/* Emacs style mode select   -*- C++ -*-
 *-----------------------------------------------------------------------------
 *
 *
 *  PrBoom a Doom port merged with LxDoom and LSDLDoom
 *  based on BOOM, a modified and improved DOOM engine
 *  Copyright (C) 1999 by
 *  id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
 *  Copyright (C) 1999-2000 by
 *  Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
 *
 *  This program 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
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 *  02111-1307, USA.
 *
 * DESCRIPTION:
 *  General plane mover and floor mover action routines
 *  Floor motion, pure changer types, raising stairs. donuts, elevators
 *
 *-----------------------------------------------------------------------------*/

#include "doomstat.h"
#include "r_main.h"
#include "p_map.h"
#include "p_spec.h"
#include "p_tick.h"
#include "s_sound.h"
#include "sounds.h"

#include "rockmacros.h"

///////////////////////////////////////////////////////////////////////
//
// Plane (floor or ceiling), Floor motion and Elevator action routines
//
///////////////////////////////////////////////////////////////////////

//
// T_MovePlane()
//
// Move a plane (floor or ceiling) and check for crushing. Called
// every tick by all actions that move floors or ceilings.
//
// Passed the sector to move a plane in, the speed to move it at,
// the dest height it is to achieve, whether it crushes obstacles,
// whether it moves a floor or ceiling, and the direction up or down
// to move.
//
// Returns a result_e:
//  ok - plane moved normally, has not achieved destination yet
//  pastdest - plane moved normally and is now at destination height
//  crushed - plane encountered an obstacle, is holding until removed
//
result_e T_MovePlane
( sector_t*     sector,
  fixed_t       speed,
  fixed_t       dest,
  boolean       crush,
  int           floorOrCeiling,
  int           direction )
{
   boolean       flag;
   fixed_t       lastpos;
   fixed_t       destheight; //jff 02/04/98 used to keep floors/ceilings
   // from moving thru each other

   switch(floorOrCeiling)
   {
   case 0:
      // Moving a floor
      switch(direction)
      {
      case -1:
         // Moving a floor down
         if (sector->floorheight - speed < dest)
         {
            lastpos = sector->floorheight;
            sector->floorheight = dest;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk
            if (flag == true)
            {
               sector->floorheight =lastpos;
               P_CheckSector(sector,crush);      //jff 3/19/98 use faster chk
            }
            return pastdest;
         }
         else
         {
            lastpos = sector->floorheight;
            sector->floorheight -= speed;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk
            /* cph - make more compatible with original Doom, by
             *  reintroducing this code. This means floors can't lower
             *  if objects are stuck in the ceiling */
            if ((flag == true) && comp[comp_floors]) {
               sector->floorheight = lastpos;
               P_ChangeSector(sector,crush);
               return crushed;
            }
         }
         break;

      case 1:
         // Moving a floor up
         // jff 02/04/98 keep floor from moving thru ceilings
         // jff 2/22/98 weaken check to demo_compatibility
         destheight = (comp[comp_floors] || dest<sector->ceilingheight)?
                      dest : sector->ceilingheight;
         if (sector->floorheight + speed > destheight)
         {
            lastpos = sector->floorheight;
            sector->floorheight = destheight;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk
            if (flag == true)
            {
               sector->floorheight = lastpos;
               P_CheckSector(sector,crush);      //jff 3/19/98 use faster chk
            }
            return pastdest;
         }
         else
         {
            // crushing is possible
            lastpos = sector->floorheight;
            sector->floorheight += speed;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk
            if (flag == true)
            {
               /* jff 1/25/98 fix floor crusher */
               if (comp[comp_floors]) {
                  if (crush == true)
                     return crushed;
               }
               sector->floorheight = lastpos;
               P_CheckSector(sector,crush);      //jff 3/19/98 use faster chk
               return crushed;
            }
         }
         break;
      }
      break;

   case 1:
      // moving a ceiling
      switch(direction)
      {
      case -1:
         // moving a ceiling down
         // jff 02/04/98 keep ceiling from moving thru floors
         // jff 2/22/98 weaken check to demo_compatibility
         destheight = (comp[comp_floors] || dest>sector->floorheight)?
                      dest : sector->floorheight;
         if (sector->ceilingheight - speed < destheight)
         {
            lastpos = sector->ceilingheight;
            sector->ceilingheight = destheight;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk

