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// SPDX-License-Identifier: GPL-2.0+
/*******************************************************************************
* QtMips - MIPS 32-bit Architecture Subset Simulator
*
* Implemented to support following courses:
*
* B35APO - Computer Architectures
* https://cw.fel.cvut.cz/wiki/courses/b35apo
*
* B4M35PAP - Advanced Computer Architectures
* https://cw.fel.cvut.cz/wiki/courses/b4m35pap/start
*
* Copyright (c) 2017-2019 Karel Koci<cynerd@email.cz>
* Copyright (c) 2019 Pavel Pisa <pisa@cmp.felk.cvut.cz>
*
* Faculty of Electrical Engineering (http://www.fel.cvut.cz)
* Czech Technical University (http://www.cvut.cz/)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
******************************************************************************/
#include "serialport.h"
#define SERP_RX_ST_REG_o 0x00
#define SERP_RX_ST_REG_READY_m 0x1
#define SERP_RX_ST_REG_IE_m 0x2
#define SERP_RX_DATA_REG_o 0x04
#define SERP_TX_ST_REG_o 0x08
#define SERP_TX_ST_REG_READY_m 0x1
#define SERP_TX_ST_REG_IE_m 0x2
#define SERP_TX_DATA_REG_o 0x0c
using namespace machine;
SerialPort::SerialPort() {
change_counter = 0;
rx_st_reg = 0;
rx_data_reg = 0;
tx_st_reg = 0;
tx_irq_level = 2; // HW Interrupt 0
rx_irq_level = 3; // HW Interrupt 1
tx_irq_active = false;
rx_irq_active = false;
}
SerialPort::~SerialPort() {
}
void SerialPort::pool_rx_byte() const {
unsigned int byte = 0;
bool available = false;
if (!(rx_st_reg & SERP_RX_ST_REG_READY_m)) {
rx_st_reg |= SERP_RX_ST_REG_READY_m;
emit rx_byte_pool(0, byte, available);
if (available) {
change_counter++;
rx_data_reg = byte;
} else {
rx_st_reg &= ~SERP_RX_ST_REG_READY_m;
}
}
}
bool SerialPort::wword(std::uint32_t address, std::uint32_t value) {
#if 0
printf("SerialPort::wword address 0x%08lx data 0x%08lx\n",
(unsigned long)address, (unsigned long)value);
#endif
emit write_notification(address, value);
switch (address & ~3) {
case SERP_RX_ST_REG_o:
rx_st_reg &= ~SERP_RX_ST_REG_IE_m;
rx_st_reg |= value & SERP_RX_ST_REG_IE_m;
rx_queue_check_internal();
update_rx_irq();
break;
case SERP_TX_ST_REG_o:
tx_st_reg &= ~SERP_TX_ST_REG_IE_m;
tx_st_reg |= value & SERP_TX_ST_REG_IE_m;
update_tx_irq();
break;
case SERP_TX_DATA_REG_o:
emit tx_byte(value & 0xff);
update_tx_irq();
break;
}
return true;
}
std::uint32_t SerialPort::rword(std::uint32_t address, bool debug_access) const {
(void)debug_access;
std::uint32_t value = 0x00000000;
#if 0
printf("SerialPort::rword address 0x%08lx\n",
(unsigned long)address);
#endif
switch (address & ~3) {
case SERP_RX_ST_REG_o:
pool_rx_byte();
value = rx_st_reg;
break;
case SERP_RX_DATA_REG_o:
pool_rx_byte();
if (rx_st_reg & SERP_RX_ST_REG_READY_m) {
value = rx_data_reg;
if (!debug_access) {
rx_st_reg &= ~SERP_RX_ST_REG_READY_m;
update_rx_irq();
emit external_change_notify(this, SERP_RX_ST_REG_o,
SERP_RX_DATA_REG_o + 3, true);
}
} else {
value = 0;
}
rx_queue_check_internal();
break;
case SERP_TX_ST_REG_o:
value = tx_st_reg | SERP_TX_ST_REG_READY_m;
break;
}
emit read_notification(address, &value);
return value;
}
std::uint32_t SerialPort::get_change_counter() const {
return change_counter;
}
void SerialPort::update_rx_irq() const {
bool active = !!(rx_st_reg & SERP_RX_ST_REG_IE_m);
active &= !!(rx_st_reg & SERP_RX_ST_REG_READY_m);
if (active != rx_irq_active) {
rx_irq_active = active;
change_counter++;
emit signal_interrupt(rx_irq_level, active);
}
}
void SerialPort::update_tx_irq() const {
bool active = !!(tx_st_reg & SERP_TX_ST_REG_IE_m);
active &= !!(tx_st_reg & SERP_TX_ST_REG_READY_m);
if (active != tx_irq_active) {
tx_irq_active = active;
change_counter++;
emit signal_interrupt(tx_irq_level, active);
}
}
void SerialPort::rx_queue_check_internal() const {
if (rx_st_reg & SERP_RX_ST_REG_IE_m)
pool_rx_byte();
update_rx_irq();
}
void SerialPort::rx_queue_check() const {
rx_queue_check_internal();
emit external_change_notify(this, SERP_RX_ST_REG_o,
SERP_RX_DATA_REG_o + 3, true);
}
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