]> git.pond.sub.org Git - empserver/blobdiff - src/lib/subs/lndsub.c
retreat: Rewrite automatic retreat code to fix its many bugs
[empserver] / src / lib / subs / lndsub.c
index 00278e89e8ef6572086cade9bf98fe11711c0059..2dd7f388252e58b0917d4d5006f7f6b91b19b7bc 100644 (file)
@@ -1,6 +1,6 @@
 /*
  *  Empire - A multi-player, client/server Internet based war game.
- *  Copyright (C) 1986-2011, Dave Pare, Jeff Bailey, Thomas Ruschak,
+ *  Copyright (C) 1986-2015, Dave Pare, Jeff Bailey, Thomas Ruschak,
  *                Ken Stevens, Steve McClure, Markus Armbruster
  *
  *  Empire is free software: you can redistribute it and/or modify
  *  Known contributors to this file:
  *     Ken Stevens, 1995
  *     Steve McClure, 1998-2000
- *     Markus Armbruster, 2004-2009
+ *     Markus Armbruster, 2004-2015
  */
 
 #include <config.h>
 
 #include <math.h>
 #include <stdlib.h>
+#include "chance.h"
 #include "combat.h"
 #include "damage.h"
 #include "empobj.h"
 #include "unit.h"
 #include "xy.h"
 
-static void lnd_stays(natid, char *, struct ulist *);
+static void lnd_mar_put_one(struct ulist *);
+static int lnd_check_one_mines(struct ulist *, int);
 static int lnd_hit_mine(struct lndstr *);
 static int has_helpful_engineer(coord, coord, natid);
 
+static struct ulist *
+lnd_find_capable(struct emp_qelem *list, int flags)
+{
+    struct emp_qelem *qp;
+    struct ulist *llp;
+
+    for (qp = list->q_back; qp != list; qp = qp->q_back) {
+       llp = (struct ulist *)qp;
+       if (lchr[llp->unit.land.lnd_type].l_flags & flags)
+           return llp;
+    }
+    return NULL;
+}
+
 double
 attack_val(int combat_mode, struct lndstr *lp)
 {
@@ -144,14 +160,6 @@ lnd_print(natid actor, struct ulist *llp, char *s)
        wu(0, actor, "%s %s\n", prland(&llp->unit.land), s);
 }
 
-void
-lnd_delete(struct ulist *llp)
-{
-    putland(llp->unit.land.lnd_uid, &llp->unit.land);
-    emp_remque((struct emp_qelem *)llp);
-    free(llp);
-}
-
 int
 lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
                        /* attacking or assaulting or paratrooping? */
@@ -161,7 +169,6 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
     int n;
     int biggest;
     int civs;
-    int nowned;
     coord ret_x, ret_y;
     coord bx, by;
     struct sctstr sect;
@@ -169,18 +176,17 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
     char buf[1024];
     int taken;
     int nowhere_to_go = 0;
-    struct sctstr rsect;
     double mobcost, bmcost;
     signed char orig;
     int mob;
 
     taken = llp->unit.land.lnd_item[I_MILIT];
     /* Spies always die */
-    if (((struct lchrstr *)llp->chrp)->l_flags & L_SPY)
+    if (lchr[llp->unit.land.lnd_type].l_flags & L_SPY)
        llp->unit.land.lnd_effic = 0;
     else {
        eff_eq = ldround(cas * 100.0 /
-           ((struct lchrstr *)llp->chrp)->l_item[I_MILIT], 1);
+           lchr[llp->unit.land.lnd_type].l_item[I_MILIT], 1);
        llp->unit.land.lnd_effic -= eff_eq;
        lnd_submil(&llp->unit.land, cas);
     }
@@ -191,7 +197,7 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
                xyas(llp->unit.land.lnd_x, llp->unit.land.lnd_y,
                     llp->unit.land.lnd_own));
        lnd_print(llp->unit.land.lnd_own, llp, buf);
-       lnd_delete(llp);
+       lnd_put_one(llp);
        /* Since we killed the unit, we killed all the mil on it */
        return taken;
     } else {
@@ -213,7 +219,7 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
     /* Have to make a retreat check */
 
