/*
 *  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.
 *
 */

// See Xilinx UG953 and UG474 for a description of the cell types below.
// http://www.xilinx.com/support/documentation/user_guides/ug474_7Series_CLB.pdf
// http://www.xilinx.com/support/documentation/sw_manuals/xilinx2014_4/ug953-vivado-7series-libraries.pdf

module VCC(output P);
  assign P = 1;
endmodule

module GND(output G);
  assign G = 0;
endmodule

module IBUF(
    output O,
    (* iopad_external_pin *)
    input I);
  parameter IOSTANDARD = "default";
  parameter IBUF_LOW_PWR = 0;
  assign O = I;
endmodule

module IBUFG(
    output O,
    (* iopad_external_pin *)
    input I);
  parameter CAPACITANCE = "DONT_CARE";
  parameter IBUF_DELAY_VALUE = "0";
  parameter IBUF_LOW_PWR = "TRUE";
  parameter IOSTANDARD = "DEFAULT";
  assign O = I;
endmodule

module OBUF(
    (* iopad_external_pin *)
    output O,
    input I);
  parameter IOSTANDARD = "default";
  parameter DRIVE = 12;
  parameter SLEW = "SLOW";
  assign O = I;
endmodule

module IOBUF (
    (* iopad_external_pin *)
    inout IO,
    output O,
    input I,
    input T
);
    parameter integer DRIVE = 12;
    parameter IBUF_LOW_PWR = "TRUE";
    parameter IOSTANDARD = "DEFAULT";
    parameter SLEW = "SLOW";
    assign IO = T ? 1'bz : I;
    assign O = IO;
endmodule

module OBUFT (
    (* iopad_external_pin *)
    output O,
    input I,
    input T
);
    parameter CAPACITANCE = "DONT_CARE";
    parameter integer DRIVE = 12;
    parameter IOSTANDARD = "DEFAULT";
    parameter SLEW = "SLOW";
    assign O = T ? 1'bz : I;
endmodule

module BUFG(
    (* clkbuf_driver *)
    output O,
    input I);

  assign O = I;
endmodule

module BUFGCTRL(
    (* clkbuf_driver *)
    output O,
    input I0, input I1,
    (* invertible_pin = "IS_S0_INVERTED" *)
    input S0,
    (* invertible_pin = "IS_S1_INVERTED" *)
    input S1,
    (* invertible_pin = "IS_CE0_INVERTED" *)
    input CE0,
    (* invertible_pin = "IS_CE1_INVERTED" *)
    input CE1,
    (* invertible_pin = "IS_IGNORE0_INVERTED" *)
    input IGNORE0,
    (* invertible_pin = "IS_IGNORE1_INVERTED" *)
    input IGNORE1);

parameter [0:0] INIT_OUT = 1'b0;
parameter PRESELECT_I0 = "FALSE";
parameter PRESELECT_I1 = "FALSE";
parameter [0:0] IS_CE0_INVERTED = 1'b0;
parameter [0:0] IS_CE1_INVERTED = 1'b0;
parameter [0:0] IS_S0_INVERTED = 1'b0;
parameter [0:0] IS_S1_INVERTED = 1'b0;
parameter [0:0] IS_IGNORE0_INVERTED = 1'b0;
parameter [0:0] IS_IGNORE1_INVERTED = 1'b0;

wire I0_internal = ((CE0 ^ IS_CE0_INVERTED) ? I0 : INIT_OUT);
wire I1_internal = ((CE1 ^ IS_CE1_INVERTED) ? I1 : INIT_OUT);
wire S0_true = (S0 ^ IS_S0_INVERTED);
wire S1_true = (S1 ^ IS_S1_INVERTED);

assign O = S0_true ? I0_internal : (S1_true ? I1_internal : INIT_OUT);

endmodule

module BUFHCE(
    (* clkbuf_driver *)
    output O,
    input I,
    (* invertible_pin = "IS_CE_INVERTED" *)
    input CE);

parameter [0:0] INIT_OUT = 1'b0;
parameter CE_TYPE = "SYNC";
parameter [0:0] IS_CE_INVERTED = 1'b0;

assign O = ((CE ^ IS_CE_INVERTED) ? I : INIT_OUT);

endmodule

// module OBUFT(output O, input I, T);
//   assign O = T ? 1'bz : I;
// endmodule

// module IOBUF(inout IO, output O, input I, T);
//   assign O = IO, IO = T ? 1'bz : I;
// endmodule

module INV(
    (* clkbuf_inv = "I" *)
    output O,
    input I
);
  assign O = !I;
endmodule

module LUT1(output O, input I0);
  parameter [1:0] INIT = 0;
  assign O = I0 ? INIT[1] : INIT[0];
endmodule

module LUT2(output O, input I0, I1);
  parameter [3:0] INIT = 0;
  wire [ 1: 0] s1 = I1 ? INIT[ 3: 2] : INIT[ 1: 0];
  assign O = I0 ? s1[1] : s1[0];
endmodule

module LUT3(output O, input I0, I1, I2);
  parameter [7:0] INIT = 0;
  wire [ 3: 0] s2 = I2 ? INIT[ 7: 4] : INIT[ 3: 0];
  wire [ 1: 0] s1 = I1 ?   s2[ 3: 2] :   s2[ 1: 0];
  assign O = I0 ? s1[1] : s1[0];
endmodule

module LUT4(output O, input I0, I1, I2, I3);
  parameter [15:0] INIT = 0;
  wire [ 7: 0] s3 = I3 ? INIT[15: 8] : INIT[ 7: 0];
  wire [ 3: 0] s2 = I2 ?   s3[ 7: 4] :   s3[ 3: 0];
  wire [ 1: 0] s1 = I1 ?   s2[ 3: 2] :   s2[ 1: 0];
  assign O = I0 ? s1[1] : s1[0];
endmodule

module LUT5(output O, input I0, I1, I2, I3, I4);
  parameter [31:0] INIT = 0;
  wire [15: 0] s4 = I4 ? INIT[31:16] : INIT[15: 0];
  wire [ 7: 0] s3 = I3 ?   s4[15: 8] :   s4[ 7: 0];
  wire [ 3: 0] s2 = I2 ?   s3[ 7: 4] :   s3[ 3: 0];
  wire [ 1: 0] s1 = I1 ?   s2[ 3: 2] :   s2[ 1: 0];
  assign O = I0 ? s1[1] : s1[0];
endmodule

module LUT6(output O, input I0, I1, I2, I3, I4, I5);
  parameter [63:0] INIT = 0;
  wire [31: 0] s5 = I5 ? INIT[63:32] : INIT[31: 0];
  wire [15: 0] s4 = I4 ?   s5[31:16] :   s5[15: 0];
  wire [ 7: 0] s3 = I3 ?   s4[15: 8] :   s4[ 7: 0];
  wire [ 3: 0] s2 = I2 ?   s3[ 7: 4] :   s3[ 3: 0];
  wire [ 1: 0] s1 = I1 ?   s2[ 3: 2] :   s2[ 1: 0];
  assign O = I0 ? s1[1] : s1[0];
endmodule

