Source:NetHack 3.6.1/src/monmove.c

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Below is the full text to monmove.c from the source code of NetHack 3.6.1. To link to a particular line, write [[Source:NetHack 3.6.1/src/monmove.c#line123]], for example.

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 /* NetHack 3.6	monmove.c	$NHDT-Date: 1517877380 2018/02/06 00:36:20 $  $NHDT-Branch: NetHack-3.6.0 $:$NHDT-Revision: 1.96 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Michael Allison, 2006. */
 /* NetHack may be freely redistributed.  See license for details. */

The NetHack General Public License applies to screenshots, source code and other content from NetHack.

This content was modified from the original NetHack source code distribution (by splitting up NetHack content between wiki pages, and possibly further editing). See the page history for a list of who changed it, and on what dates.

 
 #include "hack.h"
 #include "mfndpos.h"
 #include "artifact.h"
 
 extern boolean notonhead;
 
 STATIC_DCL void FDECL(watch_on_duty, (struct monst *));
 STATIC_DCL int FDECL(disturb, (struct monst *));
 STATIC_DCL void FDECL(release_hero, (struct monst *));
 STATIC_DCL void FDECL(distfleeck, (struct monst *, int *, int *, int *));
 STATIC_DCL int FDECL(m_arrival, (struct monst *));
 STATIC_DCL boolean FDECL(stuff_prevents_passage, (struct monst *));
 STATIC_DCL int FDECL(vamp_shift, (struct monst *, struct permonst *, BOOLEAN_P));
 

mb_trapped

 /* True if mtmp died */
 boolean
 mb_trapped(mtmp)
 struct monst *mtmp;
 {
     if (flags.verbose) {
         if (cansee(mtmp->mx, mtmp->my) && !Unaware)
             pline("KABOOM!!  You see a door explode.");
         else if (!Deaf)
             You_hear("a distant explosion.");
     }
     wake_nearto(mtmp->mx, mtmp->my, 7 * 7);
     mtmp->mstun = 1;
     mtmp->mhp -= rnd(15);
     if (mtmp->mhp <= 0) {
         mondied(mtmp);
         if (mtmp->mhp > 0) /* lifesaved */
             return FALSE;
         else
             return TRUE;
     }
     return FALSE;
 }
 

monhaskey

 /* check whether a monster is carrying a locking/unlocking tool */
 boolean
 monhaskey(mon, for_unlocking)
 struct monst *mon;
 boolean for_unlocking; /* true => credit card ok, false => not ok */
 {
     if (for_unlocking && m_carrying(mon, CREDIT_CARD))
         return TRUE;
     return m_carrying(mon, SKELETON_KEY) || m_carrying(mon, LOCK_PICK);
 }
 

mon_yells

 void
 mon_yells(mon, shout)
 struct monst *mon;
 const char *shout;
 {
     if (Deaf) {
         if (canspotmon(mon))
             /* Sidenote on "A watchman angrily waves her arms!"
              * Female being called watchman is correct (career name).
              */
             pline("%s angrily %s %s %s!",
                 Amonnam(mon),
                 nolimbs(mon->data) ? "shakes" : "waves",
                 mhis(mon),
                 nolimbs(mon->data) ? mbodypart(mon, HEAD)
                                    : makeplural(mbodypart(mon, ARM)));
     } else {
         if (canspotmon(mon))
             pline("%s yells:", Amonnam(mon));
         else
             You_hear("someone yell:");
         verbalize1(shout);
     }
 }
 

watch_on_duty

 STATIC_OVL void
 watch_on_duty(mtmp)
 register struct monst *mtmp;
 {
     int x, y;
 
     if (mtmp->mpeaceful && in_town(u.ux + u.dx, u.uy + u.dy)
         && mtmp->mcansee && m_canseeu(mtmp) && !rn2(3)) {
         if (picking_lock(&x, &y) && IS_DOOR(levl[x][y].typ)
             && (levl[x][y].doormask & D_LOCKED)) {
             if (couldsee(mtmp->mx, mtmp->my)) {
                 if (levl[x][y].looted & D_WARNED) {
                     mon_yells(mtmp, "Halt, thief!  You're under arrest!");
                     (void) angry_guards(!!Deaf);
                 } else {
                     mon_yells(mtmp, "Hey, stop picking that lock!");
                     levl[x][y].looted |= D_WARNED;
                 }
                 stop_occupation();
             }
         } else if (is_digging()) {
             /* chewing, wand/spell of digging are checked elsewhere */
             watch_dig(mtmp, context.digging.pos.x, context.digging.pos.y,
                       FALSE);
         }
     }
 }
 

dochugw

 int
 dochugw(mtmp)
 register struct monst *mtmp;
 {
     int x = mtmp->mx, y = mtmp->my;
     boolean already_saw_mon = !occupation ? 0 : canspotmon(mtmp);
     int rd = dochug(mtmp);
 
     /* a similar check is in monster_nearby() in hack.c */
     /* check whether hero notices monster and stops current activity */
     if (occupation && !rd && !Confusion && (!mtmp->mpeaceful || Hallucination)
         /* it's close enough to be a threat */
         && distu(x, y) <= (BOLT_LIM + 1) * (BOLT_LIM + 1)
         /* and either couldn't see it before, or it was too far away */
         && (!already_saw_mon || !couldsee(x, y)
             || distu(x, y) > (BOLT_LIM + 1) * (BOLT_LIM + 1))
         /* can see it now, or sense it and would normally see it */
         && (canseemon(mtmp) || (sensemon(mtmp) && couldsee(x, y)))
         && mtmp->mcanmove && !noattacks(mtmp->data)
         && !onscary(u.ux, u.uy, mtmp))
         stop_occupation();
 
     return rd;
 }
 

onscary

 boolean
 onscary(x, y, mtmp)
 int x, y;
 struct monst *mtmp;
 {
     /* creatures who are directly resistant to magical scaring:
      * Rodney, lawful minions, Angels, the Riders, shopkeepers
      * inside their own shop, priests inside their own temple */
     if (mtmp->iswiz || is_lminion(mtmp) || mtmp->data == &mons[PM_ANGEL]
         || is_rider(mtmp->data)
         || (mtmp->isshk && inhishop(mtmp))
         || (mtmp->ispriest && inhistemple(mtmp)))
         return FALSE;
 
     /* <0,0> is used by musical scaring to check for the above;
      * it doesn't care about scrolls or engravings or dungeon branch */
     if (x == 0 && y == 0)
         return TRUE;
 
     /* should this still be true for defiled/molochian altars? */
     if (IS_ALTAR(levl[x][y].typ)
         && (mtmp->data->mlet == S_VAMPIRE || is_vampshifter(mtmp)))
         return TRUE;
 
     /* the scare monster scroll doesn't have any of the below
      * restrictions, being its own source of power */
     if (sobj_at(SCR_SCARE_MONSTER, x, y))
         return TRUE;
 
     /*
      * Creatures who don't (or can't) fear a written Elbereth:
      * all the above plus shopkeepers (even if poly'd into non-human),
      * vault guards (also even if poly'd), blind or peaceful monsters,
      * humans and elves, and minotaurs.
      *
      * If the player isn't actually on the square OR the player's image
      * isn't displaced to the square, no protection is being granted.
      *
      * Elbereth doesn't work in Gehennom, the Elemental Planes, or the
      * Astral Plane; the influence of the Valar only reaches so far.
      */
     return (sengr_at("Elbereth", x, y, TRUE)
             && ((u.ux == x && u.uy == y)
                 || (Displaced && mtmp->mux == x && mtmp->muy == y))
             && !(mtmp->isshk || mtmp->isgd || !mtmp->mcansee
                  || mtmp->mpeaceful || mtmp->data->mlet == S_HUMAN
                  || mtmp->data == &mons[PM_MINOTAUR]
                  || Inhell || In_endgame(&u.uz)));
 }
 
