serial.cpp

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#include <console/serial.h>
#include <runtime/gdbstub.h>
 
using namespace MaxOS;
using namespace MaxOS::runtime;
using namespace MaxOS::console;
 
SerialConsole::SerialConsole()
: m_data_port(0x3F8),
  m_interrupt_enable_port(0x3F9),
  m_fifo_control_port(0x3FA),
  m_line_control_port(0x3FB),
  m_modem_control_port(0x3FC),
  m_line_status_port(0x3FD)
{
    // Disable all interrupts
    m_interrupt_enable_port.write(0x00);
 
    // Enable DLAB (set baud rate divisor)
    m_line_control_port.write(0x80);
 
    // Set divisor to 3
    m_data_port.write(0x03);
    m_interrupt_enable_port.write(0x00);
 
    // 8 bits, no parity, one stop bit
    m_line_control_port.write(0x03);
 
    // Enable FIFO, clear them, with 14-byte threshold
    m_fifo_control_port.write(0x07);
 
    // IRQs enabled, RTS/DSR set
    m_modem_control_port.write(0x0B);
 
    // Test serial chip
    m_modem_control_port.write(0x1E);
    m_data_port.write(0xAE);
    if (m_data_port.read() != 0xAE)
        return;
 
    // Enable serial chip
    m_modem_control_port.write(0x0F);
 
    // Enable interrupts
    m_interrupt_enable_port.write(0x01);
 
    // Clear any prexisting state
    m_fifo_control_port.read();
    while (can_read())
        read_char();
}
 
SerialConsole::SerialConsole(Logger* logger)
: SerialConsole()
{
    // Set the active serial console
    if (!DO_DEBUGGING)
        logger->add_log_writer(this);
}
 
SerialConsole::~SerialConsole() = default;
 
void SerialConsole::put_character(char c) {
 
    // Wait for the serial port to be ready
    while (0 == (m_line_status_port.read() & 0x20));
 
    // Write the character
    m_data_port.write(c);
 
}
 
void SerialConsole::write_char(char c) {
    put_character(c);
}
 
bool SerialConsole::can_read() {
    return m_line_status_port.read() & 1;
}
 
char SerialConsole::read_char() {
    return m_data_port.read();
}