     ret_chance = llp->unit.land.lnd_retreat - llp->unit.land.lnd_effic;
-    if (roll(100) < ret_chance) {
+    if (pct_chance(ret_chance)) {
        pr("\n");
        lnd_print(llp->unit.land.lnd_own, llp, "fails morale check!");
        llp->unit.land.lnd_mission = 0;
@@ -228,7 +234,6 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
             * owner. Charge mob..
             */
            biggest = -1;
-           nowned = 0;
            for (n = 1; n <= 6; ++n) {
                ret_x = llp->unit.land.lnd_x + diroff[n][0];
                ret_y = llp->unit.land.lnd_y + diroff[n][1];
@@ -237,10 +242,9 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
                    continue;
                if (sect.sct_type == SCT_MOUNT)
                    continue;
-               mobcost = lnd_mobcost(&llp->unit.land, &rsect);
+               mobcost = lnd_mobcost(&llp->unit.land, &sect);
                if (mobcost < 0)
                    continue;
-               ++nowned;
                civs = sect.sct_item[I_CIVIL];
                if (civs > biggest) {
                    biggest = civs;
@@ -249,14 +253,13 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
                    bmcost = mobcost;
                }
            }
-           if (!nowned)
+           if (biggest < 0)
                nowhere_to_go = 1;
            else {
                /* retreat to bx,by */
                llp->unit.land.lnd_x = bx;
                llp->unit.land.lnd_y = by;
                /* FIXME landmines */
-               getsect(bx, by, &rsect);
                mob = llp->unit.land.lnd_mobil - (int)bmcost;
                if (mob < -127)
                    mob = -127;
@@ -268,7 +271,7 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
                        llp->unit.land.lnd_effic,
                        xyas(bx, by, llp->unit.land.lnd_own));
                lnd_print(llp->unit.land.lnd_own, llp, buf);
-               lnd_delete(llp);
+               lnd_put_one(llp);
            }
        } else {                /* attacking from a sector */
            sprintf(buf, "leaves the battlefield at %d%% efficiency",
@@ -279,18 +282,18 @@ lnd_take_casualty(int combat_mode, struct ulist *llp, int cas)
                llp->unit.land.lnd_mobil -= (int)llp->mobil;
            llp->mobil = 0.0;
            lnd_print(llp->unit.land.lnd_own, llp, buf);
-           lnd_delete(llp);
+           lnd_put_one(llp);
        }
     }
     if (nowhere_to_go) {
        /* nowhere to go.. take more casualties */
        llp->unit.land.lnd_effic -= 10;
        lnd_submil(&llp->unit.land,
-                  ((struct lchrstr *)llp->chrp)->l_item[I_MILIT] / 10);
+                  lchr[llp->unit.land.lnd_type].l_item[I_MILIT] / 10);
        if (llp->unit.land.lnd_effic < LAND_MINEFF) {
            lnd_print(llp->unit.land.lnd_own, llp,
                      "has nowhere to retreat, and dies!");
-           lnd_delete(llp);
+           lnd_put_one(llp);
        } else
            lnd_print(llp->unit.land.lnd_own, llp,
                      "has nowhere to retreat and takes extra losses!");
@@ -396,14 +399,95 @@ intelligence_report(int destination, struct lndstr *lp, int spy,
     }
 }
 
+int
+lnd_may_mar(struct lndstr *lp, struct lndstr *ldr, char *suffix)
+{
+    struct sctstr sect;
+    int mobtype;
+
+    if (!lp->lnd_own || !getsect(lp->lnd_x, lp->lnd_y, &sect)) {
+       CANT_REACH();
+       return 0;
+    }
+
+    if (opt_MARKET && ontradingblock(EF_LAND, lp)) {
+       mpr(lp->lnd_own, "%s is on the trading block%s\n",
+           prland(lp), suffix);
+       return 0;
+    }
+
+    if (lp->lnd_ship >= 0) {
+       mpr(lp->lnd_own, "%s is on a ship%s\n", prland(lp), suffix);
+       return 0;
+    }
+    if (lp->lnd_land >= 0) {
+       mpr(lp->lnd_own, "%s is on a unit%s\n", prland(lp), suffix);
+       return 0;
+    }
+
+    if (!(lchr[lp->lnd_type].l_flags & L_SPY) &&
+       !(lchr[lp->lnd_type].l_flags & L_TRAIN) &&
+       lp->lnd_item[I_MILIT] == 0) {
+       mpr(lp->lnd_own, "%s has no mil on it to guide it%s\n",
+           prland(lp), suffix);
+       return 0;
+    }
+
+    switch (lnd_check_mar(lp, &sect)) {
+    case LND_STUCK_NOT:
+       break;
+    case LND_STUCK_NO_RAIL:
+       mpr(lp->lnd_own, "%s is stuck off the rail system%s\n",
+           prland(lp), suffix);
+       return 0;
+    default:
+       CANT_REACH();
+       /* fall through */
+    case LND_STUCK_IMPASSABLE:
+       mpr(lp->lnd_own, "%s is stuck%s\n", prland(lp), suffix);
+       return 0;
+    }
+
+    if (relations_with(sect.sct_own, lp->lnd_own) != ALLIED &&
+       !(lchr[lp->lnd_type].l_flags & L_SPY) &&
+       sect.sct_own) {
+       mpr(lp->lnd_own, "%s has been kidnapped by %s%s\n",
+           prland(lp), cname(sect.sct_own), suffix);
+       return 0;
+    }
+
+    if (ldr && (lp->lnd_x != ldr->lnd_x || lp->lnd_y != ldr->lnd_y)) {
+       mpr(lp->lnd_own, "%s is not with the leader%s\n",
+           prland(lp), suffix);
+       return 0;
+    }
+
+    /*
+     * The marching code gets confused when trains and non-trains
+     * march together.  Disallow for now.
+     */
+    mobtype = lnd_mobtype(lp);
+    if (!ldr || mobtype == lnd_mobtype(ldr))
+       ;
+    else if (mobtype == MOB_RAIL) {
+       mpr(lp->lnd_own,
+           "%s is a train and can't march with the leader%s\n",
+           prland(lp), suffix);
+       return 0;
+    } else {
+       mpr(lp->lnd_own, "%s can't rail-march with the leading train%s\n",
+           prland(lp), suffix);
+       return 0;
+    }
+
+    return 1;
+}
+
 void
 lnd_sel(struct nstr_item *ni, struct emp_qelem *list)
 {
-    struct lndstr land;
-    struct lchrstr *lcp;
+    struct lndstr land, *ldr = NULL;
     struct ulist *llp;
-    int this_mot;
-    int mobtype = MOB_MOVE;    /* indeterminate */
 
