text: 
  # Hex-Rays Decompiler project
  # Copyright (c) 2007-2018 by Hex-Rays, support@hex-rays.com
  # ALL RIGHTS RESERVED.
  #
  # Sample script for Hex-Rays Decompiler usage of udc_filter_t
  # class: decompile svc 0x900001 and svc 0x9000F8 as function calls to
  # svc_exit() and svc_exit_group() respectively.
  # NOTE: You will need to have an ARM + Linux IDB for this script to be usable
  #
  # It is also added into the right-click menu as "vds8.py:Toggle UDC"
  
  import ida_hexrays
  import ida_kernwin
  import ida_allins
  
  ACTION_NAME = "vds8.py:udcall"
  ACTION_SHORTCUT = "Ctrl+Shift+U"
  
  # --------------------------------------------------------------------------
  class udc_exit_t(ida_hexrays.udc_filter_t):
      def __init__(self, code, name):
          ida_hexrays.udc_filter_t.__init__(self)
          if not self.init("int __usercall %s@<R0>(int status@<R1>);" % name):
              raise Exception("Couldn't initialize udc_exit_t instance")
          self.code = code
          self.installed = False
  
      def match(self, cdg):
          return cdg.insn.itype == ida_allins.ARM_svc and cdg.insn.Op1.value == self.code
  
      def install(self):
          ida_hexrays.install_microcode_filter(self, True);
          self.installed = True
  
      def uninstall(self):
          ida_hexrays.install_microcode_filter(self, False);
          self.installed = False
  
      def toggle_install(self):
          if self.installed:
              self.uninstall()
          else:
              self.install()
  
  
  # --------------------------------------------------------------------------
  class toggle_udc_ah_t(ida_kernwin.action_handler_t):
      def __init__(self):
          ida_kernwin.action_handler_t.__init__(self)
  
      def activate(self, ctx):
          udc_exit.toggle_install();
          udc_exit_group.toggle_install();
          vu = ida_hexrays.get_widget_vdui(ctx.widget)
          vu.refresh_view(True)
          return 1
  
      def update(self, ctx):
          return ida_kernwin.AST_ENABLE_FOR_WIDGET if \
              ctx.widget_type == ida_kernwin.BWN_PSEUDOCODE else \
              ida_kernwin.AST_DISABLE_FOR_WIDGET
  
  
  # --------------------------------------------------------------------------
  class my_hooks_t(ida_kernwin.UI_Hooks):
      def __init__(self):
          ida_kernwin.UI_Hooks.__init__(self)
  
      def populating_widget_popup(self, widget, popup):
          if ida_kernwin.get_widget_type(widget) == ida_kernwin.BWN_PSEUDOCODE:
              ida_kernwin.attach_action_to_popup(widget, popup, ACTION_NAME)
  my_hooks = my_hooks_t()
  my_hooks.hook()
  
  
  # --------------------------------------------------------------------------
  SVC_EXIT       = 0x900001
  SVC_EXIT_GROUP = 0x9000f8
  
  if ida_hexrays.init_hexrays_plugin():
      udc_exit = udc_exit_t(SVC_EXIT, "svc_exit")
      udc_exit.toggle_install()
  
      udc_exit_group = udc_exit_t(SVC_EXIT_GROUP, "svc_exit_group")
      udc_exit_group.toggle_install()
  
      ida_kernwin.register_action(
          ida_kernwin.action_desc_t(
              ACTION_NAME,
              "vds8.py:Toggle UDC",
              toggle_udc_ah_t(),
              ACTION_SHORTCUT))
  
  