Class: LIBUSB::Context

Inherits:
Object
  • Object
show all
Defined in:
lib/libusb/context.rb,
lib/libusb/eventmachine.rb

Overview

Class representing a libusb session.

Defined Under Namespace

Classes: CompletionFlag, EMPollfdHandler, HotplugCallback, Pollfd

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Context

Initialize libusb context.



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# File 'lib/libusb/context.rb', line 100

def initialize
  m = FFI::MemoryPointer.new :pointer
  res = Call.libusb_init(m)
  LIBUSB.raise_error res, "in libusb_init" if res!=0
  @ctx = m.read_pointer
  @on_pollfd_added = nil
  @on_pollfd_removed = nil
  @hotplug_callbacks = {}
end

Instance Method Details

#debug=(level) ⇒ Object

Set message verbosity.

  • Level 0: no messages ever printed by the library (default)

  • Level 1: error messages are printed to stderr

  • Level 2: warning and error messages are printed to stderr

  • Level 3: informational messages are printed to stdout, warning and error messages are printed to stderr

The default level is 0, which means no messages are ever printed. If you choose to increase the message verbosity level, ensure that your application does not close the stdout/stderr file descriptors.

You are advised to set level 3. libusb is conservative with its message logging and most of the time, will only log messages that explain error conditions and other oddities. This will help you debug your software.

If the LIBUSB_DEBUG environment variable was set when libusb was initialized, this method does nothing: the message verbosity is fixed to the value in the environment variable.

If libusb was compiled without any message logging, this method does nothing: you’ll never get any messages.

If libusb was compiled with verbose debug message logging, this method does nothing: you’ll always get messages from all levels.

Parameters:

  • level (Fixnum) —

    debug level to set



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# File 'lib/libusb/context.rb', line 144

def debug=(level)
  Call.libusb_set_debug(@ctx, level)
end

#devices(filter_hash = {}) ⇒ Array<LIBUSB::Device>

Obtain a list of devices currently attached to the USB system, optionally matching certain criteria.

Examples:

# Return all devices of vendor 0x0ab1 where idProduct is 3 or 4:
context.device :idVendor=>0x0ab1, :idProduct=>[0x0003, 0x0004]

Parameters:

  • filter_hash (Hash) (defaults to: {}) —

    A number of criteria can be defined in key-value pairs. Only devices that equal all given criterions will be returned. If a criterion is not specified or its value is nil, any device will match that criterion. The following criteria can be filtered:

    • :idVendor, :idProduct (FixNum) for matching vendor/product ID,

    • :bClass, :bSubClass, :bProtocol (FixNum) for the device type - Devices using CLASS_PER_INTERFACE will match, if any of the interfaces match.

    • :bcdUSB, :bcdDevice, :bMaxPacketSize0 (FixNum) for the USB and device release numbers.

    Criteria can also specified as Array of several alternative values.

Returns:



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# File 'lib/libusb/context.rb', line 224

def devices(filter_hash={})
  device_list.select do |dev|
    ( !filter_hash[:bClass] || (dev.bDeviceClass==CLASS_PER_INTERFACE ?
                         dev.settings.map(&:bInterfaceClass).&([filter_hash[:bClass]].flatten).any? :
                         [filter_hash[:bClass]].flatten.include?(dev.bDeviceClass))) &&
    ( !filter_hash[:bSubClass] || (dev.bDeviceClass==CLASS_PER_INTERFACE ?
                         dev.settings.map(&:bInterfaceSubClass).&([filter_hash[:bSubClass]].flatten).any? :
                         [filter_hash[:bSubClass]].flatten.include?(dev.bDeviceSubClass))) &&
    ( !filter_hash[:bProtocol] || (dev.bDeviceClass==CLASS_PER_INTERFACE ?
                         dev.settings.map(&:bInterfaceProtocol).&([filter_hash[:bProtocol]].flatten).any? :
                         [filter_hash[:bProtocol]].flatten.include?(dev.bDeviceProtocol))) &&
    ( !filter_hash[:bMaxPacketSize0] || [filter_hash[:bMaxPacketSize0]].flatten.include?(dev.bMaxPacketSize0) ) &&
    ( !filter_hash[:idVendor] || [filter_hash[:idVendor]].flatten.include?(dev.idVendor) ) &&
    ( !filter_hash[:idProduct] || [filter_hash[:idProduct]].flatten.include?(dev.idProduct) ) &&
    ( !filter_hash[:bcdUSB] || [filter_hash[:bcdUSB]].flatten.include?(dev.bcdUSB) ) &&
    ( !filter_hash[:bcdDevice] || [filter_hash[:bcdDevice]].flatten.include?(dev.bcdDevice) )
  end
end

#eventmachine_register ⇒ Object

Register libusb’s file descriptors and timeouts to EventMachine.

