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//----------------------------------------------------------------------------
// Copyright (C) 2001 Authors
//
// 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, write to the Free Software Foundation,
// Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
//----------------------------------------------------------------------------
// 
// *File Name: dbg_uart_tasks.v
// 
// *Module Description:
//                      openMSP430 debug interface UART tasks
//
// *Author(s):
//              - Olivier Girard,    olgirard@gmail.com
//
//----------------------------------------------------------------------------
// $Rev: 154 $
// $LastChangedBy: olivier.girard $
// $LastChangedDate: 2012-10-15 22:44:20 +0200 (Mon, 15 Oct 2012) $
//----------------------------------------------------------------------------
 
// Register B/W and addresses
parameter           CPU_ID_LO    =  (8'h00 | 8'h00);
parameter           CPU_ID_HI    =  (8'h00 | 8'h01);
parameter           CPU_CTL      =  (8'h40 | 8'h02);
parameter           CPU_STAT     =  (8'h40 | 8'h03);
parameter           MEM_CTL      =  (8'h40 | 8'h04);
parameter           MEM_ADDR     =  (8'h00 | 8'h05);
parameter           MEM_DATA     =  (8'h00 | 8'h06);
parameter           MEM_CNT      =  (8'h00 | 8'h07);
parameter           BRK0_CTL     =  (8'h40 | 8'h08);
parameter           BRK0_STAT    =  (8'h40 | 8'h09);
parameter           BRK0_ADDR0   =  (8'h00 | 8'h0A);
parameter           BRK0_ADDR1   =  (8'h00 | 8'h0B);
parameter           BRK1_CTL     =  (8'h40 | 8'h0C);
parameter           BRK1_STAT    =  (8'h40 | 8'h0D);
parameter           BRK1_ADDR0   =  (8'h00 | 8'h0E);
parameter           BRK1_ADDR1   =  (8'h00 | 8'h0F);
parameter           BRK2_CTL     =  (8'h40 | 8'h10);
parameter           BRK2_STAT    =  (8'h40 | 8'h11);
parameter           BRK2_ADDR0   =  (8'h00 | 8'h12);
parameter           BRK2_ADDR1   =  (8'h00 | 8'h13);
parameter           BRK3_CTL     =  (8'h40 | 8'h14);
parameter           BRK3_STAT    =  (8'h40 | 8'h15);
parameter           BRK3_ADDR0   =  (8'h00 | 8'h16);
parameter           BRK3_ADDR1   =  (8'h00 | 8'h17);
parameter           CPU_NR       =  (8'h00 | 8'h18);
 
// Read / Write commands
parameter           DBG_WR       =   8'h80;
parameter           DBG_RD       =   8'h00;
 
// Synchronization value
parameter           DBG_SYNC     =   8'h80;
 
 
//----------------------------------------------------------------------------
// UART COMMUNICATION DATA RATE CONFIGURATION
//----------------------------------------------------------------------------
// If the auto synchronization mode is set, then the communication speed
// is configured by the testbench.
// If not, the values from the openMSP430.inc file are taken over.
`ifdef DBG_UART_AUTO_SYNC
parameter UART_BAUD   = 4000000;
integer   UART_PERIOD = 1000000000/UART_BAUD;
`else
integer   UART_PERIOD = `DBG_UART_CNT;
`endif
 
//----------------------------------------------------------------------------
// Receive UART frame from CPU Debug interface (8N1)
//----------------------------------------------------------------------------
 
task dbg_uart_rx;
   output [7:0] dbg_rxbuf;
 
   reg [7:0] 	dbg_rxbuf;
   reg [7:0] 	rxbuf;
   integer 	rxcnt;
   begin
      #(1);
      dbg_uart_rx_busy = 1'b1;
      @(negedge dbg_uart_txd);  
      dbg_rxbuf = 0;      
      rxbuf     = 0;      
      #(3*UART_PERIOD/2);
      for (rxcnt = 0; rxcnt < 8; rxcnt = rxcnt + 1)
	begin
	   rxbuf = {dbg_uart_txd, rxbuf[7:1]};
	   #(UART_PERIOD);
	end
      dbg_rxbuf        = rxbuf; 
      dbg_uart_rx_busy = 1'b0;
   end
endtask
 
