/* Units in Xconq.
   Copyright (C) 1986-1989, 1991-1997 Stanley T. Shebs.

Xconq is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.  See the file COPYING.  */

#include "conq.h"
extern void interp_utype_list PARAMS ((short *arr, Obj *lis));
#include "kernel.h"
extern int num_sides_allowed PARAMS ((int u));
extern void wreck_unit PARAMS ((Unit *unit));
extern int side_owns_occupant PARAMS ((Side *side, Unit *unit));

/* This is not a limit, just sets initial allocation of unit objects
   and how many additional to get if more are needed.  This can be
   tweaked for more frequent but smaller allocation, or less frequent
   but larger and possibly space-wasting allocation. */

#ifndef INITMAXUNITS
#define INITMAXUNITS 200
#endif

static void allocate_unit_block PARAMS ((void));
static int compare_units PARAMS ((Unit *unit1, Unit *unit2));
static int compare_units_by_keys PARAMS ((const void *e1, const void *e2));

static void leave_cell_aux PARAMS ((Unit *unit, Unit *oldtransport));

static void change_cell_aux PARAMS ((Unit *unit, int x0, int y0, int x, int y));

/* The list of available units. */

Unit *freeunits;

/* The global linked list of all units. */

Unit *unitlist;

/* A scratch global. */

Unit *tmpunit;

/* Buffers for descriptions of units. */

/* We use several and rotate among them; this is so multiple calls in
   a single printf will work as expected.  Not elegant, but simple and
   sufficient. */

#define NUMSHORTBUFS 3

static int curshortbuf;

static char *shortbufs[NUMSHORTBUFS] = { NULL, NULL, NULL };

static char *utypenamen;

char **shortestnames = NULL;

char **shortestgnames = NULL;

char *actorstatebuf = NULL;

/* Total number of units in existence. */

int numunits;

/* Total number of units that are alive. */

int numliveunits;

/* Total number of live units, by type. */

int *numlivebytype;

/* The next number to use for a unit id. */

int nextid = 1;

/* A cache of completenesses. */

short *completenesses;

/* Have units died since dead unit lists made. */

int recent_dead_flushed = TRUE;

/* Local tmp var. */

static Side *tmpside_classtest;

/* Grab a block of unit objects to work with. */

static void
allocate_unit_block()
{
    int i;
    Unit *unitblock = (Unit *) xmalloc(INITMAXUNITS * sizeof(Unit));

    for (i = 0; i < INITMAXUNITS; ++i) {
        unitblock[i].id = -1;
        unitblock[i].next = &unitblock[i+1];
    }
    unitblock[INITMAXUNITS-1].next = NULL;
    freeunits = unitblock;
    Dprintf("Allocated space for %d units.\n", INITMAXUNITS);
}

/* Init gets a first block of units, and sets up the "independent side" list,
   since newly created units will appear on it. */

void
init_units()
{
    unitlist = NULL;
    allocate_unit_block();
    init_side_unithead(indepside);
    completenesses = (short *) xmalloc(MAXUTYPES * sizeof(short));
}

/* The primitive unit creator, called by regular creator and also used to
   make the dummy units that sit at the heads of the per-side unit lists. */

Unit *
create_bare_unit(type)
int type;
{
    Unit *newunit;

    /* If our free list is empty, go and get some more units. */
    if (freeunits == NULL) {
	allocate_unit_block();
    }
    /* Take the first unit off the free list. */
    newunit = freeunits;
    freeunits = freeunits->next;
    /* Give it a valid type... */
    newunit->type = type;
    /* ...but an invalid id. */
    newunit->id = -1;
    return newunit;
}

/* The regular unit creation routine.  All the slots should have something
   reasonable in them, since individual units objects see a lot of reuse. */

Unit *
create_unit(type, makebrains)
int type, makebrains;
{
    int m;
    Unit *newunit;

    if (numlivebytype == NULL) {
    	numlivebytype = (int *) xmalloc(MAXUTYPES * sizeof(int));
    }
    /* Fill this in. */
    if (completenesses[0] == 0) {
	int i;
	for_all_unit_types(i)
	  completenesses[i] = u_cp(i) / u_parts(i);
    }
    /* Test whether we've hit any designer-specified limits. */
    if ((u_type_in_game_max(type) >= 0
	 && numlivebytype[type] >= u_type_in_game_max(type))
	|| (g_units_in_game_max() >= 0
	    && numliveunits >= g_units_in_game_max())) {
	return NULL;
    }
    /* Allocate the unit object.  Xconq will fail instead of returning null. */
    newunit = create_bare_unit(type);
    /* Init all the slots to distinguishable values.  The unit is not
       necessarily newly allocated, so we have to hit all of its slots. */
    newunit->id = nextid++;
    newunit->name = NULL;
    /* Number == 0 means unit is unnumbered. */
    newunit->number = 0;
    /* Outside the world. */
    newunit->x = newunit->y = -1;
    /* At ground level. */
    newunit->z = 0;
    /* Units default to being independent. */
    newunit->side = NULL;
    newunit->origside = NULL;
    /* Create at max hp, let others reduce if necessary. */
    newunit->hp = newunit->hp2 = u_hp(type);
    /* Create fully functional, let other routines set incompleteness. */
    newunit->cp = u_cp(type);
    /* Not in a transport. */
    newunit->transport = NULL;
    /* Note that the space never needs to be freed. */
    if (newunit->supply == NULL && nummtypes > 0) {
        newunit->supply = (short *) xmalloc(nummtypes * sizeof(short));
    }
    /* Always zero out all the supply values. */
    for_all_material_types(m)
      newunit->supply[m] = 0;
    /* Will allocate tooling state when actually needed. */
    newunit->tooling = NULL;
    /* Will allocate opinions when actually needed. */
    newunit->opinions = NULL;
    if (makebrains) {
	init_unit_actorstate(newunit, TRUE);
	init_unit_plan(newunit);
    } else {
	newunit->act = NULL;
	newunit->plan = NULL;
    }
    if (newunit->extras != NULL)
      init_unit_extras(newunit);
    newunit->occupant = NULL;
    newunit->nexthere = NULL;
    /* Glue this unit into the list of independent units. */
    newunit->next = newunit;
    newunit->prev = newunit;
    insert_unit(indepside->unithead, newunit);
    newunit->unext = unitlist;
    unitlist = newunit;
    /* Init more random slots. */
    newunit->prevx = newunit->prevy = -1;
    newunit->transport_id = lispnil;
    newunit->aihook = NULL;
    /* Add to the global unit counts. */
    ++numunits;
    ++numliveunits;
    ++(numlivebytype[type]);
    return newunit;
}

void
init_unit_tooling(unit)
Unit *unit;
{
    unit->tooling = (short *) xmalloc(numutypes * sizeof(short));
}

/* Set or resize the array of a unit's opinions about each side in a game. */

void
init_unit_opinions(unit, nsides)
Unit *unit;
int nsides;
{
    int i;
    short *temp;

    temp = NULL;
    if (u_opinion_min(unit->type) != u_opinion_max(unit->type)) {
	if (unit->opinions != NULL && nsides > numsides) {
	    temp = unit->opinions;
	    unit->opinions = NULL;
	}
	if (unit->opinions == NULL)
	  unit->opinions = (short *) xmalloc(nsides * sizeof(short));
	/* Opinions are now all neutral. */
	if (temp != NULL) {
	    /* Copy over old opinions. */
	    for (i = 0; i < numsides; ++i)
	      unit->opinions[i] = temp[i];
	    free(temp);
	}
    } else {
	if (unit->opinions != NULL)
	  free(unit->opinions);
	unit->opinions = NULL;
    }
}

/* Alter the actorstate object to be correct for this unit. */

void
init_unit_actorstate(unit, flagacp)
Unit *unit;
int flagacp;
{
    if (u_acp(unit->type) > 0 && unit->cp > 0) {
	/* Might already have an actorstate, don't realloc if so;
	   but do clear an existing actorstate, since might be reusing. */
	if (unit->act == NULL)
	  unit->act = (ActorState *) xmalloc(sizeof(ActorState));
	else
	  memset((char *) unit->act, 0, sizeof(ActorState));
	/* Indicate that the action points have not been set. */
	if (flagacp)
	  unit->act->acp = u_acp_min(unit->type) - 1;
	/* Flag the action as undefined. */
	unit->act->nextaction.type = ACTION_NONE;
    } else {
	if (unit->act != NULL)
	  free(unit->act);
	unit->act = NULL;
    }
}

void
init_unit_extras(unit)
Unit *unit;
{
    if (unit->extras == NULL) {
	unit->extras = (UnitExtras *) xmalloc(sizeof(UnitExtras));
    }
    /* Each slot must get the same value as the accessor would return
       if the structure had not been allocated. */ 
    unit->extras->point_value = -1;
    unit->extras->appear = -1;
    unit->extras->appear_var_x = -1;
    unit->extras->appear_var_y = -1;
    unit->extras->disappear = -1;
    unit->extras->priority = -1;
    unit->extras->sym = lispnil;
    unit->extras->hook = lispnil;
}

/* Changing a unit's type has many effects. */

void
change_unit_type(unit, newtype, reason)
Unit *unit;
int newtype, reason;
{
    int oldtype = unit->type, oldhp = unit->hp;
    PastUnit *pastunit;
    Side *oldside;