Examples:

require 'libusb/eventmachine'
context = LIBUSB::Context.new
EventMachine.run do
  context.eventmachine_register
end

See Also:



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# File 'lib/libusb/eventmachine.rb', line 34

def eventmachine_register
  @eventmachine_attached_fds = {}
  @eventmachine_timer = nil

  pollfds = self.pollfds
  if pollfds
    pollfds.each do |pollfd|
      eventmachine_add_pollfd(pollfd)
    end

    self.on_pollfd_added do |pollfd|
      eventmachine_add_pollfd(pollfd)
    end

    self.on_pollfd_removed do |pollfd|
      eventmachine_rm_pollfd(pollfd)
    end
  else
    # Libusb pollfd API is not available on this platform.
    # Use simple polling timer, instead:
    EventMachine.add_periodic_timer(0.01) do
      @eventmachine_timer = self.handle_events 0
    end
  end
end

#eventmachine_unregister ⇒ Object 



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# File 'lib/libusb/eventmachine.rb', line 60

def eventmachine_unregister
  @eventmachine_timer.cancel if @eventmachine_timer
  @eventmachine_attached_fds.each do |fd, watcher|
    watcher.detach
  end
end

#exit ⇒ Object

Deinitialize libusb.

Should be called after closing all open devices and before your application terminates.



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# File 'lib/libusb/context.rb', line 113

def exit
  Call.libusb_exit(@ctx)
end

#handle_events(timeout = nil, completion_flag = nil) ⇒ Object

Handle any pending events in blocking mode.

This method must be called when libusb is running asynchronous transfers. This gives libusb the opportunity to reap pending transfers, invoke callbacks, etc.

If a zero timeout is passed, this function will handle any already-pending events and then immediately return in non-blocking style.

If a non-zero timeout is passed and no events are currently pending, this method will block waiting for events to handle up until the specified timeout. If an event arrives or a signal is raised, this method will return early.

If the parameter completion_flag is used, then after obtaining the event handling lock this function will return immediately if the flag is set to completed. This allows for race free waiting for the completion of a specific transfer. See source of Transfer#submit_and_wait for a use case of completion_flag.

Parameters:

  • timeout (Integer, nil) (defaults to: nil) —

    the maximum time (in millseconds) to block waiting for events, or 0 for non-blocking mode

  • completion_flag (Context::CompletionFlag, nil) (defaults to: nil) —

    CompletionFlag to check



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# File 'lib/libusb/context.rb', line 184

def handle_events(timeout=nil, completion_flag=nil)
  if completion_flag && !completion_flag.is_a?(Context::CompletionFlag)
    raise ArgumentError, "completion_flag is not a CompletionFlag"
  end
  if timeout
    timeval = Call::Timeval.new
    timeval.in_ms = timeout
    res = if Call.respond_to?(:libusb_handle_events_timeout_completed)
      Call.libusb_handle_events_timeout_completed(@ctx, timeval, completion_flag)
    else
      Call.libusb_handle_events_timeout(@ctx, timeval)
    end
  else
    res = if Call.respond_to?(:libusb_handle_events_completed)
      Call.libusb_handle_events_completed(@ctx, completion_flag )
    else
      Call.libusb_handle_events(@ctx)
    end
  end
  LIBUSB.raise_error res, "in libusb_handle_events" if res<0
end

#next_timeout ⇒ Float?

Determine the next internal timeout that libusb needs to handle.

You only need to use this function if you are calling poll() or select() or similar on libusb’s file descriptors yourself - you do not need to use it if you are calling #handle_events directly.

You should call this function in your main loop in order to determine how long to wait for select() or poll() to return results. libusb needs to be called into at this timeout, so you should use it as an upper bound on your select() or poll() call.

When the timeout has expired, call into #handle_events (perhaps in non-blocking mode) so that libusb can handle the timeout.

This function may return zero. If this is the case, it indicates that libusb has a timeout that has already expired so you should call #handle_events immediately. A return code of nil indicates that there are no pending timeouts.

On some platforms, this function will always returns nil (no pending timeouts). See libusb’s notes on time-based events.

Returns:

  • (Float, nil) —

    the timeout in seconds



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# File 'lib/libusb/context.rb', line 291

def next_timeout
  timeval = Call::Timeval.new
  res = Call.libusb_get_next_timeout @ctx, timeval
  LIBUSB.raise_error res, "in libusb_get_next_timeout" if res<0
  res == 1 ? timeval.in_s : nil
end

#on_hotplug_event(args = {}) {|device, event| ... } ⇒ HotplugCallback

Register a hotplug event notification.

Register a callback with the LIBUSB::Context. The callback will fire when a matching event occurs on a matching device. The callback is armed until either it is deregistered with LIBUSB::Context::HotplugCallback#deregister or the supplied block returns :finish to indicate it is finished processing events.

If the flag HOTPLUG_ENUMERATE is passed the callback will be called with a :HOTPLUG_EVENT_DEVICE_ARRIVED for all devices already plugged into the machine. Note that libusb modifies its internal device list from a separate thread, while calling hotplug callbacks from #handle_events, so it is possible for a device to already be present on, or removed from, its internal device list, while the hotplug callbacks still need to be dispatched. This means that when using HOTPLUG_ENUMERATE, your callback may be called twice for the arrival of the same device, once from #on_hotplug_event and once from #handle_events; and/or your callback may be called for the removal of a device for which an arrived call was never made.

