Nasal CDU Framework

This page is a rather technical description of the Nasal code for the framework used to implement a Boeing style CDU.

Work in progress This article or section will be worked on in the upcoming hours or days. Note: Hcc23 is working on this. Find him in the FG IRC channel to discuss this page. See history for the latest developments.

Note: Although this is meant as a documentation for the code, it obviously will (always) be (slightly) outdated. However, after reading through this page, the actual source code at https://gitorious.org/fg/fgdata/trees/master/Aircraft/Instruments-3d/cdu should not present any major surprises. Hcc23 10:07, 7 May 2011 (EDT)

Basic Classes

Line

The line class represents data to be shown on a row of the CDU's display matrix. This does not mean that a line has to span a complete row of the CDU's display matrix.

 var Line = {
   # "Static"
   vector 	byID,
   func 	registerInPropTree(path),
   func 	formatOutput(input_data),
   func 	getScreenTextVector(),
   func 	new(line_data,ptp),
   
   # "Public"
   scalar 	me.id,
   scalar 	me.ptp,
   vector 	me.used_properties,
   vector 	me.line_data,
   scalar 	me.line_string_length,
   func 	me.enable(),
   func 	me.disable(),
   
   # "Private"
   scalar 	me.active,
 };

Field

A field holds two lines, the label and the data line, as well as information about what the associated line select key does.

 var Field = {
   # "Static"
   vector 	byID,
   func 	registerInPropTree(path=nil),
   func 	new(label,data,key_action=nil,ptp=nil),
   
   # "Public"
   scalar 	me.id,
   scalar 	me.ptp,
 
   func 	me.get_label_line(),
   func 	me.get_label_line(),
   func 	me.used_properties(),
   func 	me.lsk_binding(),
   func 	me.enable_lsk(),
   func 	me.disable_lsk(),
 
   # "Private"
   (Line)	me.label_line,	
   (Line) 	me.data_line,
   scalar 	me.lsk_active,
 };

SubPage

A SubPage is actually the main element in the CDU framework. It holds the content via its fields and manages the updating of the CDU screen.

 var SubPage = {
   # "Static"
   vector 	byID,
   (Field) 	blankField,
   func 	registerInPropTree(path=nil),
   func 	updateField(field, side, lsk_index),	
   func 	displayFields(field_vector, side),
   func 	displayPage(),
   func 	new(parent_base_page,name=nil,ptp=nil),
   
   # "Public"
   scalar 	me.id,
   scalar      me.separator,
   scalar 	me.ptp,
   func 	me.register_field(field_pos,field),
   func 	me.activate(),
   (Field) 	me.home

   # "Private"
   scalar 	me.parent,
   scalar      me.title,
   scalar      me.status,
   vector 	me.left_field,
   vector      me.right_field,
 };