[Freeciv-Dev] Re: (PR#4372) Missile carriers with limited fuel always crash

["Cameron Morland" <cameron@xxxxxxxxxx>]

On Tue, Jun 10, 2003 at 10:09:08AM -0700, Per I. Mathisen wrote:
> The problem is that we use punit->fuel variable temporarily for carrier
> refuelling of aircraft and missiles, assuming stupidly that a fuel limited
> unit can never itself be a carrier.
> 
> I think the fix is wrong. Adding a variable to the unit struct for
> something will only be used inside one function and then be thrown away is
> a waste of good memory. Instead, for each of pplayer->units, if punit is a
> carrier, find and refuel as many air units stacked with you as you have
> carrier capacity.

Right. This patch uses local variables instead.

The one bug I've noticed but haven't fixed yet is that a carrier,
carrying a fighter modified to carry missiles, will leave behind the
missiles which are considered to be carried by the fighter, if those
missiles are in sentry mode. (A carrier with 1 fighter and 9 missiles
will leave 2 behind when it moves.) I'm working on that part now.

-- 
+-----------------------------------------------------------------
| PGP http://www.eng.uwaterloo.ca/student/cjmorlan/public-key.pgp
| Cameron Morland             ----             Cameron@xxxxxxxxxx
|
| The reason that every major university maintains a
| department of mathematics is that it's cheaper than
| institutionalizing all those people.
+-----------------------------------------------------------------

Index: unittools.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/server/unittools.c,v
retrieving revision 1.225
diff -u -3 -p -r1.225 unittools.c
--- unittools.c 2003/06/04 20:05:40     1.225
+++ unittools.c 2003/06/10 19:15:14
@@ -318,57 +318,43 @@ static void refuel_air_units_from_carrie
   unit_list_init(&carriers);
   unit_list_init(&missile_carriers);
   
-  /* Temporarily use 'fuel' on Carriers and Subs to keep track
-     of numbers of supported Air Units:   --dwp */
-
+  /* get a list of all missile carriers and [aircraft] carriers. */
   unit_list_iterate(pplayer->units, punit) {
     if (unit_flag(punit, F_CARRIER)) {
       unit_list_insert(&carriers, punit);
-      punit->fuel = unit_type(punit)->transport_capacity;
     } else if (unit_flag(punit, F_MISSILE_CARRIER)) {
       unit_list_insert(&missile_carriers, punit);
-      punit->fuel = unit_type(punit)->transport_capacity;
     }
   } unit_list_iterate_end;
 
   /* Now iterate through missile_carriers and
    * refuel as many missiles as possible */
-
   unit_list_iterate(missile_carriers, punit) {
-    while(punit->fuel > 0) {
-      punit_to_refuel= find_best_air_unit_to_refuel(
+    int cargo_fuel = unit_type(punit)->transport_capacity;
+    while(cargo_fuel > 0) {
+      punit_to_refuel = find_best_air_unit_to_refuel(
           pplayer, punit->x, punit->y, TRUE /*missile */);
       if (!punit_to_refuel)
         break; /* Didn't find any */
       punit_to_refuel->fuel = unit_type(punit_to_refuel)->fuel;
-      punit->fuel--;
+      cargo_fuel--;
     }
   } unit_list_iterate_end;
 
   /* Now refuel air units from carriers (also not yet refuelled missiles) */
-
   unit_list_iterate(carriers, punit) {
-    while(punit->fuel > 0) {
-      punit_to_refuel= find_best_air_unit_to_refuel(
+    int cargo_fuel = unit_type(punit)->transport_capacity;
+    while(cargo_fuel > 0) {
+      punit_to_refuel = find_best_air_unit_to_refuel(
           pplayer, punit->x, punit->y, FALSE /* any */);
       if (!punit_to_refuel) 
         break;
       punit_to_refuel->fuel = unit_type(punit_to_refuel)->fuel;
-      punit->fuel--;
+      cargo_fuel--;
     }
   } unit_list_iterate_end;                     
 
-  /* Clean up temporary use of 'fuel' on Carriers and Subs: */
-  unit_list_iterate(carriers, punit) {
-    punit->fuel = 0;
-  } unit_list_iterate_end;
-
   unit_list_unlink_all(&carriers);
-
-  unit_list_iterate(missile_carriers, punit) {
-    punit->fuel = 0;
-  } unit_list_iterate_end;
-
   unit_list_unlink_all(&missile_carriers);
 }

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