     emp_initque(list);
     while (nxtitem(ni, &land)) {
@@ -412,122 +496,129 @@ lnd_sel(struct nstr_item *ni, struct emp_qelem *list)
         * but much of the code assumes that only the land unit's
         * owner can march it.
         */
-       if (land.lnd_own != player->cnum)
+       if (!land.lnd_own || land.lnd_own != player->cnum)
+           continue;
+       if (!lnd_may_mar(&land, ldr, ""))
            continue;
-       if (opt_MARKET) {
-           if (ontradingblock(EF_LAND, &land)) {
-               pr("unit #%d inelligible - it's for sale.\n",
-                  land.lnd_uid);
-               continue;
-           }
-       }
-       /*
-        * The marching code gets confused when trains and non-trains
-        * march together.  Disallow for now.
-        */
-       this_mot = lnd_mobtype(&land);
-       if (this_mot != mobtype) {
-           if (mobtype == MOB_MOVE)
-               mobtype = this_mot;
-           else if (mobtype == MOB_MARCH) {
-               pr("%s is a train and can't march with the leader.\n",
-                  prland(&land));
-               continue;
-           } else {
-               pr("%s can't rail-march with the leading train.\n",
-                  prland(&land));
-               continue;
-           }
-       }
 
-       lcp = &lchr[(int)land.lnd_type];
        land.lnd_mission = 0;
        land.lnd_rflags = 0;
-       land.lnd_harden = 0;
        memset(land.lnd_rpath, 0, sizeof(land.lnd_rpath));
        putland(land.lnd_uid, &land);
-       llp = malloc(sizeof(struct ulist));
-       llp->chrp = (struct empobj_chr *)lcp;
-       llp->unit.land = land;
-       llp->mobil = land.lnd_mobil;
-       emp_insque(&llp->queue, list);
+       llp = lnd_insque(&land, list);
+       if (!ldr)
+           ldr = &llp->unit.land;
     }
 }
 