    /* Don't do anything if we're "changing" to the same type. */
    if (oldtype == newtype)
      return;
    oldside = unit->side;
    pastunit = change_unit_to_past_unit(unit);
    if (reason >= 0)
      record_event(reason, ALLSIDES, pastunit->id, unit->id);
    /* Decrement viewing coverage of our old type. */
    cover_area(unit->side, unit, unit->transport, unit->x, unit->y, -1, -1);
    all_see_leave(unit, unit->x, unit->y, (unit->transport == NULL));
    /* Do the actual change. */
    unit->type = newtype;
    /* Set the new hp to the same ratio of max as the unit had before.
       Caller can tweak to something else if necessary. */
    unit->hp = (oldhp * u_hp_max(newtype)) / u_hp_max(oldtype);
    /* Need to guarantee a positive value though. */
    if (unit->hp < 1)
      unit->hp = 1;
    unit->hp2 = unit->hp;
    /* Invalidate the side's point value cache. */
    if (unit->side)
      unit->side->point_value_valid = FALSE;
    /* We might have to change sides as a result. */
    /* (should modify per-side counts) */
    if (!type_allowed_on_side(newtype, unit->side)) {
    	if (type_allowed_on_side(newtype, NULL)) {
	    /* Unit becomes independent. */
	    change_unit_side(unit, NULL, reason, NULL);
	} else {
	    run_warning("Leaving unit on disallowed side");
	}
    }
    /* Unit will always need a new number. */
    assign_unit_number(unit);
    init_unit_opinions(unit, numsides);
    /* This clears the unit's acp - desirable? */
    init_unit_actorstate(unit, FALSE);
    init_unit_plan(unit);
    unit->aihook = NULL;
    /* Increment viewing coverage. */
    cover_area(unit->side, unit, unit->transport, -1, -1, unit->x, unit->y);
    /* If vision range is 0, allow glimpses of adjacent cell terrain.
       This applies to terrain only, adjacent units cannot be seen. */
    if (u_vision_range(unit->type) == 0)
      glimpse_adjacent_terrain(unit);
    all_see_occupy(unit, unit->x, unit->y, (unit->transport == NULL));
    count_loss(oldside, oldtype, (reason == H_UNIT_WRECKED ? combat_loss : other_loss));
    count_gain(unit->side, newtype, other_gain);
    /* Update global counts. */
    --(numlivebytype[oldtype]);
    ++(numlivebytype[newtype]);
}

int
max_builds(u)
int u;
{
    int u2;

    for_all_unit_types(u2) {
	if (could_create(u, u2))
	  return 1;
    }
    return 0;
}

int
side_owns_occupant(side, unit)
Side *side;
Unit *unit;
{
    int suboccs = FALSE;
    Unit *occ;

    if (unit->occupant == NULL)
      return FALSE;
    for_all_occupants(unit, occ) {
	if (occ->side == side)
	  return TRUE;
	if (occ->occupant)
	  suboccs = TRUE;
    }
    if (suboccs) {
	for_all_occupants(unit, occ) {
	    if (side_owns_occupant(side, occ))
	      return TRUE;
	}
    }
    return FALSE;
}

/* A unit occupies a cell by adding itself to the list of occupants.
   It will not occupy a transport even if one is at this position
   (other code should have taken care of this case already) If
   something goes wrong, return false.  This routine is heavily
   used. */

int
enter_cell(unit, x, y)
Unit *unit;
int x, y;
{
#ifdef DEBUGGING
    /* Not necessarily an error, but indicative of bugs elsewhere. */
    if (unit->x >= 0 || unit->y >= 0) {
	run_warning("unit %d occupying cell (%d, %d), was at (%d %d)",
		    unit->id, x, y, unit->x, unit->y);
    }
#endif /* DEBUGGING */
    /* Always check this one, but not necessarily fatal. */
    if (!inside_area(x, y)) {
	run_warning("No cell at %d,%d, %s can't enter it",
		    x, y, unit_desig(unit));
	/* Let the unit remain off-world. */
	return FALSE;
    }
    if (!can_occupy_cell(unit, x, y)
	&& !can_occupy_conn(unit, x, y, unit->z)) {
	run_warning("Cell at %d,%d is too full for %s",
		    x, y, unit_desig(unit));
	/* Let the unit remain off-world. */
	return FALSE;
    }
    add_unit_to_stack(unit, x, y);
    /* Set the location slots now. */
    enter_cell_aux(unit, x, y);
    /* Inevitable side-effect of appearing in the new location. */
    all_see_occupy(unit, x, y, TRUE);
    return TRUE;
}

/* Return true if the given unit can fit onto the given cell. */

/* (should eventually account for variable-size units) */

int
can_occupy_cell(unit, x, y)
Unit *unit;
int x, y;
{
    int u = unit->type, u2, u3, t = terrain_at(x, y), numthistype = 0;
    int fullness = 0, tcap, utcap, numtypes[MAXUTYPES];
    Unit *unit2;

    if (unit == NULL)
      run_error("null unit?");  /* should never happen */
    tcap = t_capacity(t);
    utcap = ut_capacity_x(u, t);
    if (tcap <= 0 && utcap <= 0)
      return FALSE;
    for_all_unit_types(u3)
      numtypes[u3] = 0;
    for_all_stack(x, y, unit2) {
	u2 = unit2->type;
	++numtypes[u2];
	if (u2 == u)
	  ++numthistype;
	/* Only count against fullness if exclusive capacity exceeded. */
	if (numtypes[u2] > ut_capacity_x(u2, t)) {
	    fullness += ut_size(u2, t);
	}
    }
    /* Unit can be in this cell if there is dedicated space. */
    if (numthistype + 1 <= utcap)
      return TRUE;
    /* Otherwise decide on the basis of fullness. */
    return (fullness + ut_size(u, t) <= tcap);
}

int
type_can_occupy_cell(u, x, y)
int u, x, y;
{
    int t = terrain_at(x, y), u2, u3, numthistype = 0, fullness = 0;
    int tcap, utcap, numtypes[MAXUTYPES];
    Unit *unit2;

    tcap = t_capacity(t);
    utcap = ut_capacity_x(u, t);
    if (tcap <= 0 && utcap <= 0)
      return FALSE;
    for_all_unit_types(u3)
      numtypes[u3] = 0;
    for_all_stack(x, y, unit2) {
	u2 = unit2->type;
	++numtypes[u2];
	if (u2 == u)
	  ++numthistype;
	/* Only count against fullness if exclusive capacity exceeded. */
	if (numtypes[u2] > ut_capacity_x(u2, t)) {
	    fullness += ut_size(u2, t);
	}
    }
    /* Unit can be in this cell if there is dedicated space. */
    if (numthistype + 1 <= utcap)
      return TRUE;
    /* Otherwise decide on the basis of fullness. */
    return (fullness + ut_size(u, t) <= tcap);
}

/* Similar, but don't count a specific given unit when calculating. */

int
can_occupy_cell_without(unit, x, y, unit3)
Unit *unit, *unit3;
int x, y;
{
    int u = unit->type, u2, u3, t = terrain_at(x, y), numthistype = 0;
    int fullness = 0, tcap, utcap, numtypes[MAXUTYPES];
    Unit *unit2;

    if (unit == NULL)
      run_error("null unit?");  /* should never happen */
    tcap = t_capacity(t);
    utcap = ut_capacity_x(u, t);
    if (tcap <= 0 && utcap <= 0)
      return FALSE;
    for_all_unit_types(u3)
      numtypes[u3] = 0;
    for_all_stack(x, y, unit2) {
	if (unit2 == unit3)
	  continue;
	u2 = unit2->type;
	++numtypes[u2];
	if (u2 == u)
	  ++numthistype;
	/* Only count against fullness if exclusive capacity exceeded. */
	if (numtypes[u2] > ut_capacity_x(u2, t)) {
	    fullness += ut_size(u2, t);
	}
    }
    /* Unit can be in this cell if there is dedicated space. */
    if (numthistype + 1 <= utcap)
      return TRUE;
    /* Otherwise decide on the basis of fullness. */
    return (fullness + ut_size(u, t) <= tcap);
}

int
type_can_occupy_cell_without(u, x, y, unit3)
int u, x, y;
Unit *unit3;
{
    int t = terrain_at(x, y), u2, u3, numthistype = 0, fullness = 0;
    int tcap, utcap, numtypes[MAXUTYPES];
    Unit *unit2;

    tcap = t_capacity(t);
    utcap = ut_capacity_x(u, t);
    if (tcap <= 0 && utcap <= 0)
      return FALSE;
    for_all_unit_types(u3)
      numtypes[u3] = 0;
    for_all_stack(x, y, unit2) {
	if (unit2 == unit3)
	  continue;
	u2 = unit2->type;
	++numtypes[u2];
	if (u2 == u)
	  ++numthistype;
	/* Only count against fullness if exclusive capacity exceeded. */
	if (numtypes[u2] > ut_capacity_x(u2, t)) {
	    fullness += ut_size(u2, t);
	}
    }
    /* Unit can be in this cell if there is dedicated space. */
    if (numthistype + 1 <= utcap)
      return TRUE;
    /* Otherwise decide on the basis of fullness. */
    return (fullness + ut_size(u, t) <= tcap);
}