 

mon_regen

 /* regenerate lost hit points */
 void
 mon_regen(mon, digest_meal)
 struct monst *mon;
 boolean digest_meal;
 {
     if (mon->mhp < mon->mhpmax && (moves % 20 == 0 || regenerates(mon->data)))
         mon->mhp++;
     if (mon->mspec_used)
         mon->mspec_used--;
     if (digest_meal) {
         if (mon->meating) {
             mon->meating--;
             if (mon->meating <= 0)
                 finish_meating(mon);
         }
     }
 }
 

disturb

 /*
  * Possibly awaken the given monster.  Return a 1 if the monster has been
  * jolted awake.
  */
 STATIC_OVL int
 disturb(mtmp)
 register struct monst *mtmp;
 {
     /*
      * + Ettins are hard to surprise.
      * + Nymphs, jabberwocks, and leprechauns do not easily wake up.
      *
      * Wake up if:
      *  in direct LOS                                           AND
      *  within 10 squares                                       AND
      *  not stealthy or (mon is an ettin and 9/10)              AND
      *  (mon is not a nymph, jabberwock, or leprechaun) or 1/50 AND
      *  Aggravate or mon is (dog or human) or
      *      (1/7 and mon is not mimicing furniture or object)
      */
     if (couldsee(mtmp->mx, mtmp->my) && distu(mtmp->mx, mtmp->my) <= 100
         && (!Stealth || (mtmp->data == &mons[PM_ETTIN] && rn2(10)))
         && (!(mtmp->data->mlet == S_NYMPH
               || mtmp->data == &mons[PM_JABBERWOCK]
 #if 0 /* DEFERRED */
               || mtmp->data == &mons[PM_VORPAL_JABBERWOCK]
 #endif
               || mtmp->data->mlet == S_LEPRECHAUN) || !rn2(50))
         && (Aggravate_monster
             || (mtmp->data->mlet == S_DOG || mtmp->data->mlet == S_HUMAN)
             || (!rn2(7) && mtmp->m_ap_type != M_AP_FURNITURE
                 && mtmp->m_ap_type != M_AP_OBJECT))) {
         mtmp->msleeping = 0;
         return 1;
     }
     return 0;
 }
 

release_hero

 /* ungrab/expel held/swallowed hero */
 STATIC_OVL void
 release_hero(mon)
 struct monst *mon;
 {
     if (mon == u.ustuck) {
         if (u.uswallow) {
             expels(mon, mon->data, TRUE);
         } else if (!sticks(youmonst.data)) {
             unstuck(mon); /* let go */
             You("get released!");
         }
     }
 }
 

monflee

 /* monster begins fleeing for the specified time, 0 means untimed flee
  * if first, only adds fleetime if monster isn't already fleeing
  * if fleemsg, prints a message about new flight, otherwise, caller should */
 void
 monflee(mtmp, fleetime, first, fleemsg)
 struct monst *mtmp;
 int fleetime;
 boolean first;
 boolean fleemsg;
 {
     /* shouldn't happen; maybe warrants impossible()? */
     if (DEADMONSTER(mtmp))
         return;
 
     if (mtmp == u.ustuck)
         release_hero(mtmp); /* expels/unstuck */
 
     if (!first || !mtmp->mflee) {
         /* don't lose untimed scare */
         if (!fleetime)
             mtmp->mfleetim = 0;
         else if (!mtmp->mflee || mtmp->mfleetim) {
             fleetime += (int) mtmp->mfleetim;
             /* ensure monster flees long enough to visibly stop fighting */
             if (fleetime == 1)
                 fleetime++;
             mtmp->mfleetim = (unsigned) min(fleetime, 127);
         }
         if (!mtmp->mflee && fleemsg && canseemon(mtmp)
             && mtmp->m_ap_type != M_AP_FURNITURE
             && mtmp->m_ap_type != M_AP_OBJECT) {
             /* unfortunately we can't distinguish between temporary
                sleep and temporary paralysis, so both conditions
                receive the same alternate message */
             if (!mtmp->mcanmove || !mtmp->data->mmove)
                 pline("%s seems to flinch.", Adjmonnam(mtmp, "immobile"));
             else
                 pline("%s turns to flee.", Monnam(mtmp));
         }
         mtmp->mflee = 1;
     }
     /* ignore recently-stepped spaces when made to flee */
     memset(mtmp->mtrack, 0, sizeof(mtmp->mtrack));
 }
 

distfleeck

 STATIC_OVL void
 distfleeck(mtmp, inrange, nearby, scared)
 register struct monst *mtmp;
 int *inrange, *nearby, *scared;
 {
     int seescaryx, seescaryy;
     boolean sawscary = FALSE;
 
     *inrange = (dist2(mtmp->mx, mtmp->my, mtmp->mux, mtmp->muy)
                 <= (BOLT_LIM * BOLT_LIM));
     *nearby = *inrange && monnear(mtmp, mtmp->mux, mtmp->muy);
 
     /* Note: if your image is displaced, the monster sees the Elbereth
      * at your displaced position, thus never attacking your displaced
      * position, but possibly attacking you by accident.  If you are
      * invisible, it sees the Elbereth at your real position, thus never
      * running into you by accident but possibly attacking the spot
      * where it guesses you are.
      */
     if (!mtmp->mcansee || (Invis && !perceives(mtmp->data))) {
         seescaryx = mtmp->mux;
         seescaryy = mtmp->muy;
     } else {
         seescaryx = u.ux;
         seescaryy = u.uy;
     }
 
     sawscary = onscary(seescaryx, seescaryy, mtmp);
     if (*nearby && (sawscary
                     || (!mtmp->mpeaceful && in_your_sanctuary(mtmp, 0, 0)))) {
         *scared = 1;
         monflee(mtmp, rnd(rn2(7) ? 10 : 100), TRUE, TRUE);
     } else
         *scared = 0;
 }
 

m_arrival

 /* perform a special one-time action for a monster; returns -1 if nothing
    special happened, 0 if monster uses up its turn, 1 if monster is killed */
 STATIC_OVL int
 m_arrival(mon)
 struct monst *mon;
 {
     mon->mstrategy &= ~STRAT_ARRIVE; /* always reset */
 
     return -1;
 }
 

dochug

 /* returns 1 if monster died moving, 0 otherwise */
 /* The whole dochugw/m_move/distfleeck/mfndpos section is serious spaghetti
  * code. --KAA
  */
 int
 dochug(mtmp)
 register struct monst *mtmp;
 {
     register struct permonst *mdat;
     register int tmp = 0;
     int inrange, nearby, scared;
 
     /*  Pre-movement adjustments
      */
 
     mdat = mtmp->data;
 
     if (mtmp->mstrategy & STRAT_ARRIVE) {
         int res = m_arrival(mtmp);
         if (res >= 0)
             return res;
     }
 
     /* check for waitmask status change */
     if ((mtmp->mstrategy & STRAT_WAITFORU)
         && (m_canseeu(mtmp) || mtmp->mhp < mtmp->mhpmax))
         mtmp->mstrategy &= ~STRAT_WAITFORU;
 
     /* update quest status flags */
     quest_stat_check(mtmp);
 
     if (!mtmp->mcanmove || (mtmp->mstrategy & STRAT_WAITMASK)) {
         if (Hallucination)
             newsym(mtmp->mx, mtmp->my);
         if (mtmp->mcanmove && (mtmp->mstrategy & STRAT_CLOSE)
             && !mtmp->msleeping && monnear(mtmp, u.ux, u.uy))
             quest_talk(mtmp); /* give the leaders a chance to speak */
         return 0;             /* other frozen monsters can't do anything */
     }
 
     /* there is a chance we will wake it */
     if (mtmp->msleeping && !disturb(mtmp)) {
         if (Hallucination)
             newsym(mtmp->mx, mtmp->my);
         return 0;
     }
 
     /* not frozen or sleeping: wipe out texts written in the dust */
     wipe_engr_at(mtmp->mx, mtmp->my, 1, FALSE);
 
     /* confused monsters get unconfused with small probability */
     if (mtmp->mconf && !rn2(50))
         mtmp->mconf = 0;
 
     /* stunned monsters get un-stunned with larger probability */
     if (mtmp->mstun && !rn2(10))
         mtmp->mstun = 0;
 
     /* some monsters teleport */
     if (mtmp->mflee && !rn2(40) && can_teleport(mdat) && !mtmp->iswiz
         && !level.flags.noteleport) {
         (void) rloc(mtmp, TRUE);
         return 0;
     }
     if (mdat->msound == MS_SHRIEK && !um_dist(mtmp->mx, mtmp->my, 1))
         m_respond(mtmp);
     if (mdat == &mons[PM_MEDUSA] && couldsee(mtmp->mx, mtmp->my))
         m_respond(mtmp);
     if (mtmp->mhp <= 0)
         return 1; /* m_respond gaze can kill medusa */
 
