Free Hero Mesh

static Uint8 current_key;
static Value quiz_obj;
static Value traced_obj;
static Uint32 control_obj=VOIDLINK;
static Connection conn[VSTACKSIZE];
static int nconn,pconn;
static Uint8 conn_dir;
static Uint16 subst_class;
static Uint32 subst_obj;

#define Throw(x) (my_error=(x),longjmp(my_env,1))
#define StackReq(x,y) do{ if(vstackptr<(x)) Throw("Stack underflow"); if(vstackptr-(x)+(y)>=VSTACKSIZE) Throw("Stack overflow"); }while(0)
#define Push(x) (vstack[vstackptr++]=(x))
#define Pop() (vstack[--vstackptr])

// For arrival/departure masks

  while(n!=VOIDLINK) {
    if(!(objects[n]->oflags&OF_DESTROYED)) c|=classes[objects[n]->class]->collisionLayers;
    n=objects[n]->up;
  }
  return c;
}

static Uint16 collide_with(Uint8 b,Uint32 n,Uint8 x,Uint8 y,Uint16 c) {
  int i,j;
  Uint8 r=0;
  Uint32 e[8]={VOIDLINK,VOIDLINK,VOIDLINK,VOIDLINK,VOIDLINK,VOIDLINK,VOIDLINK,VOIDLINK};
  Uint8 re[8]={0,0,0,0,0,0,0,0};
  Value v;
  if(StackProtection()) Throw("Call stack overflow");
  for(i=0;i<8;i++) if(b&(1<<i)) e[i]=obj_layer_at(1<<i,x,y);
  for(i=0;i<7;i++) for(j=i+1;j<8;j++) if(e[i]==e[j]) e[j]=VOIDLINK;
  if(n!=VOIDLINK) {
    v=send_message(VOIDLINK,n,MSG_COLLIDE,NVALUE(x),NVALUE(y),NVALUE(b));
    if(v.t) Throw("Type mismatch in COLLIDE");
    r=v.u;
  }
  for(i=0;i<8;i++) if(e[i]!=VOIDLINK && !(r&0x02)) {
    v=send_message(n,e[i],MSG_COLLIDEBY,NVALUE(n==VOIDLINK?0:objects[n]->x),NVALUE(n==VOIDLINK?0:objects[n]->y),CVALUE(c));
    if(v.t==TY_CLASS) {
      subst_class=v.u;
      subst_obj=e[i];
      return 0x8001;
    } else if(v.t>TY_MAXTYPE) {
      subst_class=0;
      subst_obj=v_object(v);
      return 0x8001;
    }
    if(v.t) Throw("Type mismatch in COLLIDEBY");
    r|=re[i]=v.u;
  }
  if(!(r&0x01)) {
    // See if we can destroy some objects to make room
    b=classes[c]->collisionLayers;
    if(obj_layer_at(b,x,y)==VOIDLINK) return r;

  o->next=n;
  o->prev=objects[n]->prev;
  objects[n]->prev=obj;
  if(o->prev==VOIDLINK) firstobj=obj; else objects[o->prev]->next=obj;
  notfound:
  objects[obj]->oflags|=OF_ORDERED;
}