module LUT6_2(output O6, output O5, input I0, I1, I2, I3, I4, I5);
  parameter [63:0] INIT = 0;
  wire [31: 0] s5 = I5 ? INIT[63:32] : INIT[31: 0];
  wire [15: 0] s4 = I4 ?   s5[31:16] :   s5[15: 0];
  wire [ 7: 0] s3 = I3 ?   s4[15: 8] :   s4[ 7: 0];
  wire [ 3: 0] s2 = I2 ?   s3[ 7: 4] :   s3[ 3: 0];
  wire [ 1: 0] s1 = I1 ?   s2[ 3: 2] :   s2[ 1: 0];
  assign O6 = I0 ? s1[1] : s1[0];

  wire [15: 0] s5_4 = I4 ? INIT[31:16] : INIT[15: 0];
  wire [ 7: 0] s5_3 = I3 ? s5_4[15: 8] : s5_4[ 7: 0];
  wire [ 3: 0] s5_2 = I2 ? s5_3[ 7: 4] : s5_3[ 3: 0];
  wire [ 1: 0] s5_1 = I1 ? s5_2[ 3: 2] : s5_2[ 1: 0];
  assign O5 = I0 ? s5_1[1] : s5_1[0];
endmodule

module MUXCY(output O, input CI, DI, S);
  assign O = S ? CI : DI;
endmodule

(* abc9_box_id = 1, lib_whitebox *)
module MUXF7(output O, input I0, I1, S);
  assign O = S ? I1 : I0;
endmodule

(* abc9_box_id = 2, lib_whitebox *)
module MUXF8(output O, input I0, I1, S);
  assign O = S ? I1 : I0;
endmodule

module XORCY(output O, input CI, LI);
  assign O = CI ^ LI;
endmodule

(* abc9_box_id = 4, lib_whitebox *)
module CARRY4(
  (* abc9_carry *)
  output [3:0] CO,
  output [3:0] O,
  (* abc9_carry *)
  input        CI,
  input        CYINIT,
  input  [3:0] DI, S
);
  assign O = S ^ {CO[2:0], CI | CYINIT};
  assign CO[0] = S[0] ? CI | CYINIT : DI[0];
  assign CO[1] = S[1] ? CO[0] : DI[1];
  assign CO[2] = S[2] ? CO[1] : DI[2];
  assign CO[3] = S[3] ? CO[2] : DI[3];
endmodule

`ifdef _EXPLICIT_CARRY

module CARRY0(output CO_CHAIN, CO_FABRIC, O, input CI, CI_INIT, DI, S);
  parameter CYINIT_FABRIC = 0;
  wire CI_COMBINE;
  if(CYINIT_FABRIC) begin
    assign CI_COMBINE = CI_INIT;
  end else begin
    assign CI_COMBINE = CI;
  end
  assign CO_CHAIN = S ? CI_COMBINE : DI;
  assign CO_FABRIC = S ? CI_COMBINE : DI;
  assign O = S ^ CI_COMBINE;
endmodule

module CARRY(output CO_CHAIN, CO_FABRIC, O, input CI, DI, S);
  assign CO_CHAIN = S ? CI : DI;
  assign CO_FABRIC = S ? CI : DI;
  assign O = S ^ CI;
endmodule

`endif

// Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLL_L.sdf#L238-L250

module FDRE (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_C_INVERTED" *)
  input C,
  input CE,
  (* invertible_pin = "IS_D_INVERTED" *)
  input D,
  (* invertible_pin = "IS_R_INVERTED" *)
  input R
);
  parameter [0:0] INIT = 1'b0;
  parameter [0:0] IS_C_INVERTED = 1'b0;
  parameter [0:0] IS_D_INVERTED = 1'b0;
  parameter [0:0] IS_R_INVERTED = 1'b0;
  initial Q <= INIT;
  generate case (|IS_C_INVERTED)
    1'b0: always @(posedge C) if (R == !IS_R_INVERTED) Q <= 1'b0; else if (CE) Q <= D ^ IS_D_INVERTED;
    1'b1: always @(negedge C) if (R == !IS_R_INVERTED) Q <= 1'b0; else if (CE) Q <= D ^ IS_D_INVERTED;
  endcase endgenerate
endmodule

module FDSE (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_C_INVERTED" *)
  input C,
  input CE,
  (* invertible_pin = "IS_D_INVERTED" *)
  input D,
  (* invertible_pin = "IS_S_INVERTED" *)
  input S
);
  parameter [0:0] INIT = 1'b1;
  parameter [0:0] IS_C_INVERTED = 1'b0;
  parameter [0:0] IS_D_INVERTED = 1'b0;
  parameter [0:0] IS_S_INVERTED = 1'b0;
  initial Q <= INIT;
  generate case (|IS_C_INVERTED)
    1'b0: always @(posedge C) if (S == !IS_S_INVERTED) Q <= 1'b1; else if (CE) Q <= D ^ IS_D_INVERTED;
    1'b1: always @(negedge C) if (S == !IS_S_INVERTED) Q <= 1'b1; else if (CE) Q <= D ^ IS_D_INVERTED;
  endcase endgenerate
endmodule

module FDCE (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_C_INVERTED" *)
  input C,
  input CE,
  (* invertible_pin = "IS_D_INVERTED" *)
  input D,
  (* invertible_pin = "IS_CLR_INVERTED" *)
  input CLR
);
  parameter [0:0] INIT = 1'b0;
  parameter [0:0] IS_C_INVERTED = 1'b0;
  parameter [0:0] IS_D_INVERTED = 1'b0;
  parameter [0:0] IS_CLR_INVERTED = 1'b0;
  initial Q <= INIT;
  generate case ({|IS_C_INVERTED, |IS_CLR_INVERTED})
    2'b00: always @(posedge C, posedge CLR) if ( CLR) Q <= 1'b0; else if (CE) Q <= D ^ IS_D_INVERTED;
    2'b01: always @(posedge C, negedge CLR) if (!CLR) Q <= 1'b0; else if (CE) Q <= D ^ IS_D_INVERTED;
    2'b10: always @(negedge C, posedge CLR) if ( CLR) Q <= 1'b0; else if (CE) Q <= D ^ IS_D_INVERTED;
    2'b11: always @(negedge C, negedge CLR) if (!CLR) Q <= 1'b0; else if (CE) Q <= D ^ IS_D_INVERTED;
  endcase endgenerate
endmodule

module FDPE (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_C_INVERTED" *)
  input C,
  input CE,
  (* invertible_pin = "IS_D_INVERTED" *)
  input D,
  (* invertible_pin = "IS_PRE_INVERTED" *)
  input PRE
);
  parameter [0:0] INIT = 1'b1;
  parameter [0:0] IS_C_INVERTED = 1'b0;
  parameter [0:0] IS_D_INVERTED = 1'b0;
  parameter [0:0] IS_PRE_INVERTED = 1'b0;
  initial Q <= INIT;
  generate case ({|IS_C_INVERTED, |IS_PRE_INVERTED})
    2'b00: always @(posedge C, posedge PRE) if ( PRE) Q <= 1'b1; else if (CE) Q <= D ^ IS_D_INVERTED;
    2'b01: always @(posedge C, negedge PRE) if (!PRE) Q <= 1'b1; else if (CE) Q <= D ^ IS_D_INVERTED;
    2'b10: always @(negedge C, posedge PRE) if ( PRE) Q <= 1'b1; else if (CE) Q <= D ^ IS_D_INVERTED;
    2'b11: always @(negedge C, negedge PRE) if (!PRE) Q <= 1'b1; else if (CE) Q <= D ^ IS_D_INVERTED;
  endcase endgenerate
endmodule

