USBSerial.cpp

/*
  Copyright (c) 2015 Arduino LLC.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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 Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#if defined (USBCON) && defined(USBD_USE_CDC)

#include "USBSerial.h"
#include "usbd_cdc.h"
#include "usbd_cdc_if.h"
#include "usbd_desc.h"
#include "wiring.h"

extern __IO bool dtrState;
extern __IO bool rtsState;

USBSerial SerialUSB;
void serialEventUSB() __attribute__((weak));

void USBSerial::begin(void)
{
  CDC_init();
}

void USBSerial::begin(uint32_t /* baud_count */)
{
  // uart config is ignored in USB-CDC
  begin();
}

void USBSerial::begin(uint32_t /* baud_count */, uint8_t /* config */)
{
  // uart config is ignored in USB-CDC
  begin();
}

void USBSerial::end()
{
  CDC_deInit();
}

int USBSerial::availableForWrite()
{
  // Just transmit queue size, available for write
  return static_cast<int>(CDC_TransmitQueue_WriteSize(&TransmitQueue));
}

size_t USBSerial::write(uint8_t ch)
{
  // Just write single-byte buffer.
  return write(&ch, 1);
}

size_t USBSerial::write(const uint8_t *buffer, size_t size)
{
  size_t rest = size;
  while (rest > 0 && CDC_connected()) {
    // Determine buffer size available for write
    auto portion = (size_t)CDC_TransmitQueue_WriteSize(&TransmitQueue);
    // Truncate it to content size (if rest is greater)
    if (rest < portion) {
      portion = rest;
    }
    if (portion > 0) {
      // Only if some space in the buffer exists.
      // TS: Only main thread calls write and writeSize methods,
      // it's thread-safe since IRQ does not affects
      // TransmitQueue write position
      CDC_TransmitQueue_Enqueue(&TransmitQueue, buffer, portion);
      rest -= portion;
      buffer += portion;
      // After storing data, start transmitting process
      CDC_continue_transmit();
    }
  }
  return size - rest;
}

int USBSerial::available(void)
{
  // Just ReceiveQueue size, available for reading
  return static_cast<int>(CDC_ReceiveQueue_ReadSize(&ReceiveQueue));
}

int USBSerial::read(void)
{
  // Dequeue only one char from queue
  // TS: it safe, because only main thread affects ReceiveQueue->read pos
  auto ch = CDC_ReceiveQueue_Dequeue(&ReceiveQueue);
  // Resume receive process, if possible
  CDC_resume_receive();
  return ch;
}

size_t USBSerial::readBytes(char *buffer, size_t length)
{
  size_t read;
  size_t rest = length;
  _startMillis = millis();
  do {
    read = CDC_ReceiveQueue_Read(&ReceiveQueue, reinterpret_cast<uint8_t *>(buffer), rest);
    CDC_resume_receive();
    rest -= read;
    buffer += read;
    if (rest == 0) {
      return length;
    }
  } while (millis() - _startMillis < _timeout);
  return length - rest;
}

size_t USBSerial::readBytesUntil(char terminator, char *buffer, size_t length)
{
  uint32_t read;
  size_t rest = length;
  _startMillis = millis();
  do {
    bool found = CDC_ReceiveQueue_ReadUntil(&ReceiveQueue, static_cast<uint8_t>(terminator),
                                            reinterpret_cast<uint8_t *>(buffer), rest, &read);
    CDC_resume_receive();
    rest -= read;
    buffer += read;
    if (found) {
      return length - rest;
    }
    if (rest == 0) {
      return length;
    }
  } while (millis() - _startMillis < _timeout);
  return length - rest;
}

int USBSerial::peek(void)
{
  // Peek one symbol, it can't change receive avaiablity
  return CDC_ReceiveQueue_Peek(&ReceiveQueue);
}

void USBSerial::flush(void)
{
  // Wait for TransmitQueue read size becomes zero
  // TS: safe, because it not be stopped while receive 0
  while (CDC_TransmitQueue_ReadSize(&TransmitQueue) > 0) {}
}

uint32_t USBSerial::baud()
{
  return 115200;
}

uint8_t USBSerial::stopbits()
{
  return ONE_STOP_BIT;
}

uint8_t USBSerial::paritytype()
{
  return NO_PARITY;
}

uint8_t USBSerial::numbits()
{
  return 8;
}

void USBSerial::dtr(bool enable)
{
  CDC_enableDTR(enable);
}

bool USBSerial::dtr(void)
{
  return dtrState;
}

bool USBSerial::rts(void)
{
  return rtsState;
}

USBSerial::operator bool()
{
  delay(10);
  return dtrState;
}

#endif // USBCON && USBD_USE_CDC