            if (flag == true)
            {
               sector->ceilingheight = lastpos;
               P_CheckSector(sector,crush);      //jff 3/19/98 use faster chk
            }
            return pastdest;
         }
         else
         {
            // crushing is possible
            lastpos = sector->ceilingheight;
            sector->ceilingheight -= speed;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk

            if (flag == true)
            {
               if (crush == true)
                  return crushed;
               sector->ceilingheight = lastpos;
               P_CheckSector(sector,crush);      //jff 3/19/98 use faster chk
               return crushed;
            }
         }
         break;

      case 1:
         // moving a ceiling up
         if (sector->ceilingheight + speed > dest)
         {
            lastpos = sector->ceilingheight;
            sector->ceilingheight = dest;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk
            if (flag == true)
            {
               sector->ceilingheight = lastpos;
               P_CheckSector(sector,crush);      //jff 3/19/98 use faster chk
            }
            return pastdest;
         }
         else
         {
            lastpos = sector->ceilingheight;
            sector->ceilingheight += speed;
            flag = P_CheckSector(sector,crush); //jff 3/19/98 use faster chk
         }
         break;
      }
      break;
   }
   return ok;
}

//
// T_MoveFloor()
//
// Move a floor to it's destination (up or down).
// Called once per tick for each moving floor.
//
// Passed a floormove_t structure that contains all pertinent info about the
// move. See P_SPEC.H for fields.
// No return.
//
// jff 02/08/98 all cases with labels beginning with gen added to support
// generalized line type behaviors.
void T_MoveFloor(floormove_t* floor)
{
   result_e      res;

   res = T_MovePlane       // move the floor
         (
            floor->sector,
            floor->speed,
            floor->floordestheight,
            floor->crush,
            0,
            floor->direction
         );

   if (!(leveltime&7))     // make the floormove sound
      S_StartSound((mobj_t *)&floor->sector->soundorg, sfx_stnmov);

   if (res == pastdest)    // if destination height is reached
   {
      if (floor->direction == 1)       // going up
      {
         switch(floor->type) // handle texture/type changes
         {
         case donutRaise:
            floor->sector->special = floor->newspecial;
            floor->sector->floorpic = floor->texture;
            break;
         case genFloorChgT:
         case genFloorChg0:
            floor->sector->special = floor->newspecial;
            //jff add to fix bug in special transfers from changes
            floor->sector->oldspecial = floor->oldspecial;
            //fall thru
         case genFloorChg:
            floor->sector->floorpic = floor->texture;
            break;
         default:
            break;
         }
      }
      else if (floor->direction == -1) // going down
      {
         switch(floor->type) // handle texture/type changes
         {
         case lowerAndChange:
            floor->sector->special = floor->newspecial;
            //jff add to fix bug in special transfers from changes
            floor->sector->oldspecial = floor->oldspecial;
            floor->sector->floorpic = floor->texture;
            break;
         case genFloorChgT:
         case genFloorChg0:
            floor->sector->special = floor->newspecial;
            //jff add to fix bug in special transfers from changes
            floor->sector->oldspecial = floor->oldspecial;
            //fall thru
         case genFloorChg:
            floor->sector->floorpic = floor->texture;
            break;
         default:
            break;
         }
      }

      floor->sector->floordata = NULL; //jff 2/22/98
      P_RemoveThinker(&floor->thinker);//remove this floor from list of movers

      //jff 2/26/98 implement stair retrigger lockout while still building
      // note this only applies to the retriggerable generalized stairs

      if (floor->sector->stairlock==-2) // if this sector is stairlocked
      {
         sector_t *sec = floor->sector;
         sec->stairlock=-1;              // thinker done, promote lock to -1

         while (sec->prevsec!=-1 && sectors[sec->prevsec].stairlock!=-2)
            sec = &sectors[sec->prevsec]; // search for a non-done thinker
         if (sec->prevsec==-1)           // if all thinkers previous are done
         {
            sec = floor->sector;          // search forward
            while (sec->nextsec!=-1 && sectors[sec->nextsec].stairlock!=-2)
               sec = &sectors[sec->nextsec];
            if (sec->nextsec==-1)         // if all thinkers ahead are done too
            {
               while (sec->prevsec!=-1)    // clear all locks
               {
                  sec->stairlock = 0;
                  sec = &sectors[sec->prevsec];
               }
               sec->stairlock = 0;
            }
         }
      }