module FDRE_1 (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  input C,
  input CE, D, R
);
  parameter [0:0] INIT = 1'b0;
  initial Q <= INIT;
  always @(negedge C) if (R) Q <= 1'b0; else if(CE) Q <= D;
endmodule

module FDSE_1 (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  input C,
  input CE, D, S
);
  parameter [0:0] INIT = 1'b1;
  initial Q <= INIT;
  always @(negedge C) if (S) Q <= 1'b1; else if(CE) Q <= D;
endmodule

module FDCE_1 (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  input C,
  input CE, D, CLR
);
  parameter [0:0] INIT = 1'b0;
  initial Q <= INIT;
  always @(negedge C, posedge CLR) if (CLR) Q <= 1'b0; else if (CE) Q <= D;
endmodule

module FDPE_1 (
  (* abc9_arrival=303 *)
  output reg Q,
  (* clkbuf_sink *)
  input C,
  input CE, D, PRE
);
  parameter [0:0] INIT = 1'b1;
  initial Q <= INIT;
  always @(negedge C, posedge PRE) if (PRE) Q <= 1'b1; else if (CE) Q <= D;
endmodule

module LDCE (
  output reg Q,
  (* invertible_pin = "IS_CLR_INVERTED" *)
  input CLR,
  input D,
  (* invertible_pin = "IS_G_INVERTED" *)
  input G,
  input GE
);
  parameter [0:0] INIT = 1'b0;
  parameter [0:0] IS_CLR_INVERTED = 1'b0;
  parameter [0:0] IS_G_INVERTED = 1'b0;
  parameter MSGON = "TRUE";
  parameter XON = "TRUE";
  initial Q = INIT;
  wire clr = CLR ^ IS_CLR_INVERTED;
  wire g = G ^ IS_G_INVERTED;
  always @*
    if (clr) Q = 1'b0;
    else if (GE && g) Q = D;
endmodule

module LDPE (
  output reg Q,
  input D,
  (* invertible_pin = "IS_G_INVERTED" *)
  input G,
  input GE,
  (* invertible_pin = "IS_PRE_INVERTED" *)
  input PRE
);
  parameter [0:0] INIT = 1'b1;
  parameter [0:0] IS_G_INVERTED = 1'b0;
  parameter [0:0] IS_PRE_INVERTED = 1'b0;
  parameter MSGON = "TRUE";
  parameter XON = "TRUE";
  initial Q = INIT;
  wire g = G ^ IS_G_INVERTED;
  wire pre = PRE ^ IS_PRE_INVERTED;
  always @*
    if (pre) Q = 1'b1;
    else if (GE && g) Q = D;
endmodule

module RAM32X1D (
  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L957
  (* abc9_arrival=1153 *)
  output DPO, SPO,
  input  D,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_WCLK_INVERTED" *)
  input  WCLK,
  input  WE,
  input  A0, A1, A2, A3, A4,
  input  DPRA0, DPRA1, DPRA2, DPRA3, DPRA4
);
  parameter INIT = 32'h0;
  parameter IS_WCLK_INVERTED = 1'b0;
  wire [4:0] a = {A4, A3, A2, A1, A0};
  wire [4:0] dpra = {DPRA4, DPRA3, DPRA2, DPRA1, DPRA0};
  reg [31:0] mem = INIT;
  assign SPO = mem[a];
  assign DPO = mem[dpra];
  wire clk = WCLK ^ IS_WCLK_INVERTED;
  always @(posedge clk) if (WE) mem[a] <= D;
endmodule

module RAM64X1D (
  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L957
  (* abc9_arrival=1153 *)
  output DPO, SPO,
  input  D,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_WCLK_INVERTED" *)
  input  WCLK,
  input  WE,
  input  A0, A1, A2, A3, A4, A5,
  input  DPRA0, DPRA1, DPRA2, DPRA3, DPRA4, DPRA5
);
  parameter INIT = 64'h0;
  parameter IS_WCLK_INVERTED = 1'b0;
  wire [5:0] a = {A5, A4, A3, A2, A1, A0};
  wire [5:0] dpra = {DPRA5, DPRA4, DPRA3, DPRA2, DPRA1, DPRA0};
  reg [63:0] mem = INIT;
  assign SPO = mem[a];
  assign DPO = mem[dpra];
  wire clk = WCLK ^ IS_WCLK_INVERTED;
  always @(posedge clk) if (WE) mem[a] <= D;
endmodule

module RAM128X1D (
  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L957
  (* abc9_arrival=1153 *)
  output DPO, SPO,
  input        D,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_WCLK_INVERTED" *)
  input        WCLK,
  input        WE,
  input  [6:0] A, DPRA
);
  parameter INIT = 128'h0;
  parameter IS_WCLK_INVERTED = 1'b0;
  reg [127:0] mem = INIT;
  assign SPO = mem[A];
  assign DPO = mem[DPRA];
  wire clk = WCLK ^ IS_WCLK_INVERTED;
  always @(posedge clk) if (WE) mem[A] <= D;
endmodule

module SRL16E (
  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L904-L905
  (* abc9_arrival=1472 *)
  output Q,
  input A0, A1, A2, A3, CE,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_CLK_INVERTED" *)
  input CLK,
  input D
);
  parameter [15:0] INIT = 16'h0000;
  parameter [0:0] IS_CLK_INVERTED = 1'b0;

  reg [15:0] r = INIT;
  assign Q = r[{A3,A2,A1,A0}];
  generate
    if (IS_CLK_INVERTED) begin
      always @(negedge CLK) if (CE) r <= { r[14:0], D };
    end
    else
      always @(posedge CLK) if (CE) r <= { r[14:0], D };
  endgenerate
endmodule

module SRLC16E (
  output Q,
  output Q15,
  input A0, A1, A2, A3, CE,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_CLK_INVERTED" *)
  input CLK,
  input D
);
  parameter [15:0] INIT = 16'h0000;
  parameter [0:0] IS_CLK_INVERTED = 1'b0;

  reg [15:0] r = INIT;
  assign Q15 = r[15];
  assign Q = r[{A3,A2,A1,A0}];
  generate
    if (IS_CLK_INVERTED) begin
      always @(negedge CLK) if (CE) r <= { r[14:0], D };
    end
    else
      always @(posedge CLK) if (CE) r <= { r[14:0], D };
  endgenerate
endmodule

module SRLC32E (
  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L904-L905
  (* abc9_arrival=1472 *)
  output Q,
  (* abc9_arrival=1114 *)
  output Q31,
  input [4:0] A,
  input CE,
  (* clkbuf_sink *)
  (* invertible_pin = "IS_CLK_INVERTED" *)
  input CLK,
  input D
);
  parameter [31:0] INIT = 32'h00000000;
  parameter [0:0] IS_CLK_INVERTED = 1'b0;

  reg [31:0] r = INIT;
  assign Q31 = r[31];
  assign Q = r[A];
  generate
    if (IS_CLK_INVERTED) begin
      always @(negedge CLK) if (CE) r <= { r[30:0], D };
    end
    else
      always @(posedge CLK) if (CE) r <= { r[30:0], D };
  endgenerate
endmodule

// DSP

// Virtex 2, Virtex 2 Pro, Spartan 3.