-/* This function assumes that the list was created by lnd_sel */
+/*
+ * Append LP to LIST.
+ * Return the new list link.
+ */
+struct ulist *
+lnd_insque(struct lndstr *lp, struct emp_qelem *list)
+{
+    struct ulist *mlp = malloc(sizeof(struct ulist));
+
+    mlp->unit.land = *lp;
+    mlp->mobil = lp->lnd_mobil;
+    emp_insque(&mlp->queue, list);
+    return mlp;
+}
+
 void
-lnd_mar(struct emp_qelem *list, double *minmobp, double *maxmobp,
-       int *togetherp, natid actor)
+lnd_mar_stay_behind(struct emp_qelem *list, natid actor)
 {
     struct emp_qelem *qp;
     struct emp_qelem *next;
     struct ulist *llp;
-    struct sctstr sect;
-    struct lndstr land;
-    coord allx;
-    coord ally;
-    int first = 1;
-    char mess[128];
-
-    *minmobp = 9876.0;
-    *maxmobp = -9876.0;
-    *togetherp = 1;
+    struct lndstr *lp, *ldr = NULL;
+    char and_stays[32];
+
     for (qp = list->q_back; qp != list; qp = next) {
        next = qp->q_back;
        llp = (struct ulist *)qp;
-       getland(llp->unit.land.lnd_uid, &land);
-       if (land.lnd_own != actor) {
+       lp = &llp->unit.land;
+       getland(lp->lnd_uid, lp);
+
+       if (lp->lnd_own != actor) {
            mpr(actor, "%s was disbanded at %s\n",
-               prland(&land), xyas(land.lnd_x, land.lnd_y, actor));
-           emp_remque((struct emp_qelem *)llp);
+               prland(lp), xyas(lp->lnd_x, lp->lnd_y, actor));
+           emp_remque(&llp->queue);
            free(llp);
            continue;
        }
-       if (land.lnd_ship >= 0) {
-           lnd_stays(actor, "is on a ship", llp);
-           continue;
-       }
-       if (land.lnd_land >= 0) {
-           lnd_stays(actor, "is on a unit", llp);
-           continue;
-       }
-       if (!getsect(land.lnd_x, land.lnd_y, &sect)) {
-           lnd_stays(actor, "was sucked into the sky by a strange looking spaceland", llp);    /* heh -KHS */
-           continue;
-       }
-       if (!(lchr[(int)llp->unit.land.lnd_type].l_flags & L_SPY) &&
-           !(lchr[(int)llp->unit.land.lnd_type].l_flags & L_TRAIN) &&
-           llp->unit.land.lnd_item[I_MILIT] == 0) {
-           lnd_stays(actor, "has no mil on it to guide it", llp);
-           continue;
-       }
-       if (relations_with(sect.sct_own, actor) != ALLIED &&
-           !(lchr[(int)llp->unit.land.lnd_type].l_flags & L_SPY) &&
-           sect.sct_own) {
-           sprintf(mess, "has been kidnapped by %s", cname(sect.sct_own));
-           lnd_stays(actor, mess, llp);
+
+       snprintf(and_stays, sizeof(and_stays), " & stays in %s",
+                xyas(lp->lnd_x, lp->lnd_y, actor));
+       if (!lnd_may_mar(lp, ldr, and_stays)) {
+           lnd_mar_put_one(llp);
            continue;
        }
-       if (first) {
-           allx = land.lnd_x;
-           ally = land.lnd_y;
-           first = 0;
-       }
-       if (land.lnd_x != allx || land.lnd_y != ally)
-           *togetherp = 0;
-       if (land.lnd_mobil + 1 < (int)llp->mobil) {
-           llp->mobil = land.lnd_mobil;
+
+       if (!ldr)
+           ldr = lp;
+       if (lp->lnd_mobil + 1 < (int)llp->mobil) {
+           llp->mobil = lp->lnd_mobil;
        }
-       if (llp->mobil < *minmobp)
-           *minmobp = llp->mobil;
-       if (llp->mobil > *maxmobp)
-           *maxmobp = llp->mobil;
-       llp->unit.land = land;
+    }
+}
+
+static void
+lnd_mar_put_one(struct ulist *llp)
+{
+    if (llp->mobil < -127)
+       llp->mobil = -127;
+    llp->unit.land.lnd_mobil = llp->mobil;
+    lnd_put_one(llp);
+}
+
+void
+lnd_mar_put(struct emp_qelem *list, natid actor)
+{
+    struct emp_qelem *qp, *next;
+    struct ulist *llp;
+    struct lndstr *lp;
+
+    for (qp = list->q_back; qp != list; qp = next) {
+       next = qp->q_back;
+       llp = (struct ulist *)qp;
+       lp = &llp->unit.land;
+       mpr(actor, "%s stopped at %s\n",
+           prland(lp), xyas(lp->lnd_x, lp->lnd_y, actor));
+       lnd_mar_put_one(llp);
+    }
+}
+
+void
+lnd_put(struct emp_qelem *list)
+{
+    struct emp_qelem *qp, *next;
+
+    for (qp = list->q_back; qp != list; qp = next) {
+       next = qp->q_back;
+       lnd_put_one((struct ulist *)qp);
     }
 }
 
 void
-lnd_sweep(struct emp_qelem *land_list, int verbose, int takemob,
+lnd_put_one(struct ulist *llp)
+{
+    putland(llp->unit.land.lnd_uid, &llp->unit.land);
+    emp_remque(&llp->queue);
+    free(llp);
+}
+
+/*
+ * Sweep landmines with engineers in LAND_LIST for ACTOR.
+ * All land units in LAND_LIST must be in the same sector.
+ * If EXPLICIT is non-zero, this is for an explicit sweep command from
+ * a player.  Else it's an automatic "on the move" sweep.
+ * If TAKEMOB is non-zero, require and charge mobility.
+ * Return non-zero when the land units should stop.
+ */
+int
+lnd_sweep(struct emp_qelem *land_list, int explicit, int takemob,
          natid actor)
 {
     struct emp_qelem *qp;
@@ -535,48 +626,57 @@ lnd_sweep(struct emp_qelem *land_list, int verbose, int takemob,
     struct ulist *llp;
     struct sctstr sect;
     int mines, m, max, sshells, lshells;
+    int stopping = 0, first = 1;
+
+    llp = lnd_find_capable(land_list, L_ENGINEER);
+    if (!llp) {
+       if (explicit)
+           mpr(actor, "No engineers!\n");
+       return 0;
+    }
+
+    getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &sect);
+    if (!explicit
+       && relations_with(sect.sct_oldown, actor) == ALLIED)
+       return 0;
+    if (SCT_MINES_ARE_SEAMINES(&sect)) {
+       if (explicit)
+           mpr(actor, "%s is a %s.  No landmines there!\n",
+               xyas(sect.sct_x, sect.sct_y, actor),
+               dchr[sect.sct_type].d_name);
+       return 0;
+    }
 
