private GarminUSBPacket GetPacket()
{
GarminUSBPacket packet;
var bufferSize = 0;
var buffer = new byte[0];
while (true)
{
// Read async data until the driver returns less than the
// max async data size, which signifies the end of a packet
var tempBuffer = new byte[APIs.ASYNC_DATA_SIZE];
int bytesReturned;
IntPtr pInBuffer = Marshal.AllocHGlobal(0);
IntPtr pOutBuffer = Marshal.AllocHGlobal(APIs.ASYNC_DATA_SIZE);
bool r = APIs.DeviceIoControl(
handle.ToInt32(),
CTL_CODE(0x00000022, 0x850, 0, 0),
pInBuffer,
0,
pOutBuffer,
APIs.ASYNC_DATA_SIZE,
out bytesReturned,
0);
Marshal.Copy(pOutBuffer, tempBuffer, 0, APIs.ASYNC_DATA_SIZE);
Marshal.FreeHGlobal(pInBuffer);
Marshal.FreeHGlobal(pOutBuffer);
if (!r)
{
throw new GarminUsbException(Strings.ErrorCommunicatingWithDevice);
}
bufferSize += APIs.ASYNC_DATA_SIZE;
var newBuffer = new byte[bufferSize];
if (buffer.Length > 0)
{
Array.Copy(buffer, 0, newBuffer, 0, buffer.Length);
}
Array.Copy(tempBuffer, 0, newBuffer, bufferSize - APIs.ASYNC_DATA_SIZE, tempBuffer.Length);
buffer = newBuffer;
if (bytesReturned != APIs.ASYNC_DATA_SIZE)
{
packet = new GarminUSBPacket(buffer);
break;
}
}
// If this was a small "signal" packet, read a real
// packet using ReadFile
if (packet.Type == 0 && packet.Id == 2)
{
var newBuffer = new byte[MAX_BUFFER_SIZE];
var bytesReturned = 0;
// A full implementation would keep reading (and queueing)
// packets until the driver returns a 0 size buffer.
bool r = APIs.ReadFile(handle,
newBuffer,
MAX_BUFFER_SIZE,
ref bytesReturned,
IntPtr.Zero);
if (!r)
{
throw new GarminUsbException(Strings.ErrorCommunicatingWithDevice);
}
return(new GarminUSBPacket(newBuffer));
}
return(packet);
}
private void StartUSBCommunication()
{
ReadingNow = true;
var guid = new Guid("2C9C45C2-8E7D-4C08-A12D-816BBAE722C0");
string deviceId;
const int portIndex = 0;
IntPtr hDevInfoSet = APIs.SetupDiGetClassDevs(ref guid,
0,
IntPtr.Zero,
(int)(APIs.DeviceFlags.DigCDDeviceInterface | APIs.DeviceFlags.DigCFPresent));
APIs.DeviceInterfaceDetailData mDetailedData = GetDeviceInfo(hDevInfoSet, guid, out deviceId, portIndex);
handle = APIs.CreateFile(mDetailedData.DevicePath, FileAccess.Read | FileAccess.Write, FileShare.None, IntPtr.Zero, FileMode.Open, 0x00000080, IntPtr.Zero);
// Did we get a handle?
if ((int)handle < 0)
{
throw new GarminUsbException(Strings.ErrorFindingDevice);
}
IntPtr usbPacketSizePointer = Marshal.AllocHGlobal(sizeof(Int16));
int bytesReturned;
bool r = APIs.DeviceIoControl(
handle.ToInt32(),
CTL_CODE(0x00000022, 0x851, 0, 0),
IntPtr.Zero,
0,
usbPacketSizePointer,
(uint)sizeof(int),
out bytesReturned,
0);
if (!r)
{
throw new GarminUsbException(Strings.ErrorCommunicatingWithDevice);
}
usbPacketSize = (Int16)Marshal.PtrToStructure(usbPacketSizePointer, typeof(Int16));
Marshal.FreeHGlobal(usbPacketSizePointer);
// Tell the device that we are starting a session.
var startSessionPacket = new GarminUSBPacket {
Id = 5
};
SendPacket(startSessionPacket);
GarminUSBPacket packet;
while (true)
{
packet = GetPacket();
if (packet.Type == 0 && packet.Id == 6)
{
break;
}
}
}