/* Test whether the given position has a connection that the unit may use. */

int can_occupy_conn_1 PARAMS ((Unit *unit, int nx, int ny, int c));

int
can_occupy_conn(unit, nx, ny, nz)
Unit *unit;
int nx, ny, nz;
{
    int c;

    if (numconntypes == 0)
      return FALSE;
    if ((nz & 1) == 1) {
	c = nz / 2;
	if (!t_is_connection(c) || !aux_terrain_defined(c))
	  run_warning("%s is on an invalid connection type %d?",
		      unit_desig(unit), c);
	return can_occupy_conn_1(unit, nx, ny, c);
    } else {
	/* Test each connection type to see if it will work. */
	for_all_terrain_types(c) {
	    if (t_is_connection(c)
		&& aux_terrain_defined(c)
		&& can_occupy_conn_1(unit, nx, ny, c))
	      return TRUE;
	}
	return FALSE;
    }
}

int
can_occupy_conn_1(unit, nx, ny, c)
Unit *unit;
int nx, ny, c;
{
    int u, u2, tcap, utcap, fullness, numthistype, numtypes[MAXUTYPES];
    Unit *unit2;

    if (!any_connections_at(nx, ny, c))
      return FALSE;
    u = unit->type;
    tcap = t_capacity(c);
    utcap = ut_capacity_x(u, c);
    if (tcap <= 0 && utcap <= 0)
      return FALSE;
    for_all_unit_types(u2)
      numtypes[u2] = 0;
    fullness = 0;
    numthistype = 0;
    for_all_stack(nx, ny, unit2) {
	u2 = unit2->type;
	if (ut_capacity_neg(u2, c))
	  return FALSE;
	/* (should also count units assumed to be on connection) */
	if ((unit2->z & 1) == 1 && (unit2->z >> 1) == c) {
	    ++numtypes[u2];
	    if (u2 == u)
	      ++numthistype;
	    /* Only count against fullness if exclusive capacity exceeded. */
	   if (numtypes[u2] > ut_capacity_x(u2, c))
	     fullness += ut_size(u2, c);
	}
    }
    if (numthistype + 1 <= utcap)
      return TRUE;
    return (fullness + ut_size(u, c) <= tcap);
}

/* Recursive helper to update everybody's position.  This should be one of
   two routines that modify actual unit positions (leaving is the other). */

void
enter_cell_aux(unit, x, y)
Unit *unit;
int x, y;
{
    int u = unit->type;
    Unit *occ;

#ifdef DEBUGGING
    /* Not necessarily an error, but indicative of bugs elsewhere. */
    if (unit->x >= 0 || unit->y >= 0) {
	run_warning("unit %d occupying cell (%d, %d), was at (%d %d)",
		    unit->id, x, y, unit->x, unit->y);
    }
#endif /* DEBUGGING */
    if (!in_area(x, y))
      run_error("trying to enter cell outside world");
    /* Actually set the unit position. */
    set_unit_position(unit, x, y, unit->z);
    /* Increment viewing coverage. */
    cover_area(unit->side, unit, unit->transport, -1, -1, x, y);
    /* If vision range is 0, allow glimpses of adjacent cell terrain.
       This applies to terrain only, adjacent units cannot be seen. */
    if (u_vision_range(u) == 0)
      glimpse_adjacent_terrain(unit);
    /* Do for all the occupants too, recursively. */
    for_all_occupants(unit, occ) {
	enter_cell_aux(occ, x, y);
    }
}

/* Decide whether the given unit can actually be in the given transport. */

/* (this still needs to account for multipart units) */

int
can_occupy(unit, transport)
Unit *transport, *unit;
{
    return can_carry(transport, unit);
}

int
can_carry(transport, unit)
Unit *transport, *unit;
{
    int u = unit->type, u2 = transport->type, u3, o;
    int numthistype = 0, numalltypes = 0, occvolume = 0;
    int ucap, uucap;
    int numtypes[MAXUTYPES];
    Unit *occ;

    /* Intercept nonsensical arguments. */
    if (transport == unit)
      return FALSE;
    /* Don't allow occupation of incomplete transports unless the unit is
       of a type that can help complete. */
    if (!completed(transport) && uu_acp_to_build(u, u2) < 1)
      return FALSE;
    if (unit->occupant != NULL && !uu_occ_can_have_occs(u, u2))
      return FALSE;
    ucap = u_capacity(u2);
    uucap = uu_capacity_x(u2, u);
    if (ucap <= 0 && uucap <= 0)
      return FALSE;
    for_all_unit_types(u3)
      numtypes[u3] = 0;
    /* Compute the transport's fullness. */
    for_all_occupants(transport, occ) {
    	o = occ->type;
	++numalltypes;
	++numtypes[occ->type];
	if (o == u)
	  ++numthistype;
	/* Only count against fullness if exclusive capacity exceeded. */
	if (numtypes[o] > uu_capacity_x(u2, o)) {
	    occvolume += uu_size(o, u2);
	}
    }
    /* Can carry if dedicated space available. */
    if (numthistype + 1 <= uucap)
      return TRUE;
    /* Check upper limit on count of occupants of this type. */
    if (uu_occ_max(u2, u) >= 0
        && numthistype + 1 - uucap > uu_occ_max(u2, u))
      return FALSE;
    /* Check upper limit on count of occupants of all types. */
    if (u_occ_total_max(u2) >= 0
        && numalltypes + 1 > u_occ_total_max(u2))
      return FALSE;
    /* Can carry if general unit hold has room. */
    return (occvolume + uu_size(u, u2) <= ucap);
}

/* (should share with prev routine somehow) */

int
type_can_occupy(u, transport)
int u;
Unit *transport;
{
    int u2 = transport->type, u3, o;
    int numthistype = 0, numalltypes = 0, occvolume = 0;
    int ucap, uucap;
    int numtypes[MAXUTYPES];
    Unit *occ;

    /* Don't allow occupation of incomplete transports unless the unit is
       of a type that can help complete. */
    if (!completed(transport) && uu_acp_to_build(u, u2) < 1)
      return FALSE;
    ucap = u_capacity(u2);
    uucap = uu_capacity_x(u2, u);
    if (ucap <= 0 && uucap <= 0)
      return FALSE;
    for_all_unit_types(u3)
      numtypes[u3] = 0;
    /* Compute the transport's fullness. */
    for_all_occupants(transport, occ) {
    	o = occ->type;
	++numalltypes;
	++numtypes[o];
	if (o == u)
	  ++numthistype;
	/* Only count against fullness if exclusive capacity exceeded. */
	if (numtypes[o] > uu_capacity_x(u2, o)) {
	    occvolume += uu_size(o, u2);
	}
    }
    /* Can carry if dedicated space available. */
    if (numthistype + 1 <= uucap)
      return TRUE;
    /* Check upper limit on count of occupants of this type. */
    if (uu_occ_max(u2, u) >= 0
        && numthistype + 1 - uucap > uu_occ_max(u2, u))
      return FALSE;
    /* Check upper limit on count of occupants of all types. */
    if (u_occ_total_max(u2) >= 0
        && numalltypes + 1 > u_occ_total_max(u2))
      return FALSE;
    /* Can carry if general unit hold has room. */
    return (occvolume + uu_size(u, u2) <= ucap);
}

int
can_occupy_type(unit, u2)
Unit *unit;
int u2;
{
    int u = unit->type;

    /* Can occupy if nonzero reserved capacity for this type. */
    if (uu_capacity_x(u2, u) > 0)
      return TRUE;
    /* Can occupy if general unit hold has room for at least one unit. */
    return (uu_size(u, u2) <= u_capacity(u2));
}

int
can_carry_type(transport, u)
Unit *transport;
int u;
{
    return type_can_occupy(u, transport);
}

/* Units become occupants by linking into the transport's occupant list. */

void
enter_transport(unit, transport)
Unit *unit, *transport;
{
    int u = unit->type, ustack, u2stack;
    Unit *unit2, *topunit, *prevunit = NULL, *nextunit = NULL;

    if (unit == transport) {
    	run_error("Unit is trying to enter itself");
    }
    topunit = transport->occupant;
    if (topunit) {
    	/* Insert the entering unit into the occupant list at
	   its correct position. */
    	ustack = u_stack_order(u);
    	for_all_occupants(transport, unit2) {
	    u2stack = u_stack_order(unit2->type);
	    if (ustack > u2stack
		|| (ustack == u2stack && unit->id < unit2->id)) {
		nextunit = unit2;
		if (unit2 == topunit)
		  topunit = unit;
		break;
	    }
	    prevunit = unit2;
    	}
    	if (prevunit != NULL)
    	  prevunit->nexthere = unit;
    } else {
    	topunit = unit;
    }
    unit->nexthere = nextunit;
    transport->occupant = topunit;
    /* Point from the unit back to its transport. */
    unit->transport = transport;
    /* If the transport is not yet on the map (such as when patching
       object refs during readin), skip anything that needs the transport's
       location.  It will be handled when the transport is placed. */
    if (inside_area(transport->x, transport->y)) {
	/* Set the passenger's coords to match the transport's. */
	enter_cell_aux(unit, transport->x, transport->y);
	/* Others might be watching. */
	all_see_occupy(unit, transport->x, transport->y, FALSE);
    }
}

