// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
//
// Each core or library found in this collection may have its own licensing terms. 
// The user should keep this in in mind while exploring these cores. 
//
// Redistribution and use in source and binary forms,
// with or without modification of this file, are permitted under the terms of either
//  (at the option of the user):
//
//   1. The GNU General Public License version 2 as published by the
//      Free Software Foundation, which can be found in the top level directory, or at:
// https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html
//
// OR
//
//   2.  An ADI specific BSD license as noted in the top level directory, or on-line at:
// https://github.com/analogdevicesinc/hdl/blob/dev/LICENSE
//
// ***************************************************************************
// ***************************************************************************

`timescale 1ns/1ps

module axi_ad9361_tdd_if#(

  parameter       LEVEL_OR_PULSE_N = 0) (

  // clock

  input                   clk,
  input                   rst,

  // control signals from the tdd control

  input                   tdd_rx_vco_en,
  input                   tdd_tx_vco_en,
  input                   tdd_rx_rf_en,
  input                   tdd_tx_rf_en,

  // device interface

  output                  ad9361_txnrx,
  output                  ad9361_enable,

  // interface status

  output      [ 7:0]      ad9361_tdd_status);


  localparam      PULSE_MODE = 0;
  localparam      LEVEL_MODE = 1;

  // internal registers

  reg             tdd_rx_rf_en_d = 1'b0;
  reg             tdd_tx_rf_en_d = 1'b0;

  reg             tdd_vco_overlap = 1'b0;
  reg             tdd_rf_overlap = 1'b0;

  wire            ad9361_txnrx_s;
  wire            ad9361_enable_s;

  // just one VCO can be enabled at a time
  assign ad9361_txnrx_s = tdd_tx_vco_en & ~tdd_rx_vco_en;

  always @(posedge clk) begin
    tdd_rx_rf_en_d <= tdd_rx_rf_en;
    tdd_tx_rf_en_d <= tdd_tx_rf_en;
  end

  assign ad9361_enable_s = (LEVEL_OR_PULSE_N == PULSE_MODE) ?
                          ((~tdd_rx_rf_en_d & tdd_rx_rf_en) | (tdd_rx_rf_en_d & ~tdd_rx_rf_en) |
                           (~tdd_tx_rf_en_d & tdd_tx_rf_en) | (tdd_tx_rf_en_d & ~tdd_tx_rf_en)) :
                           (tdd_rx_rf_en | tdd_tx_rf_en);

  always @(posedge clk) begin
    if(rst == 1'b1) begin
      tdd_vco_overlap <= 1'b0;
      tdd_rf_overlap <= 1'b0;
    end else begin
      tdd_vco_overlap <= tdd_rx_vco_en & tdd_tx_vco_en;
      tdd_rf_overlap <= tdd_rx_rf_en & tdd_tx_rf_en;
    end
  end

  assign ad9361_tdd_status = {6'b0, tdd_rf_overlap, tdd_vco_overlap};

  assign ad9361_txnrx = ad9361_txnrx_s;
  assign ad9361_enable = ad9361_enable_s;

endmodule