      // make floor stop sound
      S_StartSound((mobj_t *)&floor->sector->soundorg, sfx_pstop);
   }
}

//
// T_MoveElevator()
//
// Move an elevator to it's destination (up or down)
// Called once per tick for each moving floor.
//
// Passed an elevator_t structure that contains all pertinent info about the
// move. See P_SPEC.H for fields.
// No return.
//
// jff 02/22/98 added to support parallel floor/ceiling motion
//
void T_MoveElevator(elevator_t* elevator)
{
   result_e      res;

   if (elevator->direction<0)      // moving down
   {
      res = T_MovePlane             //jff 4/7/98 reverse order of ceiling/floor
            (
               elevator->sector,
               elevator->speed,
               elevator->ceilingdestheight,
               0,
               1,                          // move floor
               elevator->direction
            );
      if (res==ok || res==pastdest) // jff 4/7/98 don't move ceil if blocked
         T_MovePlane
         (
            elevator->sector,
            elevator->speed,
            elevator->floordestheight,
            0,
            0,                        // move ceiling
            elevator->direction
         );
   }
   else // up
   {
      res = T_MovePlane             //jff 4/7/98 reverse order of ceiling/floor
            (
               elevator->sector,
               elevator->speed,
               elevator->floordestheight,
               0,
               0,                          // move ceiling
               elevator->direction
            );
      if (res==ok || res==pastdest) // jff 4/7/98 don't move floor if blocked
         T_MovePlane
         (
            elevator->sector,
            elevator->speed,
            elevator->ceilingdestheight,
            0,
            1,                        // move floor
            elevator->direction
         );
   }

   // make floor move sound
   if (!(leveltime&7))
      S_StartSound((mobj_t *)&elevator->sector->soundorg, sfx_stnmov);

   if (res == pastdest)            // if destination height acheived
   {
      elevator->sector->floordata = NULL;     //jff 2/22/98
      elevator->sector->ceilingdata = NULL;   //jff 2/22/98
      P_RemoveThinker(&elevator->thinker);    // remove elevator from actives

      // make floor stop sound
      S_StartSound((mobj_t *)&elevator->sector->soundorg, sfx_pstop);
   }
}

///////////////////////////////////////////////////////////////////////
//
// Floor motion linedef handlers
//
///////////////////////////////////////////////////////////////////////

//
// EV_DoFloor()
//
// Handle regular and extended floor types
//
// Passed the line that activated the floor and the type of floor motion
// Returns true if a thinker was created.
//
int EV_DoFloor
( line_t*       line,
  floor_e       floortype )
{
   int           secnum;
   int           rtn;
   int           i;
   sector_t*     sec;
   floormove_t*  floor;

   secnum = -1;
   rtn = 0;
   // move all floors with the same tag as the linedef
   while ((secnum = P_FindSectorFromLineTag(line,secnum)) >= 0)
   {
      sec = &sectors[secnum];

      // Don't start a second thinker on the same floor
      if (P_SectorActive(floor_special,sec)) //jff 2/23/98
         continue;

      // new floor thinker
      rtn = 1;
      floor = Z_Malloc (sizeof(*floor), PU_LEVSPEC, 0);
      P_AddThinker (&floor->thinker);
      sec->floordata = floor; //jff 2/22/98
      floor->thinker.function = T_MoveFloor;
      floor->type = floortype;
      floor->crush = false;

      // setup the thinker according to the linedef type
      switch(floortype)
      {
      case lowerFloor:
         floor->direction = -1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = P_FindHighestFloorSurrounding(sec);
         break;

         //jff 02/03/30 support lowering floor by 24 absolute
      case lowerFloor24:
         floor->direction = -1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = floor->sector->floorheight + 24 * FRACUNIT;
         break;

         //jff 02/03/30 support lowering floor by 32 absolute (fast)
      case lowerFloor32Turbo:
         floor->direction = -1;
         floor->sector = sec;
         floor->speed = FLOORSPEED*4;
         floor->floordestheight = floor->sector->floorheight + 32 * FRACUNIT;
         break;

      case lowerFloorToLowest:
         floor->direction = -1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = P_FindLowestFloorSurrounding(sec);
         break;