     /* fleeing monsters might regain courage */
     if (mtmp->mflee && !mtmp->mfleetim && mtmp->mhp == mtmp->mhpmax
         && !rn2(25))
         mtmp->mflee = 0;
 
     /* cease conflict-induced swallow/grab if conflict has ended */
     if (mtmp == u.ustuck && mtmp->mpeaceful && !mtmp->mconf && !Conflict) {
         release_hero(mtmp);
         return 0; /* uses up monster's turn */
     }
 
     set_apparxy(mtmp);
     /* Must be done after you move and before the monster does.  The
      * set_apparxy() call in m_move() doesn't suffice since the variables
      * inrange, etc. all depend on stuff set by set_apparxy().
      */
 
     /* Monsters that want to acquire things */
     /* may teleport, so do it before inrange is set */
     if (is_covetous(mdat))
         (void) tactics(mtmp);
 
     /* check distance and scariness of attacks */
     distfleeck(mtmp, &inrange, &nearby, &scared);
 
     if (find_defensive(mtmp)) {
         if (use_defensive(mtmp) != 0)
             return 1;
     } else if (find_misc(mtmp)) {
         if (use_misc(mtmp) != 0)
             return 1;
     }
 
     /* Demonic Blackmail! */
     if (nearby && mdat->msound == MS_BRIBE && mtmp->mpeaceful && !mtmp->mtame
         && !u.uswallow) {
         if (mtmp->mux != u.ux || mtmp->muy != u.uy) {
             pline("%s whispers at thin air.",
                   cansee(mtmp->mux, mtmp->muy) ? Monnam(mtmp) : "It");
 
             if (is_demon(youmonst.data)) {
                 /* "Good hunting, brother" */
                 if (!tele_restrict(mtmp))
                     (void) rloc(mtmp, TRUE);
             } else {
                 mtmp->minvis = mtmp->perminvis = 0;
                 /* Why?  For the same reason in real demon talk */
                 pline("%s gets angry!", Amonnam(mtmp));
                 mtmp->mpeaceful = 0;
                 set_malign(mtmp);
                 /* since no way is an image going to pay it off */
             }
         } else if (demon_talk(mtmp))
             return 1; /* you paid it off */
     }
 
     /* the watch will look around and see if you are up to no good :-) */
     if (is_watch(mdat)) {
         watch_on_duty(mtmp);
 
     } else if (is_mind_flayer(mdat) && !rn2(20)) {
         struct monst *m2, *nmon = (struct monst *) 0;
 
         if (canseemon(mtmp))
             pline("%s concentrates.", Monnam(mtmp));
         if (distu(mtmp->mx, mtmp->my) > BOLT_LIM * BOLT_LIM) {
             You("sense a faint wave of psychic energy.");
             goto toofar;
         }
         pline("A wave of psychic energy pours over you!");
         if (mtmp->mpeaceful
             && (!Conflict || resist(mtmp, RING_CLASS, 0, 0))) {
             pline("It feels quite soothing.");
         } else if (!u.uinvulnerable) {
             register boolean m_sen = sensemon(mtmp);
 
             if (m_sen || (Blind_telepat && rn2(2)) || !rn2(10)) {
                 int dmg;
                 pline("It locks on to your %s!",
                       m_sen ? "telepathy" : Blind_telepat ? "latent telepathy"
                                                           : "mind");
                 dmg = rnd(15);
                 if (Half_spell_damage)
                     dmg = (dmg + 1) / 2;
                 losehp(dmg, "psychic blast", KILLED_BY_AN);
             }
         }
         for (m2 = fmon; m2; m2 = nmon) {
             nmon = m2->nmon;
             if (DEADMONSTER(m2))
                 continue;
             if (m2->mpeaceful == mtmp->mpeaceful)
                 continue;
             if (mindless(m2->data))
                 continue;
             if (m2 == mtmp)
                 continue;
             if ((telepathic(m2->data) && (rn2(2) || m2->mblinded))
                 || !rn2(10)) {
                 if (cansee(m2->mx, m2->my))
                     pline("It locks on to %s.", mon_nam(m2));
                 m2->mhp -= rnd(15);
                 if (m2->mhp <= 0)
                     monkilled(m2, "", AD_DRIN);
                 else
                     m2->msleeping = 0;
             }
         }
     }
 toofar:
 
     /* If monster is nearby you, and has to wield a weapon, do so.   This
      * costs the monster a move, of course.
      */
     if ((!mtmp->mpeaceful || Conflict) && inrange
         && dist2(mtmp->mx, mtmp->my, mtmp->mux, mtmp->muy) <= 8
         && attacktype(mdat, AT_WEAP)) {
         struct obj *mw_tmp;
 
         /* The scared check is necessary.  Otherwise a monster that is
          * one square near the player but fleeing into a wall would keep
          * switching between pick-axe and weapon.  If monster is stuck
          * in a trap, prefer ranged weapon (wielding is done in thrwmu).
          * This may cost the monster an attack, but keeps the monster
          * from switching back and forth if carrying both.
          */
         mw_tmp = MON_WEP(mtmp);
         if (!(scared && mw_tmp && is_pick(mw_tmp))
             && mtmp->weapon_check == NEED_WEAPON
             && !(mtmp->mtrapped && !nearby && select_rwep(mtmp))) {
             mtmp->weapon_check = NEED_HTH_WEAPON;
             if (mon_wield_item(mtmp) != 0)
                 return 0;
         }
     }
 
     /*  Now the actual movement phase
      */
 
     if (!nearby || mtmp->mflee || scared || mtmp->mconf || mtmp->mstun
         || (mtmp->minvis && !rn2(3))
         || (mdat->mlet == S_LEPRECHAUN && !findgold(invent)
             && (findgold(mtmp->minvent) || rn2(2)))
         || (is_wanderer(mdat) && !rn2(4)) || (Conflict && !mtmp->iswiz)
         || (!mtmp->mcansee && !rn2(4)) || mtmp->mpeaceful) {
         /* Possibly cast an undirected spell if not attacking you */
         /* note that most of the time castmu() will pick a directed
            spell and do nothing, so the monster moves normally */
         /* arbitrary distance restriction to keep monster far away
            from you from having cast dozens of sticks-to-snakes
            or similar spells by the time you reach it */
         if (dist2(mtmp->mx, mtmp->my, u.ux, u.uy) <= 49
             && !mtmp->mspec_used) {
             struct attack *a;
 
             for (a = &mdat->mattk[0]; a < &mdat->mattk[NATTK]; a++) {
                 if (a->aatyp == AT_MAGC
                     && (a->adtyp == AD_SPEL || a->adtyp == AD_CLRC)) {
                     if (castmu(mtmp, a, FALSE, FALSE)) {
                         tmp = 3;
                         break;
                     }
                 }
             }
         }
 
         tmp = m_move(mtmp, 0);
         if (tmp != 2)
             distfleeck(mtmp, &inrange, &nearby, &scared); /* recalc */
 
         switch (tmp) { /* for pets, cases 0 and 3 are equivalent */
         case 0: /* no movement, but it can still attack you */
         case 3: /* absolutely no movement */
             /* vault guard might have vanished */
             if (mtmp->isgd && (mtmp->mhp < 1 || mtmp->mx == 0))
                 return 1; /* behave as if it died */
             /* During hallucination, monster appearance should
              * still change - even if it doesn't move.
              */
             if (Hallucination)
                 newsym(mtmp->mx, mtmp->my);
             break;
         case 1: /* monster moved */
             /* Maybe it stepped on a trap and fell asleep... */
             if (mtmp->msleeping || !mtmp->mcanmove)
                 return 0;
             /* Monsters can move and then shoot on same turn;
                our hero can't.  Is that fair? */
             if (!nearby && (ranged_attk(mdat) || find_offensive(mtmp)))
                 break;
             /* engulfer/grabber checks */
             if (mtmp == u.ustuck) {
                 /* a monster that's digesting you can move at the
                  * same time -dlc
                  */
                 if (u.uswallow)
                     return mattacku(mtmp);
                 /* if confused grabber has wandered off, let go */
                 if (distu(mtmp->mx, mtmp->my) > 2)
                     unstuck(mtmp);
             }
             return 0;
         case 2: /* monster died */
             return 1;
         }
     }
 
