_VECT_INDX:0] req_bank_r,
    input [nBANK_MACHS-1:0] req_ras,
    input [nBANK_MACHS-1:0] req_cas,
    input [nBANK_MACHS-1:0] req_wr_r,
    input [nBANK_MACHS-1:0] grant_row_r,
    input [nBANK_MACHS-1:0] grant_pre_r,
    input [ROW_VECT_INDX:0] row_addr,
    input [nBANK_MACHS-1:0] row_cmd_wr,
    input insert_maint_r1,
    input maint_zq_r,
    input maint_sre_r,
    input maint_srx_r,
    input [RANK_WIDTH-1:0] maint_rank_r,
    
    input [nBANK_MACHS-1:0] req_periodic_rd_r,
    input [nBANK_MACHS-1:0] req_size_r,
    input [nBANK_MACHS-1:0] rd_wr_r,
    input [ROW_VECT_INDX:0] req_row_r,
    input [ROW_VECT_INDX:0] col_addr,
    input [DATA_BUF_ADDR_VECT_INDX:0] req_data_buf_addr_r,
    input [nBANK_MACHS-1:0] grant_col_r,
    input [nBANK_MACHS-1:0] grant_col_wr,

    input [6*RANKS-1:0]     calib_rddata_offset,
    input [6*RANKS-1:0]     calib_rddata_offset_1,
    input [6*RANKS-1:0]     calib_rddata_offset_2,
    input [5:0]             col_channel_offset,
    
    input [nBANK_MACHS-1:0] grant_config_r,
    input rnk_config_strobe,

    input [7:0] slot_0_present,
    input [7:0] slot_1_present,

    input send_cmd0_row,
    input send_cmd0_col,
    input send_cmd1_row,
    input send_cmd1_col,
    input send_cmd2_row,
    input send_cmd2_col,
    input send_cmd2_pre,
    input send_cmd3_col,

    input sent_col,
    
    input cs_en0,
    input cs_en1,
    input cs_en2,
    input cs_en3

  );

  localparam OUT_CMD_WIDTH = RANK_WIDTH + BANK_WIDTH + ROW_WIDTH + 1 + 1 + 1;

  reg  col_rd_wr_ns;
  reg  col_rd_wr_r = 1'b0;
  reg [OUT_CMD_WIDTH-1:0] col_cmd_r = {OUT_CMD_WIDTH {1'b0}};
  reg [OUT_CMD_WIDTH-1:0] row_cmd_r = {OUT_CMD_WIDTH {1'b0}};
  
  // calib_rd_data_offset for currently targeted rank
  reg [5:0] rank_rddata_offset_0;
  reg [5:0] rank_rddata_offset_1;
  reg [5:0] rank_rddata_offset_2;

  // Toggle CKE[0] when entering and exiting self-refresh, disable CKE[1]
  assign mc_aux_out0[0] = (maint_sre_r || maint_srx_r) & insert_maint_r1;
  assign mc_aux_out0[2] = 1'b0;

  reg  cke_r;
  reg  cke_ns;
  generate
  if(CKE_ODT_AUX == "FALSE")begin
    always @(posedge clk) 
    begin
      if (rst)
         cke_r = 1'b1;
      else
         cke_r = cke_ns;
    end

    always @(*) 
    begin
      cke_ns = 1'b1;
      if (maint_sre_r & insert_maint_r1)
         cke_ns = 1'b0;
      else if (cke_r==1'b0)
      begin
         if (maint_srx_r & insert_maint_r1)
           cke_ns = 1'b1;
         else
           cke_ns = 1'b0;
      end
    end
  end
  endgenerate
  
  // Disable ODT & CKE toggle enable high bits
  assign mc_aux_out1 = 4'b0;

  // implement PHY command word  
  assign mc_cmd[0] = sent_col;
  assign mc_cmd[1] = EVEN_CWL_2T_MODE == "ON" ?
                        sent_col && col_rd_wr_r :
                        sent_col && col_rd_wr_ns;
  assign mc_cmd[2] = ~sent_col;