         //jff 02/03/30 support lowering floor to next lowest floor
      case lowerFloorToNearest:
         floor->direction = -1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight =
            P_FindNextLowestFloor(sec,floor->sector->floorheight);
         break;

      case turboLower:
         floor->direction = -1;
         floor->sector = sec;
         floor->speed = FLOORSPEED * 4;
         floor->floordestheight = P_FindHighestFloorSurrounding(sec);
         if (floor->floordestheight != sec->floorheight)
            floor->floordestheight += 8*FRACUNIT;
         break;

      case raiseFloorCrush:
         floor->crush = true;
         /* fallthrough */
      case raiseFloor:
         floor->direction = 1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = P_FindLowestCeilingSurrounding(sec);
         if (floor->floordestheight > sec->ceilingheight)
            floor->floordestheight = sec->ceilingheight;
         floor->floordestheight -= (8*FRACUNIT)*(floortype == raiseFloorCrush);
         break;

      case raiseFloorTurbo:
         floor->direction = 1;
         floor->sector = sec;
         floor->speed = FLOORSPEED*4;
         floor->floordestheight = P_FindNextHighestFloor(sec,sec->floorheight);
         break;

      case raiseFloorToNearest:
         floor->direction = 1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = P_FindNextHighestFloor(sec,sec->floorheight);
         break;

      case raiseFloor24:
         floor->direction = 1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = floor->sector->floorheight + 24 * FRACUNIT;
         break;

         // jff 2/03/30 support straight raise by 32 (fast)
      case raiseFloor32Turbo:
         floor->direction = 1;
         floor->sector = sec;
         floor->speed = FLOORSPEED*4;
         floor->floordestheight = floor->sector->floorheight + 32 * FRACUNIT;
         break;

      case raiseFloor512:
         floor->direction = 1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = floor->sector->floorheight + 512 * FRACUNIT;
         break;

      case raiseFloor24AndChange:
         floor->direction = 1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = floor->sector->floorheight + 24 * FRACUNIT;
         sec->floorpic = line->frontsector->floorpic;
         sec->special = line->frontsector->special;
         //jff 3/14/98 transfer both old and new special
         sec->oldspecial = line->frontsector->oldspecial;
         break;

      case raiseToTexture:
         {
            int minsize = INT_MAX;
            side_t*     side;

            /* jff 3/13/98 no ovf */
            if (!comp[comp_model]) minsize = 32000<<FRACBITS;
            floor->direction = 1;
            floor->sector = sec;
            floor->speed = FLOORSPEED;
            for (i = 0; i < sec->linecount; i++)
            {
               if (twoSided (secnum, i) )
               {
                  side = getSide(secnum,i,0);
                  // jff 8/14/98 don't scan texture 0, its not real
                  if (side->bottomtexture > 0 ||
                        (comp[comp_model] && !side->bottomtexture))
                     if (textureheight[side->bottomtexture] < minsize)
                        minsize = textureheight[side->bottomtexture];
                  side = getSide(secnum,i,1);
                  // jff 8/14/98 don't scan texture 0, its not real
                  if (side->bottomtexture > 0 ||
                        (comp[comp_model] && !side->bottomtexture))
                     if (textureheight[side->bottomtexture] < minsize)
                        minsize = textureheight[side->bottomtexture];
               }
            }
            if (comp[comp_model])
               floor->floordestheight = floor->sector->floorheight + minsize;
            else
            {
               floor->floordestheight =
                  (floor->sector->floorheight>>FRACBITS) + (minsize>>FRACBITS);
               if (floor->floordestheight>32000)
                  floor->floordestheight = 32000;        //jff 3/13/98 do not
               floor->floordestheight<<=FRACBITS;       // allow height overflow
            }
         }
         break;

      case lowerAndChange:
         floor->direction = -1;
         floor->sector = sec;
         floor->speed = FLOORSPEED;
         floor->floordestheight = P_FindLowestFloorSurrounding(sec);
         floor->texture = sec->floorpic;

         // jff 1/24/98 make sure floor->newspecial gets initialized
         // in case no surrounding sector is at floordestheight
         // --> should not affect compatibility <--
         floor->newspecial = sec->special;
         //jff 3/14/98 transfer both old and new special
         floor->oldspecial = sec->oldspecial;

         //jff 5/23/98 use model subroutine to unify fixes and handling
         sec = P_FindModelFloorSector(floor->floordestheight,sec-sectors);
         if (sec)
         {
            floor->texture = sec->floorpic;
            floor->newspecial = sec->special;
            //jff 3/14/98 transfer both old and new special
            floor->oldspecial = sec->oldspecial;
         }
         break;
      default:
         break;
      }
   }
   return rtn;
}

