// Copyright (C) 2020-2021  The SymbiFlow Authors.
//
// Use of this source code is governed by a ISC-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/ISC
//
// SPDX-License-Identifier:ISC

(* abc9_box, lib_whitebox *)
module adder_lut4(
   output lut4_out,
   (* abc9_carry *)
   output cout,
   input [0:3] in,
   (* abc9_carry *)
   input cin
);
    parameter [0:15] LUT=0;
    parameter IN2_IS_CIN = 0;

    wire [0:3] li = (IN2_IS_CIN) ? {in[0], in[1], cin, in[3]} : {in[0], in[1], in[2], in[3]};

    // Output function
    wire [0:7] s1 = li[0] ?
        {LUT[0], LUT[2], LUT[4], LUT[6], LUT[8], LUT[10], LUT[12], LUT[14]}:
        {LUT[1], LUT[3], LUT[5], LUT[7], LUT[9], LUT[11], LUT[13], LUT[15]};

    wire [0:3] s2 = li[1] ? {s1[0], s1[2], s1[4], s1[6]} : 
                            {s1[1], s1[3], s1[5], s1[7]};

    wire [0:1] s3 = li[2] ? {s2[0], s2[2]} : {s2[1], s2[3]};

    assign lut4_out = li[3] ? s3[0] : s3[1];
    
    // Carry out function
    assign cout = (s2[2]) ? cin : s2[3];
endmodule

(* abc9_lut=1, lib_whitebox *)
module frac_lut4(
   input [0:3] in,
   output [0:1] lut2_out,
   output lut4_out
);
    parameter [0:15] LUT = 0;
    
    // Effective LUT input
    wire [0:3] li = in;

    // Output function
    wire [0:7] s1 = li[0] ?
        {LUT[0], LUT[2], LUT[4], LUT[6], LUT[8], LUT[10], LUT[12], LUT[14]}:
        {LUT[1], LUT[3], LUT[5], LUT[7], LUT[9], LUT[11], LUT[13], LUT[15]};

    wire [0:3] s2 = li[1] ? {s1[0], s1[2], s1[4], s1[6]} : 
                            {s1[1], s1[3], s1[5], s1[7]};

    wire [0:1] s3 = li[2] ? {s2[0], s2[2]} : {s2[1], s2[3]};

    assign lut2_out[0] = s2[2];
    assign lut2_out[1] = s2[3];

    assign  lut4_out = li[3] ? s3[0] : s3[1];

endmodule

(* abc9_flop, lib_whitebox *)
module scff(
    output reg Q,
    input D,
    input clk
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(posedge clk)
        Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dff(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(posedge C)
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dffr(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C,
    input R
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(posedge C or negedge R)
        if (!R)
            Q <= 1'b0;
        else 
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module sh_dff(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(posedge C)
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dffs(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C,
    input S
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(posedge C or negedge S)
        if (!S)
            Q <= 1'b1;
        else
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dffn(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(negedge C)
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dffnr(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C,
    input R
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(negedge C or negedge R)
        if (!R)
            Q <= 1'b0;
        else 
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dffns(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C,
    input S
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(negedge C or negedge S)
        if (!S)
            Q <= 1'b1;
        else
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dffsr(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C,
    input R,
    input S
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(posedge C or negedge S or negedge R)
        if (!S)
            Q <= 1'b1;
        else if (!R)
            Q <= 1'b0;
        else
            Q <= D;
endmodule

(* abc9_flop, lib_whitebox *)
module dffnsr(
    output reg Q,
    input D,
    (* clkbuf_sink *)
    input C,
    input R,
    input S
);
    parameter [0:0] INIT = 1'b0;
    initial Q = INIT;

    always @(negedge C or negedge S or negedge R)
        if (!S)
            Q <= 1'b1;
        else if (!R)
            Q <= 1'b0;
        else
            Q <= D;
endmodule