  // generate calib_rd_data_offset for current rank - only use rank 0 values for now
  always @(calib_rddata_offset or calib_rddata_offset_1 or calib_rddata_offset_2) begin
    rank_rddata_offset_0 = calib_rddata_offset[5:0];
    rank_rddata_offset_1 = calib_rddata_offset_1[5:0];
    rank_rddata_offset_2 = calib_rddata_offset_2[5:0];
  end

  // generate data offset
  generate
    if(EVEN_CWL_2T_MODE == "ON") begin : gen_mc_data_offset_even_cwl_2t
      assign mc_data_offset =   ~sent_col ?
                                  6'b0 :
                                col_rd_wr_r ?
                                    rank_rddata_offset_0 + col_channel_offset :
                                nCK_PER_CLK == 2 ? 
                                  CWL - 2 + col_channel_offset :
                            //  nCK_PER_CLK == 4
                                  CWL + 2 + col_channel_offset;
      assign mc_data_offset_1 = ~sent_col ?
                                  6'b0 :
                                col_rd_wr_r ?
                                    rank_rddata_offset_1 + col_channel_offset :
                                nCK_PER_CLK == 2 ? 
                                  CWL - 2 + col_channel_offset :
                            //  nCK_PER_CLK == 4
                                  CWL + 2 + col_channel_offset;
      assign mc_data_offset_2 = ~sent_col ?
                                  6'b0 :
                                col_rd_wr_r ?
                                    rank_rddata_offset_2 + col_channel_offset :
                                nCK_PER_CLK == 2 ? 
                                  CWL - 2 + col_channel_offset :
                            //  nCK_PER_CLK == 4
                                  CWL + 2 + col_channel_offset;
    end
    else begin : gen_mc_data_offset_not_even_cwl_2t
      assign mc_data_offset   = ~sent_col ?
                                  6'b0 :
                                col_rd_wr_ns ?
                                    rank_rddata_offset_0 + col_channel_offset :
                                nCK_PER_CLK == 2 ? 
                                  CWL - 2 + col_channel_offset :
                            //  nCK_PER_CLK == 4
                                  CWL + 2 + col_channel_offset;
      assign mc_data_offset_1 = ~sent_col ?
                                  6'b0 :
                                col_rd_wr_ns ?
                                    rank_rddata_offset_1 + col_channel_offset :
                                nCK_PER_CLK == 2 ? 
                                  CWL - 2 + col_channel_offset :
                            //  nCK_PER_CLK == 4
                                  CWL + 2 + col_channel_offset;
      assign mc_data_offset_2 = ~sent_col ?
                                  6'b0 :
                                col_rd_wr_ns ?
                                    rank_rddata_offset_2 + col_channel_offset :
                                nCK_PER_CLK == 2 ? 
                                  CWL - 2 + col_channel_offset :
                            //  nCK_PER_CLK == 4
                                  CWL + 2 + col_channel_offset;
    end
  endgenerate

  assign mc_cas_slot = col_channel_offset[1:0];

// Based on arbitration results, select the row and column commands.

  integer    i;
  reg [OUT_CMD_WIDTH-1:0] row_cmd_ns;
  generate
    begin : row_mux
      wire [OUT_CMD_WIDTH-1:0] maint_cmd =
                     {maint_rank_r,                     // maintenance rank
                      row_cmd_r[15+:(BANK_WIDTH+ROW_WIDTH-11)],
                                              // bank plus upper address bits
                      1'b0,                            // A10 = 0 for ZQCS
                      row_cmd_r[3+:10],                // address bits [9:0]
                      // ZQ, SRX or SRE/REFRESH
                      (maint_zq_r ? 3'b110 : maint_srx_r ? 3'b111 : 3'b001)
                     };
      always @(/*AS**/grant_row_r or insert_maint_r1 or maint_cmd
               or req_bank_r or req_cas or req_rank_r or req_ras
               or row_addr or row_cmd_r or row_cmd_wr or rst)
        begin
          row_cmd_ns = rst
                         ? {RANK_WIDTH{1'b0}}
                         : insert_maint_r1
                            ? maint_cmd
                            : row_cmd_r;
          for (i=0; i<nBANK_MACHS; i=i+1)
            if (grant_row_r[i])
               row_cmd_ns = {req_rank_r[(RANK_WIDTH*i)+:RANK_WIDTH],
                             req_bank_r[(BANK_WIDTH*i)+:BANK_WIDTH],
                             row_addr[(ROW_WIDTH*i)+:ROW_WIDTH],
                             req_ras[i],
                             req_cas[i],
                             row_cmd_wr[i]};
        end