//
// EV_DoChange()
//
// Handle pure change types. These change floor texture and sector type
// by trigger or numeric model without moving the floor.
//
// The linedef causing the change and the type of change is passed
// Returns true if any sector changes
//
// jff 3/15/98 added to better support generalized sector types
//
int EV_DoChange
( line_t*       line,
  change_e      changetype )
{
   int                   secnum;
   int                   rtn;
   sector_t*             sec;
   sector_t*             secm;

   secnum = -1;
   rtn = 0;
   // change all sectors with the same tag as the linedef
   while ((secnum = P_FindSectorFromLineTag(line,secnum)) >= 0)
   {
      sec = &sectors[secnum];

      rtn = 1;

      // handle trigger or numeric change type
      switch(changetype)
      {
      case trigChangeOnly:
         sec->floorpic = line->frontsector->floorpic;
         sec->special = line->frontsector->special;
         sec->oldspecial = line->frontsector->oldspecial;
         break;
      case numChangeOnly:
         secm = P_FindModelFloorSector(sec->floorheight,secnum);
         if (secm) // if no model, no change
         {
            sec->floorpic = secm->floorpic;
            sec->special = secm->special;
            sec->oldspecial = secm->oldspecial;
         }
         break;
      default:
         break;
      }
   }
   return rtn;
}

/*
 * EV_BuildStairs()
 *
 * Handles staircase building. A sequence of sectors chosen by algorithm
 * rise at a speed indicated to a height that increases by the stepsize
 * each step.
 *
 * Passed the linedef triggering the stairs and the type of stair rise
 * Returns true if any thinkers are created
 *
 * cph 2001/09/21 - compatibility nightmares again
 * There are three different ways this function has, during its history, stepped
 * through all the stairs to be triggered by the single switch
 * - original Doom used a linear P_FindSectorFromLineTag, but failed to preserve
 * the index of the previous sector found, so instead it would restart its
 * linear search from the last sector of the previous staircase
 * - MBF/PrBoom with comp_stairs fail to emulate this, because their
 * P_FindSectorFromLineTag is a chained hash table implementation. Instead they
 * start following the hash chain from the last sector of the previous
 * staircase, which will (probably) have the wrong tag, so they miss any further
 * stairs
 * - Boom fixed the bug, and MBF/PrBoom without comp_stairs work right
 */
static inline int P_FindSectorFromLineTagWithLowerBound
(line_t* l, int start, int min)
{
   /* Emulate original Doom's linear lower-bounded P_FindSectorFromLineTag
    * as needed */
   do {
      start = P_FindSectorFromLineTag(l,start);
   } while (start >= 0 && start <= min);
   return start;
}

int EV_BuildStairs
( line_t*       line,
  stair_e       type )
{
   /* cph 2001/09/22 - cleaned up this function to save my sanity. A separate
    * outer loop index makes the logic much cleared, and local variables moved
    * into the inner blocks helps too */
   int                   ssec = -1;
   int                   minssec = -1;
   int                   rtn = 0;

   // start a stair at each sector tagged the same as the linedef
   while ((ssec = P_FindSectorFromLineTagWithLowerBound(line,ssec,minssec)) >= 0)
   {
      int           secnum = ssec;
      sector_t*     sec = &sectors[secnum];

      // don't start a stair if the first step's floor is already moving
      if (!P_SectorActive(floor_special,sec)) { //jff 2/22/98
         floormove_t*  floor;
         int           texture, height;
         fixed_t       stairsize;
         fixed_t       speed;
         int           ok;

         // create new floor thinker for first step
         rtn = 1;
         floor = Z_Malloc (sizeof(*floor), PU_LEVSPEC, 0);
         P_AddThinker (&floor->thinker);
         sec->floordata = floor;
         floor->thinker.function = T_MoveFloor;
         floor->direction = 1;
         floor->sector = sec;
         floor->type = buildStair;   //jff 3/31/98 do not leave uninited

         // set up the speed and stepsize according to the stairs type
         switch(type)
         {
         default: // killough -- prevent compiler warning
         case build8:
            speed = FLOORSPEED/4;
            stairsize = 8*FRACUNIT;
            if (!demo_compatibility)
               floor->crush = false; //jff 2/27/98 fix uninitialized crush field
            break;
         case turbo16:
            speed = FLOORSPEED*4;
            stairsize = 16*FRACUNIT;
            if (!demo_compatibility)
               floor->crush = true;  //jff 2/27/98 fix uninitialized crush field
            break;
         }
         floor->speed = speed;
         height = sec->floorheight + stairsize;
         floor->floordestheight = height;

         texture = sec->floorpic;

