root/chrome/browser/extensions/api/serial/serial_connection_win.cc

DEFINITIONS

1. BitrateToSpeedConstant
2. DataBitsEnumToConstant
3. ParityBitEnumToConstant
4. StopBitsEnumToConstant
5. SpeedConstantToBitrate
6. DataBitsConstantToEnum
7. ParityBitConstantToEnum
8. StopBitsConstantToEnum
9. ConfigurePort
10. PostOpen
11. Flush
12. GetControlSignals
13. SetControlSignals
14. GetPortInfo
15. MaybeFixUpPortName

// Copyright 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/extensions/api/serial/serial_connection.h"

#include <windows.h>

#include <string>

namespace extensions {

namespace {

int BitrateToSpeedConstant(int bitrate) {
#define BITRATE_TO_SPEED_CASE(x) case x: return CBR_ ## x;
  switch (bitrate) {
    BITRATE_TO_SPEED_CASE(110);
    BITRATE_TO_SPEED_CASE(300);
    BITRATE_TO_SPEED_CASE(600);
    BITRATE_TO_SPEED_CASE(1200);
    BITRATE_TO_SPEED_CASE(2400);
    BITRATE_TO_SPEED_CASE(4800);
    BITRATE_TO_SPEED_CASE(9600);
    BITRATE_TO_SPEED_CASE(14400);
    BITRATE_TO_SPEED_CASE(19200);
    BITRATE_TO_SPEED_CASE(38400);
    BITRATE_TO_SPEED_CASE(57600);
    BITRATE_TO_SPEED_CASE(115200);
    BITRATE_TO_SPEED_CASE(128000);
    BITRATE_TO_SPEED_CASE(256000);
    default:
      // If the bitrate doesn't match that of one of the standard
      // index constants, it may be provided as-is to the DCB
      // structure, according to MSDN.
      return bitrate;
  }
#undef BITRATE_TO_SPEED_CASE
}

int DataBitsEnumToConstant(api::serial::DataBits data_bits) {
  switch (data_bits) {
    case api::serial::DATA_BITS_SEVEN:
      return 7;
    case api::serial::DATA_BITS_EIGHT:
    default:
      return 8;
  }
}

int ParityBitEnumToConstant(api::serial::ParityBit parity_bit) {
  switch (parity_bit) {
    case api::serial::PARITY_BIT_EVEN:
      return EVENPARITY;
    case api::serial::PARITY_BIT_ODD:
      return SPACEPARITY;
    case api::serial::PARITY_BIT_NO:
    default:
      return NOPARITY;
  }
}

int StopBitsEnumToConstant(api::serial::StopBits stop_bits) {
  switch (stop_bits) {
    case api::serial::STOP_BITS_TWO:
      return TWOSTOPBITS;
    case api::serial::STOP_BITS_ONE:
    default:
      return ONESTOPBIT;
  }
}

int SpeedConstantToBitrate(int speed) {
#define SPEED_TO_BITRATE_CASE(x) case CBR_ ## x: return x;
  switch (speed) {
    SPEED_TO_BITRATE_CASE(110);
    SPEED_TO_BITRATE_CASE(300);
    SPEED_TO_BITRATE_CASE(600);
    SPEED_TO_BITRATE_CASE(1200);
    SPEED_TO_BITRATE_CASE(2400);
    SPEED_TO_BITRATE_CASE(4800);
    SPEED_TO_BITRATE_CASE(9600);
    SPEED_TO_BITRATE_CASE(14400);
    SPEED_TO_BITRATE_CASE(19200);
    SPEED_TO_BITRATE_CASE(38400);
    SPEED_TO_BITRATE_CASE(57600);
    SPEED_TO_BITRATE_CASE(115200);
    SPEED_TO_BITRATE_CASE(128000);
    SPEED_TO_BITRATE_CASE(256000);
    default:
      // If it's not one of the standard index constants,
      // it should be an integral baud rate, according to
      // MSDN.
      return speed;
  }
#undef SPEED_TO_BITRATE_CASE
}

api::serial::DataBits DataBitsConstantToEnum(int data_bits) {
  switch (data_bits) {
    case 7:
      return api::serial::DATA_BITS_SEVEN;
    case 8:
    default:
      return api::serial::DATA_BITS_EIGHT;
  }
}

api::serial::ParityBit ParityBitConstantToEnum(int parity_bit) {
  switch (parity_bit) {
    case EVENPARITY:
      return api::serial::PARITY_BIT_EVEN;
    case ODDPARITY:
      return api::serial::PARITY_BIT_ODD;
    case NOPARITY:
    default:
      return api::serial::PARITY_BIT_NO;
  }
}

api::serial::StopBits StopBitsConstantToEnum(int stop_bits) {
  switch (stop_bits) {
    case TWOSTOPBITS:
      return api::serial::STOP_BITS_TWO;
    case ONESTOPBIT:
    default:
      return api::serial::STOP_BITS_ONE;
  }
}

