design/sys/iop/dmu/rtl/dmu_psb_csrpipe_1.v

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//
// OpenSPARC T2 Processor File: dmu_psb_csrpipe_1.v
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module dmu_psb_csrpipe_1
        (
        clk,
        rst_l,
        reg_in,
        reg_out,
        data0,
        sel0,
        out
        );

//====================================================================
//     Polarity declarations
//====================================================================
input  clk;  // Clock signal
input  rst_l;  // Reset signal
input  reg_in;  // Set to constant. 0: sel* non-reg  1: sel* reg
input  reg_out;  // Set to constant. 0: out non-reg   1: out registered
input  [`FIRE_CSRBUS_DATA_WIDTH-1:0] data0;  // Read data
input  sel0;  // Set to 1 if reg_in==0
output [`FIRE_CSRBUS_DATA_WIDTH-1:0] out;  // Read data out

//====================================================================
//     Type declarations
//====================================================================
wire clk;  // Clock signal
wire rst_l;  // Reset signal
wire reg_in;  // Set to constant. 0: sel* non-reg  1: sel* reg
wire reg_out;  // Set to constant. 0: out non-reg   1: out registered
wire [`FIRE_CSRBUS_DATA_WIDTH-1:0] data0;  // Read data
wire sel0;  // Set to 1 if reg_in==0
wire [`FIRE_CSRBUS_DATA_WIDTH-1:0] out;  // Read data out

//====================================================================
//     Local variables
//====================================================================
reg [`FIRE_CSRBUS_DATA_WIDTH-1:0] out_p1;
reg sel0_p1;

//====================================================================
//     Logic
//====================================================================
//select required ?
wire sel0_int=reg_in?sel0_p1:sel0;

//generate AND/OR
wire [`FIRE_CSRBUS_DATA_WIDTH-1:0] out_d =
      {`FIRE_CSRBUS_DATA_WIDTH { sel0_int } } & data0;

//reg out or combo
assign out=reg_out?out_p1:out_d;

//pipe control/data
always @(posedge clk)
  begin
     if(~rst_l)
       begin
          sel0_p1<=1'b0;
          out_p1<=`FIRE_CSRBUS_DATA_WIDTH'b0;
        end
      else
        begin
          sel0_p1<=sel0;
          out_p1<=out_d;
        end
  end

endmodule // dmu_psb_csrpipe_1