         // Find next sector to raise
         //   1. Find 2-sided line with same sector side[0] (lowest numbered)
         //   2. Other side is the next sector to raise
         //   3. Unless already moving, or different texture, then stop building
         do
         {
            int i;
            ok = 0;

            for (i = 0;i < sec->linecount;i++)
            {
               sector_t* tsec = (sec->lines[i])->frontsector;
               int newsecnum;
               if ( !((sec->lines[i])->flags & ML_TWOSIDED) )
                  continue;

               newsecnum = tsec-sectors;

               if (secnum != newsecnum)
                  continue;

               tsec = (sec->lines[i])->backsector;
               if (!tsec) continue;     //jff 5/7/98 if no backside, continue
               newsecnum = tsec - sectors;

               // if sector's floor is different texture, look for another
               if (tsec->floorpic != texture)
                  continue;

               /* jff 6/19/98 prevent double stepsize
               * killough 10/98: intentionally left this way [MBF comment]
               * cph 2001/02/06: stair bug fix should be controlled by comp_stairs,
               *  except if we're emulating MBF which perversly reverted the fix
               */
               if (comp[comp_stairs] || (compatibility_level == mbf_compatibility))
                  height += stairsize; // jff 6/28/98 change demo compatibility

               // if sector's floor already moving, look for another
               if (P_SectorActive(floor_special,tsec)) //jff 2/22/98
                  continue;

               /* cph - see comment above - do this iff we didn't do so above */
               if (!comp[comp_stairs] && (compatibility_level != mbf_compatibility))
                  height += stairsize;

               sec = tsec;
               secnum = newsecnum;

               // create and initialize a thinker for the next step
               floor = Z_Malloc (sizeof(*floor), PU_LEVSPEC, 0);
               P_AddThinker (&floor->thinker);

               sec->floordata = floor; //jff 2/22/98
               floor->thinker.function = T_MoveFloor;
               floor->direction = 1;
               floor->sector = sec;
               floor->speed = speed;
               floor->floordestheight = height;
               floor->type = buildStair; //jff 3/31/98 do not leave uninited
               //jff 2/27/98 fix uninitialized crush field
               if (!demo_compatibility)
                  floor->crush = type==build8? false : true;
               ok = 1;
               break;
            }
         } while(ok);      // continue until no next step is found

      }
      /* killough 10/98: compatibility option */
      if (comp[comp_stairs]) {
         /* cph 2001/09/22 - emulate buggy MBF comp_stairs for demos, with logic
          * reversed since we now have a separate outer loop index.
          * DEMOSYNC - what about boom_compatibility_compatibility?
          */
         if ((compatibility_level >= mbf_compatibility) && (compatibility_level <
               prboom_3_compatibility)) ssec = secnum; /* Trash outer loop index */
         else {
            /* cph 2001/09/22 - now the correct comp_stairs - Doom used a linear
             * search from the last secnum, so we set that as a minimum value and do
             * a fresh tag search
             */
            ssec = -1; minssec = secnum;
         }
      }
   }
   return rtn;
}

//
// EV_DoDonut()
//
// Handle donut function: lower pillar, raise surrounding pool, both to height,
// texture and type of the sector surrounding the pool.
//
// Passed the linedef that triggered the donut
// Returns whether a thinker was created
//
int EV_DoDonut(line_t*  line)
{
   sector_t* s1;
   sector_t* s2;
   sector_t* s3;
   int       secnum;
   int       rtn;
   int       i;
   floormove_t* floor;

   secnum = -1;
   rtn = 0;
   // do function on all sectors with same tag as linedef
   while ((secnum = P_FindSectorFromLineTag(line,secnum)) >= 0)
   {
      s1 = &sectors[secnum];                // s1 is pillar's sector

      // do not start the donut if the pillar is already moving
      if (P_SectorActive(floor_special,s1)) //jff 2/22/98
         continue;

      s2 = getNextSector(s1->lines[0],s1);  // s2 is pool's sector
      if (!s2) continue;                    // note lowest numbered line around
      // pillar must be two-sided