      if (ADDR_CMD_MODE == "2T" && nCK_PER_CLK == 2)
        always @(posedge clk) row_cmd_r <= #TCQ row_cmd_ns;

    end  // row_mux
  endgenerate

  reg [OUT_CMD_WIDTH-1:0] pre_cmd_ns;
  generate
    if((nCK_PER_CLK == 4) && (ADDR_CMD_MODE != "2T")) begin : pre_mux
      reg [OUT_CMD_WIDTH-1:0] pre_cmd_r = {OUT_CMD_WIDTH {1'b0}};
      always @(/*AS**/grant_pre_r or req_bank_r or req_cas or req_rank_r or req_ras
               or row_addr or pre_cmd_r or row_cmd_wr or rst)
        begin
          pre_cmd_ns = rst
                         ? {RANK_WIDTH{1'b0}}
                         : pre_cmd_r;
          for (i=0; i<nBANK_MACHS; i=i+1)
            if (grant_pre_r[i])
               pre_cmd_ns = {req_rank_r[(RANK_WIDTH*i)+:RANK_WIDTH],
                             req_bank_r[(BANK_WIDTH*i)+:BANK_WIDTH],
                             row_addr[(ROW_WIDTH*i)+:ROW_WIDTH],
                             req_ras[i],
                             req_cas[i],
                             row_cmd_wr[i]};
        end

    end  // pre_mux
  endgenerate

  reg [OUT_CMD_WIDTH-1:0] col_cmd_ns;
  generate
    begin : col_mux
      reg col_periodic_rd_ns;
      reg col_periodic_rd_r;
      reg col_rmw_ns;
      reg col_rmw_r;
      reg col_size_ns;
      reg col_size_r;
      reg [ROW_WIDTH-1:0] col_row_ns;
      reg [ROW_WIDTH-1:0] col_row_r;
      reg [DATA_BUF_ADDR_WIDTH-1:0] col_data_buf_addr_ns;
      reg [DATA_BUF_ADDR_WIDTH-1:0] col_data_buf_addr_r;