     for (qp = land_list->q_back; qp != land_list; qp = next) {
        next = qp->q_back;
        llp = (struct ulist *)qp;
-       if (!(((struct lchrstr *)llp->chrp)->l_flags & L_ENGINEER)) {
-           if (verbose)
-               mpr(actor, "%s is not an engineer!\n",
-                   prland(&llp->unit.land));
-           continue;
-       }
-       if (takemob && llp->mobil < 0.0) {
-           if (verbose)
-               lnd_stays(actor, "is out of mobility", llp);
-           continue;
-       }
-       getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &sect);
-       if (sect.sct_oldown == llp->unit.land.lnd_own) {
-           if (verbose)
-               mpr(actor,
-                   "%s is in a sector completely owned by you.  Don't bother digging up mines there!\n",
-                   prland(&llp->unit.land));
+       if (!(lchr[llp->unit.land.lnd_type].l_flags & L_ENGINEER))
            continue;
-       }
-       if (SCT_MINES_ARE_SEAMINES(&sect)) {
-           if (verbose)
-               mpr(actor, "%s is in a %s sector.  No landmines there!\n",
-                   prland(&llp->unit.land), dchr[sect.sct_type].d_name);
-           continue;
-       }
        if (takemob) {
+           if (llp->mobil <= 0.0) {
+               if (explicit)
+                   mpr(actor, "%s is out of mobility!\n",
+                       prland(&llp->unit.land));
+               continue;
+           }
            llp->mobil -= lnd_pathcost(&llp->unit.land, 0.2);
            llp->unit.land.lnd_mobil = (int)llp->mobil;
            llp->unit.land.lnd_harden = 0;
        }
        putland(llp->unit.land.lnd_uid, &llp->unit.land);
+       getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &sect);
        if (!(mines = sect.sct_mines))
            continue;
-       max = ((struct lchrstr *)llp->chrp)->l_item[I_SHELL];
+       max = lchr[llp->unit.land.lnd_type].l_item[I_SHELL];
        lshells = llp->unit.land.lnd_item[I_SHELL];
        sshells = sect.sct_item[I_SHELL];
        for (m = 0; mines > 0 && m < max * 2; m++) {
-           if (chance(0.5 * ((struct lchrstr *)llp->chrp)->l_att)) {
+           if (chance(0.5 * lchr[llp->unit.land.lnd_type].l_att)) {
+               if (first) {
+                   mpr(actor, "Approaching minefield at %s...\n",
+                       xyas(sect.sct_x, sect.sct_y, actor));
+                   first = 0;
+               }
                mpr(actor, "Sweep...\n");
                mines--;
                if (lshells < max)
@@ -590,21 +690,31 @@ lnd_sweep(struct emp_qelem *land_list, int verbose, int takemob,
        sect.sct_item[I_SHELL] = sshells;
        putland(llp->unit.land.lnd_uid, &llp->unit.land);
        putsect(&sect);
+       stopping |= lnd_check_one_mines(llp, 1);
     }
+    return stopping;
 }
 
 static int
-contains_engineer(struct emp_qelem *list)
+lnd_check_one_mines(struct ulist *llp, int with_eng)
 {
-    struct emp_qelem *qp;
-    struct emp_qelem *next;
-    struct ulist *llp;
+    struct sctstr sect;
 
-    for (qp = list->q_back; qp != list; qp = next) {
-       next = qp->q_back;
-       llp = (struct ulist *)qp;
-       if (((struct lchrstr *)llp->chrp)->l_flags & L_ENGINEER)
-           return 1;
+    getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &sect);
+    if (SCT_LANDMINES(&sect) == 0)
+       return 0;
+    if (relations_with(sect.sct_oldown, llp->unit.land.lnd_own) == ALLIED)
+       return 0;
+    if (chance(DMINE_LHITCHANCE(sect.sct_mines) / (1 + 2 * with_eng))) {
+       lnd_hit_mine(&llp->unit.land);
+       sect.sct_mines--;
+       putsect(&sect);
+       putland(llp->unit.land.lnd_uid, &llp->unit.land);
+       if (!llp->unit.land.lnd_own) {
+           emp_remque(&llp->queue);
+           free(llp);
+       }
+       return 1;
     }
     return 0;
 }
@@ -614,59 +724,25 @@ lnd_check_mines(struct emp_qelem *land_list)
 {
     struct emp_qelem *qp;
     struct emp_qelem *next;
-    struct ulist *llp;
-    struct sctstr sect;
     int stopping = 0;
-    int with_eng = contains_engineer(land_list);
+    int with_eng = !!lnd_find_capable(land_list, L_ENGINEER);
 