// Asynchronous mode.

module MULT18X18 (
    input signed [17:0] A,
    input signed [17:0] B,
    output signed [35:0] P
);

assign P = A * B;

endmodule

// Synchronous mode.

module MULT18X18S (
    input signed [17:0] A,
    input signed [17:0] B,
    output reg signed [35:0] P,
    (* clkbuf_sink *)
    input C,
    input CE,
    input R
);

always @(posedge C)
	if (R)
		P <= 0;
	else if (CE)
		P <= A * B;

endmodule

// Spartan 3E, Spartan 3A.

module MULT18X18SIO (
    input signed [17:0] A,
    input signed [17:0] B,
    output signed [35:0] P,
    (* clkbuf_sink *)
    input CLK,
    input CEA,
    input CEB,
    input CEP,
    input RSTA,
    input RSTB,
    input RSTP,
    input signed [17:0] BCIN,
    output signed [17:0] BCOUT
);

parameter integer AREG = 1;
parameter integer BREG = 1;
parameter B_INPUT = "DIRECT";
parameter integer PREG = 1;

// The multiplier.
wire signed [35:0] P_MULT;
assign P_MULT = A_MULT * B_MULT;

// The cascade output.
assign BCOUT = B_MULT;

// The B input multiplexer.
wire signed [17:0] B_MUX;
assign B_MUX = (B_INPUT == "DIRECT") ? B : BCIN;

// The registers.
reg signed [17:0] A_REG;
reg signed [17:0] B_REG;
reg signed [35:0] P_REG;

initial begin
	A_REG = 0;
	B_REG = 0;
	P_REG = 0;
end

always @(posedge CLK) begin
	if (RSTA)
		A_REG <= 0;
	else if (CEA)
		A_REG <= A;

	if (RSTB)
		B_REG <= 0;
	else if (CEB)
		B_REG <= B_MUX;

	if (RSTP)
		P_REG <= 0;
	else if (CEP)
		P_REG <= P_MULT;
end

// The register enables.
wire signed [17:0] A_MULT;
wire signed [17:0] B_MULT;
assign A_MULT = (AREG == 1) ? A_REG : A;
assign B_MULT = (BREG == 1) ? B_REG : B_MUX;
assign P = (PREG == 1) ? P_REG : P_MULT;

endmodule

// Spartan 3A DSP.

module DSP48A (
    input signed [17:0] A,
    input signed [17:0] B,
    input signed [47:0] C,
    input signed [17:0] D,
    input signed [47:0] PCIN,
    input CARRYIN,
    input [7:0] OPMODE,
    output signed [47:0] P,
    output signed [17:0] BCOUT,
    output signed [47:0] PCOUT,
    output CARRYOUT,
    (* clkbuf_sink *)
    input CLK,
    input CEA,
    input CEB,
    input CEC,
    input CED,
    input CEM,
    input CECARRYIN,
    input CEOPMODE,
    input CEP,
    input RSTA,
    input RSTB,
    input RSTC,
    input RSTD,
    input RSTM,
    input RSTCARRYIN,
    input RSTOPMODE,
    input RSTP
);

parameter integer A0REG = 0;
parameter integer A1REG = 1;
parameter integer B0REG = 0;
parameter integer B1REG = 1;
parameter integer CREG = 1;
parameter integer DREG = 1;
parameter integer MREG = 1;
parameter integer CARRYINREG = 1;
parameter integer OPMODEREG = 1;
parameter integer PREG = 1;
parameter CARRYINSEL = "CARRYIN";
parameter RSTTYPE = "SYNC";

// This is a strict subset of Spartan 6 -- reuse its model.

DSP48A1 #(
	.A0REG(A0REG),
	.A1REG(A1REG),
	.B0REG(B0REG),
	.B1REG(B1REG),
	.CREG(CREG),
	.DREG(DREG),
	.MREG(MREG),
	.CARRYINREG(CARRYINREG),
	.CARRYOUTREG(0),
	.OPMODEREG(OPMODEREG),
	.PREG(PREG),
	.CARRYINSEL(CARRYINSEL),
	.RSTTYPE(RSTTYPE)
) upgrade (
	.A(A),
	.B(B),
	.C(C),
	.D(D),
	.PCIN(PCIN),
	.CARRYIN(CARRYIN),
	.OPMODE(OPMODE),
	// M unconnected
	.P(P),
	.BCOUT(BCOUT),
	.PCOUT(PCOUT),
	.CARRYOUT(CARRYOUT),
	// CARRYOUTF unconnected
	.CLK(CLK),
	.CEA(CEA),
	.CEB(CEB),
	.CEC(CEC),
	.CED(CED),
	.CEM(CEM),
	.CECARRYIN(CECARRYIN),
	.CEOPMODE(CEOPMODE),
	.CEP(CEP),
	.RSTA(RSTA),
	.RSTB(RSTB),
	.RSTC(RSTC),
	.RSTD(RSTD),
	.RSTM(RSTM),
	.RSTCARRYIN(RSTCARRYIN),
	.RSTOPMODE(RSTOPMODE),
	.RSTP(RSTP)
);

endmodule

// Spartan 6.

module DSP48A1 (
    input signed [17:0] A,
    input signed [17:0] B,
    input signed [47:0] C,
    input signed [17:0] D,
    input signed [47:0] PCIN,
    input CARRYIN,
    input [7:0] OPMODE,
    output signed [35:0] M,
    output signed [47:0] P,
    output signed [17:0] BCOUT,
    output signed [47:0] PCOUT,
    output CARRYOUT,
    output CARRYOUTF,
    (* clkbuf_sink *)
    input CLK,
    input CEA,
    input CEB,
    input CEC,
    input CED,
    input CEM,
    input CECARRYIN,
    input CEOPMODE,
    input CEP,
    input RSTA,
    input RSTB,
    input RSTC,
    input RSTD,
    input RSTM,
    input RSTCARRYIN,
    input RSTOPMODE,
    input RSTP
);

parameter integer A0REG = 0;
parameter integer A1REG = 1;
parameter integer B0REG = 0;
parameter integer B1REG = 1;
parameter integer CREG = 1;
parameter integer DREG = 1;
parameter integer MREG = 1;
parameter integer CARRYINREG = 1;
parameter integer CARRYOUTREG = 1;
parameter integer OPMODEREG = 1;
parameter integer PREG = 1;
parameter CARRYINSEL = "OPMODE5";
parameter RSTTYPE = "SYNC";

wire signed [35:0] M_MULT;
wire signed [47:0] P_IN;
wire signed [17:0] A0_OUT;
wire signed [17:0] B0_OUT;
wire signed [17:0] A1_OUT;
wire signed [17:0] B1_OUT;
wire signed [17:0] B1_IN;
wire signed [47:0] C_OUT;
wire signed [17:0] D_OUT;
wire signed [7:0] OPMODE_OUT;
wire CARRYIN_OUT;
wire CARRYOUT_IN;
wire CARRYIN_IN;
reg signed [47:0] XMUX;
reg signed [47:0] ZMUX;