      always @(col_addr or col_cmd_r or col_data_buf_addr_r
               or col_periodic_rd_r or col_rmw_r or col_row_r
               or col_size_r or grant_col_r or rd_wr_r or req_bank_r
               or req_data_buf_addr_r or req_periodic_rd_r
               or req_rank_r or req_row_r or req_size_r or req_wr_r
               or rst or col_rd_wr_r)
        begin
          col_periodic_rd_ns = ~rst && col_periodic_rd_r;
          col_cmd_ns = {(rst ? {RANK_WIDTH{1'b0}}
                             : col_cmd_r[(OUT_CMD_WIDTH-1)-:RANK_WIDTH]),
                        ((rst && ECC != "OFF")
                           ? {OUT_CMD_WIDTH-3-RANK_WIDTH{1'b0}}
                           : col_cmd_r[3+:(OUT_CMD_WIDTH-3-RANK_WIDTH)]),
                        (rst ? 3'b0 : col_cmd_r[2:0])};
          col_rmw_ns = col_rmw_r;
          col_size_ns = rst ? 1'b0 : col_size_r;
          col_row_ns = col_row_r;
          col_rd_wr_ns = col_rd_wr_r;
          col_data_buf_addr_ns = col_data_buf_addr_r;
          for (i=0; i<nBANK_MACHS; i=i+1)
            if (grant_col_r[i]) begin
              col_periodic_rd_ns = req_periodic_rd_r[i];
              col_cmd_ns = {req_rank_r[(RANK_WIDTH*i)+:RANK_WIDTH],
                            req_bank_r[(BANK_WIDTH*i)+:BANK_WIDTH],
                            col_addr[(ROW_WIDTH*i)+:ROW_WIDTH],
                            1'b1,
                            1'b0,
                            rd_wr_r[i]};
              col_rmw_ns = req_wr_r[i] && rd_wr_r[i];
              col_size_ns = req_size_r[i];
              col_row_ns = req_row_r[(ROW_WIDTH*i)+:ROW_WIDTH];
              col_rd_wr_ns = rd_wr_r[i];
              col_data_buf_addr_ns =
           req_data_buf_addr_r[(DATA_BUF_ADDR_WIDTH*i)+:DATA_BUF_ADDR_WIDTH];
            end
        end // always @ (...

      if (EARLY_WR_DATA_ADDR == "OFF") begin : early_wr_data_addr_off
        assign col_wr_data_buf_addr = col_data_buf_addr_ns;
      end
      else begin : early_wr_data_addr_on
        reg [DATA_BUF_ADDR_WIDTH-1:0] col_wr_data_buf_addr_ns;
        reg [DATA_BUF_ADDR_WIDTH-1:0] col_wr_data_buf_addr_r;
        always @(/*AS**/col_wr_data_buf_addr_r or grant_col_wr
                 or req_data_buf_addr_r) begin
          col_wr_data_buf_addr_ns = col_wr_data_buf_addr_r;
          for (i=0; i<nBANK_MACHS; i=i+1)
            if (grant_col_wr[i])
              col_wr_data_buf_addr_ns =
           req_data_buf_addr_r[(DATA_BUF_ADDR_WIDTH*i)+:DATA_BUF_ADDR_WIDTH];
        end
        always @(posedge clk) col_wr_data_buf_addr_r <= 
                                #TCQ col_wr_data_buf_addr_ns;
        assign col_wr_data_buf_addr = col_wr_data_buf_addr_ns;
      end

      always @(posedge clk) col_periodic_rd_r <= #TCQ col_periodic_rd_ns;
      always @(posedge clk) col_rmw_r <= #TCQ col_rmw_ns;
      always @(posedge clk) col_size_r <= #TCQ col_size_ns;
      always @(posedge clk) col_data_buf_addr_r <=
                              #TCQ col_data_buf_addr_ns;

      if (ECC != "OFF" || EVEN_CWL_2T_MODE == "ON") begin
        always @(posedge clk) col_cmd_r <= #TCQ col_cmd_ns;
        always @(posedge clk) col_row_r <= #TCQ col_row_ns;
      end

      always @(posedge clk) col_rd_wr_r <= #TCQ col_rd_wr_ns;

      if(EVEN_CWL_2T_MODE == "ON") begin

        assign col_periodic_rd = col_periodic_rd_r;
        assign col_ra = col_cmd_r[3+ROW_WIDTH+BANK_WIDTH+:RANK_WIDTH];
        assign col_ba = col_cmd_r[3+ROW_WIDTH+:BANK_WIDTH];
        assign col_a = col_cmd_r[3+:ROW_WIDTH];
        assign col_rmw = col_rmw_r;
        assign col_rd_wr = col_rd_wr_r;
        assign col_size = col_size_r;
        assign col_row = col_row_r;
        assign col_data_buf_addr = col_data_buf_addr_r;
      
