Simplify use of shp_missile_interdiction()

shp_missile_interdiction() does nothing when there are no suitable
targets.  Its users avoid to call it when there are none, probably to
save a few cycles.  Optimize shp_missile_interdiction() for that case,
and simplify the callers.

diff --git a/src/lib/subs/shpsub.c b/src/lib/subs/shpsub.c
index 50e942f78f95a32f765dac9348446412a49334d4..f2862146a356d37ccc2c0ed7dd28eb64b7518f7a 100644 (file)
--- a/src/lib/subs/shpsub.c
+++ b/src/lib/subs/shpsub.c
@@ -486,13 +486,16 @@ shp_missile_interdiction(struct emp_qelem *list, coord newx, coord newy,
     struct plist *plp;
     struct ulist *mvs;
 
+    mvs = most_valuable_ship(list, newx, newy);
+    if (!mvs)
+       return 0;
+
     msl_sel(&msl_list, newx, newy, victim, P_T | P_MAR, 0, MI_INTERDICT);
 
     for (qp = msl_list.q_back; qp != &msl_list; qp = newqp) {
        newqp = qp->q_back;
        plp = (struct plist *)qp;
 
-       mvs = most_valuable_ship(list, newx, newy);
        if (mvs && mission_pln_equip(plp, NULL, 'p') >= 0) {
            if (msl_launch(&plp->plane, EF_SHIP, prship(&mvs->unit.ship),
                           newx, newy, victim, &sublaunch) < 0)
@@ -512,6 +515,7 @@ shp_missile_interdiction(struct emp_qelem *list, coord newx, coord newy,
                dam = pln_damage(&plp->plane, 'p', 0);
                collateral_damage(newx, newy, dam);
            }
+           mvs = most_valuable_ship(list, newx, newy);
        use_up_msl:
            plp->plane.pln_effic = 0;
            putplane(plp->plane.pln_uid, &plp->plane);
@@ -651,10 +655,7 @@ shp_interdict(struct emp_qelem *list, coord newx, coord newy, natid victim)
                                          shp_easiest_target(list, 0, M_SUB),
                                          MI_INTERDICT),
                           0, M_SUB, newx, newy);
-           if (most_valuable_ship(list, newx, newy)) {
-               stopping |=
-                   shp_missile_interdiction(list, newx, newy, victim);
-           }
+           stopping |= shp_missile_interdiction(list, newx, newy, victim);
        }
     }
     if (shp_contains(list, newx, newy, M_SUB, 0)) {
@@ -909,20 +910,18 @@ shp_missdef(struct shpstr *sp, natid victim)
     sprintf(buf, "%s", prship(&mlp->unit.ship));
 
     eff = sp->shp_effic;
-    if (most_valuable_ship(&list, sp->shp_x, sp->shp_y)) {
-       shp_missile_interdiction(&list, sp->shp_x, sp->shp_y, sp->shp_own);
-       getship(sp->shp_uid, sp);
-
-       if (!sp->shp_own) {
-           wu(0, victim,
-              "missiles launched in defense did 100%% damage to %s\n",
-              buf);
-           wu(0, victim, "%s sunk!\n", buf);
-       } else if (eff > 0 && sp->shp_effic < eff) {
-           wu(0, victim,
-              "missiles launched in defense did %d%% damage to %s\n",
-              100 * (eff - sp->shp_effic) / eff, buf);
-       }
+    shp_missile_interdiction(&list, sp->shp_x, sp->shp_y, sp->shp_own);
+    getship(sp->shp_uid, sp);
+
+    if (!sp->shp_own) {
+       wu(0, victim,
+          "missiles launched in defense did 100%% damage to %s\n",
+          buf);
+       wu(0, victim, "%s sunk!\n", buf);
+    } else if (eff > 0 && sp->shp_effic < eff) {
+       wu(0, victim,
+          "missiles launched in defense did %d%% damage to %s\n",
+          100 * (eff - sp->shp_effic) / eff, buf);
     }
     if (!QEMPTY(&list))
        free(mlp);