Author: jtn
Date: Tue Nov 15 11:22:17 2016
New Revision: 34514
URL: http://svn.gna.org/viewcvs/freeciv?rev=34514&view=rev
Log:
Small optimisation to autoattack transport depth check.
See gna patch #7985.
Modified:
branches/S2_5/server/unittools.c
Modified: branches/S2_5/server/unittools.c
URL:
http://svn.gna.org/viewcvs/freeciv/branches/S2_5/server/unittools.c?rev=34514&r1=34513&r2=34514&view=diff
==============================================================================
--- branches/S2_5/server/unittools.c (original)
+++ branches/S2_5/server/unittools.c Tue Nov 15 11:22:17 2016
@@ -3025,10 +3025,10 @@
/**************************************************************************
This function is passed to unit_list_sort() to sort a list of units
- according to their win chance against autoattack_target modified by
+ according to their win chance against autoattack_target, modified by
transportation relationships.
- The reason for making sure that a cargo unit is ahead of it
+ The reason for making sure that a cargo unit is ahead of its
transporter(s) is to leave transports out of combat if at all possible.
(The transport could be destroyed during combat.)
**************************************************************************/
@@ -3041,10 +3041,26 @@
int q1uwc = unit_win_chance(*q1, q1def);
/* Sort by transport depth first. This makes sure that no transport
- * attacks before its cargo does. */
- if (unit_transport_depth(*p1) != unit_transport_depth(*q1)) {
- /* The units have a different number of recursive transporters. */
- return unit_transport_depth(*q1) - unit_transport_depth(*p1);
+ * attacks before its cargo does -- cargo sorts earlier in the list. */
+ {
+ const struct unit *p1trans = *p1, *q1trans = *q1;
+
+ /* Walk the transport stacks in parallel, so as to bail out as soon as
+ * one of them is empty (avoid walking deep stacks more often than
+ * necessary). */
+ while (p1trans && q1trans) {
+ p1trans = unit_transport_get(p1trans);
+ q1trans = unit_transport_get(q1trans);
+ }
+ if (!p1trans && q1trans) {
+ /* q1 is at greater depth (perhaps it's p1's cargo). It should sort
+ * earlier in the list (p1 > q1). */
+ return 1;
+ } else if (p1trans && !q1trans) {
+ /* p1 is at greater depth, so should sort earlier (p1 < q1). */
+ return -1;
+ }
+ /* else same depth, so move on to checking win chance: */
}
if (p1uwc < q1uwc) {
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