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//////////////////////////////////////////////////////////////////////
////                                                              ////
////  8051 cores timer/counter control                            ////
////                                                              ////
////  This file is part of the 8051 cores project                 ////
////  http://www.opencores.org/cores/8051/                        ////
////                                                              ////
////  Description                                                 ////
////   timers and counters handling for 8051 core                 ////
////                                                              ////
////  To Do:                                                      ////
////   Nothing                                                    ////
////                                                              ////
////  Author(s):                                                  ////
////      - Simon Teran, simont@opencores.org                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// 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                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: not supported by cvs2svn $
// Revision 1.4  2002/09/30 17:33:59  simont
// prepared header
//
//
 
`include "oc8051_defines.v"
 
//synopsys translate_off
`include "oc8051_timescale.v"
//synopsys translate_on
 
 
 
module oc8051_tc (clk, rst, wr_addr, rd_addr, data_in, wr, wr_bit, ie0, ie1, tr0, tr1, t0, t1, data_out,
            tf0, tf1);
 
input [7:0] wr_addr, data_in, rd_addr;
input clk, rst, wr, wr_bit, ie0, ie1, tr0, tr1, t0, t1;
output [7:0] data_out;
output tf0, tf1;
 
reg [7:0] tmod, tl0, th0, tl1, th1, data_out;
reg tf0, tf1_0, tf1_1, t0_buff, t1_buff;
 
wire tc0_add, tc1_add;
 
assign tc0_add = (tr0 & (!tmod[3] | !ie0) & (!(tmod[2]) | (tmod[2] & !t0 & t0_buff)));
assign tc1_add = (tr1 & (!tmod[7] | !ie1) & (!(tmod[6]) | (tmod[6] & !t1 & t1_buff)));
assign tf1= tf1_0 | tf1_1;
 
//
// read or write from one of the addresses in tmod
//
always @(posedge clk or posedge rst)
begin
 if (rst) begin
   tmod <=#1 `OC8051_RST_TMOD;
 end else if ((wr) & !(wr_bit) & (wr_addr==`OC8051_SFR_TMOD))
    tmod <= #1 data_in;
end
 
//
// TIMER COUNTER 0
//
always @(posedge clk or posedge rst)
begin
 if (rst) begin
   tl0 <=#1 `OC8051_RST_TL0;
   th0 <=#1 `OC8051_RST_TH0;
   tf0 <= #1 1'b0;
   tf1_0 <= #1 1'b0;
 end else if ((wr) & !(wr_bit) & (wr_addr==`OC8051_SFR_TL0)) begin
   tl0 <= #1 data_in;
   tf0 <= #1 1'b0;
   tf1_0 <= #1 1'b0;
 end else if ((wr) & !(wr_bit) & (wr_addr==`OC8051_SFR_TH0)) begin
   th0 <= #1 data_in;
   tf0 <= #1 1'b0;
   tf1_0 <= #1 1'b0;
 end else begin
     case (tmod[1:0])
      `OC8051_MODE0: begin                       // mode 0
        tf1_0 <= #1 1'b0;
        if (tc0_add)
          {tf0, th0,tl0[4:0]} <= #1 {1'b0, th0, tl0[4:0]}+ 1'b1;
      end
      `OC8051_MODE1: begin                       // mode 1
        tf1_0 <= #1 1'b0;
        if (tc0_add)
          {tf0, th0,tl0} <= #1 {1'b0, th0, tl0}+ 1'b1;
      end
 
      `OC8051_MODE2: begin                       // mode 2
        tf1_0 <= #1 1'b0;
        if (tc0_add) begin
	  if (tl0 == 8'b1111_1111) begin
            tf0 <=#1 1'b1;
            tl0 <=#1 th0;
           end
          else begin
            tl0 <=#1 tl0 + 8'h1;
            tf0 <= #1 1'b0;
          end
	end
      end
      `OC8051_MODE3: begin                       // mode 3
 
	 if (tc0_add)
	   {tf0, tl0} <= #1 {1'b0, tl0} +1'b1;
 
         if (tr1)
	   {tf1_0, th0} <= #1 {1'b0, th0} +1'b1;
 
      end
      default:begin
        tf0 <= #1 1'b0;
        tf1_0 <= #1 1'b0;
      end
    endcase
 end
end
 
//
// TIMER COUNTER 1
//
always @(posedge clk or posedge rst)
begin
 if (rst) begin
   tl1 <=#1 `OC8051_RST_TL1;
   th1 <=#1 `OC8051_RST_TH1;
   tf1_1 <= #1 1'b0;
 end else if ((wr) & !(wr_bit) & (wr_addr==`OC8051_SFR_TL1)) begin
   tl1 <= #1 data_in;
   tf1_1 <= #1 1'b0;
 end else if ((wr) & !(wr_bit) & (wr_addr==`OC8051_SFR_TH1)) begin
   th1 <= #1 data_in;
   tf1_1 <= #1 1'b0;
 end else begin
     case (tmod[5:4])
      `OC8051_MODE0: begin                       // mode 0
        if (tc1_add)
          {tf1_1, th1,tl1[4:0]} <= #1 {1'b0, th1, tl1[4:0]}+ 1'b1;
      end
      `OC8051_MODE1: begin                       // mode 1
        if (tc1_add)
          {tf1_1, th1,tl1} <= #1 {1'b0, th1, tl1}+ 1'b1;
      end
 
      `OC8051_MODE2: begin                       // mode 2
        if (tc1_add) begin
	  if (tl1 == 8'b1111_1111) begin
            tf1_1 <=#1 1'b1;
            tl1 <=#1 th1;
           end
          else begin
            tl1 <=#1 tl1 + 8'h1;
            tf1_1 <= #1 1'b0;
          end
	end
      end
      default:begin
        tf1_1 <= #1 1'b0;
      end
    endcase
 end
end
 
always @(posedge clk or posedge rst)
begin
  if (rst) data_out <= #1 8'h0;
  else if (wr & !wr_bit & (wr_addr==rd_addr) & ((wr_addr==`OC8051_SFR_TH0) |
     (wr_addr==`OC8051_SFR_TH1)|(wr_addr==`OC8051_SFR_TL0)|(wr_addr==`OC8051_SFR_TL1)|
     (wr_addr==`OC8051_SFR_TMOD))) begin
    data_out <= #1 data_in;
  end else begin
    case (rd_addr)
      `OC8051_SFR_TH0: data_out <= #1 th0;
      `OC8051_SFR_TH1: data_out <= #1 th1;
      `OC8051_SFR_TL0: data_out <= #1 tl0;
      `OC8051_SFR_TL1: data_out <= #1 tl1;
      default: data_out <= #1 tmod;
    endcase
  end
end
 
 
always @(posedge clk or posedge rst)
  if (rst) begin
    t0_buff <= #1 1'b0;
    t1_buff <= #1 1'b0;
  end else begin
    t0_buff <= #1 t0;
    t1_buff <= #1 t1;
  end
endmodule