/* Unit departs from a cell by zeroing out pointer if in cell or by being
   removed from the list of transport occupants. */

/* Dead units (hp = 0) may be run through here, so don't error out. */

void
leave_cell(unit)
Unit *unit;
{
    int ux = unit->x, uy = unit->y;
    Unit *transport = unit->transport;

    if (ux < 0 || uy < 0) {
	/* Sometimes called twice */
    } else if (transport != NULL) {
	leave_transport(unit);
	leave_cell_aux(unit, transport);
	all_see_leave(unit, ux, uy, FALSE);
	/* not all_see_cell here because can't see inside transports */
	update_unit_display(transport->side, transport, TRUE);
    } else {
	remove_unit_from_stack(unit);
	/* Now bash the coords. */
	leave_cell_aux(unit, NULL);
	/* Now let everybody observe that the unit is gone. */
	all_see_leave(unit, ux, uy, TRUE);
    }
}

/* When leaving, remove view coverage, record old position, and then
   trash the old coordinates just in case.  Catches many bugs.  Do
   this for all the occupants as well. */

static void
leave_cell_aux(unit, oldtransport)
Unit *unit, *oldtransport;
{
    Unit *occ;

    if (unit->x < 0 && unit->y < 0)
      run_warning("unit %s has already left the cell", unit_desig(unit));
    /* Stash the old coords. */
    unit->prevx = unit->x;  unit->prevy = unit->y;
    /* Set to a recognizable value. */
    unit->x = -1;  unit->y = -1;
    /* Make any occupants leave too. */
    for_all_occupants(unit, occ) {
	leave_cell_aux(occ, unit);
    }
    /* Decrement viewing coverage around our old location. */
    cover_area(unit->side, unit, oldtransport, unit->prevx, unit->prevy, -1, -1);
}

/* Disembarking unlinks from the list of passengers only, leaves the unit
   hanging in limbo, so should have it occupy something immediately. */

void
leave_transport(unit)
Unit *unit;
{
    Unit *transport = unit->transport, *occ;

    if (unit == transport) {
    	run_error("Unit is trying to leave itself");
    }
    if (unit == transport->occupant) {
	transport->occupant = unit->nexthere;
    } else {
	for_all_occupants(transport, occ) {
	    if (unit == occ->nexthere) {
		occ->nexthere = occ->nexthere->nexthere;
		break;
	    }
	}
    }
    /* Bash the now-spurious link. */
    unit->transport = NULL;
}

int
change_cell(unit, x, y)
Unit *unit;
int x, y;
{
    int ux = unit->x, uy = unit->y;
    Unit *transport = unit->transport;

    /* Always check this one, but not necessarily fatal. */
    if (!inside_area(x, y)) {
	run_warning("No cell at %d,%d, %s can't enter it",
		    x, y, unit_desig(unit));
	/* Let the unit remain off-world. */
	return FALSE;
    }
    if (!can_occupy_cell(unit, x, y)) {
	run_warning("Cell at %d,%d is too full for %s",
		    x, y, unit_desig(unit));
	/* Let the unit remain off-world. */
	return FALSE;
    }
    if (transport != NULL) {
	leave_transport(unit);
	update_unit_display(transport->side, transport, TRUE);
    } else {
	remove_unit_from_stack(unit);
    }
    add_unit_to_stack(unit, x, y);
    change_cell_aux(unit, ux, uy, x, y);
    all_see_leave(unit, ux, uy, (transport == NULL));
    /* Inevitable side-effect of appearing in the new location. */
    all_see_occupy(unit, x, y, TRUE);
    return TRUE;
}

void
set_unit_position(unit, x, y, z)
Unit *unit;
int x, y;
{
    int u, t, tmpz;

    /* Actually set the unit position. */
    unit->x = x;  unit->y = y;  unit->z = z;
    /* Constrain the altitude according to terrain if nonzero. */
    if (unit->z != 0) {
	if (unit->z & 1 == 0) {
	    u = unit->type;
	    t = terrain_at(x, y);
	    tmpz = unit->z / 2;
	    tmpz = min(tmpz, ut_alt_max(u, t));
	    tmpz = max(tmpz, ut_alt_min(u, t));
	    unit->z = tmpz * 2;
	} else {
	    /* (should adjust connection type?) */
	}
    }
}

static void
change_cell_aux(unit, x0, y0, x, y)
Unit *unit;
int x0, y0, x, y;
{
    int u = unit->type;
    Unit *occ;

    /* Stash the old coords. */
    unit->prevx = x0;  unit->prevy = y0;
    set_unit_position(unit, x, y, unit->z);
    /* Change viewing coverage. */
    cover_area(unit->side, unit, unit->transport, x0, y0, x, y);
    /* If vision range is 0, allow glimpses of adjacent cell terrain.
       This applies to terrain only, adjacent units cannot be seen. */
    if (u_vision_range(u) == 0)
      glimpse_adjacent_terrain(unit);
    /* Do for all the occupants too, recursively. */
    for_all_occupants(unit, occ) {
	change_cell_aux(occ, x0, y0, x, y);
    }
}

/* Put the given unit into the cell and/or unit stack at the
   given location.  Do not modify the unit's actual xyz position,
   just the unit layer and links to other units. */

void
add_unit_to_stack(unit, x, y)
Unit *unit;
int x, y;
{
    int u = unit->type, ustack, u2stack;
    Unit *topunit, *unit2, *prevunit = NULL, *nextunit = NULL;

    topunit = unit_at(x, y);
    if (topunit) {
    	/* Insert the entering unit into the stack at its correct position. */
    	ustack = u_stack_order(u);
    	for_all_stack(x, y, unit2) {
	    u2stack = u_stack_order(unit2->type);
	    if (ustack > u2stack
		|| (ustack == u2stack && unit->id < unit2->id)) {
		nextunit = unit2;
		if (unit2 == topunit)
		  topunit = unit;
		break;
	    }
	    prevunit = unit2;
    	}
    	if (prevunit != NULL)
	  prevunit->nexthere = unit;
    } else {
    	topunit = unit;
    }
    unit->nexthere = nextunit;
    set_unit_at(x, y, topunit);
}

/* Remove the given unit from the stack at its current
   location. */

void
remove_unit_from_stack(unit)
Unit *unit;
{
    int ux = unit->x, uy = unit->y;
    Unit *other;

    /* Unsplice ourselves from the list of units in this cell. */
    if (unit == unit_at(ux, uy)) {
	set_unit_at(ux, uy, unit->nexthere);
    } else {
	for_all_stack(ux, uy, other) {
	    if (unit == other->nexthere) {
		other->nexthere = other->nexthere->nexthere;
		break;
	    }
	} 
    }
    /* Bash this now-spurious link. */
    unit->nexthere = NULL;
}

void
glimpse_adjacent_terrain(unit)
Unit *unit;
{
    int x = unit->x, y = unit->y, dir, x1, y1;
    Side *side = unit->side;

    if (u_vision_range(unit->type) == 0
	&& unit->transport == NULL
	&& !all_see_all
	&& !g_terrain_seen()
	&& side != NULL) {
	for_all_directions(dir) {
		if (point_in_dir(x, y, dir, &x1, &y1)) {
		    if (terrain_view(side, x1, y1) == UNSEEN) {
			set_terrain_view(side, x1, y1,
					 buildtview(terrain_at(x1, y1)));
			update_cell_display(side, x1, y1, TRUE);
		    }
		}
	}
    }
}

/* Given an overfull unit, spew out occupants until back within limits. */

void
eject_excess_occupants(unit)
Unit *unit;
{
    int u, u2 = unit->type, overfull = TRUE, count;
    int numalltypes = 0, occvolume = 0;
    int numeachtype[MAXUTYPES], sharedeachtype[MAXUTYPES];
    Unit *occ;

    for_all_unit_types(u)
      numeachtype[u] = sharedeachtype[u] = 0;
    /* Eject occupants overflowing counts in shared space. */
    for_all_occupants(unit, occ)
      ++numeachtype[occ->type];
    for_all_unit_types(u) {
    	if (numeachtype[u] > uu_capacity_x(u2, u)) {
	    sharedeachtype[u] = numeachtype[u] - uu_capacity_x(u2, u);
	    if (uu_occ_max(u2, u) >= 0
	    	&& sharedeachtype[u] > uu_occ_max(u2, u)) {
	    		count = sharedeachtype[u] - uu_occ_max(u2, u);
	    		while (count > 0) {
			    	for_all_occupants(unit, occ) {
		    			if (occ->type == u) {
		    				eject_occupant(unit, occ);
		    				--count;
		    				break;
		    			}
		    		}
		    	}
	    }
	}
    }
    /* Eject occupants over the total max count allowed. */
    for_all_occupants(unit, occ)
      ++numalltypes;
    if (u_occ_total_max(u2) >= 0 && numalltypes > u_occ_total_max(u2)) {
    	count = numalltypes - u_occ_total_max(u2);
    	while (unit->occupant != NULL) {
	    eject_occupant(unit, unit->occupant);
	    if (--count <= 0)
	      break;
    	}
    }
    /* Eject occupants overflowing volume of shared space. */
    while (overfull) {
	for_all_unit_types(u)
	  numeachtype[u] = 0;
	occvolume = 0;
	for_all_occupants(unit, occ)
	  ++numeachtype[occ->type];
	for_all_unit_types(u) {
	    occvolume +=
	      max(0, numeachtype[u] - uu_capacity_x(u2, u)) * uu_size(u, u2);
	}
	if (occvolume > u_capacity(u2)) {
	    overfull = TRUE;
	    eject_occupant(unit, unit->occupant);
	} else {
	    overfull = FALSE;
	}
    }
}