     for (qp = land_list->q_back; qp != land_list; qp = next) {
        next = qp->q_back;
-       llp = (struct ulist *)qp;
-       getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &sect);
-       if (SCT_LANDMINES(&sect) == 0)
-           continue;
-       if (relations_with(sect.sct_oldown, llp->unit.land.lnd_own)
-           == ALLIED)
-           continue;
-       if (chance(DMINE_LHITCHANCE(sect.sct_mines) / (1 + 2 * with_eng))) {
-           lnd_hit_mine(&llp->unit.land);
-           sect.sct_mines--;
-           putsect(&sect);
-           putland(llp->unit.land.lnd_uid, &llp->unit.land);
-           if (!llp->unit.land.lnd_own) {
-               stopping = 1;
-               emp_remque(qp);
-               free(qp);
-           }
-       }
+       stopping |= lnd_check_one_mines((struct ulist *)qp, with_eng);
     }
     return stopping;
 }
 
-static void
-lnd_stays(natid actor, char *str, struct ulist *llp)
-{
-    mpr(actor, "%s %s & stays in %s\n",
-       prland(&llp->unit.land), str,
-       xyas(llp->unit.land.lnd_x, llp->unit.land.lnd_y, actor));
-    if (llp->mobil < -127)
-       llp->mobil = -127;
-    llp->unit.land.lnd_mobil = llp->mobil;
-    lnd_delete(llp);
-}
-
-static int
-lnd_count(struct emp_qelem *list)
+/* Return whether and why SP would be stuck in SECTP.  */
+enum lnd_stuck
+lnd_check_mar(struct lndstr *lp, struct sctstr *sectp)
 {
-    struct emp_qelem *qp;
-    struct emp_qelem *next;
-    int count = 0;
-
-    for (qp = list->q_back; qp != list; qp = next) {
-       next = qp->q_back;
-       ++count;
-    }
-    return count;
+    if (dchr[sectp->sct_type].d_mob0 < 0)
+       return LND_STUCK_IMPASSABLE;
+    if (lnd_mobtype(lp) == MOB_RAIL && !SCT_HAS_RAIL(sectp))
+       return LND_STUCK_NO_RAIL;
+    return LND_STUCK_NOT;
 }
 
 static int
@@ -678,7 +754,7 @@ lnd_damage(struct emp_qelem *list, int totdam)
     int dam;
     int count;
 
-    if (!totdam || !(count = lnd_count(list)))
+    if (!totdam || !(count = emp_quelen(list)))
        return 0;
     dam = ldround((double)totdam / count, 1);
     for (qp = list->q_back; qp != list; qp = next) {
@@ -721,7 +797,7 @@ static int
 lnd_missile_interdiction(struct emp_qelem *list, coord newx, coord newy,
                         natid victim)
 {
-    int mindam = lnd_count(list) * 20;
+    int mindam = emp_quelen(list) * 20;
     int hardtarget = lnd_easiest_target(list);
     int dam, newdam, sublaunch;
     int stopping = 0;
@@ -899,92 +975,114 @@ lnd_mobcost(struct lndstr *lp, struct sctstr *sp)
     return lnd_pathcost(lp, sector_mcost(sp, lnd_mobtype(lp)));
 }
 
+/*
+ * Ask user to confirm sector abandonment, if any.
+ * All land units in LIST must be in the same sector.
+ * If removing the land units in LIST would abandon their sector, ask
+ * the user to confirm.
+ * Return zero when abandonment was declined, else non-zero.
+ */
+int lnd_abandon_askyn(struct emp_qelem *list)
+{
+    struct ulist *llp;
+    struct sctstr sect;
+    struct emp_qelem *qp;
+
+    if (QEMPTY(list))
+       return 1;
+    llp = (struct ulist *)list->q_back;
+    getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &sect);
+    if (!abandon_askyn(&sect, I_CIVIL, 0, llp))
+       return 0;
+    if (!check_sect_ok(&sect))
+       return 0;
+    for (qp = list->q_back; qp != list; qp = qp->q_back) {
+       if (!check_land_ok(&((struct ulist *)qp)->unit.land))
+           return 0;
+    }
+    return 1;
+}
+
 int
-lnd_mar_one_sector(struct emp_qelem *list, int dir, natid actor,
-                  int together)
+lnd_mar_dir(struct emp_qelem *list, int dir, natid actor)
 {
     struct sctstr sect, osect;
     struct emp_qelem *qp;
-    struct emp_qelem *qp2;
     struct emp_qelem *next;
     struct ulist *llp;
-    struct emp_qelem cur, done;
     coord dx;
     coord dy;
     coord newx;
     coord newy;
-    int stopping = 0;
-    int visible;
-    int stop;
-    char dp[80];
+    int move;
     int rel;
     int oldown;
 