// The registers.
reg signed [17:0] A0_REG;
reg signed [17:0] A1_REG;
reg signed [17:0] B0_REG;
reg signed [17:0] B1_REG;
reg signed [47:0] C_REG;
reg signed [17:0] D_REG;
reg signed [35:0] M_REG;
reg signed [47:0] P_REG;
reg [7:0] OPMODE_REG;
reg CARRYIN_REG;
reg CARRYOUT_REG;

initial begin
	A0_REG = 0;
	A1_REG = 0;
	B0_REG = 0;
	B1_REG = 0;
	C_REG = 0;
	D_REG = 0;
	M_REG = 0;
	P_REG = 0;
	OPMODE_REG = 0;
	CARRYIN_REG = 0;
	CARRYOUT_REG = 0;
end

generate

if (RSTTYPE == "SYNC") begin
	always @(posedge CLK) begin
		if (RSTA) begin
			A0_REG <= 0;
			A1_REG <= 0;
		end else if (CEA) begin
			A0_REG <= A;
			A1_REG <= A0_OUT;
		end
	end

	always @(posedge CLK) begin
		if (RSTB) begin
			B0_REG <= 0;
			B1_REG <= 0;
		end else if (CEB) begin
			B0_REG <= B;
			B1_REG <= B1_IN;
		end
	end

	always @(posedge CLK) begin
		if (RSTC) begin
			C_REG <= 0;
		end else if (CEC) begin
			C_REG <= C;
		end
	end

	always @(posedge CLK) begin
		if (RSTD) begin
			D_REG <= 0;
		end else if (CED) begin
			D_REG <= D;
		end
	end

	always @(posedge CLK) begin
		if (RSTM) begin
			M_REG <= 0;
		end else if (CEM) begin
			M_REG <= M_MULT;
		end
	end

	always @(posedge CLK) begin
		if (RSTP) begin
			P_REG <= 0;
		end else if (CEP) begin
			P_REG <= P_IN;
		end
	end

	always @(posedge CLK) begin
		if (RSTOPMODE) begin
			OPMODE_REG <= 0;
		end else if (CEOPMODE) begin
			OPMODE_REG <= OPMODE;
		end
	end

	always @(posedge CLK) begin
		if (RSTCARRYIN) begin
			CARRYIN_REG <= 0;
			CARRYOUT_REG <= 0;
		end else if (CECARRYIN) begin
			CARRYIN_REG <= CARRYIN_IN;
			CARRYOUT_REG <= CARRYOUT_IN;
		end
	end
end else begin
	always @(posedge CLK, posedge RSTA) begin
		if (RSTA) begin
			A0_REG <= 0;
			A1_REG <= 0;
		end else if (CEA) begin
			A0_REG <= A;
			A1_REG <= A0_OUT;
		end
	end

	always @(posedge CLK, posedge RSTB) begin
		if (RSTB) begin
			B0_REG <= 0;
			B1_REG <= 0;
		end else if (CEB) begin
			B0_REG <= B;
			B1_REG <= B1_IN;
		end
	end

	always @(posedge CLK, posedge RSTC) begin
		if (RSTC) begin
			C_REG <= 0;
		end else if (CEC) begin
			C_REG <= C;
		end
	end

	always @(posedge CLK, posedge RSTD) begin
		if (RSTD) begin
			D_REG <= 0;
		end else if (CED) begin
			D_REG <= D;
		end
	end

	always @(posedge CLK, posedge RSTM) begin
		if (RSTM) begin
			M_REG <= 0;
		end else if (CEM) begin
			M_REG <= M_MULT;
		end
	end

	always @(posedge CLK, posedge RSTP) begin
		if (RSTP) begin
			P_REG <= 0;
		end else if (CEP) begin
			P_REG <= P_IN;
		end
	end

	always @(posedge CLK, posedge RSTOPMODE) begin
		if (RSTOPMODE) begin
			OPMODE_REG <= 0;
		end else if (CEOPMODE) begin
			OPMODE_REG <= OPMODE;
		end
	end

	always @(posedge CLK, posedge RSTCARRYIN) begin
		if (RSTCARRYIN) begin
			CARRYIN_REG <= 0;
			CARRYOUT_REG <= 0;
		end else if (CECARRYIN) begin
			CARRYIN_REG <= CARRYIN_IN;
			CARRYOUT_REG <= CARRYOUT_IN;
		end
	end
end

endgenerate

// The register enables.
assign A0_OUT = (A0REG == 1) ? A0_REG : A;
assign A1_OUT = (A1REG == 1) ? A1_REG : A0_OUT;
assign B0_OUT = (B0REG == 1) ? B0_REG : B;
assign B1_OUT = (B1REG == 1) ? B1_REG : B1_IN;
assign C_OUT = (CREG == 1) ? C_REG : C;
assign D_OUT = (DREG == 1) ? D_REG : D;
assign M = (MREG == 1) ? M_REG : M_MULT;
assign P = (PREG == 1) ? P_REG : P_IN;
assign OPMODE_OUT = (OPMODEREG == 1) ? OPMODE_REG : OPMODE;
assign CARRYIN_OUT = (CARRYINREG == 1) ? CARRYIN_REG : CARRYIN_IN;
assign CARRYOUT = (CARRYOUTREG == 1) ? CARRYOUT_REG : CARRYOUT_IN;
assign CARRYOUTF = CARRYOUT;

// The pre-adder.
wire signed [17:0] PREADDER;
assign B1_IN = OPMODE_OUT[4] ? PREADDER : B0_OUT;
assign PREADDER = OPMODE_OUT[6] ? D_OUT - B0_OUT : D_OUT + B0_OUT;

// The multiplier.
assign M_MULT = A1_OUT * B1_OUT;

// The carry in selection.
assign CARRYIN_IN = (CARRYINSEL == "OPMODE5") ? OPMODE_OUT[5] : CARRYIN;

// The post-adder inputs.
always @* begin
	case (OPMODE_OUT[1:0])
		2'b00: XMUX <= 0;
		2'b01: XMUX <= M;
		2'b10: XMUX <= P;
		2'b11: XMUX <= {D_OUT[11:0], B1_OUT, A1_OUT};
		default: XMUX <= 48'hxxxxxxxxxxxx;
	endcase
end

always @* begin
	case (OPMODE_OUT[3:2])
		2'b00: ZMUX <= 0;
		2'b01: ZMUX <= PCIN;
		2'b10: ZMUX <= P;
		2'b11: ZMUX <= C_OUT;
		default: ZMUX <= 48'hxxxxxxxxxxxx;
	endcase
end

// The post-adder.
wire signed [48:0] X_EXT;
wire signed [48:0] Z_EXT;
assign X_EXT = XMUX;
assign Z_EXT = ZMUX;
assign {CARRYOUT_IN, P_IN} = OPMODE_OUT[7] ? (Z_EXT - (X_EXT + CARRYIN_OUT)) : (Z_EXT + X_EXT + CARRYIN_OUT);

// Cascade outputs.
assign BCOUT = B1_OUT;
assign PCOUT = P;

endmodule

// TODO: DSP48 (Virtex 4).