     /*  Now, attack the player if possible - one attack set per monst
      */
 
     if (!mtmp->mpeaceful || (Conflict && !resist(mtmp, RING_CLASS, 0, 0))) {
         if (inrange && !noattacks(mdat)
             && (Upolyd ? u.mh : u.uhp) > 0 && !scared && tmp != 3)
             if (mattacku(mtmp))
                 return 1; /* monster died (e.g. exploded) */
 
         if (mtmp->wormno)
             wormhitu(mtmp);
     }
     /* special speeches for quest monsters */
     if (!mtmp->msleeping && mtmp->mcanmove && nearby)
         quest_talk(mtmp);
     /* extra emotional attack for vile monsters */
     if (inrange && mtmp->data->msound == MS_CUSS && !mtmp->mpeaceful
         && couldsee(mtmp->mx, mtmp->my) && !mtmp->minvis && !rn2(5))
         cuss(mtmp);
 
     return (tmp == 2);
 }
 
 static NEARDATA const char practical[] = { WEAPON_CLASS, ARMOR_CLASS,
                                            GEM_CLASS, FOOD_CLASS, 0 };
 static NEARDATA const char magical[] = { AMULET_CLASS, POTION_CLASS,
                                          SCROLL_CLASS, WAND_CLASS,
                                          RING_CLASS,   SPBOOK_CLASS, 0 };
 static NEARDATA const char indigestion[] = { BALL_CLASS, ROCK_CLASS, 0 };
 static NEARDATA const char boulder_class[] = { ROCK_CLASS, 0 };
 static NEARDATA const char gem_class[] = { GEM_CLASS, 0 };
 

itsstuck

 boolean
 itsstuck(mtmp)
 register struct monst *mtmp;
 {
     if (sticks(youmonst.data) && mtmp == u.ustuck && !u.uswallow) {
         pline("%s cannot escape from you!", Monnam(mtmp));
         return TRUE;
     }
     return FALSE;
 }
 

should_displace

 /*
  * should_displace()
  *
  * Displacement of another monster is a last resort and only
  * used on approach. If there are better ways to get to target,
  * those should be used instead. This function does that evaluation.
  */
 boolean
 should_displace(mtmp, poss, info, cnt, gx, gy)
 struct monst *mtmp;
 coord *poss; /* coord poss[9] */
 long *info;  /* long info[9] */
 int cnt;
 xchar gx, gy;
 {
     int shortest_with_displacing = -1;
     int shortest_without_displacing = -1;
     int count_without_displacing = 0;
     register int i, nx, ny;
     int ndist;
 
     for (i = 0; i < cnt; i++) {
         nx = poss[i].x;
         ny = poss[i].y;
         ndist = dist2(nx, ny, gx, gy);
         if (MON_AT(nx, ny) && (info[i] & ALLOW_MDISP) && !(info[i] & ALLOW_M)
             && !undesirable_disp(mtmp, nx, ny)) {
             if (shortest_with_displacing == -1
                 || (ndist < shortest_with_displacing))
                 shortest_with_displacing = ndist;
         } else {
             if ((shortest_without_displacing == -1)
                 || (ndist < shortest_without_displacing))
                 shortest_without_displacing = ndist;
             count_without_displacing++;
         }
     }
     if (shortest_with_displacing > -1
         && (shortest_with_displacing < shortest_without_displacing
             || !count_without_displacing))
         return TRUE;
     return FALSE;
 }
 

m_digweapon_check

 boolean
 m_digweapon_check(mtmp, nix, niy)
 struct monst *mtmp;
 xchar nix,niy;
 {
     boolean can_tunnel = 0;
     struct obj *mw_tmp;
 
     if (!Is_rogue_level(&u.uz))
         can_tunnel = tunnels(mtmp->data);
 
     if (can_tunnel && needspick(mtmp->data)
         && mtmp->weapon_check != NO_WEAPON_WANTED
         && ((IS_ROCK(levl[nix][niy].typ) && may_dig(nix, niy))
             || closed_door(nix, niy))) {
         if (closed_door(nix, niy)) {
             if (!(mw_tmp = MON_WEP(mtmp))
                 || !is_pick(mw_tmp)
                 || !is_axe(mw_tmp))
                 mtmp->weapon_check = NEED_PICK_OR_AXE;
         } else if (IS_TREE(levl[nix][niy].typ)) {
             if (!(mw_tmp = MON_WEP(mtmp)) || !is_axe(mw_tmp))
                 mtmp->weapon_check = NEED_AXE;
         } else if (!(mw_tmp = MON_WEP(mtmp)) || !is_pick(mw_tmp)) {
             mtmp->weapon_check = NEED_PICK_AXE;
         }
         if (mtmp->weapon_check >= NEED_PICK_AXE && mon_wield_item(mtmp))
             return TRUE;
     }
     return FALSE;
 }
 

m_move

 /* Return values:
  * 0: did not move, but can still attack and do other stuff.
  * 1: moved, possibly can attack.
  * 2: monster died.
  * 3: did not move, and can't do anything else either.
  */
 int
 m_move(mtmp, after)
 register struct monst *mtmp;
 register int after;
 {
     register int appr;
     xchar gx, gy, nix, niy, chcnt;
     int chi; /* could be schar except for stupid Sun-2 compiler */
     boolean likegold = 0, likegems = 0, likeobjs = 0, likemagic = 0,
             conceals = 0;
     boolean likerock = 0, can_tunnel = 0;
     boolean can_open = 0, can_unlock = 0, doorbuster = 0;
     boolean uses_items = 0, setlikes = 0;
     boolean avoid = FALSE;
     boolean better_with_displacing = FALSE;
     boolean sawmon = canspotmon(mtmp); /* before it moved */
     struct permonst *ptr;
     struct monst *mtoo;
     schar mmoved = 0; /* not strictly nec.: chi >= 0 will do */
     long info[9];
     long flag;
     int omx = mtmp->mx, omy = mtmp->my;
 
     if (mtmp->mtrapped) {
         int i = mintrap(mtmp);
 
         if (i >= 2) {
             newsym(mtmp->mx, mtmp->my);
             return 2;
         } /* it died */
         if (i == 1)
             return 0; /* still in trap, so didn't move */
     }
     ptr = mtmp->data; /* mintrap() can change mtmp->data -dlc */
 
     if (mtmp->meating) {
         mtmp->meating--;
         if (mtmp->meating <= 0)
             finish_meating(mtmp);
         return 3; /* still eating */
     }
     if (hides_under(ptr) && OBJ_AT(mtmp->mx, mtmp->my) && rn2(10))
         return 0; /* do not leave hiding place */
 
     set_apparxy(mtmp);
     /* where does mtmp think you are? */
     /* Not necessary if m_move called from this file, but necessary in
      * other calls of m_move (ex. leprechauns dodging)
      */
     if (!Is_rogue_level(&u.uz))
         can_tunnel = tunnels(ptr);
     can_open = !(nohands(ptr) || verysmall(ptr));
     can_unlock =
         ((can_open && monhaskey(mtmp, TRUE)) || mtmp->iswiz || is_rider(ptr));
     doorbuster = is_giant(ptr);
     if (mtmp->wormno)
         goto not_special;
     /* my dog gets special treatment */
     if (mtmp->mtame) {
         mmoved = dog_move(mtmp, after);
         goto postmov;
     }
 
     /* likewise for shopkeeper */
     if (mtmp->isshk) {
         mmoved = shk_move(mtmp);
         if (mmoved == -2)
             return 2;
         if (mmoved >= 0)
             goto postmov;
         mmoved = 0; /* follow player outside shop */
     }
 
     /* and for the guard */
     if (mtmp->isgd) {
         mmoved = gd_move(mtmp);
         if (mmoved == -2)
             return 2;
         if (mmoved >= 0)
             goto postmov;
         mmoved = 0;
     }
 