/* Given that an occupant must leave its transport, decide what happens; either
   move out into the open, into another unit, or vanish. */

/* (should be generic test) */
#define ut_dies_on(u, t) (ut_vanishes_on(u,t) || ut_wrecks_on(u, t))

void
eject_occupant(unit, occ)
Unit *unit, *occ;
{
    if (!in_play(unit) || !in_play(occ))
      return;
    /* If the occupant is mobile and the current cell has room, let it escape
       but be stacked in the transport's cell. */
    if (mobile(occ->type)
        && !ut_dies_on(occ->type, terrain_at(unit->x, unit->y))
        && can_occupy_cell(occ, unit->x, unit->y)) {
        leave_cell(occ);
        enter_cell(occ, unit->x, unit->y);
        return;
    }
    /* (should let occupants escape into other units in cell) */
    /* (should let occupants with acp escape into adj cells) */
    /* Evaporating the occupant is our last option. */
    kill_unit(occ, H_UNIT_KILLED);
}

/* Handle the general situation of a unit changing allegiance from one side
   to another.  This is a common internal routine, so no messages here. */

void
change_unit_side(unit, newside, reason, agent)
Unit *unit, *agent;
Side *newside;
int reason;
{
    int ux = unit->x, uy = unit->y;
    Side *oldside = unit->side;
    Unit *occ;

    if (newside == indepside) {
	run_warning("non-null indepside");
	newside = NULL;
    }
    if (oldside == newside)
      return;
    /* Fail if the unit may not be on the new side. */
    if (!unit_allowed_on_side(unit, newside))
	return;
    if (reason >= 0)
      record_unit_side_change(unit, newside, reason, agent);
    if (oldside != NULL) {
	/* Last view of unit on its old side. */
	update_unit_display(oldside, unit, TRUE);
    }
    /* (Should this be switchable maybe?) */
    for_all_occupants(unit, occ) {
	change_unit_side(occ, newside, reason, agent);
    }
    /* Adjust view coverage.  The sequencing here is to make sure that no
       viewing coverage gets left on or off inadvertantly. */
    if (alive(unit) && inside_area(ux, uy)) {
	/* Uncover the current viewed area. */
	cover_area(unit->side, unit, unit->transport, ux, uy, -1, -1);
	/* Actually set the side slot of the unit here. */
	set_unit_side(unit, newside);
	/* Cover it for the new side now. */
	cover_area(unit->side, unit, unit->transport, -1, -1, ux, uy);
	/* A freebie for the unit's previous side. */
	see_exact(oldside, ux, uy);
    }
    /* Reflect the changeover in any appropriate displays. */
    if (oldside != NULL) {
	/* Now we see the unit as belonging to someone else. */
	update_unit_display(oldside, unit, TRUE);
    }
    if (newside != NULL) {
	update_unit_display(newside, unit, TRUE);
    }
}

/* This is a general test as to whether the given unit can be
   on the given side. */

int
unit_allowed_on_side(unit, side)
Unit *unit;
Side *side;
{
    int u;

    if (unit == NULL)
      return FALSE;
    u = unit->type;
    /* Test general limitations on the type. */
    if (!type_allowed_on_side(u, side))
      return FALSE;
    /* Test specific game limits. */
    if (u_type_per_side_max(u) >= 0) {
	if (side->numunits[u] >= u_type_per_side_max(u))
	  return FALSE;
    }
    if (g_units_per_side_max() >= 0) {
	int u2, sum;

	sum = 0;
	for_all_unit_types(u2) {
	    sum += side->numunits[u2];
	}
	if (sum >= g_units_per_side_max())
	  return FALSE;
    }
    return TRUE;
}

int
test_class_membership(leaf)
Obj *leaf;
{
    char *sclass;

    if (stringp(leaf)) {
	sclass = c_string(leaf);
	if (tmpside_classtest != NULL && tmpside_classtest != indepside) {
	    if (empty_string(tmpside_classtest->sideclass))
	      return FALSE;
	    return (strcmp(sclass, tmpside_classtest->sideclass) == 0);
	} else {
	    return (strcmp(sclass, "independent") == 0);
	}
    } else {
	init_warning("testing side against garbled class expression");
	/* Be permissive if continued. */
	return TRUE;
    }
}

int
type_allowed_on_side(u, side)
int u;
Side *side;
{
    if (side == NULL)
      side = indepside;
    if (side->uavail == NULL) {
	int u2;

	side->uavail = (short *) xmalloc(numutypes * sizeof(short));
	for_all_unit_types(u2) {
	    tmpside_classtest = side;
	    side->uavail[u2] =
	      eval_boolean_expression(u_possible_sides(u2), test_class_membership, TRUE);
	}
    }
    return side->uavail[u];
}

int
num_sides_allowed(u)
int u;
{
    int rslt;
    Side *side;

    rslt = 0;
    for_all_sides_plus_indep(side) {
	if (type_allowed_on_side(u, side)) {
	    ++rslt;
	}
    }
    return rslt;
}

int
unit_trusts_unit(unit1, unit2)
Unit *unit1, *unit2;
{
    if (unit1->side == NULL || unit2->side == NULL)
      return FALSE;
    /* (should eventually be possible for some indeps to trust) */
    return (unit1->side == unit2->side
	    || trusted_side(unit1->side, unit2->side));
}

/* Put the given unit on the given side, without all the fancy effects.
   Important to handle independents, because this gets called during init.
   This is the only way that a unit's side may be altered. */

/* Note that this may be run on dead units, as part of clearing out a
   side's units, in which case we just want to relink, don't care about
   testing whether the type is allowed or not. */

int
set_unit_side(unit, side)
Unit *unit;
Side *side;
{
    int u = unit->type;
    Side *oldside, *newside;

    if (side == indepside)
      side = NULL;
    if (unit->side != side) {
	/* Subtract from the counts for the ex-side. */
	oldside = (unit->side ? unit->side : indepside);
	if (oldside->numunits)
	  --(oldside->numunits[u]);
	if (oldside->numlive && in_play(unit))
	  --(oldside->numlive[u]);
	/* Set the unit's slot. */
	/* Note that indep units have a NULL side, even though there
	   is an actual side object for independents. */
	unit->side = side;
	/* Make sure this unit is off anybody else's list. */
	delete_unit(unit);
	newside = (side ? side : indepside);
	insert_unit(newside->unithead, unit);
	/* Add to counts for the side. */
	if (newside->numunits)
	  ++(newside->numunits[u]);
	if (newside->numlive && in_play(unit))
	  ++(newside->numlive[u]);
	/* Invalidate both sides' point value caches. */
	oldside->point_value_valid = FALSE;
	newside->point_value_valid = FALSE;
	/* Bump the tech level if owning this type helps. */
	if (side != NULL
	    && side->tech[u] < u_tech_from_ownership(u)) {
	    side->tech[u] = u_tech_from_ownership(u);
	    /* (should update any displays of tech - how to ensure?) */
	}
    }
    return TRUE;
}

int
set_unit_origside(unit, side)
Unit *unit;
Side *side;
{
    if (unit->origside != side) {
	/* Set the unit's slot. */
	unit->origside = side;
    }
    return TRUE;
}

void
set_unit_name(side, unit, newname)
Side *side;
Unit *unit;
char *newname;
{
    /* Always turn 0-length names into NULL. */
    if (newname != NULL && strlen(newname) == 0)
      newname = NULL;
    /* Don't do anything if the name didn't actually change. */
    if ((unit->name == NULL && newname == NULL)
        || (unit->name != NULL
	    && newname != NULL
	    && strcmp(unit->name, newname) == 0))
      return;
    /* Record this in the history. */
    record_unit_name_change(unit, newname);
    unit->name = newname;
    update_unit_display(side, unit, TRUE);
    update_unit_display(unit->side, unit, TRUE);
    /* (should also send to any other side directly viewing this unit!) */
}

void
change_morale(unit, sign, morchange)
Unit *unit;
int morchange;
{
    int u = unit->type, oldmorale;

    if (morchange != 0) {
	oldmorale = unit->morale;
	unit->morale += (sign * prob_fraction(morchange));
	if (unit->morale < 0)
	  unit->morale = 0;
	if (unit->morale > u_morale_max(u))
	  unit->morale = u_morale_max(u);
	if (unit->morale != oldmorale) {
	    update_unit_display(unit->side, unit, TRUE);
	    /* (should also send to any other side directly viewing this unit?) */
	}
    }
}

int
disband_unit(side, unit)
Side *side;
Unit *unit;
{
    int rslt;