// TODO: DSP48E (Virtex 5).

// Virtex 6, Series 7.

module DSP48E1 (
    output [29:0] ACOUT,
    output [17:0] BCOUT,
    output reg CARRYCASCOUT,
    output reg [3:0] CARRYOUT,
    output reg MULTSIGNOUT,
    output OVERFLOW,
    output reg signed [47:0] P,
    output reg PATTERNBDETECT,
    output reg PATTERNDETECT,
    output [47:0] PCOUT,
    output UNDERFLOW,
    input signed [29:0] A,
    input [29:0] ACIN,
    input [3:0] ALUMODE,
    input signed [17:0] B,
    input [17:0] BCIN,
    input [47:0] C,
    input CARRYCASCIN,
    input CARRYIN,
    input [2:0] CARRYINSEL,
    input CEA1,
    input CEA2,
    input CEAD,
    input CEALUMODE,
    input CEB1,
    input CEB2,
    input CEC,
    input CECARRYIN,
    input CECTRL,
    input CED,
    input CEINMODE,
    input CEM,
    input CEP,
    (* clkbuf_sink *) input CLK,
    input [24:0] D,
    input [4:0] INMODE,
    input MULTSIGNIN,
    input [6:0] OPMODE,
    input [47:0] PCIN,
    input RSTA,
    input RSTALLCARRYIN,
    input RSTALUMODE,
    input RSTB,
    input RSTC,
    input RSTCTRL,
    input RSTD,
    input RSTINMODE,
    input RSTM,
    input RSTP
);
    parameter integer ACASCREG = 1;
    parameter integer ADREG = 1;
    parameter integer ALUMODEREG = 1;
    parameter integer AREG = 1;
    parameter AUTORESET_PATDET = "NO_RESET";
    parameter A_INPUT = "DIRECT";
    parameter integer BCASCREG = 1;
    parameter integer BREG = 1;
    parameter B_INPUT = "DIRECT";
    parameter integer CARRYINREG = 1;
    parameter integer CARRYINSELREG = 1;
    parameter integer CREG = 1;
    parameter integer DREG = 1;
    parameter integer INMODEREG = 1;
    parameter integer MREG = 1;
    parameter integer OPMODEREG = 1;
    parameter integer PREG = 1;
    parameter SEL_MASK = "MASK";
    parameter SEL_PATTERN = "PATTERN";
    parameter USE_DPORT = "FALSE";
    parameter USE_MULT = "MULTIPLY";
    parameter USE_PATTERN_DETECT = "NO_PATDET";
    parameter USE_SIMD = "ONE48";
    parameter [47:0] MASK = 48'h3FFFFFFFFFFF;
    parameter [47:0] PATTERN = 48'h000000000000;
    parameter [3:0] IS_ALUMODE_INVERTED = 4'b0;
    parameter [0:0] IS_CARRYIN_INVERTED = 1'b0;
    parameter [0:0] IS_CLK_INVERTED = 1'b0;
    parameter [4:0] IS_INMODE_INVERTED = 5'b0;
    parameter [6:0] IS_OPMODE_INVERTED = 7'b0;

    initial begin
`ifdef __ICARUS__
        if (AUTORESET_PATDET != "NO_RESET") $fatal(1, "Unsupported AUTORESET_PATDET value");
        if (SEL_MASK != "MASK")     $fatal(1, "Unsupported SEL_MASK value");
        if (SEL_PATTERN != "PATTERN") $fatal(1, "Unsupported SEL_PATTERN value");
        if (USE_SIMD != "ONE48" && USE_SIMD != "TWO24" && USE_SIMD != "FOUR12")    $fatal(1, "Unsupported USE_SIMD value");
        if (IS_ALUMODE_INVERTED != 4'b0) $fatal(1, "Unsupported IS_ALUMODE_INVERTED value");
        if (IS_CARRYIN_INVERTED != 1'b0) $fatal(1, "Unsupported IS_CARRYIN_INVERTED value");
        if (IS_CLK_INVERTED != 1'b0) $fatal(1, "Unsupported IS_CLK_INVERTED value");
        if (IS_INMODE_INVERTED != 5'b0) $fatal(1, "Unsupported IS_INMODE_INVERTED value");
        if (IS_OPMODE_INVERTED != 7'b0) $fatal(1, "Unsupported IS_OPMODE_INVERTED value");
`endif
    end

    wire signed [29:0] A_muxed;
    wire signed [17:0] B_muxed;

    generate
        if (A_INPUT == "CASCADE") assign A_muxed = ACIN;
        else assign A_muxed = A;

        if (B_INPUT == "CASCADE") assign B_muxed = BCIN;
        else assign B_muxed = B;
    endgenerate

    reg signed [29:0] Ar1, Ar2;
    reg signed [24:0] Dr;
    reg signed [17:0] Br1, Br2;
    reg signed [47:0] Cr;
    reg        [4:0]  INMODEr = 5'b0;
    reg        [6:0]  OPMODEr = 7'b0;
    reg        [3:0]  ALUMODEr = 4'b0;
    reg        [2:0]  CARRYINSELr = 3'b0;

    generate
        // Configurable A register
        if (AREG == 2) begin
            initial Ar1 = 30'b0;
            initial Ar2 = 30'b0;
            always @(posedge CLK)
                if (RSTA) begin
                    Ar1 <= 30'b0;
                    Ar2 <= 30'b0;
                end else begin
                    if (CEA1) Ar1 <= A_muxed;
                    if (CEA2) Ar2 <= Ar1;
                end
        end else if (AREG == 1) begin
            //initial Ar1 = 30'b0;
            initial Ar2 = 30'b0;
            always @(posedge CLK)
                if (RSTA) begin
                    Ar1 <= 30'b0;
                    Ar2 <= 30'b0;
                end else begin
                    if (CEA1) Ar1 <= A_muxed;
                    if (CEA2) Ar2 <= A_muxed;
                end
        end else begin
            always @* Ar1 <= A_muxed;
            always @* Ar2 <= A_muxed;
        end

        // Configurable B register
        if (BREG == 2) begin
            initial Br1 = 25'b0;
            initial Br2 = 25'b0;
            always @(posedge CLK)
                if (RSTB) begin
                    Br1 <= 18'b0;
                    Br2 <= 18'b0;
                end else begin
                    if (CEB1) Br1 <= B_muxed;
                    if (CEB2) Br2 <= Br1;
                end
        end else if (BREG == 1) begin
            //initial Br1 = 25'b0;
            initial Br2 = 25'b0;
            always @(posedge CLK)
                if (RSTB) begin
                    Br1 <= 18'b0;
                    Br2 <= 18'b0;
                end else begin
                    if (CEB1) Br1 <= B_muxed;
                    if (CEB2) Br2 <= B_muxed;
                end
        end else begin
            always @* Br1 <= B_muxed;
            always @* Br2 <= B_muxed;
        end