     /* and the acquisitive monsters get special treatment */
     if (is_covetous(ptr)) {
         xchar tx = STRAT_GOALX(mtmp->mstrategy),
               ty = STRAT_GOALY(mtmp->mstrategy);
         struct monst *intruder = m_at(tx, ty);
         /*
          * if there's a monster on the object or in possession of it,
          * attack it.
          */
         if ((dist2(mtmp->mx, mtmp->my, tx, ty) < 2) && intruder
             && (intruder != mtmp)) {
             notonhead = (intruder->mx != tx || intruder->my != ty);
             if (mattackm(mtmp, intruder) == 2)
                 return 2;
             mmoved = 1;
         } else
             mmoved = 0;
         goto postmov;
     }
 
     /* and for the priest */
     if (mtmp->ispriest) {
         mmoved = pri_move(mtmp);
         if (mmoved == -2)
             return 2;
         if (mmoved >= 0)
             goto postmov;
         mmoved = 0;
     }
 
 #ifdef MAIL
     if (ptr == &mons[PM_MAIL_DAEMON]) {
         if (!Deaf && canseemon(mtmp))
             verbalize("I'm late!");
         mongone(mtmp);
         return 2;
     }
 #endif
 
     /* teleport if that lies in our nature */
     if (ptr == &mons[PM_TENGU] && !rn2(5) && !mtmp->mcan
         && !tele_restrict(mtmp)) {
         if (mtmp->mhp < 7 || mtmp->mpeaceful || rn2(2))
             (void) rloc(mtmp, TRUE);
         else
             mnexto(mtmp);
         mmoved = 1;
         goto postmov;
     }
 not_special:
     if (u.uswallow && !mtmp->mflee && u.ustuck != mtmp)
         return 1;
     omx = mtmp->mx;
     omy = mtmp->my;
     gx = mtmp->mux;
     gy = mtmp->muy;
     appr = mtmp->mflee ? -1 : 1;
     if (mtmp->mconf || (u.uswallow && mtmp == u.ustuck)) {
         appr = 0;
     } else {
         struct obj *lepgold, *ygold;
         boolean should_see = (couldsee(omx, omy)
                               && (levl[gx][gy].lit || !levl[omx][omy].lit)
                               && (dist2(omx, omy, gx, gy) <= 36));
 
         if (!mtmp->mcansee
             || (should_see && Invis && !perceives(ptr) && rn2(11))
             || is_obj_mappear(&youmonst,STRANGE_OBJECT) || u.uundetected
             || (is_obj_mappear(&youmonst,GOLD_PIECE) && !likes_gold(ptr))
             || (mtmp->mpeaceful && !mtmp->isshk) /* allow shks to follow */
             || ((monsndx(ptr) == PM_STALKER || ptr->mlet == S_BAT
                  || ptr->mlet == S_LIGHT) && !rn2(3)))
             appr = 0;
 
         if (monsndx(ptr) == PM_LEPRECHAUN && (appr == 1)
             && ((lepgold = findgold(mtmp->minvent))
                 && (lepgold->quan
                     > ((ygold = findgold(invent)) ? ygold->quan : 0L))))
             appr = -1;
 
         if (!should_see && can_track(ptr)) {
             register coord *cp;
 
             cp = gettrack(omx, omy);
             if (cp) {
                 gx = cp->x;
                 gy = cp->y;
             }
         }
     }
 
     if ((!mtmp->mpeaceful || !rn2(10)) && (!Is_rogue_level(&u.uz))) {
         boolean in_line = (lined_up(mtmp)
                && (distmin(mtmp->mx, mtmp->my, mtmp->mux, mtmp->muy)
                    <= (throws_rocks(youmonst.data) ? 20 : ACURRSTR / 2 + 1)));
 
         if (appr != 1 || !in_line) {
             /* Monsters in combat won't pick stuff up, avoiding the
              * situation where you toss arrows at it and it has nothing
              * better to do than pick the arrows up.
              */
             register int pctload =
                 (curr_mon_load(mtmp) * 100) / max_mon_load(mtmp);
 
             /* look for gold or jewels nearby */
             likegold = (likes_gold(ptr) && pctload < 95);
             likegems = (likes_gems(ptr) && pctload < 85);
             uses_items = (!mindless(ptr) && !is_animal(ptr) && pctload < 75);
             likeobjs = (likes_objs(ptr) && pctload < 75);
             likemagic = (likes_magic(ptr) && pctload < 85);
             likerock = (throws_rocks(ptr) && pctload < 50 && !Sokoban);
             conceals = hides_under(ptr);
             setlikes = TRUE;
         }
     }
 
 #define SQSRCHRADIUS 5
 
     {
         register int minr = SQSRCHRADIUS; /* not too far away */
         register struct obj *otmp;
         register int xx, yy;
         int oomx, oomy, lmx, lmy;
 
         /* cut down the search radius if it thinks character is closer. */
         if (distmin(mtmp->mux, mtmp->muy, omx, omy) < SQSRCHRADIUS
             && !mtmp->mpeaceful)
             minr--;
         /* guards shouldn't get too distracted */
         if (!mtmp->mpeaceful && is_mercenary(ptr))
             minr = 1;
 
         if ((likegold || likegems || likeobjs || likemagic || likerock
              || conceals) && (!*in_rooms(omx, omy, SHOPBASE)
                               || (!rn2(25) && !mtmp->isshk))) {
         look_for_obj:
             oomx = min(COLNO - 1, omx + minr);
             oomy = min(ROWNO - 1, omy + minr);
             lmx = max(1, omx - minr);
             lmy = max(0, omy - minr);
             for (otmp = fobj; otmp; otmp = otmp->nobj) {
                 /* monsters may pick rocks up, but won't go out of their way
                    to grab them; this might hamper sling wielders, but it cuts
                    down on move overhead by filtering out most common item */
                 if (otmp->otyp == ROCK)
                     continue;
                 xx = otmp->ox;
                 yy = otmp->oy;
                 /* Nymphs take everything.  Most other creatures should not
                  * pick up corpses except as a special case like in
                  * searches_for_item().  We need to do this check in
                  * mpickstuff() as well.
                  */
                 if (xx >= lmx && xx <= oomx && yy >= lmy && yy <= oomy) {
                     /* don't get stuck circling around object that's
                        underneath an immobile or hidden monster;
                        paralysis victims excluded */
                     if ((mtoo = m_at(xx, yy)) != 0
                         && (mtoo->msleeping || mtoo->mundetected
                             || (mtoo->mappearance && !mtoo->iswiz)
                             || !mtoo->data->mmove))
                         continue;
                     /* the mfndpos() test for whether to allow a move to a
                        water location accepts flyers, but they can't reach
                        underwater objects, so being able to move to a spot
                        is insufficient for deciding whether to do so */
                     if ((is_pool(xx, yy) && !is_swimmer(ptr))
                         || (is_lava(xx, yy) && !likes_lava(ptr)))
                         continue;
 
                     if (((likegold && otmp->oclass == COIN_CLASS)
                          || (likeobjs && index(practical, otmp->oclass)
                              && (otmp->otyp != CORPSE
                                  || (ptr->mlet == S_NYMPH
                                      && !is_rider(&mons[otmp->corpsenm]))))
                          || (likemagic && index(magical, otmp->oclass))
                          || (uses_items && searches_for_item(mtmp, otmp))
                          || (likerock && otmp->otyp == BOULDER)
                          || (likegems && otmp->oclass == GEM_CLASS
                              && objects[otmp->otyp].oc_material != MINERAL)
                          || (conceals && !cansee(otmp->ox, otmp->oy))
                          || (ptr == &mons[PM_GELATINOUS_CUBE]
                              && !index(indigestion, otmp->oclass)
                              && !(otmp->otyp == CORPSE
                                   && touch_petrifies(&mons[otmp->corpsenm]))))
                         && touch_artifact(otmp, mtmp)) {
                         if (can_carry(mtmp, otmp) > 0
                             && (throws_rocks(ptr) || !sobj_at(BOULDER, xx, yy))
                             && (!is_unicorn(ptr)
                                 || objects[otmp->otyp].oc_material == GEMSTONE)
                             /* Don't get stuck circling an Elbereth */
                             && !onscary(xx, yy, mtmp)) {
                             minr = distmin(omx, omy, xx, yy);
                             oomx = min(COLNO - 1, omx + minr);
                             oomy = min(ROWNO - 1, omy + minr);
                             lmx = max(1, omx - minr);
                             lmy = max(0, omy - minr);
                             gx = otmp->ox;
                             gy = otmp->oy;
                             if (gx == omx && gy == omy) {
                                 mmoved = 3; /* actually unnecessary */
                                 goto postmov;
                             }
                         }
                     }
                 }
             }
         } else if (likegold) {
             /* don't try to pick up anything else, but use the same loop */
             uses_items = 0;
             likegems = likeobjs = likemagic = likerock = conceals = 0;
             goto look_for_obj;
         }
 
         if (minr < SQSRCHRADIUS && appr == -1) {
             if (distmin(omx, omy, mtmp->mux, mtmp->muy) <= 3) {
                 gx = mtmp->mux;
                 gy = mtmp->muy;
             } else
                 appr = 1;
         }
     }
 