}  // namespace

bool SerialConnection::ConfigurePort(
    const api::serial::ConnectionOptions& options) {
  DCB config = { 0 };
  config.DCBlength = sizeof(config);
  if (!GetCommState(file_.GetPlatformFile(), &config)) {
    return false;
  }
  if (options.bitrate.get())
    config.BaudRate = BitrateToSpeedConstant(*options.bitrate);
  if (options.data_bits != api::serial::DATA_BITS_NONE)
    config.ByteSize = DataBitsEnumToConstant(options.data_bits);
  if (options.parity_bit != api::serial::PARITY_BIT_NONE)
    config.Parity = ParityBitEnumToConstant(options.parity_bit);
  if (options.stop_bits != api::serial::STOP_BITS_NONE)
    config.StopBits = StopBitsEnumToConstant(options.stop_bits);
  if (options.cts_flow_control.get()) {
    if (*options.cts_flow_control) {
      config.fOutxCtsFlow = TRUE;
      config.fRtsControl = RTS_CONTROL_HANDSHAKE;
    } else {
      config.fOutxCtsFlow = FALSE;
      config.fRtsControl = RTS_CONTROL_ENABLE;
    }
  }
  return SetCommState(file_.GetPlatformFile(), &config) != 0;
}

bool SerialConnection::PostOpen() {
  // A ReadIntervalTimeout of MAXDWORD will cause async reads to complete
  // immediately with any data that's available, even if there is none.
  // This is OK because we never issue a read request until WaitCommEvent
  // signals that data is available.
  COMMTIMEOUTS timeouts = { 0 };
  timeouts.ReadIntervalTimeout = MAXDWORD;
  if (!::SetCommTimeouts(file_.GetPlatformFile(), &timeouts)) {
    return false;
  }

  DCB config = { 0 };
  config.DCBlength = sizeof(config);
  if (!GetCommState(file_.GetPlatformFile(), &config)) {
    return false;
  }
  // Setup some sane default state.
  config.fBinary = TRUE;
  config.fParity = FALSE;
  config.fAbortOnError = TRUE;
  config.fOutxCtsFlow = FALSE;
  config.fOutxDsrFlow = FALSE;
  config.fRtsControl = RTS_CONTROL_ENABLE;
  config.fDtrControl = DTR_CONTROL_ENABLE;
  config.fDsrSensitivity = FALSE;
  config.fOutX = FALSE;
  config.fInX = FALSE;
  return SetCommState(file_.GetPlatformFile(), &config) != 0;
}

bool SerialConnection::Flush() const {
  return PurgeComm(file_.GetPlatformFile(), PURGE_RXCLEAR | PURGE_TXCLEAR) != 0;
}

bool SerialConnection::GetControlSignals(
    api::serial::DeviceControlSignals* signals) const {
  DWORD status;
  if (!GetCommModemStatus(file_.GetPlatformFile(), &status)) {
    return false;
  }
  signals->dcd = (status & MS_RLSD_ON) != 0;
  signals->cts = (status & MS_CTS_ON) != 0;
  signals->dsr = (status & MS_DSR_ON) != 0;
  signals->ri = (status & MS_RING_ON) != 0;
  return true;
}

bool SerialConnection::SetControlSignals(
    const api::serial::HostControlSignals& signals) {
  if (signals.dtr.get()) {
    if (!EscapeCommFunction(file_.GetPlatformFile(),
                            *signals.dtr ? SETDTR : CLRDTR)) {
      return false;
    }
  }
  if (signals.rts.get()) {
    if (!EscapeCommFunction(file_.GetPlatformFile(),
                            *signals.rts ? SETRTS : CLRRTS)) {
      return false;
    }
  }
  return true;
}

bool SerialConnection::GetPortInfo(api::serial::ConnectionInfo* info) const {
  DCB config = { 0 };
  config.DCBlength = sizeof(config);
  if (!GetCommState(file_.GetPlatformFile(), &config)) {
    return false;
  }
  info->bitrate.reset(new int(SpeedConstantToBitrate(config.BaudRate)));
  info->data_bits = DataBitsConstantToEnum(config.ByteSize);
  info->parity_bit = ParityBitConstantToEnum(config.Parity);
  info->stop_bits = StopBitsConstantToEnum(config.StopBits);
  info->cts_flow_control.reset(new bool(config.fOutxCtsFlow != 0));
  return true;
}

std::string SerialConnection::MaybeFixUpPortName(
    const std::string &port_name) {
  // For COM numbers less than 9, CreateFile is called with a string such as
  // "COM1". For numbers greater than 9, a prefix of "\\\\.\\" must be added.
  if (port_name.length() > std::string("COM9").length())
    return std::string("\\\\.\\").append(port_name);

  return port_name;
}

}  // namespace extensions