        // C and D registers
        if (CREG == 1) initial Cr = 48'b0;
        if (CREG == 1) begin always @(posedge CLK) if (RSTC) Cr <= 48'b0; else if (CEC) Cr <= C; end
        else           always @* Cr <= C;

        if (CREG == 1) initial Dr = 25'b0;
        if (DREG == 1) begin always @(posedge CLK) if (RSTD) Dr <= 25'b0; else if (CED) Dr <= D; end
        else           always @* Dr <= D;

        // Control registers
        if (INMODEREG == 1) initial INMODEr = 5'b0;
        if (INMODEREG == 1) begin always @(posedge CLK) if (RSTINMODE) INMODEr <= 5'b0; else if (CEINMODE) INMODEr <= INMODE; end
        else           always @* INMODEr <= INMODE;
        if (OPMODEREG == 1) initial OPMODEr = 7'b0;
        if (OPMODEREG == 1) begin always @(posedge CLK) if (RSTCTRL) OPMODEr <= 7'b0; else if (CECTRL) OPMODEr <= OPMODE; end
        else           always @* OPMODEr <= OPMODE;
        if (ALUMODEREG == 1) initial ALUMODEr = 4'b0;
        if (ALUMODEREG == 1) begin always @(posedge CLK) if (RSTALUMODE) ALUMODEr <= 4'b0; else if (CEALUMODE) ALUMODEr <= ALUMODE; end
        else           always @* ALUMODEr <= ALUMODE;
        if (CARRYINSELREG == 1) initial CARRYINSELr = 3'b0;
        if (CARRYINSELREG == 1) begin always @(posedge CLK) if (RSTCTRL) CARRYINSELr <= 3'b0; else if (CECTRL) CARRYINSELr <= CARRYINSEL; end
        else           always @* CARRYINSELr <= CARRYINSEL;
    endgenerate

    // A and B cascade
    generate
        if (ACASCREG == 1 && AREG == 2) assign ACOUT = Ar1;
        else assign ACOUT = Ar2;
        if (BCASCREG == 1 && BREG == 2) assign BCOUT = Br1;
        else assign BCOUT = Br2;
    endgenerate

    // A/D input selection and pre-adder
    wire signed [29:0] Ar12_muxed = INMODEr[0] ? Ar1 : Ar2;
    wire signed [24:0] Ar12_gated = INMODEr[1] ? 25'b0 : Ar12_muxed;
    wire signed [24:0] Dr_gated   = INMODEr[2] ? Dr : 25'b0;
    wire signed [24:0] AD_result  = INMODEr[3] ? (Dr_gated - Ar12_gated) : (Dr_gated + Ar12_gated);
    reg  signed [24:0] ADr;

    generate
        if (ADREG == 1) initial ADr = 25'b0;
        if (ADREG == 1) begin always @(posedge CLK) if (RSTD) ADr <= 25'b0; else if (CEAD) ADr <= AD_result; end
        else            always @* ADr <= AD_result;
    endgenerate

    // 25x18 multiplier
    wire signed [24:0] A_MULT;
    wire signed [17:0] B_MULT = INMODEr[4] ? Br1 : Br2;
    generate
        if (USE_DPORT == "TRUE") assign A_MULT = ADr;
        else assign A_MULT = Ar12_gated;
    endgenerate

    wire signed [42:0] M = A_MULT * B_MULT;
    wire signed [42:0] Mx = (CARRYINSEL == 3'b010) ? 43'bx : M;
    reg  signed [42:0] Mr = 43'b0;

    // Multiplier result register
    generate
        if (MREG == 1) begin always @(posedge CLK) if (RSTM) Mr <= 43'b0; else if (CEM) Mr <= Mx; end
        else           always @* Mr <= Mx;
    endgenerate

    wire signed [42:0] Mrx = (CARRYINSELr == 3'b010) ? 43'bx : Mr;

    // X, Y and Z ALU inputs
    reg signed [47:0] X, Y, Z;

    always @* begin
        // X multiplexer
        case (OPMODEr[1:0])
            2'b00: X = 48'b0;
            2'b01: begin X = $signed(Mrx);
`ifdef __ICARUS__
                if (OPMODEr[3:2] != 2'b01) $fatal(1, "OPMODEr[3:2] must be 2'b01 when OPMODEr[1:0] is 2'b01");
`endif
            end
            2'b10: begin X = P;
`ifdef __ICARUS__
                if (PREG != 1) $fatal(1, "PREG must be 1 when OPMODEr[1:0] is 2'b10");
`endif
            end
            2'b11: X = $signed({Ar2, Br2});
            default: X = 48'bx;
        endcase

        // Y multiplexer
        case (OPMODEr[3:2])
            2'b00: Y = 48'b0;
            2'b01: begin Y = 48'b0; // FIXME: more accurate partial product modelling?
`ifdef __ICARUS__
                if (OPMODEr[1:0] != 2'b01) $fatal(1, "OPMODEr[1:0] must be 2'b01 when OPMODEr[3:2] is 2'b01");
`endif
            end
            2'b10: Y = {48{1'b1}};
            2'b11: Y = Cr;
            default: Y = 48'bx;
        endcase

        // Z multiplexer
        case (OPMODEr[6:4])
            3'b000: Z = 48'b0;
            3'b001: Z = PCIN;
            3'b010: begin Z = P;
`ifdef __ICARUS__
                if (PREG != 1) $fatal(1, "PREG must be 1 when OPMODEr[6:4] i0s 3'b010");
`endif
            end
            3'b011: Z = Cr;
            3'b100: begin Z = P;
`ifdef __ICARUS__
                if (PREG != 1) $fatal(1, "PREG must be 1 when OPMODEr[6:4] is 3'b100");
                if (OPMODEr[3:0] != 4'b1000) $fatal(1, "OPMODEr[3:0] must be 4'b1000 when OPMODEr[6:4] i0s 3'b100");
`endif
            end
            3'b101: Z = $signed(PCIN[47:17]);
            3'b110: Z = $signed(P[47:17]);
            default: Z = 48'bx;
        endcase
    end