task dbg_uart_rx16;
 
   reg [7:0] rxbuf_lo;
   reg [7:0] rxbuf_hi;
   begin
      rxbuf_lo = 8'h00;
      rxbuf_hi = 8'h00;
      dbg_uart_rx(rxbuf_lo);
      dbg_uart_rx(rxbuf_hi);
      dbg_uart_buf = {rxbuf_hi, rxbuf_lo};
   end
endtask
 
task dbg_uart_rx8;
 
   reg [7:0] rxbuf;
   begin
      rxbuf = 8'h00;
      dbg_uart_rx(rxbuf);
      dbg_uart_buf = {8'h00, rxbuf};
   end
endtask
 
//----------------------------------------------------------------------------
// Transmit UART frame to CPU Debug interface (8N1)
//----------------------------------------------------------------------------
task dbg_uart_tx;
   input  [7:0] txbuf;
 
   reg [9:0] 	txbuf_full;
   integer 	txcnt;
   begin
      #(1);
      dbg_uart_tx_busy = 1'b1;
      dbg_uart_rxd_pre = 1'b1;
      txbuf_full       = {1'b1, txbuf, 1'b0};
      for (txcnt = 0; txcnt < 10; txcnt = txcnt + 1)
	begin
	   #(UART_PERIOD);
	   dbg_uart_rxd_pre =  txbuf_full[txcnt];
	end
      dbg_uart_tx_busy = 1'b0;
   end
endtask
 
task dbg_uart_tx16;
   input  [15:0] txbuf;
 
   begin
      dbg_uart_tx(txbuf[7:0]);
      dbg_uart_tx(txbuf[15:8]);
   end
endtask
 
always @(posedge mclk or posedge dbg_rst)
  if (dbg_rst)
    begin
       dbg_uart_rxd_sel <= 1'b0;
       dbg_uart_rxd_dly <= 1'b1;
    end
  else if (dbg_en)
    begin
       dbg_uart_rxd_sel <= dbg_uart_rxd_meta ? $random : 1'b0;
       dbg_uart_rxd_dly <= dbg_uart_rxd_pre;
    end
 
assign dbg_uart_rxd = dbg_uart_rxd_sel ? dbg_uart_rxd_dly : dbg_uart_rxd_pre;
 
 
//----------------------------------------------------------------------------
// Write to Debug register
//----------------------------------------------------------------------------
task dbg_uart_wr;
   input  [7:0] dbg_reg;
   input [15:0] dbg_data;
 
   begin
      dbg_uart_tx(DBG_WR | dbg_reg);
      dbg_uart_tx(dbg_data[7:0]);
      if (~dbg_reg[6])
	dbg_uart_tx(dbg_data[15:8]);
   end
endtask
 
 
//----------------------------------------------------------------------------
// Read Debug register
//----------------------------------------------------------------------------
task dbg_uart_rd;
   input  [7:0] dbg_reg;
 
   reg [7:0] 	rxbuf_lo;
   reg [7:0] 	rxbuf_hi;
   begin
      rxbuf_lo = 8'h00;
      rxbuf_hi = 8'h00;
      dbg_uart_tx(DBG_RD | dbg_reg);
      dbg_uart_rx(rxbuf_lo);
      if (~dbg_reg[6])
	dbg_uart_rx(rxbuf_hi);
 
      dbg_uart_buf = {rxbuf_hi, rxbuf_lo};
      end
endtask
 
//----------------------------------------------------------------------------
// Send synchronization frame
//----------------------------------------------------------------------------
task dbg_uart_sync;
   begin
      dbg_uart_tx(DBG_SYNC);
      repeat(10) @(posedge mclk);
   end
endtask