#ifdef DESIGNERS
    if (side->designer) {
	return designer_disband(unit);
    }
#endif /* DESIGNERS */
    if (side_can_disband(side, unit)) {
	rslt = disband_unit_directly(side, unit);
	if (rslt) {
	    /* Nothing to do */
	} else if (unit->plan) {
	    set_disband_task(unit);
	} else {
	    /* In order for this to work, we would need a way to direct one
	       sort of unit to disband another.  Just fail for now. */
	    return FALSE;
	}
	return TRUE;
    } else {
	return FALSE;
    }
}

int
disband_unit_directly(side, unit)
Side *side;
Unit *unit;
{
    if (side_can_disband(side, unit)) {
	if (!completed(unit)) {
	    /* Nothing complicated about getting rid of an incomplete unit. */
	    kill_unit(unit, H_UNIT_DISBANDED);
	    return TRUE;
	} else {
	    return FALSE;
	}
    } else {
	return FALSE;
    }
}

void
wreck_unit(unit)
Unit *unit;
{
    int u = unit->type, nu;

    /* Change the unit's type at its new location. */
    change_unit_type(unit, u_wrecked_type(u), H_UNIT_WRECKED);
    nu = unit->type;
    /* Restore to default hp for the new type. */
    unit->hp = unit->hp2 = u_hp(nu);
    /* Get rid of occupants if now overfull. */
    eject_excess_occupants(unit);
}

/* Remove a unit from play.  This is different from making it available for
   reallocation - only the unit flusher can do that.  We remove all the
   passengers too, recursively.  Sometimes units are "killed twice", so
   be sure not to run all this twice.  Also count up occupant deaths, being
   sure not to count the unit itself as an occupant. */

void
kill_unit(unit, reason)
Unit *unit;
int reason;
{
    int u = unit->type, selfdied = FALSE;
    int ux = unit->x, uy = unit->y;

    if (alive(unit)) {
	if (unit->side && unit->side->self_unit == unit)
	  selfdied = TRUE;
	leave_cell(unit);
	/* A freebie for the unit's side. */
	see_exact(unit->side, ux, uy);
	kill_unit_aux(unit, reason);
	if (selfdied) {
	    if (u_self_resurrects(u)) {
		/* should find and designate a new self unit */
		return;
	    } else {
		/* Make sure this doesn't have serious consequences? */
		if (unit->side->ingame)
		  side_loses(unit->side, NULL, -2);
		/* (can't do all consequences just yet?) */
	    }
	}
	recent_dead_flushed = FALSE;
    }
}

/* Trash it now - occupant doesn't need to leave_cell.  Also record the
   event, and update the apropriate display.  The unit here should
   be known to be alive. */

void
kill_unit_aux(unit, reason)
Unit *unit;
int reason;
{
    int u = unit->type;
    Unit *occ;
    Side *side = unit->side;
    
    unit->hp = 0;
    /* Get rid of the unit's plan/tasks.  This should be safe, because
       unit death should only happen during action execution and in
       between turns, and plans/tasks should not be in use at those times. */
    dispose_of_plan(unit);
    /* Maybe enter the loss into the historical record. */
    if (reason >= 0)
      record_unit_death(unit, reason);
    remove_unit_from_vector((unit->side ? unit->side : indepside)->actionvector, unit, -1);
    if (side != NULL) {
	/* Invalidate the side's point value cache. */
	side->point_value_valid = FALSE;
	update_unit_display(side, unit, TRUE);
    }
    /* Kill all the occupants in turn. */
    for_all_occupants(unit, occ) {
	if (alive(occ))
	  kill_unit_aux(occ, reason);
    }
    /* Update global counts. */
    --numliveunits;
    --(numlivebytype[u]);
}

/* Get rid of all dead units at once.
   (This routine is basically a garbage collector, and should not be called
   during a unit list traversal.) The process starts by finding the first
   live unit, making it the head, then linking around all in the middle.
   Dead units stay on the dead unit list for each side until that side has had
   a chance to move.  Then they are finally flushed in a permanent fashion. */ 

static void flush_one_unit PARAMS ((Unit *unit));

void
flush_dead_units()
{
    Unit *unit, *prevunit, *nextunit;

    if (unitlist == NULL)
      return;
    unit = unitlist;
    while (!alive(unit)) {
	nextunit = unit->unext;
	delete_unit(unit);
	flush_one_unit(unit);
	unit = nextunit;
	if (unit == NULL)
	  break;
    }
    unitlist = unit;
    /* Since the first unit of unitlist is guaranteed live now,
       we know that prevunit will always be set correctly;
       but mollify insufficiently intelligent compilers. */
    prevunit = NULL;
    for_all_units(unit) {
	if (!alive(unit)) {
	    nextunit = unit->unext;
	    prevunit->unext = unit->unext;
	    delete_unit(unit);
	    flush_one_unit(unit);
	    unit = prevunit;
	} else {
	    prevunit = unit;
	}
    }
}

/* Keep it clean - hit all links to other places.  Some might not be
   strictly necessary, but this is not an area to take chances with. */

static void
flush_one_unit(unit)
Unit *unit;
{
    unit->id = -1;
    unit->occupant = NULL;
    unit->transport = NULL;
    unit->nexthere = NULL;
    unit->prev = NULL;
    unit->unext = NULL;
    /* Add it on the front of the list of available units. */
    unit->next = freeunits;
    freeunits = unit;
}

/* Do a bubble sort.
   Data is generally coherent, so bubble sort not too bad if we allow
   early termination when everything is already in order.  */

/* If slowness objectionable, replace with something clever, but be
   sure that average performance in real games is what's being improved. */

void
sort_units(byidonly)
int byidonly;
{
    int flips;
    int passes = 0;
    register Unit *unit, *nextunit;
    Side *side;

    for_all_sides_plus_indep(side) {
	passes = 0;
	flips = TRUE;
	while (flips) {
	    flips = FALSE;
	    for_all_side_units(side, unit) {
		if (unit->next != side->unithead
		    && (byidonly ? ((unit->id - unit->next->id) > 0)
				 : (compare_units(unit, unit->next) > 0))) {
		    flips = TRUE;
		    /* Reorder the units by fiddling with their links. */
		    nextunit = unit->next;
		    unit->prev->next = nextunit;
		    nextunit->next->prev = unit;
		    nextunit->prev = unit->prev;
		    unit->next = nextunit->next;
		    nextunit->next = unit;
		    unit->prev = nextunit;
		}
		++passes;
	    }
	}
    }
    Dprintf("Sorting passes = %d\n", passes);
}

static int
compare_units(unit1, unit2)
Unit *unit1, *unit2;
{
    if (unit1->type != unit2->type)
      return (unit1->type - unit2->type);
    if (unit1->name && unit2->name == NULL)
      return -1;
    if (unit1->name == NULL && unit2->name)
      return 1;
    if (unit1->name && unit2->name)
      return strcmp(unit1->name, unit2->name);
    if (unit1->number != unit2->number)
      return (unit1->number - unit2->number);
    /* Ids impose a total ordering. */
    return (unit1->id - unit2->id);
}

/* Useful for the machine player to know how long it can move this
   piece before it should go home.  Assumes can't replenish from
   terrain.  Result may be negative, in which case it's time to go! */

int
moves_till_low_supplies(unit)
Unit *unit;
{
    int u = unit->type, m, moves = 1234567, tmp;

    for_all_material_types(m) {
	if ((um_consumption_per_move(u, m) > 0)) {
	    tmp = (unit->supply[m] - um_storage_x(u, m) / 2) / um_consumption_per_move(u, m);
	    moves = min(moves, tmp);
	}
    }
    return moves;
}

/* Short, unreadable, but greppable listing of unit.  Primarily useful
   for debugging and warnings.  We use several buffers and rotate between
   them so we can call this more than once in a single printf. */

char *
unit_desig(unit)
Unit *unit;
{
    int i;
    char *shortbuf;

    /* Allocate if not yet done so. */
    for (i = 0; i < NUMSHORTBUFS; ++i) {
	if (shortbufs[i] == NULL)
	  shortbufs[i] = xmalloc(BUFSIZE);
    }
    /* Note that we test here, so that unit_desig(NULL) can be used
       to allocate any space that this routine might need later. */
    if (unit == NULL)
      return "no unit";
    shortbuf = shortbufs[curshortbuf];
    curshortbuf = (curshortbuf + 1) % NUMSHORTBUFS;
    if (unit->id == -1) {
	sprintf(shortbuf, "s%d head", side_number(unit->side));
	return shortbuf;
    } else if (is_unit_type(unit->type)) {
	sprintf(shortbuf, "s%d %s %d (%d,%d",
		side_number(unit->side), shortest_unique_name(unit->type),
		unit->id, unit->x, unit->y);
	if (unit->z != 0)
	  tprintf(shortbuf, ",%d", unit->z);
	if (unit->transport)
	  tprintf(shortbuf, ",in%d", unit->transport->id);
	strcat(shortbuf, ")");  /* close out the unit location */
	return shortbuf;
    } else {
	return "!garbage unit!";
    }
}