      /* do not start the donut if the pool is already moving
       * cph - DEMOSYNC - was !compatibility */
      if (!comp[comp_floors] && P_SectorActive(floor_special,s2))
         continue;                           //jff 5/7/98

      // find a two sided line around the pool whose other side isn't the pillar
      for (i = 0;i < s2->linecount;i++)
      {
         //jff 3/29/98 use true two-sidedness, not the flag
         // killough 4/5/98: changed demo_compatibility to compatibility
         if (comp[comp_model])
         {
            if (!(s2->lines[i]->flags & ML_TWOSIDED) ||
                  (s2->lines[i]->backsector == s1))
               continue;
         }
         else if (!s2->lines[i]->backsector || s2->lines[i]->backsector == s1)
            continue;

         rtn = 1; //jff 1/26/98 no donut action - no switch change on return

         s3 = s2->lines[i]->backsector;      // s3 is model sector for changes

         //  Spawn rising slime
         floor = Z_Malloc (sizeof(*floor), PU_LEVSPEC, 0);
         P_AddThinker (&floor->thinker);
         s2->floordata = floor; //jff 2/22/98
         floor->thinker.function = T_MoveFloor;
         floor->type = donutRaise;
         floor->crush = false;
         floor->direction = 1;
         floor->sector = s2;
         floor->speed = FLOORSPEED / 2;
         floor->texture = s3->floorpic;
         floor->newspecial = 0;
         floor->floordestheight = s3->floorheight;

         //  Spawn lowering donut-hole pillar
         floor = Z_Malloc (sizeof(*floor), PU_LEVSPEC, 0);
         P_AddThinker (&floor->thinker);
         s1->floordata = floor; //jff 2/22/98
         floor->thinker.function = T_MoveFloor;
         floor->type = lowerFloor;
         floor->crush = false;
         floor->direction = -1;
         floor->sector = s1;
         floor->speed = FLOORSPEED / 2;
         floor->floordestheight = s3->floorheight;
         break;
      }
   }
   return rtn;
}

//
// EV_DoElevator
//
// Handle elevator linedef types
//
// Passed the linedef that triggered the elevator and the elevator action
//
// jff 2/22/98 new type to move floor and ceiling in parallel
//
int EV_DoElevator
( line_t*       line,
  elevator_e    elevtype )
{
   int                   secnum;
   int                   rtn;
   sector_t*             sec;
   elevator_t*           elevator;

   secnum = -1;
   rtn = 0;
   // act on all sectors with the same tag as the triggering linedef
   while ((secnum = P_FindSectorFromLineTag(line,secnum)) >= 0)
   {
      sec = &sectors[secnum];

      // If either floor or ceiling is already activated, skip it
      if (sec->floordata || sec->ceilingdata) //jff 2/22/98
         continue;

      // create and initialize new elevator thinker
      rtn = 1;
      elevator = Z_Malloc (sizeof(*elevator), PU_LEVSPEC, 0);
      P_AddThinker (&elevator->thinker);
      sec->floordata = elevator; //jff 2/22/98
      sec->ceilingdata = elevator; //jff 2/22/98
      elevator->thinker.function = T_MoveElevator;
      elevator->type = elevtype;

      // set up the fields according to the type of elevator action
      switch(elevtype)
      {
         // elevator down to next floor
      case elevateDown:
         elevator->direction = -1;
         elevator->sector = sec;
         elevator->speed = ELEVATORSPEED;
         elevator->floordestheight =
            P_FindNextLowestFloor(sec,sec->floorheight);
         elevator->ceilingdestheight =
            elevator->floordestheight + sec->ceilingheight - sec->floorheight;
         break;

         // elevator up to next floor
      case elevateUp:
         elevator->direction = 1;
         elevator->sector = sec;
         elevator->speed = ELEVATORSPEED;
         elevator->floordestheight =
            P_FindNextHighestFloor(sec,sec->floorheight);
         elevator->ceilingdestheight =
            elevator->floordestheight + sec->ceilingheight - sec->floorheight;
         break;

         // elevator to floor height of activating switch's front sector
      case elevateCurrent:
         elevator->sector = sec;
         elevator->speed = ELEVATORSPEED;
         elevator->floordestheight = line->frontsector->floorheight;
         elevator->ceilingdestheight =
            elevator->floordestheight + sec->ceilingheight - sec->floorheight;
         elevator->direction =
            elevator->floordestheight>sec->floorheight?  1 : -1;
         break;

      default:
         break;
      }
   }
   return rtn;
}