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//////////////////////////////////////////////////////////////////////////////
// SPDX-FileCopyrightText: 2021 , Dinesh Annayya
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// SPDX-License-Identifier: Apache-2.0
// SPDX-FileContributor: Created by Dinesh Annayya <dinesha@opencores.org>
////////////////////////////////////////////////////////////////////////
//// ////
//// Tubo 8051 cores common library Module ////
//// ////
//// This file is part of the Turbo 8051 cores project ////
//// https://github.com/dineshannayya/yifive_r0.git ////
//// http://www.opencores.org/cores/turbo8051/ ////
//// ////
//// Description ////
//// Turbo 8051 definitions. ////
//// ////
//// To Do: ////
//// nothing ////
//// ////
//// Author(s): ////
//// - Dinesh Annayya, dinesha@opencores.org ////
//// ////
//// Revision : Mar 2, 2011 ////
//// ////
//////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2000 Authors and OPENCORES.ORG ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer. ////
//// ////
//// This source file is free software; you can redistribute it ////
//// and/or modify it under the terms of the GNU Lesser General ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any ////
//// later version. ////
//// ////
//// This source 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 Lesser General Public License for more ////
//// details. ////
//// ////
//// You should have received a copy of the GNU Lesser General ////
//// Public License along with this source; if not, download it ////
//// from http://www.opencores.org/lgpl.shtml ////
//// ////
//////////////////////////////////////////////////////////////////////
// #################################################################
// Module: clk_ctl
//
// Description: Generic clock control logic , clk-out = mclk/(2+clk_div_ratio)
//
//
// #################################################################
module clk_ctl (
// Outputs
clk_o,
// Inputs
mclk,
reset_n,
clk_div_ratio
);
//---------------------------------
// CLOCK Default Divider value.
// This value will be change from outside
//---------------------------------
parameter WD = 'h1;
//---------------------------------------------
// All the input to this block are declared here
// --------------------------------------------
input mclk ;//
input reset_n ;// primary reset signal
input [WD:0] clk_div_ratio ;// primary clock divide ratio
// output clock = selected clock / (div_ratio+1)
//---------------------------------------------
// All the output to this block are declared here
// --------------------------------------------
output clk_o ; // clock out
//------------------------------------
// Clock Divide func is done here
//------------------------------------
reg [WD-1:0] high_count ; // high level counter
reg [WD-1:0] low_count ; // low level counter
reg mclk_div ; // divided clock
assign clk_o = mclk_div;
always @ (posedge mclk or negedge reset_n)
begin // {
if(reset_n == 1'b0)
begin
high_count <= 'h0;
low_count <= 'h0;
mclk_div <= 'b0;
end
else
begin
if(high_count != 0)
begin // {
high_count <= high_count - 1;
mclk_div <= 1'b1;
end // }
else if(low_count != 0)
begin // {
low_count <= low_count - 1;
mclk_div <= 1'b0;
end // }
else
begin // {
high_count <= clk_div_ratio[WD:1] + clk_div_ratio[0];
low_count <= clk_div_ratio[WD:1] + 1;
mclk_div <= ~mclk_div;
end // }
end // }
end // }
endmodule