/* Short, unreadable, but greppable listing of unit that omits anything
   that changes from turn to turn. */

char *
unit_desig_no_loc(unit)
Unit *unit;
{
    char *shortbuf;

    if (unit == NULL)
      return "no unit";
    /* Allocate if not yet done so. */
    if (shortbufs[curshortbuf] == NULL)
      shortbufs[curshortbuf] = xmalloc(BUFSIZE);
    shortbuf = shortbufs[curshortbuf];
    curshortbuf = (curshortbuf + 1) % NUMSHORTBUFS;
    if (unit->id == -1) {
	sprintf(shortbuf, "s%d head", side_number(unit->side));
	return shortbuf;
    } else if (is_unit_type(unit->type)) {
	sprintf(shortbuf, "s%d %-3.3s %d",
		side_number(unit->side), shortest_unique_name(unit->type),
		unit->id);
	return shortbuf;
    } else {
	return "!garbage unit!";
    }
}

/* Come up with a unit type name that fits in the given space. */

char *
utype_name_n(u, n)
int u, n;
{
    char *utypename, *shortname, *rawname;

    utypename = u_type_name(u);
    if (n <= 0 || strlen(utypename) <= n) {
	return utypename;
    } else if (n == 1 && !empty_string(u_uchar(u))) {
	/* Use the unit char if possible. */
	return u_uchar(u);
    } else if (!empty_string(u_short_name(u))) {
    	shortname = u_short_name(u);
	if (strlen(shortname) <= n) {
	    return shortname;
	} else {
	    rawname = shortname;
	}
    } else {
    	rawname = utypename;
    }
    /* Copy what will fit. */
    if (utypenamen == NULL)
      utypenamen = xmalloc(BUFSIZE);
    if (n > BUFSIZE - 1)
      n = BUFSIZE - 1;
    strncpy(utypenamen, rawname, n);
    utypenamen[n] = '\0';
    return utypenamen;
}

char *
shortest_unique_name(u)
int u;
{
    char namebuf[BUFSIZE], *name1;
    int u1, u2, i, allhavechars, firstuniq[MAXUTYPES], firstuniq1;
    int shortestdone[MAXUTYPES];

    if (shortestnames == NULL) {
	shortestnames = (char **) xmalloc(numutypes * sizeof(char *));
	/* First use game definition's single chars if possible. */
	allhavechars = TRUE;
	for_all_unit_types(u1) {
	    shortestdone[u1] = FALSE;
	    if (!empty_string(u_uchar(u1))) {
		namebuf[0] = (u_uchar(u1))[0];
		namebuf[1] = '\0';
		shortestnames[u1] = copy_string(namebuf);
		shortestdone[u1] = TRUE;
		firstuniq[u1] = 0;
	    } else {
		allhavechars = FALSE;
	    }
	}
	if (!allhavechars) {
	    /* Start with copies of full name for all types not
               already named. */
	    for_all_unit_types(u1) {
		if (shortestnames[u1] == NULL) {
		    shortestnames[u1] = copy_string(u_type_name(u1));
		    firstuniq[u1] = 0;
		}
	    }
	    for_all_unit_types(u1) {
		if (!shortestdone[u1]) {
		    name1 = shortestnames[u1];
		    firstuniq1 = firstuniq[u1];
		    for_all_unit_types(u2) {
			if (u1 != u2) {
			    /* Look through the supposedly minimal
			       unique substring and see if it is the
			       same. */
			    for (i = 0; i < firstuniq1; ++i ) {
				if (name1[i] != (shortestnames[u2])[i]) {
				    break;
				}
			    }
			    /* If so, must extend the unique substring. */
			    if (i == firstuniq1) {
				/* Look for the first nonmatching char. */
				while (name1[firstuniq1] == (shortestnames[u2])[firstuniq1]) {
				    ++firstuniq1;
				}
			    }
			}
		    }
		    firstuniq[u1] = firstuniq1;
		}
	    }
	    /* For any types where the unique short name is shorter
	       than the seed name, truncate appropriately. */
	    for_all_unit_types(u1) {
		if (firstuniq[u1] + 1 < strlen(shortestnames[u1])) {
		    (shortestnames[u1])[firstuniq[u1] + 1] = '\0';
		}
	    }
	}
	if (Debug) {
	    for_all_unit_types(u1) {
		Dprintf("Shortest type name: %s for %s\n",
			shortestnames[u1], u_type_name(u1));
	    }
	}
    }
    return shortestnames[u];
}

/* Similar to shortest_unique_name, but returns a generic name/char
   instead. */

char *
shortest_generic_name(u)
int u;
{
    char namebuf[BUFSIZE], *name1;
    int u1, u2, i, allhavechars, firstuniq[MAXUTYPES], firstuniq1;
    int shortestdone[MAXUTYPES];

    if (shortestgnames == NULL) {
	shortestgnames = (char **) xmalloc(numutypes * sizeof(char *));
	/* First use game definition's single chars if possible. */
	allhavechars = TRUE;
	for_all_unit_types(u1) {
	    shortestdone[u1] = FALSE;
	    if (!empty_string(u_gchar(u1))) {
		namebuf[0] = (u_gchar(u1))[0];
		namebuf[1] = '\0';
		shortestgnames[u1] = copy_string(namebuf);
		shortestdone[u1] = TRUE;
		firstuniq[u1] = 0;
	    } else if (!empty_string(u_uchar(u1))) {
		namebuf[0] = (u_uchar(u1))[0];
		namebuf[1] = '\0';
		shortestgnames[u1] = copy_string(namebuf);
		shortestdone[u1] = TRUE;
		firstuniq[u1] = 0;
	    } else {
		allhavechars = FALSE;
	    }
	}
	if (!allhavechars) {
	    /* Start with copies of full name for all types not
               already named. */
	    for_all_unit_types(u1) {
		if (shortestgnames[u1] == NULL) {
		    name1 = (!empty_string(u_generic_name(u1)) ? u_generic_name(u1) : u_type_name(u1));
		    shortestgnames[u1] = copy_string(name1);
		    firstuniq[u1] = 0;
		}
	    }
	    for_all_unit_types(u1) {
		if (!shortestdone[u1]) {
		    name1 = shortestgnames[u1];
		    firstuniq1 = firstuniq[u1];
		    for_all_unit_types(u2) {
			if (u1 != u2) {
			    /* Look through the supposedly minimal
			       unique substring and see if it is the
			       same. */
			    for (i = 0; i < firstuniq1; ++i ) {
				if (name1[i] != (shortestgnames[u2])[i]) {
				    break;
				}
			    }
			    /* If so, must extend the unique substring. */
			    if (i == firstuniq1) {
				/* Look for the first nonmatching char. */
				while (name1[firstuniq1] == (shortestgnames[u2])[firstuniq1]) {
				    ++firstuniq1;
				}
			    }
			}
		    }
		    firstuniq[u1] = firstuniq1;
		}
	    }
	    /* For any types where the unique short name is shorter
	       than the seed name, truncate appropriately. */
	    for_all_unit_types(u1) {
		if (firstuniq[u1] + 1 < strlen(shortestgnames[u1])) {
		    (shortestgnames[u1])[firstuniq[u1] + 1] = '\0';
		}
	    }
	}
	if (Debug) {
	    for_all_unit_types(u1) {
		Dprintf("Shortest generic type name: %s for %s\n",
			shortestgnames[u1], u_type_name(u1));
	    }
	}
    }
    return shortestgnames[u];
}

/* This formats an actorstate readably. */

char *
actorstate_desig(as)
ActorState *as;
{
    if (actorstatebuf == NULL)
      actorstatebuf = xmalloc(BUFSIZE);
    if (as != NULL) {
	sprintf(actorstatebuf, "acp %d/%d %s",
		as->acp, as->initacp, action_desig(&(as->nextaction)));
	return actorstatebuf;
    } else {
	return "no act";
    }
}

/* Search for a unit with the given id number. */

/* This is used a lot, it should be sped up. */

Unit *
find_unit(n)
int n;
{
    Unit *unit;

    for_all_units(unit) {
	if (unit->id == n && alive(unit))
	  return unit;
    }
    return NULL;
}

/* Same, but don't by picky about liveness. */

Unit *
find_unit_dead_or_alive(n)
int n;
{
    Unit *unit;

    for_all_units(unit) {
	if (unit->id == n)
	  return unit;
    }
    return NULL;
}

/* Find a unit with the given name, either alive or dead. */

Unit *
find_unit_by_name(nm)
char *nm;
{
    Unit *unit;

    if (nm == NULL)
      return NULL;
    for_all_units(unit) {
	if (unit->name != NULL && strcmp(unit->name, nm) == 0)
	  return unit;
    }
    return NULL;
}

/* Find a unit with the given number, either alive or dead. */

Unit *
find_unit_by_number(nb)
int nb;
{
    Unit *unit;

    for_all_units(unit) {
	if (unit->number == nb)
	  return unit;
    }
    return NULL;
}

/* Find a unit with the given symbol, either alive or dead. */

Unit *
find_unit_by_symbol(sym)
Obj *sym;
{
    Unit *unit;

    if (sym == lispnil)
      return NULL;
    for_all_units(unit) {
	if (equal(unit_symbol(unit), sym))
	  return unit;
    }
    return NULL;
}

/* Given a name, find the type. */

int
find_unit_name(str)
char *str;
{
    int u;

    for_all_unit_types(u)
      if (strcmp(str, u_short_name(u)) == 0
	  || strcmp(str, u_type_name(u)) == 0) 
	return u;
    return NONUTYPE;
}

/* Insert the given unit after the other given unit. */

void
insert_unit(unithead, unit)
Unit *unithead, *unit;
{
    unit->next = unithead->next;
    unit->prev = unithead;
    unithead->next->prev = unit;
    unithead->next = unit;
}

