Subversion Repositories s80186

// Copyright Jamie Iles, 2017

//

// This file is part of s80x86.

//

// s80x86 is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// s80x86 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 s80x86.  If not, see .

module IP(input logic clk,

          input logic reset,

          input logic start_instruction,

          input logic rollback,

          input logic inc,

          input logic wr_en,

          input logic [15:0] wr_val,

          output logic [15:0] val);

reg [15:0] cur_val;

reg [15:0] instruction_start_addr;

assign val = cur_val;

always_ff @(posedge clk or posedge reset)

    if (reset)

        instruction_start_addr <= 16'b0;

    else if (start_instruction)

        instruction_start_addr <= wr_en ? wr_val : cur_val;

always @(posedge clk or posedge reset)

    if (reset)

        cur_val <= 16'b0;

    else if (wr_en)

        cur_val <= wr_val;

    else if (rollback)

        cur_val <= instruction_start_addr;

    else if (inc)

        cur_val <= cur_val + 1'b1;

endmodule