// ----------------------------------------------------------------------------
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// ----------------------------------------------------------------------------
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// SystemC Uart: implementation
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// SystemC Uart: implementation
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// This file is part of the cycle accurate model of the OpenRISC 1000 based
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// This file is part of the cycle accurate model of the OpenRISC 1000 based
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// system-on-chip, ORPSoC, built using Verilator.
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// system-on-chip, ORPSoC, built using Verilator.
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// This program is free software: you can redistribute it and/or modify it
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// This program is free software: you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published by
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// under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or (at your
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// the Free Software Foundation, either version 3 of the License, or (at your
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// option) any later version.
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// option) any later version.
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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// License for more details.
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// License for more details.
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// You should have received a copy of the GNU Lesser General Public License
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// You should have received a copy of the GNU Lesser General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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// ----------------------------------------------------------------------------
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// ----------------------------------------------------------------------------
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// $Id: $
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// $Id: $
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#include <iostream>
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#include <iostream>
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#include <iomanip>
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#include <iomanip>
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#include <cmath>
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#include <cmath>
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#include "UartSC.h"
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#include "UartSC.h"
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//#define UART_SC_DEBUG
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SC_HAS_PROCESS( UartSC );
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SC_HAS_PROCESS( UartSC );
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//! Constructor for the Uart system C model
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//! Constructor for the Uart system C model
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//! @param[in] name Name of this module, passed to the parent constructor.
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//! @param[in] name Name of this module, passed to the parent constructor.
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// Todo: Probably some sort of scaler parameter
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// Todo: Probably some sort of scaler parameter
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UartSC::UartSC (sc_core::sc_module_name name):
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UartSC::UartSC (sc_core::sc_module_name name):
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sc_module (name)
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sc_module (name)
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{
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{
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SC_METHOD (checkTx);
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SC_METHOD (checkTx);
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dont_initialize();
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dont_initialize();
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sensitive << clk.pos();
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sensitive << clk.pos();
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//sensitive << uarttx;
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//sensitive << uarttx;
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} // UartSC ()
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} // UartSC ()
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void
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void
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UartSC::initUart (int clk_freq_hz, // Presume in NS
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UartSC::initUart (int clk_freq_hz, // Presume in NS
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int uart_baud
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int uart_baud
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)
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)
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{
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{
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// Calculate number of clocks per UART bit
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// Calculate number of clocks per UART bit
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clocks_per_bit = (int)(clk_freq_hz/uart_baud);
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clocks_per_bit = (int)(clk_freq_hz/uart_baud);
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bits_received=0;
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#ifdef UART_SC_DEBUG
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printf("UartSC Initialised: Sys. clk. freq.: %d Hz, Baud: %d, cpb: %d\n", clk_freq_hz, uart_baud, clocks_per_bit);
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#endif
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}
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}
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// Maybe do this with threads instead?!
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// Maybe do this with threads instead?!
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void
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void
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UartSC::checkTx () {
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UartSC::checkTx () {
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#ifdef UART_SC_DEBUG
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//printf("Uart TX activity: level is : 0x%x\n", uarttx.read()&1);
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//printf("Uart TX activity: level is : 0x%x\n", uarttx.read()&1);
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#endif
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// Check the number of bits received
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// Check the number of bits received
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if (bits_received==0)
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if (bits_received==0)
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{
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{
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// Check if tx is low
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// Check if tx is low
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if ((uarttx.read()&1) == 0)
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if ((uarttx.read()&1) == 0)
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{
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{
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// Line pulled low, begin receive of new char
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// Line pulled low, begin receive of new char
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current_char = 0;
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current_char = 0;
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// Start
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// Start
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counter = 1;
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counter = 1;
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bits_received++; // We got the start bit
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bits_received++; // We got the start bit
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//cout << "UartSC checkTx: got start bit at time " << sc_time_stamp() << endl;
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#ifdef UART_SC_DEBUG
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cout << "UartSC checkTx: got start bit at time " << sc_time_stamp() << endl;
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#endif
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}
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}
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}
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}
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else if (bits_received > 0 && bits_received < 9)
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else if (bits_received > 0 && bits_received < 9)
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{
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{
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// Check the counter - see if it's time to sample the line
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// Check the counter - see if it's time to sample the line
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// We do an extra half-bit delay on first bit read
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// We do an extra half-bit delay on first bit read
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if ( ((bits_received==1) &&
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if ( ((bits_received==1) &&
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(counter == (clocks_per_bit + (clocks_per_bit/2)))) ||
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(counter == (clocks_per_bit + (clocks_per_bit/2)))) ||
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((bits_received > 1) && (counter == clocks_per_bit)) )
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((bits_received > 1) && (counter == clocks_per_bit)) )
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{
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{
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//printf("UartSC checkTx: read bit %d as 0x%x at time", bits_received, uarttx.read()&1);
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//printf("UartSC checkTx: read bit %d as 0x%x at time", bits_received, uarttx.read()&1);
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//cout << sc_time_stamp() << endl;
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//cout << sc_time_stamp() << endl;
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// Shift in the current value of the tx into our char
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// Shift in the current value of the tx into our char
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current_char |= ((uarttx.read() & 1) << (bits_received-1));
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current_char |= ((uarttx.read() & 1) << (bits_received-1));
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// Reset the counter
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// Reset the counter
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counter = 1;
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counter = 1;
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// Increment bit number
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// Increment bit number
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bits_received++;
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bits_received++;
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}
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}
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else
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else
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counter++;
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counter++;
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}
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}
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else if (bits_received == 9)
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else if (bits_received == 9)
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{
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{
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// Now check for stop bit 1
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// Now check for stop bit 1
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if (counter == clocks_per_bit)
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if (counter == clocks_per_bit)
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{
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{
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// Check that the value is 1 - this should be the stop bit
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// Check that the value is 1 - this should be the stop bit
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if ((uarttx.read() & 1) != 1)
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if ((uarttx.read() & 1) != 1)
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{
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{
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printf("UART TX framing error at time\n");
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printf("UART TX framing error at time\n");
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cout << sc_time_stamp() << endl;
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cout << sc_time_stamp() << endl;
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// Perhaps do something else here to deal with this
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// Perhaps do something else here to deal with this
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bits_received = 0;
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bits_received = 0;
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counter = 0;
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counter = 0;
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}
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}
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else
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else
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{
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{
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// Print the char
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// Print the char
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//printf("Char received: 0x%2x time: ", current_char);
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#ifdef UART_SC_DEBUG
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//cout << sc_time_stamp() << endl;
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printf("Char received: 0x%2x time: ", current_char);
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cout << current_char;
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cout << sc_time_stamp() << endl;
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#endif
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// cout'ing the char didn't work for some systems - jb 090613ol
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//cout << current_char;
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printf("%c",current_char);
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bits_received = 0;
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bits_received = 0;
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counter = 0;
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counter = 0;
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}
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}
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}
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}
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else
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else
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counter++;
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counter++;
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}
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}
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}
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}
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