      end

      else begin
      
        assign col_periodic_rd = col_periodic_rd_ns;
        assign col_ra = col_cmd_ns[3+ROW_WIDTH+BANK_WIDTH+:RANK_WIDTH];
        assign col_ba = col_cmd_ns[3+ROW_WIDTH+:BANK_WIDTH];
        assign col_a = col_cmd_ns[3+:ROW_WIDTH];
        assign col_rmw = col_rmw_ns;
        assign col_rd_wr = col_rd_wr_ns;
        assign col_size = col_size_ns;
        assign col_row = col_row_ns;
        assign col_data_buf_addr = col_data_buf_addr_ns;
        
      end
        
     end // col_mux
  endgenerate

  reg [OUT_CMD_WIDTH-1:0] cmd0 = {OUT_CMD_WIDTH{1'b1}};
  reg cke0;
  always @(send_cmd0_row or send_cmd0_col or row_cmd_ns or row_cmd_r or col_cmd_ns or col_cmd_r or cke_ns or cke_r ) begin
    cmd0 = {OUT_CMD_WIDTH{1'b1}};
    if (send_cmd0_row) cmd0 = row_cmd_ns;
    if (send_cmd0_row && EVEN_CWL_2T_MODE == "ON" && nCK_PER_CLK == 2) cmd0 = row_cmd_r;
    if (send_cmd0_col) cmd0 = col_cmd_ns;
    if (send_cmd0_col && EVEN_CWL_2T_MODE == "ON") cmd0 = col_cmd_r;
    if (send_cmd0_row) cke0 = cke_ns;
    else cke0 =  cke_r ;
  end

  reg [OUT_CMD_WIDTH-1:0] cmd1 = {OUT_CMD_WIDTH{1'b1}};
  generate
    if ((nCK_PER_CLK == 2) || (nCK_PER_CLK == 4))
      always @(send_cmd1_row or send_cmd1_col or row_cmd_ns or col_cmd_ns or pre_cmd_ns) begin
        cmd1 = {OUT_CMD_WIDTH{1'b1}};
        if (send_cmd1_row) cmd1 = row_cmd_ns;
        if (send_cmd1_col) cmd1 = col_cmd_ns;
      end
  endgenerate

  reg [OUT_CMD_WIDTH-1:0] cmd2 = {OUT_CMD_WIDTH{1'b1}};
  reg [OUT_CMD_WIDTH-1:0] cmd3 = {OUT_CMD_WIDTH{1'b1}};
  generate
    if (nCK_PER_CLK == 4)
      always @(send_cmd2_row or send_cmd2_col or send_cmd2_pre or send_cmd3_col or row_cmd_ns or col_cmd_ns or pre_cmd_ns) begin
        cmd2 = {OUT_CMD_WIDTH{1'b1}};
        cmd3 = {OUT_CMD_WIDTH{1'b1}};
        if (send_cmd2_row) cmd2 = row_cmd_ns;
        if (send_cmd2_col) cmd2 = col_cmd_ns;
        if (send_cmd2_pre) cmd2 = pre_cmd_ns;
        if (send_cmd3_col) cmd3 = col_cmd_ns;
      end
  endgenerate
  
  // Output command bus 0.
  wire [RANK_WIDTH-1:0] ra0;

  // assign address
  assign {ra0, mc_bank[BANK_WIDTH-1:0], mc_address[ROW_WIDTH-1:0], mc_ras_n[0], mc_cas_n[0], mc_we_n[0]} = cmd0;

  // Output command bus 1.
  wire [RANK_WIDTH-1:0] ra1;

  // assign address
  assign {ra1, mc_bank[2*BANK_WIDTH-1:BANK_WIDTH], mc_address[2*ROW_WIDTH-1:ROW_WIDTH], mc_ras_n[1], mc_cas_n[1], mc_we_n[1]} = cmd1;

  wire [RANK_WIDTH-1:0] ra2;
  wire [RANK_WIDTH-1:0] ra3;
generate 
if(nCK_PER_CLK == 4) begin
  // Output command bus 2.

