/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
 *
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

module VCC (output V);
   assign V = 1'b1;
endmodule // VCC

module GND (output G);
   assign G = 1'b0;
endmodule // GND

/* Altera Cyclone IV (GX) devices Input Buffer Primitive */
module cycloneiv_io_ibuf (output o, input i, input ibar);
   assign ibar = ibar;
   assign o    = i;
endmodule // fiftyfivenm_io_ibuf

/* Altera Cyclone IV (GX)  devices Output Buffer Primitive */
module cycloneiv_io_obuf (output o, input i, input oe);
   assign o  = i;
   assign oe = oe;
endmodule // fiftyfivenm_io_obuf

/* Altera MAX10 4-input non-fracturable LUT Primitive */
module cycloneiv_lcell_comb (output combout, cout,
                             input dataa, datab, datac, datad, cin);

/* Internal parameters which define the behaviour
   of the LUT primitive.
   lut_mask define the lut function, can be expressed in 16-digit bin or hex.
   sum_lutc_input define the type of LUT (combinational | arithmetic).
   dont_touch for retiming || carry options.
   lpm_type for WYSIWYG */

parameter lut_mask = 16'hFFFF;
parameter dont_touch = "off";
parameter lpm_type = "cycloneiv_lcell_comb";
parameter sum_lutc_input = "datac";

reg [1:0] lut_type;
reg cout_rt;
reg combout_rt;
wire dataa_w;
wire datab_w;
wire datac_w;
wire datad_w;
wire cin_w;

assign dataa_w = dataa;
assign datab_w = datab;
assign datac_w = datac;
assign datad_w = datad;

function lut_data;
input [15:0] mask;
input        dataa, datab, datac, datad;
reg [7:0]   s3;
reg [3:0]   s2;
reg [1:0]   s1;
  begin
       s3 = datad ? mask[15:8] : mask[7:0];
       s2 = datac ?   s3[7:4]  :   s3[3:0];
       s1 = datab ?   s2[3:2]  :   s2[1:0];
       lut_data = dataa ? s1[1] : s1[0];
  end

endfunction

initial begin
    if (sum_lutc_input == "datac") lut_type = 0;
    else
    if (sum_lutc_input == "cin")   lut_type = 1;
    else begin
      $error("Error in sum_lutc_input. Parameter %s is not a valid value.\n", sum_lutc_input);
      $finish();
    end
end

always @(dataa_w or datab_w or datac_w or datad_w or cin_w) begin
    if (lut_type == 0) begin // logic function
        combout_rt = lut_data(lut_mask, dataa_w, datab_w,
                            datac_w, datad_w);
    end
    else if (lut_type == 1) begin // arithmetic function
        combout_rt = lut_data(lut_mask, dataa_w, datab_w,
                            cin_w, datad_w);
    end
    cout_rt = lut_data(lut_mask, dataa_w, datab_w, cin_w, 'b0);
end

assign combout = combout_rt & 1'b1;
assign cout = cout_rt & 1'b1;

endmodule // cycloneiv_lcell_comb

/* Altera Cyclone IV Flip-Flop Primitive */
// TODO: Implement advanced simulation functions
module dffeas ( output q,
                input d, clk, clrn, prn, ena,
		input asdata, aload, sclr, sload );

parameter power_up="dontcare";
parameter is_wysiwyg="false";
  reg q;

  always @(posedge clk)
    q <= d;

endmodule