File content as of revision 6:d772ad205bc7:

#include "mbed.h"
#include "pinout.h"
#include "serialIO.h"

// buffer for TX and RX
char tx_buffer[buffer_size];
char rx_buffer[buffer_size];
// buffer for sscanf and sprintf
char tx_line[80];
char rx_line[80];

// index marking the begin/end of rx_buffer and tx_buffer
volatile int tx_out = 0;
volatile int tx_in = 0;
volatile int rx_out = 0;
volatile int rx_in = 0;

// Copy tx line buffer to large tx buffer for tx interrupt routine
void send_line() {
    int i;
    char temp_char;
    bool empty;
    i = 0;
// Start Critical Section - don't interrupt while changing global buffer variables
    NVIC_DisableIRQ(USB_IRQn);
    empty = (tx_in == tx_out);
    while ((i==0) || (tx_line[i-1] != '\n')) {
// Wait if buffer full
        if (((tx_in + 1) % buffer_size) == tx_out) {
// End Critical Section - need to let interrupt routine empty buffer by sending
            NVIC_EnableIRQ(USB_IRQn);
            while (((tx_in + 1) % buffer_size) == tx_out) {
            }
// Start Critical Section - don't interrupt while changing global buffer variables
            NVIC_DisableIRQ(USB_IRQn);
        }
        tx_buffer[tx_in] = tx_line[i];
        i++;
        tx_in = (tx_in + 1) % buffer_size;
    }
    if (pc.writeable() && (empty)) {
        temp_char = tx_buffer[tx_out];
        tx_out = (tx_out + 1) % buffer_size;
// Send first character to start tx interrupts, if stopped
        pc.putc(temp_char);
    }
// End Critical Section
    NVIC_EnableIRQ(USB_IRQn);
    return;
}

// Interupt Routine to write out data to serial port
void Tx_interrupt() {
// Loop to fill more than one character in UART's transmit FIFO buffer
// Stop if buffer empty
    while ((pc.writeable()) && (tx_in != tx_out)) {
        pc.putc(tx_buffer[tx_out]);
        tx_out = (tx_out + 1) % buffer_size;
    }
    return;
}

// Read a line from the large rx buffer from rx interrupt routine
void read_line() {
    int i;
    i = 0;
// Start Critical Section - don't interrupt while changing global buffer variables
    NVIC_DisableIRQ(USB_IRQn);
// Loop reading rx buffer characters until end of line character
    while ((i==0) || (rx_line[i-1] != '\r')) {
// Wait if buffer empty
        if (rx_in == rx_out) {
// End Critical Section - need to allow rx interrupt to get new characters for buffer
            NVIC_EnableIRQ(USB_IRQn);
            while (rx_in == rx_out) {
            }
// Start Critical Section - don't interrupt while changing global buffer variables
            NVIC_DisableIRQ(USB_IRQn);
        }
        rx_line[i] = rx_buffer[rx_out];
        i++;
        rx_out = (rx_out + 1) % buffer_size;
    }
// End Critical Section
    NVIC_EnableIRQ(USB_IRQn);
    rx_line[i-1] = 0;
    return;
}

// Interupt Routine to read in data from serial port
void Rx_interrupt() {
// Loop just in case more than one character is in UART's receive FIFO buffer
// Stop if buffer full
    while ((pc.readable()) && (((rx_in + 1) % buffer_size) != rx_out)) {
        rx_buffer[rx_in] = pc.getc();
// Uncomment to Echo to USB serial to watch data flow
//        monitor_device.putc(rx_buffer[rx_in]);
        rx_in = (rx_in + 1) % buffer_size;
    }
    return;
}