Method: LIBUSB::Context#initialize

Defined in:
lib/libusb/context.rb

#initialize(options = {}) ⇒ Context

Initialize libusb context.

Parameters:

  • options (Hash{Call::Options => Object}) (defaults to: {}) —

    Options are available since libusb-1.0.27

Options Hash (options):

  • :OPTION_LOG_LEVEL (Integer, Symbol) —

    The log Level as a Integer or Symbol. See Call::LogLevels

  • :OPTION_USE_USBDK (nil) —

    Enable the use of USBDK driver. Pass a nil as value like so: OPTION_USE_USBDK: nil

  • :OPTION_NO_DEVICE_DISCOVERY (nil) —

    Disable device discovery for use with libusb_wrap_sys_device(). Pass a nil as value like so: OPTION_NO_DEVICE_DISCOVERY: nil

  • :OPTION_LOG_CB (Proc) —

    Set a context related log callback Proc. It is called with parameters (context, level, logstring).



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# File 'lib/libusb/context.rb', line 105

def initialize(options={})
  m = FFI::MemoryPointer.new :pointer
  if options.empty?
    res = Call.libusb_init(m)
    LIBUSB.raise_error res, "in libusb_init" if res!=0
  else
    raise ArgumentError, "options require libusb-1.0.27+" unless Call.respond_to?(:libusb_init_context)
    i_opts = options.size
    p_opts = FFI::MemoryPointer.new(Call::InitOption, i_opts)
    options.each_with_index do |(k, v), i|
      opt = Call::InitOption.new(p_opts + i * Call::InitOption.size)
      opt[:option] = k

      ffitype, ffival = LIBUSB.send(:option_args_to_ffi, k, Array(v), self)
      case ffitype
        when NilClass then nil
        when :libusb_log_level then
          opt[:value][:ival] = ffival
        when :libusb_log_cb then
          opt[:value][:log_cbval] = ffival
        else raise ArgumentError, "internal error: unexpected ffitype: #{ffitype.inspect}"
      end
    end
    res = Call.libusb_init_context(m, p_opts, i_opts)
    LIBUSB.raise_error res, "in libusb_init_context" if res!=0
  end
  @ctx = m.read_pointer
  @on_pollfd_added = nil
  @on_pollfd_removed = nil
  @hotplug_callbacks = {}

  def @ctx.free_context(id)
    @free_context = true
    if @refs == 0
      # puts "final libusb_exit #{to_i} #{id} #{caller[0]}"
      if id # Is Context is about to be garbage collected?
        # In GC mode there's no way to call the registered collbacks, since they are GC'ed as well.
        # So disable callbacks now.
        if Call.respond_to?(:libusb_set_log_cb)
          Call.libusb_set_log_cb(self, nil, LOG_CB_CONTEXT)
        end
        Call.libusb_set_pollfd_notifiers(self, nil, nil, nil)
      end
      Call.libusb_exit(self)
      @refs = nil
    end
  end
  def @ctx.ref_context
    @refs += 1
    # puts "ref_context #{to_i} #{@refs} #{caller[1]}"
    self
  end
  def @ctx.unref_context
    @refs -= 1
    # puts "unref_context #{to_i} #{@refs}"
    raise "more unref_context than ref_context" if @refs < 0
    free_context(true) if @refs == 0 && @free_context
    self
  end
  def @ctx.setref_context
    @refs = 0
    @free_context = false
  end
  def @ctx.refs
    @refs
  end
  @ctx.setref_context
  ObjectSpace.define_finalizer(self, @ctx.method(:free_context))
end