Subversion Repositories s6soc

//

//

// Filename:    uartsim.cpp

//

// Project:     FPGA library development (S6 development board)

//

// Purpose:     To emulate the external parameters of a UART device, providing

//              the UART output to, and input from, the command

//              console/terminal while also providing the controller with

//              appropriate busy lines as necessary.

//

// Creator:     Dan Gisselquist

//              Gisselquist Tecnology, LLC

//

// Copyright:   2016

//

//

#include <unistd.h>

#include <fcntl.h>

#include <stdio.h>

#include "uartsim.h"

UARTSIM::UARTSIM(int baud_counts, int fdin, int fdout) {

        int fctl_flags;

        m_fdin = fdin;

        m_fdout = fdout;

        m_baud_counts = baud_counts;

        m_tx_busy_count = 0;

        m_rx_busy_count = -1;

        // Set the linux O_NONBLOCK on fdin

        fctl_flags = fcntl(fdin, F_GETFL, 0);

        fcntl(fdin, F_SETFL, fctl_flags | O_NONBLOCK);

}

int     UARTSIM::rx(unsigned char &data) {

        if (m_rx_busy_count >= 0) {

                if (m_rx_busy_count-- == 0) {

                        data = (unsigned char)m_rx_next;

                        return 1;

                }

        }

        if (read(m_fdin, &m_rx_next, 1) > 0)

                m_rx_busy_count = m_baud_counts;

        return 0;

}

int     UARTSIM::tx(int stb, char data) {

        if (m_tx_busy_count > 0) {

                // This write may block--if so, we don't care.  Just write it.

                if (--m_tx_busy_count == 0)

                        if (write(m_fdout, &m_tx_data, 1) != 1)

                                perror("O/S Write Err:");

                return 1;

        } else if (stb) {

                m_tx_data = data;

                m_tx_busy_count = m_baud_counts;

        }

        return 0;

}