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// ========== Copyright Header Begin ==========================================

// 

// OpenSPARC T1 Processor File: sparc_exu_reg.v

// Copyright (c) 2006 Sun Microsystems, Inc.  All Rights Reserved.

// DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.

// 

// The above named program is free software; you can redistribute it and/or

// modify it under the terms of the GNU General Public

// License version 2 as published by the Free Software Foundation.

// 

// The above named program is distributed in the hope that it will be 

// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

// General Public License for more details.

// 

// You should have received a copy of the GNU General Public

// License along with this work; if not, write to the Free Software

// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

// 

// ========== Copyright Header End ============================================

module sparc_exu_reg (/*AUTOARG*/

   // Outputs

   data_out,

   // Inputs

   clk, se, thr_out, wen_w, thr_w, data_in_w

   ) ;

   parameter SIZE = 3;

   input     clk;

   input     se;

   input [3:0]       thr_out;

   input             wen_w;

   input [3:0]       thr_w;

   input [SIZE -1:0] data_in_w;

   output [SIZE-1:0] data_out;

   wire [SIZE-1:0]   data_thr0;

   wire [SIZE-1:0]   data_thr1;

   wire [SIZE-1:0]   data_thr2;

   wire [SIZE-1:0]   data_thr3;

   wire [SIZE-1:0]   data_thr0_next;

   wire [SIZE-1:0]   data_thr1_next;

   wire [SIZE-1:0]   data_thr2_next;

   wire [SIZE-1:0]   data_thr3_next;

   wire          wen_thr0_w;

   wire          wen_thr1_w;

   wire          wen_thr2_w;

   wire          wen_thr3_w;

   //////////////////////////////////

   //  Output selection for reg

   //////////////////////////////////

`ifdef FPGA_SYN_1THREAD

   assign        data_out[SIZE -1:0] = data_thr0[SIZE -1:0];

   assign        wen_thr0_w = (thr_w[0] & wen_w);

   // mux between new and current value

   mux2ds #(SIZE) data_next0_mux(.dout(data_thr0_next[SIZE -1:0]),

                               .in0(data_thr0[SIZE -1:0]),

                               .in1(data_in_w[SIZE -1:0]),

                               .sel0(~wen_thr0_w),

                               .sel1(wen_thr0_w));

   dff_s #(SIZE) dff_reg_thr0(.din(data_thr0_next[SIZE -1:0]), .clk(clk), .q(data_thr0[SIZE -1:0]),

                       .se(se), .si(), .so());

`else // !`ifdef FPGA_SYN_1THREAD

   // mux between the 4 regs

   mux4ds #(SIZE) mux_data_out1(.dout(data_out[SIZE -1:0]), .sel0(thr_out[0]),

                               .sel1(thr_out[1]), .sel2(thr_out[2]),

                               .sel3(thr_out[3]), .in0(data_thr0[SIZE -1:0]),

                               .in1(data_thr1[SIZE -1:0]), .in2(data_thr2[SIZE -1:0]),

                               .in3(data_thr3[SIZE -1:0]));

   //////////////////////////////////////

   //  Storage of reg

   //////////////////////////////////////

   // enable input for each thread

   assign        wen_thr0_w = (thr_w[0] & wen_w);

   assign        wen_thr1_w = (thr_w[1] & wen_w);

   assign        wen_thr2_w = (thr_w[2] & wen_w);

   assign        wen_thr3_w = (thr_w[3] & wen_w);

   // mux between new and current value

   mux2ds #(SIZE) data_next0_mux(.dout(data_thr0_next[SIZE -1:0]),

                               .in0(data_thr0[SIZE -1:0]),

                               .in1(data_in_w[SIZE -1:0]),

                               .sel0(~wen_thr0_w),

                               .sel1(wen_thr0_w));

   mux2ds #(SIZE) data_next1_mux(.dout(data_thr1_next[SIZE -1:0]),

                               .in0(data_thr1[SIZE -1:0]),

                               .in1(data_in_w[SIZE -1:0]),

                               .sel0(~wen_thr1_w),

                               .sel1(wen_thr1_w));

   mux2ds #(SIZE) data_next2_mux(.dout(data_thr2_next[SIZE -1:0]),

                               .in0(data_thr2[SIZE -1:0]),

                               .in1(data_in_w[SIZE -1:0]),

                               .sel0(~wen_thr2_w),

                               .sel1(wen_thr2_w));

   mux2ds #(SIZE) data_next3_mux(.dout(data_thr3_next[SIZE -1:0]),

                               .in0(data_thr3[SIZE -1:0]),

                               .in1(data_in_w[SIZE -1:0]),

                               .sel0(~wen_thr3_w),

                               .sel1(wen_thr3_w));

   // store new value

   dff_s #(SIZE) dff_reg_thr0(.din(data_thr0_next[SIZE -1:0]), .clk(clk), .q(data_thr0[SIZE -1:0]),

                       .se(se), .si(), .so());

   dff_s #(SIZE) dff_reg_thr1(.din(data_thr1_next[SIZE -1:0]), .clk(clk), .q(data_thr1[SIZE -1:0]),

                       .se(se), .si(), .so());

   dff_s #(SIZE) dff_reg_thr2(.din(data_thr2_next[SIZE -1:0]), .clk(clk), .q(data_thr2[SIZE -1:0]),

                       .se(se), .si(), .so());

   dff_s #(SIZE) dff_reg_thr3(.din(data_thr3_next[SIZE -1:0]), .clk(clk), .q(data_thr3[SIZE -1:0]),

                       .se(se), .si(), .so());

`endif // !`ifdef FPGA_SYN_1THREAD

endmodule // sparc_exu_reg