    // Carry in
    wire A24_xnor_B17d = A_MULT[24] ~^ B_MULT[17];
    reg CARRYINr = 1'b0, A24_xnor_B17 = 1'b0;
    generate
        if (CARRYINREG == 1) begin always @(posedge CLK) if (RSTALLCARRYIN) CARRYINr <= 1'b0; else if (CECARRYIN) CARRYINr <= CARRYIN; end
        else                 always @* CARRYINr = CARRYIN;

        if (MREG == 1) begin always @(posedge CLK) if (RSTALLCARRYIN) A24_xnor_B17 <= 1'b0; else if (CEM) A24_xnor_B17 <= A24_xnor_B17d; end
        else                 always @* A24_xnor_B17 = A24_xnor_B17d;
    endgenerate

    reg cin_muxed;

    always @(*) begin
        case (CARRYINSELr)
            3'b000: cin_muxed = CARRYINr;
            3'b001: cin_muxed = ~PCIN[47];
            3'b010: cin_muxed = CARRYCASCIN;
            3'b011: cin_muxed = PCIN[47];
            3'b100: cin_muxed = CARRYCASCOUT;
            3'b101: cin_muxed = ~P[47];
            3'b110: cin_muxed = A24_xnor_B17;
            3'b111: cin_muxed = P[47];
            default: cin_muxed = 1'bx;
        endcase
    end

    wire alu_cin = (ALUMODEr[3] || ALUMODEr[2]) ? 1'b0 : cin_muxed;

    // ALU core
    wire [47:0] Z_muxinv = ALUMODEr[0] ? ~Z : Z;
    wire [47:0] xor_xyz = X ^ Y ^ Z_muxinv;
    wire [47:0] maj_xyz = (X & Y) | (X & Z_muxinv) | (Y & Z_muxinv);

    wire [47:0] xor_xyz_muxed = ALUMODEr[3] ? maj_xyz : xor_xyz;
    wire [47:0] maj_xyz_gated = ALUMODEr[2] ? 48'b0 :  maj_xyz;

    wire [48:0] maj_xyz_simd_gated;
    wire [3:0] int_carry_in, int_carry_out, ext_carry_out;
    wire [47:0] alu_sum;
    assign int_carry_in[0] = 1'b0;
    wire [3:0] carryout_reset;

    generate
        if (USE_SIMD == "FOUR12") begin
            assign maj_xyz_simd_gated = {
                    maj_xyz_gated[47:36],
                    1'b0, maj_xyz_gated[34:24],
                    1'b0, maj_xyz_gated[22:12],
                    1'b0, maj_xyz_gated[10:0],
                    alu_cin
                };
            assign int_carry_in[3:1] = 3'b000;
            assign ext_carry_out = {
                    int_carry_out[3],
                    maj_xyz_gated[35] ^ int_carry_out[2],
                    maj_xyz_gated[23] ^ int_carry_out[1],
                    maj_xyz_gated[11] ^ int_carry_out[0]
                };
            assign carryout_reset = 4'b0000;
        end else if (USE_SIMD == "TWO24") begin
            assign maj_xyz_simd_gated = {
                    maj_xyz_gated[47:24],
                    1'b0, maj_xyz_gated[22:0],
                    alu_cin
                };
            assign int_carry_in[3:1] = {int_carry_out[2], 1'b0, int_carry_out[0]};
            assign ext_carry_out = {
                    int_carry_out[3],
                    1'bx,
                    maj_xyz_gated[23] ^ int_carry_out[1],
                    1'bx
                };
            assign carryout_reset = 4'b0x0x;
        end else begin
            assign maj_xyz_simd_gated = {maj_xyz_gated, alu_cin};
            assign int_carry_in[3:1] = int_carry_out[2:0];
            assign ext_carry_out = {
                    int_carry_out[3],
                    3'bxxx
                };
            assign carryout_reset = 4'b0xxx;
        end

        genvar i;
        for (i = 0; i < 4; i = i + 1)
            assign {int_carry_out[i], alu_sum[i*12 +: 12]} = {1'b0, maj_xyz_simd_gated[i*12 +: ((i == 3) ? 13 : 12)]}
                                                              + xor_xyz_muxed[i*12 +: 12] + int_carry_in[i];
    endgenerate

    wire signed [47:0] Pd = ALUMODEr[1] ? ~alu_sum : alu_sum;
    wire [3:0] CARRYOUTd = (OPMODEr[3:0] == 4'b0101 || ALUMODEr[3:2] != 2'b00) ? 4'bxxxx :
                           ((ALUMODEr[0] & ALUMODEr[1]) ? ~ext_carry_out : ext_carry_out);
    wire CARRYCASCOUTd = ext_carry_out[3];
    wire MULTSIGNOUTd = Mrx[42];

    generate
        if (PREG == 1) begin
            initial P = 48'b0;
            initial CARRYOUT = carryout_reset;
            initial CARRYCASCOUT = 1'b0;
            initial MULTSIGNOUT = 1'b0;
            always @(posedge CLK)
                if (RSTP) begin
                    P <= 48'b0;
                    CARRYOUT <= carryout_reset;
                    CARRYCASCOUT <= 1'b0;
                    MULTSIGNOUT <= 1'b0;
                end else if (CEP) begin
                    P <= Pd;
                    CARRYOUT <= CARRYOUTd;
                    CARRYCASCOUT <= CARRYCASCOUTd;
                    MULTSIGNOUT <= MULTSIGNOUTd;
                end
        end else begin
            always @* begin
                P = Pd;
                CARRYOUT = CARRYOUTd;
                CARRYCASCOUT = CARRYCASCOUTd;
                MULTSIGNOUT = MULTSIGNOUTd;
            end
        end
    endgenerate

    assign PCOUT = P;

    generate
        wire PATTERNDETECTd, PATTERNBDETECTd;

        if (USE_PATTERN_DETECT == "PATDET") begin
            // TODO: Support SEL_PATTERN != "PATTERN" and SEL_MASK != "MASK
            assign PATTERNDETECTd = &(~(Pd ^ PATTERN) | MASK);
            assign PATTERNBDETECTd = &((Pd ^ PATTERN) | MASK);
        end else begin
            assign PATTERNDETECTd = 1'b1;
            assign PATTERNBDETECTd = 1'b1;
        end

        if (PREG == 1) begin
            reg PATTERNDETECTPAST, PATTERNBDETECTPAST;
            initial PATTERNDETECT = 1'b0;
            initial PATTERNBDETECT = 1'b0;
            initial PATTERNDETECTPAST = 1'b0;
            initial PATTERNBDETECTPAST = 1'b0;
            always @(posedge CLK)
                if (RSTP) begin
                    PATTERNDETECT <= 1'b0;
                    PATTERNBDETECT <= 1'b0;
                    PATTERNDETECTPAST <= 1'b0;
                    PATTERNBDETECTPAST <= 1'b0;
                end else if (CEP) begin
                    PATTERNDETECT <= PATTERNDETECTd;
                    PATTERNBDETECT <= PATTERNBDETECTd;
                    PATTERNDETECTPAST <= PATTERNDETECT;
                    PATTERNBDETECTPAST <= PATTERNBDETECT;
                end
            assign OVERFLOW = &{PATTERNDETECTPAST, ~PATTERNBDETECT, ~PATTERNDETECT};
            assign UNDERFLOW = &{PATTERNBDETECTPAST, ~PATTERNBDETECT, ~PATTERNDETECT};
        end else begin
            always @* begin
                PATTERNDETECT = PATTERNDETECTd;
                PATTERNBDETECT = PATTERNBDETECTd;
            end
            assign OVERFLOW = 1'bx, UNDERFLOW = 1'bx;
        end
    endgenerate

endmodule

// TODO: DSP48E2 (Ultrascale).