private void runReadOnBackground() {
m_SyncStart.waitAndSync();
while (!m_StopThread) {
// In Linux read() from a HID device we always try to read at least as many bytes as there can
// be in a report
// the kernel will return with the actual number of bytes in the report (plus one if numbered
// reports are used)
// and the data will be preceded with the report number if and only if numbered reports are
// used, which is
// kind of stupid because then we need to know this and to know that it is necessary to (be
// able to!) read
// the HID descriptor AND parse it. I like the Mac OS and Windows ways better, what a mess the
// world is!
int bytes_read = read(m_DeviceHandle, m_InputReportBytes, m_InputReportBytes.length);
if (m_InputReportListener != null) {
byte reportID = 0;
if (m_UsesNumberedReports) {
reportID = m_InputReportBytes[0];
bytes_read--;
System.arraycopy(m_InputReportBytes, 1, m_InputReportBytes, 0, bytes_read);
}
m_InputReportListener.onInputReport(this, reportID, m_InputReportBytes, bytes_read);
}
}
m_SyncShutdown.waitAndSync();
}
/* package */ HidDevice(String path, Frontend frontend) throws IOException {
m_Frontend = frontend;
udev udev = udev_new();
udev_device raw_dev = udev_device_new_from_syspath(udev, path);
String dev_path = udev_device_get_devnode(raw_dev);
udev_unref(udev);
m_HidDeviceInfo = new HidDeviceInfo(path);
// OPEN HERE //
m_DeviceHandle = open(dev_path, O_RDWR);
// If we have a good handle, return it.
if (m_DeviceHandle <= 0) throw new IOException("open() failed, errno " + Native.getLastError());
// Get the report descriptor
int[] desc_size = {0};
int res;
hidraw_report_descriptor rpt_desc = new hidraw_report_descriptor();
// Get Report Descriptor Size
res = ioctl(m_DeviceHandle, HIDIOCGRDESCSIZE, desc_size);
if (res < 0) // FIXME ERROR HANDLING
throw new IOException("ioctl(...HIDIOCGRDESCSIZE..) failed"); // perror("HIDIOCGRDESCSIZE");
// Get Report Descriptor
rpt_desc.size = desc_size[0];
res = ioctl(m_DeviceHandle, HIDIOCGRDESC, rpt_desc);
if (res < 0) throw new IOException("ioctl(...HIDIOCGRDESC..) failed");
// Determine if this device uses numbered reports.
m_UsesNumberedReports = uses_numbered_reports(rpt_desc.value, rpt_desc.size);
// ---------------
// Magic here, assume that no HID device ever uses reports longer than 4kB
m_InputReportBytes = new byte[4096 + 1];
m_OutputReportBytes = new byte[4096 + 1];
m_SyncStart = new SyncPoint(2);
m_SyncShutdown = new SyncPoint(2);
m_Thread =
new Thread(
new Runnable() {
@Override
public void run() {
try {
runReadOnBackground();
} catch (Exception e) {
e.printStackTrace();
}
}
},
m_HidDeviceInfo.getPath());
m_Thread.start();
m_SyncStart.waitAndSync();
}
@Override
public synchronized void close() {
if (!m_Open) throw new IllegalStateException("device not open");
m_StopThread = true;
UdevLibrary.close(m_DeviceHandle);
m_Thread.interrupt();
m_SyncShutdown.waitAndSync();
m_Frontend.closeDevice(this);
m_Open = false;
}