-    if (dir <= DIR_STOP || dir >= DIR_VIEW) {
-       unit_put(list, actor);
+    if (CANT_HAPPEN(QEMPTY(list)))
+       return 1;
+
+    if (dir <= DIR_STOP || dir > DIR_LAST) {
+       CANT_HAPPEN(dir != DIR_STOP);
+       lnd_mar_put(list, actor);
        return 1;
     }
     dx = diroff[dir][0];
     dy = diroff[dir][1];
+
+    llp = (struct ulist *)list->q_back;
+    getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &osect);
+    oldown = osect.sct_own;
+    newx = xnorm(llp->unit.land.lnd_x + dx);
+    newy = ynorm(llp->unit.land.lnd_y + dy);
+    getsect(newx, newy, &sect);
+    rel = sect.sct_own ? relations_with(sect.sct_own, actor) : ALLIED;
+
+    move = 0;
     for (qp = list->q_back; qp != list; qp = next) {
        next = qp->q_back;
        llp = (struct ulist *)qp;
-       getsect(llp->unit.land.lnd_x, llp->unit.land.lnd_y, &osect);
-       oldown = osect.sct_own;
-       newx = xnorm(llp->unit.land.lnd_x + dx);
-       newy = ynorm(llp->unit.land.lnd_y + dy);
-       getsect(newx, newy, &sect);
-       rel = relations_with(sect.sct_own, actor);
-       if ((rel != ALLIED &&
-            !(lchr[(int)llp->unit.land.lnd_type].l_flags & L_SPY) &&
-            sect.sct_own) || (sect.sct_type == SCT_WATER ||
-                              sect.sct_type == SCT_SANCT ||
-                              sect.sct_type == SCT_WASTE)) {
-           if (together) {
-               mpr(actor, "can't go to %s\n", xyas(newx, newy, actor));
-               return 1;
-           } else {
-               sprintf(dp, "can't go to %s", xyas(newx, newy, actor));
-               lnd_stays(actor, dp, llp);
-               continue;
-           }
-       }
-       if (!SCT_HAS_RAIL(&sect)
-           && lnd_mobtype(&llp->unit.land) == MOB_RAIL) {
-           if (together) {
+       switch (lnd_check_mar(&llp->unit.land, &sect)) {
+       case LND_STUCK_NOT:
+           if (rel == ALLIED
+               || (lchr[llp->unit.land.lnd_type].l_flags & L_SPY))
+               move = 1;
+           break;
+       case LND_STUCK_NO_RAIL:
+           if (rel == ALLIED)
                mpr(actor, "no rail system in %s\n",
                    xyas(newx, newy, actor));
-               return 1;
-           } else {
-               sprintf(dp, "has no rail system in %s",
-                       xyas(newx, newy, actor));
-               lnd_stays(actor, dp, llp);
-               continue;
-           }
+           else
+               mpr(actor, "can't go to %s\n", xyas(newx, newy, actor));
+           return 1;
+       default:
+           CANT_REACH();
+           /* fall through */
+       case LND_STUCK_IMPASSABLE:
+           mpr(actor, "can't go to %s\n", xyas(newx, newy, actor));
+           return 1;
        }
-       /* Note we check would_abandon first because we don't want
-          to always have to do these checks */
-       if (would_abandon(&osect, I_CIVIL, 0, &llp->unit.land)) {
-           stop = 0;
-           if (!want_to_abandon(&osect, I_CIVIL, 0, &llp->unit.land)) {
-               stop = 1;
-           }
-           /* now check stuff */
-           if (!check_sect_ok(&sect))
-               return 1;
-           if (!check_sect_ok(&osect))
-               return 1;
-           for (qp2 = list->q_back; qp2 != list; qp2 = qp2->q_back) {
-               if (!check_land_ok(&((struct ulist *)qp2)->unit.land))
-                   return 1;
-           }
-           if (stop) {
-               lnd_stays(actor, "stops", llp);
-               continue;
-           }
+    }
+    if (!move) {
+       mpr(actor, "can't go to %s\n", xyas(newx, newy, actor));
+       return 1;
+    }
+
+    for (qp = list->q_back; qp != list; qp = next) {
+       next = qp->q_back;
+       llp = (struct ulist *)qp;
+       if (rel != ALLIED
+           && !(lchr[llp->unit.land.lnd_type].l_flags & L_SPY)) {
+           mpr(actor, "%s can't go to %s & stays in %s\n",
+               prland(&llp->unit.land), xyas(newx, newy, actor),
+               xyas(llp->unit.land.lnd_x, llp->unit.land.lnd_y, actor));
+           lnd_mar_put_one(llp);
+           continue;
        }
        if (llp->mobil <= 0.0) {
-           lnd_stays(actor, "is out of mobility", llp);
+           mpr(actor, "%s is out of mobility & stays in %s\n",
+               prland(&llp->unit.land),
+               xyas(llp->unit.land.lnd_x, llp->unit.land.lnd_y, actor));
+           lnd_mar_put_one(llp);
            continue;
        }
        llp->unit.land.lnd_x = newx;
@@ -1000,7 +1098,8 @@ lnd_mar_one_sector(struct emp_qelem *list, int dir, natid actor,
            mpr(actor, "You no longer own %s\n",
                xyas(osect.sct_x, osect.sct_y, actor));
        }
-       if (rel != ALLIED && sect.sct_own) {    /* must be a spy */
+       if (rel != ALLIED) {
+           /* must be a spy */
            /* Always a 10% chance of getting caught. */
            if (chance(LND_SPY_DETECT_CHANCE(llp->unit.land.lnd_effic))) {
                if (rel == NEUTRAL || rel == FRIENDLY) {
@@ -1016,50 +1115,41 @@ lnd_mar_one_sector(struct emp_qelem *list, int dir, natid actor,
                        prland(&llp->unit.land));
                    llp->unit.land.lnd_effic = 0;
                    putland(llp->unit.land.lnd_uid, &llp->unit.land);
-                   lnd_delete(llp);
+                   lnd_put_one(llp);
                }
            }
        }
     }
+
+    return 0;
+}
+
+int
+lnd_mar_gauntlet(struct emp_qelem *list, int interdict, natid actor)
+{
+    struct ulist *mlp = (struct ulist *)list->q_back;
+    coord newx = mlp->unit.land.lnd_x;
+    coord newy = mlp->unit.land.lnd_y;
+    int stopping, visible;
+    struct emp_qelem *qp, *next;
+    struct ulist *llp;
+
+    stopping = lnd_sweep(list, 0, 1, actor);
     if (QEMPTY(list))
        return stopping;
-    lnd_sweep(list, 0, 1, actor);
     stopping |= lnd_check_mines(list);
     if (QEMPTY(list))
        return stopping;
 