   // assign address
   assign {ra2, mc_bank[3*BANK_WIDTH-1:2*BANK_WIDTH], mc_address[3*ROW_WIDTH-1:2*ROW_WIDTH], mc_ras_n[2], mc_cas_n[2], mc_we_n[2]} = cmd2;
   
  // Output command bus 3.

   // assign address
   assign {ra3, mc_bank[4*BANK_WIDTH-1:3*BANK_WIDTH], mc_address[4*ROW_WIDTH-1:3*ROW_WIDTH], mc_ras_n[3], mc_cas_n[3], mc_we_n[3]} =
     cmd3;
     
end
endgenerate


generate
  if(CKE_ODT_AUX == "FALSE")begin
    assign mc_cke[0] = cke0;
    assign mc_cke[1] = cke_ns;
    if(nCK_PER_CLK == 4) begin
      assign mc_cke[2] = cke_ns;
      assign mc_cke[3] = cke_ns;
    end
  end
endgenerate

// Output cs busses.

  localparam ONE = {nCS_PER_RANK{1'b1}};

  wire [(CS_WIDTH*nCS_PER_RANK)-1:0] cs_one_hot = 
                     {{CS_WIDTH{1'b0}},ONE};
  assign mc_cs_n[CS_WIDTH*nCS_PER_RANK -1  :0 ] =
     {(~(cs_one_hot << (nCS_PER_RANK*ra0)) | {CS_WIDTH*nCS_PER_RANK{~cs_en0}})};
  assign mc_cs_n[2*CS_WIDTH*nCS_PER_RANK -1  : CS_WIDTH*nCS_PER_RANK ] =
     {(~(cs_one_hot << (nCS_PER_RANK*ra1)) | {CS_WIDTH*nCS_PER_RANK{~cs_en1}})};

  generate
    if(nCK_PER_CLK  == 4) begin

      assign mc_cs_n[3*CS_WIDTH*nCS_PER_RANK -1  :2*CS_WIDTH*nCS_PER_RANK ] =
        {(~(cs_one_hot << (nCS_PER_RANK*ra2)) | {CS_WIDTH*nCS_PER_RANK{~cs_en2}})};

      assign mc_cs_n[4*CS_WIDTH*nCS_PER_RANK -1  :3*CS_WIDTH*nCS_PER_RANK ] =
        {(~(cs_one_hot << (nCS_PER_RANK*ra3)) | {CS_WIDTH*nCS_PER_RANK{~cs_en3}})};

    end
  endgenerate
  
  // Output rnk_config info.

  reg [RANK_WIDTH-1:0] rnk_config_ns;
  reg [RANK_WIDTH-1:0] rnk_config_r;
  always @(/*AS**/grant_config_r
           or rnk_config_r or rnk_config_strobe or req_rank_r or rst) begin
    if (rst) rnk_config_ns = {RANK_WIDTH{1'b0}};
    else begin
      rnk_config_ns = rnk_config_r;
      if (rnk_config_strobe)
        for (i=0; i<nBANK_MACHS; i=i+1)
          if (grant_config_r[i]) rnk_config_ns = req_rank_r[(RANK_WIDTH*i)+:RANK_WIDTH];
    end
  end

  always @(posedge clk) rnk_config_r <= #TCQ rnk_config_ns;
  assign rnk_config = rnk_config_ns;

// Generate ODT signals.

  wire [CS_WIDTH-1:0] col_ra_one_hot = cs_one_hot << col_ra;

  wire slot_0_select = (nSLOTS == 1) ? |(col_ra_one_hot & slot_0_present)
                       : (slot_0_present[2] & slot_0_present[0]) ?
                         |(col_ra_one_hot[CS_WIDTH-1:0] & {slot_0_present[2],
              slot_0_present[0]}) : (slot_0_present[0])?
                          col_ra_one_hot[0] : 1'b0;
  wire slot_0_read = EVEN_CWL_2T_MODE == "ON" ?
                      slot_0_select && col_rd_wr_r :
                      slot_0_select && col_rd_wr_ns;
  wire slot_0_write = EVEN_CWL_2T_MODE == "ON" ?
                        slot_0_select && ~col_rd_wr_r :
                        slot_0_select && ~col_rd_wr_ns;

  reg [1:0] slot_1_population = 2'b0;

  reg[1:0] slot_0_population;
  always @(/*AS**/slot_0_present) begin
    slot_0_population = 2'b0;
    for (i=0; i<8; i=i+1)
      if (~slot_0_population[1])
        if (slot_0_present[i] == 1'b1) slot_0_population =
                                         slot_0_population + 2'b1;
  end