     /* don't tunnel if hostile and close enough to prefer a weapon */
     if (can_tunnel && needspick(ptr)
         && ((!mtmp->mpeaceful || Conflict)
             && dist2(mtmp->mx, mtmp->my, mtmp->mux, mtmp->muy) <= 8))
         can_tunnel = FALSE;
 
     nix = omx;
     niy = omy;
     flag = 0L;
     if (mtmp->mpeaceful && (!Conflict || resist(mtmp, RING_CLASS, 0, 0)))
         flag |= (ALLOW_SANCT | ALLOW_SSM);
     else
         flag |= ALLOW_U;
     if (is_minion(ptr) || is_rider(ptr))
         flag |= ALLOW_SANCT;
     /* unicorn may not be able to avoid hero on a noteleport level */
     if (is_unicorn(ptr) && !level.flags.noteleport)
         flag |= NOTONL;
     if (passes_walls(ptr))
         flag |= (ALLOW_WALL | ALLOW_ROCK);
     if (passes_bars(ptr))
         flag |= ALLOW_BARS;
     if (can_tunnel)
         flag |= ALLOW_DIG;
     if (is_human(ptr) || ptr == &mons[PM_MINOTAUR])
         flag |= ALLOW_SSM;
     if ((is_undead(ptr) && ptr->mlet != S_GHOST) || is_vampshifter(mtmp))
         flag |= NOGARLIC;
     if (throws_rocks(ptr))
         flag |= ALLOW_ROCK;
     if (can_open)
         flag |= OPENDOOR;
     if (can_unlock)
         flag |= UNLOCKDOOR;
     if (doorbuster)
         flag |= BUSTDOOR;
     {
         register int i, j, nx, ny, nearer;
         int jcnt, cnt;
         int ndist, nidist;
         register coord *mtrk;
         coord poss[9];
 
         cnt = mfndpos(mtmp, poss, info, flag);
         chcnt = 0;
         jcnt = min(MTSZ, cnt - 1);
         chi = -1;
         nidist = dist2(nix, niy, gx, gy);
         /* allow monsters be shortsighted on some levels for balance */
         if (!mtmp->mpeaceful && level.flags.shortsighted
             && nidist > (couldsee(nix, niy) ? 144 : 36) && appr == 1)
             appr = 0;
         if (is_unicorn(ptr) && level.flags.noteleport) {
             /* on noteleport levels, perhaps we cannot avoid hero */
             for (i = 0; i < cnt; i++)
                 if (!(info[i] & NOTONL))
                     avoid = TRUE;
         }
         better_with_displacing =
             should_displace(mtmp, poss, info, cnt, gx, gy);
         for (i = 0; i < cnt; i++) {
             if (avoid && (info[i] & NOTONL))
                 continue;
             nx = poss[i].x;
             ny = poss[i].y;
 
             if (MON_AT(nx, ny) && (info[i] & ALLOW_MDISP)
                 && !(info[i] & ALLOW_M) && !better_with_displacing)
                 continue;
             if (appr != 0) {
                 mtrk = &mtmp->mtrack[0];
                 for (j = 0; j < jcnt; mtrk++, j++)
                     if (nx == mtrk->x && ny == mtrk->y)
                         if (rn2(4 * (cnt - j)))
                             goto nxti;
             }
 
             nearer = ((ndist = dist2(nx, ny, gx, gy)) < nidist);
 
             if ((appr == 1 && nearer) || (appr == -1 && !nearer)
                 || (!appr && !rn2(++chcnt)) || !mmoved) {
                 nix = nx;
                 niy = ny;
                 nidist = ndist;
                 chi = i;
                 mmoved = 1;
             }
         nxti:
             ;
         }
     }
 
     if (mmoved) {
         register int j;
 
         if (mmoved == 1 && (u.ux != nix || u.uy != niy) && itsstuck(mtmp))
             return 3;
 
         if (mmoved == 1 && m_digweapon_check(mtmp, nix,niy))
             return 3;
 
         /* If ALLOW_U is set, either it's trying to attack you, or it
          * thinks it is.  In either case, attack this spot in preference to
          * all others.
          */
         /* Actually, this whole section of code doesn't work as you'd expect.
          * Most attacks are handled in dochug().  It calls distfleeck(), which
          * among other things sets nearby if the monster is near you--and if
          * nearby is set, we never call m_move unless it is a special case
          * (confused, stun, etc.)  The effect is that this ALLOW_U (and
          * mfndpos) has no effect for normal attacks, though it lets a
          * confused monster attack you by accident.
          */
         if (info[chi] & ALLOW_U) {
             nix = mtmp->mux;
             niy = mtmp->muy;
         }
         if (nix == u.ux && niy == u.uy) {
             mtmp->mux = u.ux;
             mtmp->muy = u.uy;
             return 0;
         }
         /* The monster may attack another based on 1 of 2 conditions:
          * 1 - It may be confused.
          * 2 - It may mistake the monster for your (displaced) image.
          * Pets get taken care of above and shouldn't reach this code.
          * Conflict gets handled even farther away (movemon()).
          */
         if ((info[chi] & ALLOW_M) || (nix == mtmp->mux && niy == mtmp->muy)) {
             struct monst *mtmp2;
             int mstatus;
             mtmp2 = m_at(nix, niy);
 
             notonhead = mtmp2 && (nix != mtmp2->mx || niy != mtmp2->my);
             /* note: mstatus returns 0 if mtmp2 is nonexistent */
             mstatus = mattackm(mtmp, mtmp2);
 
             if (mstatus & MM_AGR_DIED) /* aggressor died */
                 return 2;
 
             if ((mstatus & MM_HIT) && !(mstatus & MM_DEF_DIED) && rn2(4)
                 && mtmp2->movement >= NORMAL_SPEED) {
                 mtmp2->movement -= NORMAL_SPEED;
                 notonhead = 0;
                 mstatus = mattackm(mtmp2, mtmp); /* return attack */
                 if (mstatus & MM_DEF_DIED)
                     return 2;
             }
             return 3;
         }
 
         if ((info[chi] & ALLOW_MDISP)) {
             struct monst *mtmp2;
             int mstatus;
             mtmp2 = m_at(nix, niy);
             mstatus = mdisplacem(mtmp, mtmp2, FALSE);
             if ((mstatus & MM_AGR_DIED) || (mstatus & MM_DEF_DIED))
                 return 2;
             if (mstatus & MM_HIT)
                 return 1;
             return 3;
         }
 
         if (!m_in_out_region(mtmp, nix, niy))
             return 3;
         remove_monster(omx, omy);
         place_monster(mtmp, nix, niy);
         for (j = MTSZ - 1; j > 0; j--)
             mtmp->mtrack[j] = mtmp->mtrack[j - 1];
         mtmp->mtrack[0].x = omx;
         mtmp->mtrack[0].y = omy;
         /* Place a segment at the old position. */
         if (mtmp->wormno)
             worm_move(mtmp);
     } else {
         if (is_unicorn(ptr) && rn2(2) && !tele_restrict(mtmp)) {
             (void) rloc(mtmp, TRUE);
             return 1;
         }
         if (mtmp->wormno)
             worm_nomove(mtmp);
     }
 postmov:
     if (mmoved == 1 || mmoved == 3) {
         boolean canseeit = cansee(mtmp->mx, mtmp->my);
 
         if (mmoved == 1) {
             newsym(omx, omy); /* update the old position */
             if (mintrap(mtmp) >= 2) {
                 if (mtmp->mx)
                     newsym(mtmp->mx, mtmp->my);
                 return 2; /* it died */
             }
             ptr = mtmp->data;
 
