Simplify take_move_in_mob()

Actually, this isn't just simplification.  When mobility gain per
update was configured to be greater than 128, mobility could go from 1
to less than -127 when assaulting from a landing ship, and thus
overflow.  Make it saturate at -127.  Note that you can expect plenty
of trouble elsewhere with such a silly configuration.

diff --git a/src/lib/subs/attsub.c b/src/lib/subs/attsub.c
index 7fe008f6bdf94b40430d67be218fbc787000a803..03d1cc3ca3d28d0ca8f9d4d40f77cd805578fc81 100644 (file)
--- a/src/lib/subs/attsub.c
+++ b/src/lib/subs/attsub.c
@@ -2523,43 +2523,37 @@ static void
 take_move_in_mob(int combat_mode, struct ulist *llp, struct combat *off,
                 struct combat *def)
 {
-    int mobcost;
-    int new;
+    double mob = llp->unit.land.lnd_mobil;
+    double gain = etu_per_update * land_mob_scale;
+    double mobcost;
 
     switch (combat_mode) {
     case A_ATTACK:
        mobcost = lnd_pathcost(&llp->unit.land,
                               att_mobcost(off->own, def,
                                           lnd_mobtype(&llp->unit.land)));
-       new = llp->unit.land.lnd_mobil - mobcost;
-       if (new < -127)
-           new = -127;
-       llp->unit.land.lnd_mobil = new;
        break;
     case A_ASSAULT:
-       if (off->shp_mcp->m_flags & M_LAND) {
-           if (((struct lchrstr *)llp->chrp)->l_flags & L_MARINE)
-               llp->unit.land.lnd_mobil -=
-                   (float)etu_per_update * land_mob_scale * 0.5;
-           else
-               llp->unit.land.lnd_mobil -= (float)etu_per_update *
-                   land_mob_scale;
-       } else {
-           if (((struct lchrstr *)llp->chrp)->l_flags & L_MARINE)
-               llp->unit.land.lnd_mobil = 0;
-           else
-               llp->unit.land.lnd_mobil = -(float)etu_per_update *
-                   land_mob_scale;
-       }
+       if (((struct lchrstr *)llp->chrp)->l_flags & L_MARINE)
+           mobcost = off->shp_mcp->m_flags & M_LAND ? gain / 2.0 : mob;
+       else
+           mobcost = off->shp_mcp->m_flags & M_LAND ? gain : mob + gain;
        break;
     case A_BOARD:
-       /* I arbitrarily chose the numbers 10 and 40 below -KHS */
        if (((struct lchrstr *)llp->chrp)->l_flags & L_MARINE)
-           llp->unit.land.lnd_mobil -= 10;
+           mobcost = 10;
        else
-           llp->unit.land.lnd_mobil -= 40;
+           mobcost = 40;
        break;
+    default:
+       CANT_REACH();
+       mobcost = 0;
     }
+
+    mob -= mobcost;
+    if (mob < -127.0)
+       mob = -127.0;
+    llp->unit.land.lnd_mobil = (signed char)mob;
     llp->unit.land.lnd_harden = 0;
 }