-    /* interdict land units sector by sector */
-    emp_initque(&cur);
-    emp_initque(&done);
-    while (!QEMPTY(list)) {
-       llp = (struct ulist *)list->q_back;
-       newx = llp->unit.land.lnd_x;
-       newy = llp->unit.land.lnd_y;
-       /* move units in NEWX,NEWY to cur */
-       visible = 0;
-       for (qp = list->q_back; qp != list; qp = next) {
-           next = qp->q_back;
-           llp = (struct ulist *)qp;
-           if (llp->unit.land.lnd_x == newx && llp->unit.land.lnd_y == newy) {
-               emp_remque(qp);
-               emp_insque(qp, &cur);
-               if (!(lchr[(int)llp->unit.land.lnd_type].l_flags & L_SPY))
-                   visible = 1;
-           }
-       }
-       /* interdict them */
-       if (visible)
-           stopping |= lnd_interdict(&cur, newx, newy, actor);
-       /* move survivors to done */
-       for (qp = cur.q_back; qp != &cur; qp = next) {
-           next = qp->q_back;
-           emp_remque(qp);
-           emp_insque(qp, &done);
-       }
+    visible = 0;
+    for (qp = list->q_back; qp != list; qp = next) {
+       next = qp->q_back;
+       llp = (struct ulist *)qp;
+       if (!(lchr[(int)llp->unit.land.lnd_type].l_flags & L_SPY))
+           visible = 1;
     }
-    /* assign surviving land units back to list */
-    emp_insque(list, &done);
-    emp_remque(&done);
+    if (visible && interdict)
+       stopping |= lnd_interdict(list, newx, newy, actor);
 
     return stopping;
 }
@@ -1102,7 +1192,7 @@ lnd_support(natid victim, natid attacker, coord x, coord y, int defending)
            nreport(land.lnd_own, N_FIRE_BACK, victim, 1);
        else
            nreport(land.lnd_own, N_FIRE_L_ATTACK, victim, 1);
-       if (roll(100) < lnd_acc(&land))
+       if (pct_chance(lnd_acc(&land) - 1))
            dam2 /= 2;
        dam += dam2;
        if (land.lnd_own != attacker)