             /* open a door, or crash through it, if 'mtmp' can */
             if (IS_DOOR(levl[mtmp->mx][mtmp->my].typ)
                 && !passes_walls(ptr) /* doesn't need to open doors */
                 && !can_tunnel) {     /* taken care of below */
                 struct rm *here = &levl[mtmp->mx][mtmp->my];
                 boolean btrapped = (here->doormask & D_TRAPPED) != 0,
                         observeit = canseeit && canspotmon(mtmp);
 
                 /* if mon has MKoT, disarm door trap; no message given */
                 if (btrapped && has_magic_key(mtmp)) {
                     /* BUG: this lets a vampire or blob or a doorbuster
                        holding the Key disarm the trap even though it isn't
                        using that Key when squeezing under or smashing the
                        door.  Not significant enough to worry about; perhaps
                        the Key's magic is more powerful for monsters? */
                     here->doormask &= ~D_TRAPPED;
                     btrapped = FALSE;
                 }
                 if ((here->doormask & (D_LOCKED | D_CLOSED)) != 0
                     && (amorphous(ptr)
                         || (can_fog(mtmp)
                             && vamp_shift(mtmp, &mons[PM_FOG_CLOUD],
                                           sawmon)))) {
                     /* update cached value for vamp_shift() case */
                     ptr = mtmp->data;
                     if (flags.verbose && canseemon(mtmp))
                         pline("%s %s under the door.", Monnam(mtmp),
                               (ptr == &mons[PM_FOG_CLOUD]
                                || ptr->mlet == S_LIGHT)
                                   ? "flows"
                                   : "oozes");
                 } else if (here->doormask & D_LOCKED && can_unlock) {
                     if (btrapped) {
                         here->doormask = D_NODOOR;
                         newsym(mtmp->mx, mtmp->my);
                         unblock_point(mtmp->mx, mtmp->my); /* vision */
                         if (mb_trapped(mtmp))
                             return 2;
                     } else {
                         if (flags.verbose) {
                             if (observeit)
                                 pline("%s unlocks and opens a door.",
                                       Monnam(mtmp));
                             else if (canseeit)
                                 You_see("a door unlock and open.");
                             else if (!Deaf)
                                 You_hear("a door unlock and open.");
                         }
                         here->doormask = D_ISOPEN;
                         /* newsym(mtmp->mx, mtmp->my); */
                         unblock_point(mtmp->mx, mtmp->my); /* vision */
                     }
                 } else if (here->doormask == D_CLOSED && can_open) {
                     if (btrapped) {
                         here->doormask = D_NODOOR;
                         newsym(mtmp->mx, mtmp->my);
                         unblock_point(mtmp->mx, mtmp->my); /* vision */
                         if (mb_trapped(mtmp))
                             return 2;
                     } else {
                         if (flags.verbose) {
                             if (observeit)
                                 pline("%s opens a door.", Monnam(mtmp));
                             else if (canseeit)
                                 You_see("a door open.");
                             else if (!Deaf)
                                 You_hear("a door open.");
                         }
                         here->doormask = D_ISOPEN;
                         /* newsym(mtmp->mx, mtmp->my); */  /* done below */
                         unblock_point(mtmp->mx, mtmp->my); /* vision */
                     }
                 } else if (here->doormask & (D_LOCKED | D_CLOSED)) {
                     /* mfndpos guarantees this must be a doorbuster */
                     if (btrapped) {
                         here->doormask = D_NODOOR;
                         newsym(mtmp->mx, mtmp->my);
                         unblock_point(mtmp->mx, mtmp->my); /* vision */
                         if (mb_trapped(mtmp))
                             return 2;
                     } else {
                         if (flags.verbose) {
                             if (observeit)
                                 pline("%s smashes down a door.",
                                       Monnam(mtmp));
                             else if (canseeit)
                                 You_see("a door crash open.");
                             else if (!Deaf)
                                 You_hear("a door crash open.");
                         }
                         if ((here->doormask & D_LOCKED) != 0 && !rn2(2))
                             here->doormask = D_NODOOR;
                         else
                             here->doormask = D_BROKEN;
                         /* newsym(mtmp->mx, mtmp->my); */  /* done below */
                         unblock_point(mtmp->mx, mtmp->my); /* vision */
                     }
                     /* if it's a shop door, schedule repair */
                     if (*in_rooms(mtmp->mx, mtmp->my, SHOPBASE))
                         add_damage(mtmp->mx, mtmp->my, 0L);
                 }
             } else if (levl[mtmp->mx][mtmp->my].typ == IRONBARS) {
                 if (may_dig(mtmp->mx, mtmp->my)
                     && (dmgtype(ptr, AD_RUST) || dmgtype(ptr, AD_CORR))) {
                     if (canseemon(mtmp))
                         pline("%s eats through the iron bars.", Monnam(mtmp));
                     dissolve_bars(mtmp->mx, mtmp->my);
                     return 3;
                 } else if (flags.verbose && canseemon(mtmp))
                     Norep("%s %s %s the iron bars.", Monnam(mtmp),
                           /* pluralization fakes verb conjugation */
                           makeplural(locomotion(ptr, "pass")),
                           passes_walls(ptr) ? "through" : "between");
             }
 
             /* possibly dig */
             if (can_tunnel && mdig_tunnel(mtmp))
                 return 2; /* mon died (position already updated) */
 
             /* set also in domove(), hack.c */
             if (u.uswallow && mtmp == u.ustuck
                 && (mtmp->mx != omx || mtmp->my != omy)) {
                 /* If the monster moved, then update */
                 u.ux0 = u.ux;
                 u.uy0 = u.uy;
                 u.ux = mtmp->mx;
                 u.uy = mtmp->my;
                 swallowed(0);
             } else
                 newsym(mtmp->mx, mtmp->my);
         }
         if (OBJ_AT(mtmp->mx, mtmp->my) && mtmp->mcanmove) {
             /* recompute the likes tests, in case we polymorphed
              * or if the "likegold" case got taken above */
             if (setlikes) {
                 int pctload = (curr_mon_load(mtmp) * 100) / max_mon_load(mtmp);
 
                 /* look for gold or jewels nearby */
                 likegold = (likes_gold(ptr) && pctload < 95);
                 likegems = (likes_gems(ptr) && pctload < 85);
                 uses_items =
                     (!mindless(ptr) && !is_animal(ptr) && pctload < 75);
                 likeobjs = (likes_objs(ptr) && pctload < 75);
                 likemagic = (likes_magic(ptr) && pctload < 85);
                 likerock = (throws_rocks(ptr) && pctload < 50 && !Sokoban);
                 conceals = hides_under(ptr);
             }
 
             /* Maybe a rock mole just ate some metal object */
             if (metallivorous(ptr)) {
                 if (meatmetal(mtmp) == 2)
                     return 2; /* it died */
             }
 
             if (g_at(mtmp->mx, mtmp->my) && likegold)
                 mpickgold(mtmp);
 
