[flight_plan] add call_once primitive

<set needs a variable name and <call needs a function that returns a bool.
There is no elegant solution for handlers, while paparazzi has more and more handlers.
So we introduce the flightplan <call_once fun="KillThrottle()"/> block. It does also not cause a delay and moves to the next statement.

conf/flight_plans/flight_plan.dtd

@@ -19,21 +19,22 @@
 <!ELEMENT exceptions (exception*)>
 
 <!ELEMENT blocks (block+)>
-<!ELEMENT block (exception|while|heading|attitude|go|xyz|set|call|circle|deroute|stay|follow|survey_rectangle|for|return|eight|oval|home|path)*>
+<!ELEMENT block (exception|while|heading|attitude|go|xyz|set|call|call_once|circle|deroute|stay|follow|survey_rectangle|for|return|eight|oval|home|path)*>
 
 <!ELEMENT include (arg|with)*>
 <!ELEMENT arg EMPTY>
 <!ELEMENT with EMPTY>
 
 <!ELEMENT while (exception|while|heading|attitude|go|xyz|set|call|circle|deroute|stay|follow|survey_rectangle|for|return|eight|oval|path)*>
-<!ELEMENT for (exception|while|heading|attitude|go|xyz|set|call|circle|deroute|stay|follow|survey_rectangle|for|return|eight|oval|path)*>
+<!ELEMENT for (exception|while|heading|attitude|go|xyz|set|call|call_once|circle|deroute|stay|follow|survey_rectangle|for|return|eight|oval|path)*>
 <!ELEMENT exception EMPTY>
 <!ELEMENT heading EMPTY>
 <!ELEMENT attitude EMPTY>
 <!ELEMENT go EMPTY>
 <!ELEMENT xyz EMPTY>
 <!ELEMENT set EMPTY>
 <!ELEMENT call EMPTY>
+<!ELEMENT call_once EMPTY>
 <!ELEMENT circle EMPTY>
 <!ELEMENT home EMPTY>
 <!ELEMENT eight EMPTY>
@@ -164,6 +165,9 @@ value CDATA #REQUIRED>
 fun CDATA #REQUIRED
 until CDATA #IMPLIED>
 
+<!ATTLIST call_once
+fun CDATA #REQUIRED>
+
 <!ATTLIST follow
 ac_id CDATA #REQUIRED
 distance CDATA #REQUIRED

sw/lib/ocaml/fp_proc.ml

@@ -144,7 +144,7 @@ let transform_stage = fun prefix reroutes env xml ->
               assert (children=[]);
               let attribs = transform_values ["wp"; "vmode"] env attribs in
               Xml.Element (tag, attribs, children)
-            | "call" | "set" ->
+            | "call" | "set" | "call_once" ->
               let attribs = transform_values ["var"] env attribs in
               Xml.Element (tag, attribs, children)
             | _ -> failwith (sprintf "Fp_proc: Unexpected tag: '%s'" tag)

sw/tools/generators/gen_flight_plan.ml

@@ -265,7 +265,7 @@ let rec index_stage = fun x ->
         incr stage; (* To count the loop stage *)
         Xml.Element (Xml.tag x, Xml.attribs x@["no", soi n], l)
       | "return" | "goto"  | "deroute" | "exit_block" | "follow" | "call" | "home"
-      | "heading" | "attitude" | "go" | "stay" | "xyz" | "set" | "circle" ->
+      | "heading" | "attitude" | "go" | "stay" | "xyz" | "set" | "call_once" | "circle" ->
         incr stage;
         Xml.Element (Xml.tag x, Xml.attribs x@["no", soi !stage], Xml.children x)
       | "survey_rectangle" | "eight" | "oval"->
@@ -491,6 +491,11 @@ let rec print_stage = fun index_of_waypoints x ->
         and value = parsed_attrib  x "value" in
         lprintf "%s = %s;\n" var value;
         lprintf "NextStage();\n"
+      | "call_once" ->
+        stage ();
+        let func = ExtXml.attrib  x "fun" in
+        lprintf "%s;\n" func;
+        lprintf "NextStage();\n"
       | "call" ->
         stage ();
         let statement = ExtXml.attrib  x "fun" in