/* Delete the unit from its list. */

void
delete_unit(unit)
Unit *unit;
{
    unit->next->prev = unit->prev;
    unit->prev->next = unit->next;
}

int
num_occupants(unit)
Unit *unit;
{
    int num = 0;
    Unit *occ;

    for_all_occupants(unit, occ) {
	num += 1;
    }
    return num;
}

int
num_units_at(x, y)
int x, y;
{
    int num = 0;
    Unit *unit;

    x = wrapx(x);
    if (!in_area(x, y)) {
	run_warning("num_units_at %d,%d??", x, y);
	return 0;
    }
    for_all_stack(x, y, unit) {
	num += 1;
    }
    return num;
}

/* Call this to doublecheck invariants on units. */

void
check_all_units()
{
    Unit *unit;

    for_all_units(unit) {
	check_unit(unit);
    }
}

void
check_unit(unit)
Unit *unit;
{
    if (alive(unit) && unit->transport && !alive(unit->transport)) {
    	run_warning("%s is inside a dead transport", unit_desig(unit));
    }
    /* etc */
}

UnitVector *
make_unit_vector(initsize)
int initsize;
{
    UnitVector *vec;
	
    vec = (UnitVector *)
      xmalloc(sizeof(UnitVector) + initsize * sizeof(UnitVectorEntry));
    vec->size = initsize;
    vec->numunits = 0;
    return vec;
}

void
clear_unit_vector(vec)
UnitVector *vec;
{
    vec->numunits = 0;
}

UnitVector *
add_unit_to_vector(vec, unit, flag)
UnitVector *vec;
Unit *unit;
int flag;
{
    int i;
    UnitVector *newvec;

    /* Can't add to something that doesn't exist! */
    if (vec == NULL)
      run_error("No actionvector!");
    /* (should search to see if already present) */
    if (vec->numunits >= vec->size) {
	newvec = make_unit_vector((3 * vec->size) / 2);
	newvec->numunits = vec->numunits;
	for (i = 0; i < vec->numunits; ++i) {
	    newvec->units[i] = vec->units[i];
	}
	vec = newvec;
    }
    ((vec->units)[vec->numunits]).unit = unit;
    ((vec->units)[vec->numunits]).flag = flag;
    ++(vec->numunits);
    return vec;
}

void
remove_unit_from_vector(vec, unit, pos)
UnitVector *vec;
Unit *unit;
int pos;
{
    int j;

    /* It's probably a bug that the vector is null sometimes,
       but don't flip out over it. */
    if (vec == NULL)
      return;
    /* Search for unit in vector. */
    if (pos < 0) {
	for (j = 0; j < vec->numunits; ++j) {
	    if (unit == vec->units[j].unit) {
		pos = j;
		break;
	    }
	}
    }
    if (pos < 0)
      return;
    if (unit != vec->units[pos].unit)
      run_error("unit mismatch in remove_unit_from_vector, %s not at %d",
		unit_desig(unit), pos);	
    for (j = pos + 1; j < vec->numunits; ++j)
      vec->units[j-1] = vec->units[j];
    --(vec->numunits);
}

enum sortkeys tmpsortkeys[MAXSORTKEYS];

static int
compare_units_by_keys(e1, e2)
CONST void *e1, *e2;
{
    int i;
    Unit *unit1 = ((UnitVectorEntry *) e1)->unit;
    Unit *unit2 = ((UnitVectorEntry *) e2)->unit;
    
    if (unit1 == unit2)
      return 0;
    if (unit1 == NULL)
      return 1;
    if (unit2 == NULL)
      return -1;
    for (i = 0; i < MAXSORTKEYS; ++i) {
	switch (tmpsortkeys[i]) {
	  case byside:
	    if (unit1->side != unit2->side) {
		int s1 = side_number(unit1->side);
		int s2 = side_number(unit2->side);
		
		/* Put independents at the end of any list. */
		if (s1 == 0)
		  s1 = numsides + 1;
		if (s2 == 0)
		  s2 = numsides + 1;
		return (s1 - s2);
	    }
	    break;
	  case bytype:
	    if (unit1->type != unit2->type) {
		return (unit1->type - unit2->type);
	    }
	    break;
	  case byname:
	    if (unit1->name) {
		if (unit2->name) {
		    return strcmp(unit1->name, unit2->name);
		} else {
		    return -1;
		}
	    } else if (unit1->number > 0) {
		if (unit2->name) {
		    return 1;
		} else if (unit2->number > 0) {
		    return (unit1->number - unit2->number);
		} else {
		    return -1;
		}
	    } else if (unit2->name) {
		return 1;
	    } else if (unit2->number > 0) {
		return 1;
	    }
	    break;
	  case byactorder:
	    /* (should sort by action priority?) */
	    break;
	  case bylocation:
	    if (unit1->y != unit2->y) {
		return (unit2->y - unit1->y);
	    } else if (unit1->x != unit2->x) {
		return (unit1->x - unit2->x);
	    } else {
		/* Both units are at the same location. Sort by transport. */
		if (unit1->transport) {
		    if (unit2->transport) {
		    } else {
			return 1;
		    }
		} else {
		    if (unit2->transport) {
			return -1;
		    } else {
		    }
		}
	    }
	    break;
	  case bynothing:
	    return (unit1->id - unit2->id);
	  default:
	    break;
	}
    }
    /* Unit ids are all unique, so this is a reliable default sort key. */
    return (unit1->id - unit2->id);
}

void
sort_unit_vector(vec)
UnitVector *vec;
{
    qsort(vec->units, vec->numunits, sizeof(UnitVectorEntry),
	  compare_units_by_keys);
}

Obj *
get_x_property(unit, subkey)
Unit *unit;
int subkey;
{
    Obj *lis, *bdg;

    for_all_list(unit_hook(unit), lis) {
	bdg = car(lis);
	if (symbolp(car(bdg)) && keyword_code(c_string(car(bdg))) == subkey)
	  return cdr(bdg);
    }
    return lispnil;
}

Obj *
get_x_property_by_name(unit, str)
Unit *unit;
char *str;
{
    Obj *lis, *bdg;

    for_all_list(unit_hook(unit), lis) {
	bdg = car(lis);
	if (symbolp(car(bdg)) && strcmp(c_string(car(bdg)), str) == 0)
	  return cdr(bdg);
    }
    return lispnil;
}

/* This isn't the best place, but read.c getting too large, no
   overflow file. */
/* Note that the array is not initialized, allows for multiple calls. */

void
interp_utype_list(arr, lis)
short *arr;
Obj *lis;
{
    int u = 0;
    Obj *rest, *head;

    /* Assume that if the destination array does not exist, there is
       probably a reason, and it's not our concern. */
    if (arr == NULL)
      return;
    lis = eval(lis);
    if (!consp(lis))
      lis = cons(lis, lispnil);
    if (numberp(car(lis)) && length(lis) == numutypes) {
	u = 0;
	for_all_list(lis, rest)
	  arr[u++] = c_number(car(rest));
    } else {
	for_all_list(lis, rest) {
	    head = car(rest);
	    if (utypep(head)) {
		arr[c_number(head)] = TRUE;
	    } else {
		/* syntax error */
	    }
	}
    }
}

#ifdef DESIGNERS

/* A designer can call this to create an arbitrary unit during the game. */

Unit *
designer_create_unit(side, u, s, x, y)
Side *side;
int u, s, x, y;
{
    Unit *newunit;
    Side *side2;

    if (!type_can_occupy_cell(u, x, y))
      return NULL;
    newunit = create_unit(u, TRUE);
    if (newunit != NULL) {
	if (s != 0) {
	    side2 = side_n(s);
	    if (unit_allowed_on_side(newunit, side2)) {
	    	set_unit_side(newunit, side2);
	    	set_unit_origside(newunit, side2);
	    	/* (should ensure that any changed counts are set correctly also) */
	    }
	}
	init_supply(newunit);
	if (can_occupy_cell(newunit, x, y)) {
	    enter_cell(newunit, x, y);
	} else {
	    return NULL;
	}
	update_cell_display(side, x, y, TRUE);
	update_unit_display(side, newunit, TRUE);
	return newunit;
    } else {
	return NULL;
    }
}

/* Move a unit to a given location instantly, with all sides observing. */

int
designer_teleport(unit, x, y, other)
Unit *unit, *other;
int x, y;
{
    if (other != NULL && can_occupy(unit, other)) {
	leave_cell(unit);
	enter_transport(unit, other);
	all_see_cell(x, y);
	return TRUE;
    } else if (can_occupy_cell(unit, x, y)) {
	leave_cell(unit);
	enter_cell(unit, x, y);
	all_see_cell(x, y);
	return TRUE;
    } else {
	return FALSE;
    }
}

int
designer_change_side(unit, side)
Unit *unit;
Side *side;
{
    Side *side2;

    change_unit_side(unit, side, -1, NULL);
    for_all_sides(side2) {
	if (1 /* side2 should see change */) {
	    update_unit_display(side2, unit, TRUE);
	}
    }
    return TRUE;
}

int
designer_disband(unit)
Unit *unit;
{
    kill_unit(unit, -1);
    return TRUE;
}

#endif /* DESIGNERS */