             /* Maybe a cube ate just about anything */
             if (ptr == &mons[PM_GELATINOUS_CUBE]) {
                 if (meatobj(mtmp) == 2)
                     return 2; /* it died */
             }
 
             if (!*in_rooms(mtmp->mx, mtmp->my, SHOPBASE) || !rn2(25)) {
                 boolean picked = FALSE;
 
                 if (likeobjs)
                     picked |= mpickstuff(mtmp, practical);
                 if (likemagic)
                     picked |= mpickstuff(mtmp, magical);
                 if (likerock)
                     picked |= mpickstuff(mtmp, boulder_class);
                 if (likegems)
                     picked |= mpickstuff(mtmp, gem_class);
                 if (uses_items)
                     picked |= mpickstuff(mtmp, (char *) 0);
                 if (picked)
                     mmoved = 3;
             }
 
             if (mtmp->minvis) {
                 newsym(mtmp->mx, mtmp->my);
                 if (mtmp->wormno)
                     see_wsegs(mtmp);
             }
         }
 
         if (hides_under(ptr) || ptr->mlet == S_EEL) {
             /* Always set--or reset--mundetected if it's already hidden
                (just in case the object it was hiding under went away);
                usually set mundetected unless monster can't move.  */
             if (mtmp->mundetected
                 || (mtmp->mcanmove && !mtmp->msleeping && rn2(5)))
                 (void) hideunder(mtmp);
             newsym(mtmp->mx, mtmp->my);
         }
         if (mtmp->isshk) {
             after_shk_move(mtmp);
         }
     }
     return mmoved;
 }
 

dissolve_bars

 void
 dissolve_bars(x, y)
 register int x, y;
 {
     levl[x][y].typ = (Is_special(&u.uz) || *in_rooms(x, y, 0)) ? ROOM : CORR;
     newsym(x, y);
 }
 

closed_door

 boolean
 closed_door(x, y)
 register int x, y;
 {
     return (boolean) (IS_DOOR(levl[x][y].typ)
                       && (levl[x][y].doormask & (D_LOCKED | D_CLOSED)));
 }
 

accessible

 boolean
 accessible(x, y)
 register int x, y;
 {
     int levtyp = levl[x][y].typ;
 
     /* use underlying terrain in front of closed drawbridge */
     if (levtyp == DRAWBRIDGE_UP)
         levtyp = db_under_typ(levl[x][y].drawbridgemask);
 
     return (boolean) (ACCESSIBLE(levtyp) && !closed_door(x, y));
 }
 

set_apparxy

 /* decide where the monster thinks you are standing */
 void
 set_apparxy(mtmp)
 register struct monst *mtmp;
 {
     boolean notseen, gotu;
     register int disp, mx = mtmp->mux, my = mtmp->muy;
     long umoney = money_cnt(invent);
 
     /*
      * do cheapest and/or most likely tests first
      */
 
     /* pet knows your smell; grabber still has hold of you */
     if (mtmp->mtame || mtmp == u.ustuck)
         goto found_you;
 
     /* monsters which know where you are don't suddenly forget,
        if you haven't moved away */
     if (mx == u.ux && my == u.uy)
         goto found_you;
 
     notseen = (!mtmp->mcansee || (Invis && !perceives(mtmp->data)));
     /* add cases as required.  eg. Displacement ... */
     if (notseen || Underwater) {
         /* Xorns can smell quantities of valuable metal
             like that in solid gold coins, treat as seen */
         if ((mtmp->data == &mons[PM_XORN]) && umoney && !Underwater)
             disp = 0;
         else
             disp = 1;
     } else if (Displaced) {
         disp = couldsee(mx, my) ? 2 : 1;
     } else
         disp = 0;
     if (!disp)
         goto found_you;
 
     /* without something like the following, invisibility and displacement
        are too powerful */
     gotu = notseen ? !rn2(3) : Displaced ? !rn2(4) : FALSE;
 
     if (!gotu) {
         register int try_cnt = 0;
         do {
             if (++try_cnt > 200)
                 goto found_you; /* punt */
             mx = u.ux - disp + rn2(2 * disp + 1);
             my = u.uy - disp + rn2(2 * disp + 1);
         } while (!isok(mx, my)
                  || (disp != 2 && mx == mtmp->mx && my == mtmp->my)
                  || ((mx != u.ux || my != u.uy) && !passes_walls(mtmp->data)
                      && !(accessible(mx, my)
                           || (closed_door(mx, my)
                               && (can_ooze(mtmp) || can_fog(mtmp)))))
                  || !couldsee(mx, my));
     } else {
     found_you:
         mx = u.ux;
         my = u.uy;
     }
 
     mtmp->mux = mx;
     mtmp->muy = my;
 }
 

undesirable_disp

 /*
  * mon-to-mon displacement is a deliberate "get out of my way" act,
  * not an accidental bump, so we don't consider mstun or mconf in
  * undesired_disp().
  *
  * We do consider many other things about the target and its
  * location however.
  */
 boolean
 undesirable_disp(mtmp, x, y)
 struct monst *mtmp;
 xchar x, y;
 {
     boolean is_pet = (mtmp && mtmp->mtame && !mtmp->isminion);
     struct trap *trap = t_at(x, y);
 
     if (is_pet) {
         /* Pets avoid a trap if you've seen it usually. */
         if (trap && trap->tseen && rn2(40))
             return TRUE;
         /* Pets avoid cursed locations */
         if (cursed_object_at(x, y))
             return TRUE;
 
     /* Monsters avoid a trap if they've seen that type before */
     } else if (trap && rn2(40)
                && (mtmp->mtrapseen & (1 << (trap->ttyp - 1))) != 0) {
         return TRUE;
     }
 
     return FALSE;
 }
 

stuff_prevents_passage

 /*
  * Inventory prevents passage under door.
  * Used by can_ooze() and can_fog().
  */
 STATIC_OVL boolean
 stuff_prevents_passage(mtmp)
 struct monst *mtmp;
 {
     struct obj *chain, *obj;
 
     if (mtmp == &youmonst) {
         chain = invent;
     } else {
         chain = mtmp->minvent;
     }
     for (obj = chain; obj; obj = obj->nobj) {
         int typ = obj->otyp;
 
         if (typ == COIN_CLASS && obj->quan > 100L)
             return TRUE;
         if (obj->oclass != GEM_CLASS && !(typ >= ARROW && typ <= BOOMERANG)
             && !(typ >= DAGGER && typ <= CRYSKNIFE) && typ != SLING
             && !is_cloak(obj) && typ != FEDORA && !is_gloves(obj)
             && typ != LEATHER_JACKET && typ != CREDIT_CARD && !is_shirt(obj)
             && !(typ == CORPSE && verysmall(&mons[obj->corpsenm]))
             && typ != FORTUNE_COOKIE && typ != CANDY_BAR && typ != PANCAKE
             && typ != LEMBAS_WAFER && typ != LUMP_OF_ROYAL_JELLY
             && obj->oclass != AMULET_CLASS && obj->oclass != RING_CLASS
             && obj->oclass != VENOM_CLASS && typ != SACK
             && typ != BAG_OF_HOLDING && typ != BAG_OF_TRICKS
             && !Is_candle(obj) && typ != OILSKIN_SACK && typ != LEASH
             && typ != STETHOSCOPE && typ != BLINDFOLD && typ != TOWEL
             && typ != TIN_WHISTLE && typ != MAGIC_WHISTLE
             && typ != MAGIC_MARKER && typ != TIN_OPENER && typ != SKELETON_KEY
             && typ != LOCK_PICK)
             return TRUE;
         if (Is_container(obj) && obj->cobj)
             return TRUE;
     }
     return FALSE;
 }
 

can_ooze

 boolean
 can_ooze(mtmp)
 struct monst *mtmp;
 {
     if (!amorphous(mtmp->data) || stuff_prevents_passage(mtmp))
         return FALSE;
     return TRUE;
 }
 

can_fog

 /* monster can change form into a fog if necessary */
 boolean
 can_fog(mtmp)
 struct monst *mtmp;
 {
     if (!(mvitals[PM_FOG_CLOUD].mvflags & G_GENOD) && is_vampshifter(mtmp)
         && !Protection_from_shape_changers && !stuff_prevents_passage(mtmp))
         return TRUE;
     return FALSE;
 }
 

vamp_shift

 STATIC_OVL int
 vamp_shift(mon, ptr, domsg)
 struct monst *mon;
 struct permonst *ptr;
 boolean domsg;
 {
     int reslt = 0;
     char oldmtype[BUFSZ];
 
     /* remember current monster type before shapechange */
     Strcpy(oldmtype, domsg ? noname_monnam(mon, ARTICLE_THE) : "");
 
     if (mon->data == ptr) {
         /* already right shape */
         reslt = 1;
         domsg = FALSE;
     } else if (is_vampshifter(mon)) {
         reslt = newcham(mon, ptr, FALSE, FALSE);
     }
 
     if (reslt && domsg) {
         pline("You %s %s where %s was.",
               !canseemon(mon) ? "now detect" : "observe",
               noname_monnam(mon, ARTICLE_A), oldmtype);
     }
 
     return reslt;
 }
 
 /*monmove.c*/