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/* ****************************************************************************

  This Source Code Form is subject to the terms of the

  Open Hardware Description License, v. 1.0. If a copy

  of the OHDL was not distributed with this file, You

  can obtain one at http://juliusbaxter.net/ohdl/ohdl.txt

  Description: RF writeback mux for espresso pipeline

  Choose between ALU and LSU input. All combinatorial

  Copyright (C) 2012 Authors

  Author(s): Julius Baxter <juliusbaxter@gmail.com>

***************************************************************************** */

`include "mor1kx-defines.v"

module mor1kx_wb_mux_espresso

  (/*AUTOARG*/

   // Outputs

   rf_result_o,

   // Inputs

   clk, rst, alu_result_i, lsu_result_i, ppc_i, pc_fetch_next_i,

   spr_i, op_jal_i, op_lsu_load_i, op_mfspr_i

   );

   parameter OPTION_OPERAND_WIDTH = 32;

   input clk, rst;

   input [OPTION_OPERAND_WIDTH-1:0] alu_result_i;

   input [OPTION_OPERAND_WIDTH-1:0] lsu_result_i;

   input [OPTION_OPERAND_WIDTH-1:0] ppc_i;

   input [OPTION_OPERAND_WIDTH-1:0] pc_fetch_next_i;

   input [OPTION_OPERAND_WIDTH-1:0] spr_i;

   output [OPTION_OPERAND_WIDTH-1:0] rf_result_o;

   input                              op_jal_i;

   input                              op_lsu_load_i;

   input                              op_mfspr_i;

   assign rf_result_o = op_lsu_load_i ? lsu_result_i :

                        op_mfspr_i ? spr_i :

                        // Use the PC we've calcuated from the fetch unit

                        // to save inferring a 32-bit adder here like we

                        // would if we did "ppc_i + 8"

                        op_jal_i ? pc_fetch_next_i:

                        alu_result_i;

endmodule // mor1kx_wb_mux_espresso