Since libusb version 1.0.16.

Parameters:

  • args (Hash) (defaults to: {})

Options Hash (args):

  • :events (Fixnum, Symbol) —

    bitwise or of events that will trigger this callback. Default is LIBUSB::HOTPLUG_EVENT_DEVICE_ARRIVED|LIBUSB::HOTPLUG_EVENT_DEVICE_LEFT . See HotplugEvents

  • :flags (Fixnum, Symbol) —

    hotplug callback flags. Default is 0. See HotplugFlags

  • :vendor_id (Fixnum) —

    the vendor id to match. Default is HOTPLUG_MATCH_ANY.

  • :product_id (Fixnum) —

    the product id to match. Default is HOTPLUG_MATCH_ANY.

  • :dev_class (Fixnum) —

    the device class to match. Default is HOTPLUG_MATCH_ANY.

Yield Parameters:

Yield Returns:

  • (Symbol) —

    :finish to deregister the callback, :repeat to receive additional events

Returns:

Raises:



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# File 'lib/libusb/context.rb', line 369

def on_hotplug_event(args={}, &block)
  events = args.delete(:events) || (HOTPLUG_EVENT_DEVICE_ARRIVED | HOTPLUG_EVENT_DEVICE_LEFT)
  flags = args.delete(:flags) || 0
  vendor_id = args.delete(:vendor_id) || HOTPLUG_MATCH_ANY
  product_id = args.delete(:product_id) || HOTPLUG_MATCH_ANY
  dev_class = args.delete(:dev_class) || HOTPLUG_MATCH_ANY
  raise ArgumentError, "invalid params #{args.inspect}" unless args.empty?

  handle = HotplugCallback.new self, @ctx, @hotplug_callbacks

  block2 = proc do |ctx, pDevice, event, _user_data|
    raise "internal error: unexpected context" unless @ctx==ctx
    dev = Device.new @ctx, pDevice

    blres = block.call(dev, event)

    case blres
    when :finish
      1
    when :repeat
      0
    else
      raise ArgumentError, "hotplug event handler must return :finish or :repeat"
    end
  end

  res = Call.libusb_hotplug_register_callback(@ctx,
              events, flags,
              vendor_id, product_id, dev_class,
              block2, nil, handle)

  LIBUSB.raise_error res, "in libusb_hotplug_register_callback" if res<0

  # Avoid GC'ing of the block:
  @hotplug_callbacks[handle[:handle]] = block2

  return handle
end

#on_pollfd_added {|pollfd| ... } ⇒ Object

Register a notification block for file descriptor additions.

This block will be invoked for every new file descriptor that libusb uses as an event source.

Note that file descriptors may have been added even before you register these notifiers (e.g. at #initialize time).

Yield Parameters:

  • pollfd (Pollfd) —

    The added file descriptor is yielded to the block



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# File 'lib/libusb/context.rb', line 307

def on_pollfd_added &block
  @on_pollfd_added = proc do |fd, events, _|
    pollfd = Pollfd.new fd, events
    block.call pollfd
  end
  Call.libusb_set_pollfd_notifiers @ctx, @on_pollfd_added, @on_pollfd_removed, nil
end

#on_pollfd_removed {|pollfd| ... } ⇒ Object

Register a notification block for file descriptor removals.

This block will be invoked for every removed file descriptor that libusb uses as an event source.

Note that the removal notifier may be called during #exit (e.g. when it is closing file descriptors that were opened and added to the poll set at #initialize time). If you don’t want this, overwrite the notifier immediately before calling #exit.

Yield Parameters:

  • pollfd (Pollfd) —

    The removed file descriptor is yielded to the block



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# File 'lib/libusb/context.rb', line 326

def on_pollfd_removed &block
  @on_pollfd_removed = proc do |fd, _|
    pollfd = Pollfd.new fd
    block.call pollfd
  end
  Call.libusb_set_pollfd_notifiers @ctx, @on_pollfd_added, @on_pollfd_removed, nil
end

#pollfds ⇒ Array<Pollfd>

Retrieve a list of file descriptors that should be polled by your main loop as libusb event sources.

As file descriptors are a Unix-specific concept, this function is not available on Windows and will always return nil.

Returns:

  • (Array<Pollfd>) —

    list of Pollfd objects, nil on error, nil on platforms where the functionality is not available



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# File 'lib/libusb/context.rb', line 253

def pollfds
  ppPollfds = Call.libusb_get_pollfds(@ctx)
  return nil if ppPollfds.null?
  offs = 0
  pollfds = []
  while !(pPollfd=ppPollfds.get_pointer(offs)).null?
    pollfd = Call::Pollfd.new pPollfd
    pollfds << Pollfd.new(pollfd[:fd], pollfd[:events])
    offs += FFI.type_size :pointer
  end
  # ppPollfds has to be released by free() -> give the GC this job
  ppPollfds.autorelease = true
  pollfds
end