  // ODT on in slot 0 for writes to slot 0 (and R/W to slot 1 for DDR3)
  wire slot_0_odt = (DRAM_TYPE == "DDR3") ? ~slot_0_read : slot_0_write;
  assign mc_aux_out0[1] = slot_0_odt & sent_col;  // Only send for COL cmds

  generate
    if (nSLOTS > 1) begin : slot_1_configured
      wire slot_1_select = (slot_1_present[3] & slot_1_present[1])? 
            |({col_ra_one_hot[slot_0_population+1],
            col_ra_one_hot[slot_0_population]}) :
       (slot_1_present[1]) ? col_ra_one_hot[slot_0_population] :1'b0;
      wire slot_1_read = EVEN_CWL_2T_MODE == "ON" ?
                          slot_1_select && col_rd_wr_r :
                          slot_1_select && col_rd_wr_ns;
      wire slot_1_write = EVEN_CWL_2T_MODE == "ON" ?
                            slot_1_select && ~col_rd_wr_r :
                            slot_1_select && ~col_rd_wr_ns;

      // ODT on in slot 1 for writes to slot 1 (and R/W to slot 0 for DDR3)
      wire slot_1_odt = (DRAM_TYPE == "DDR3") ? ~slot_1_read : slot_1_write;
      assign mc_aux_out0[3] = slot_1_odt & sent_col;  // Only send for COL cmds

    end // if (nSLOTS > 1)
    else begin
      
      // Disable slot 1 ODT when not present
      assign mc_aux_out0[3] = 1'b0;

    end // else: !if(nSLOTS > 1)
  endgenerate
 

 generate
 if(CKE_ODT_AUX == "FALSE")begin
   reg[1:0] mc_aux_out_r ;
   reg[1:0] mc_aux_out_r_1 ;
   reg[1:0] mc_aux_out_r_2 ;

   always@(posedge clk) begin
      mc_aux_out_r[0] <= #TCQ mc_aux_out0[1] ;
      mc_aux_out_r[1] <= #TCQ mc_aux_out0[3] ;
      mc_aux_out_r_1 <= #TCQ mc_aux_out_r ;
      mc_aux_out_r_2 <= #TCQ mc_aux_out_r_1 ;
   end 

   if((nCK_PER_CLK == 4) && (nSLOTS > 1 )) begin:odt_high_time_4_1_dslot
    assign mc_odt[0] = mc_aux_out0[1] | mc_aux_out_r[0] | mc_aux_out_r_1[0];
    assign mc_odt[1] = mc_aux_out0[3] | mc_aux_out_r[1] | mc_aux_out_r_1[1];
   end else if(nCK_PER_CLK == 4) begin:odt_high_time_4_1
    assign mc_odt[0] = mc_aux_out0[1] | mc_aux_out_r[0] ;
    assign mc_odt[1] = mc_aux_out0[3] | mc_aux_out_r[1] ;
   end else if(nCK_PER_CLK == 2) begin:odt_high_time_2_1
    assign mc_odt[0] = mc_aux_out0[1] | mc_aux_out_r[0] | mc_aux_out_r_1[0] | mc_aux_out_r_2[0] ;
    assign mc_odt[1] = mc_aux_out0[3] | mc_aux_out_r[1] | mc_aux_out_r_1[1] | mc_aux_out_r_2[1] ;
   end 
 end
 endgenerate 


endmodule