static Uint32 x_create(Uint32 from,Uint16 c,Uint32 x,Uint32 y,Uint32 d,Value arg1,Value arg2,Value arg3) {
  // This function is only called if x and y and d are already verified to be valid, so need not be checked again.
  Uint32 m,n;
  int i,xx,yy;
  Object*o;
  Object*p;
  Value v;
  if(c==control_class || !c) return VOIDLINK;
  // Although this function can be called recursively, StackProtection() is unnecessary,
  // because in the case that it is called recursively, it is guaranteed to call either
  // collide_with or execute_program (indirectly), which then calls StackProtection().
  if((i=classes[c]->collisionLayers) && (xx=collisions_at(x,y)&i)) {
    if((i=collide_with(xx,VOIDLINK,x,y,c))&0x01) {
      if(i&0x8000) {
        if(subst_class) {
          m=subst_obj;
          v=destroy(VOIDLINK,m,5);
          if(v.t) return VOIDLINK;
          n=x_create(m,subst_class,x,y,d,arg1,arg2,arg3);
          if(n!=VOIDLINK) objects[from]->replacement=objects[m]->replacement=OVALUE(n);
          return n;
        } else {
          return subst_obj;
        }
      }
      return VOIDLINK;
    }
  }
  n=objalloc(c);
  if(n==VOIDLINK) Throw("Error creating object");
  o=objects[n];
  o->x=x;
  o->y=y;
  o->image=0;
  o->dir=d;
  o->oflags&=~OF_BIZARRO;
  objects[from]->replacement=OVALUE(n);
  pflink(n);
  v=send_message(from,n,MSG_XCREATE,arg1,arg2,arg3);
  if(v.t>TY_MAXTYPE) {
    if(classes[objects[n]->class]->order && !(o->oflags&OF_DESTROYED)) set_order(n);
    return v_object(v);
  } else if(v.t) {
    Throw("Type mismatch");
  }
  if(o->oflags&OF_DESTROYED) return VOIDLINK;
  if(v.u) goto skip;
  v=send_message(VOIDLINK,n,MSG_CREATE,NVALUE(0),NVALUE(0),NVALUE(0));
  if(o->oflags&OF_DESTROYED) return VOIDLINK;
  if(o->oflags&OF_BIZARRO) {
    skip:
    if(classes[objects[n]->class]->order) set_order(n);
    return n;
  }
  for(y=0;y<5;y++) for(x=0;x<5;x++) {
    xx=o->x+x-2; yy=o->y+y-2;
    if(xx<1 || xx>pfwidth || yy<1 || yy>pfheight) continue;
    i=x+5*(4-y);
    m=playfield[xx+yy*64-65];
    while(m!=VOIDLINK) {
      p=objects[m];
      if(p->arrivals&(1<<i)) if(m!=n) send_message(n,m,MSG_CREATED,NVALUE(o->x),NVALUE(o->y),v);
      m=p->up;
    }
  }
  if(o->oflags&OF_DESTROYED) return VOIDLINK;
  if(classes[objects[n]->class]->order) set_order(n);
  m=objects[n]->up;
  if(m!=VOIDLINK) {
    v=send_message(VOIDLINK,n,MSG_SUNK,NVALUE(0),NVALUE(0),v);
    while(m!=VOIDLINK) {
      send_message(n,m,MSG_FLOATED,NVALUE(0),NVALUE(0),v);
      m=objects[m]->up;
    }
  }
  if(o->oflags&OF_DESTROYED) return VOIDLINK;
  return n;
}

static Uint32 create(Uint32 from,Uint16 c,Uint32 x,Uint32 y,Uint32 im,Uint32 d) {
  Uint32 m,n;
  int i,xx,yy;
  Object*o;
  Object*p;
  Value v;
  if(d>7) d=0;
  if(x<1 || y<1 || x>pfwidth || y>pfheight || c==control_class) return VOIDLINK;
  if(!(classes[c]->oflags&OF_BIZARRO) && (i=classes[c]->collisionLayers) && (xx=collisions_at(x,y)&i)) {
    if((i=collide_with(xx,VOIDLINK,x,y,c))&0x01) {
      if(i&0x8000) {
        if(subst_class) {
          m=subst_obj;
          v=destroy(VOIDLINK,m,5);
          if(v.t) return VOIDLINK;
          n=x_create(m,subst_class,x,y,d,CVALUE(c),NVALUE(im),NVALUE(0));
          if(n!=VOIDLINK) objects[m]->replacement=OVALUE(n);
          return n;
        } else {
          return subst_obj;
        }
      }
      return VOIDLINK;
    }
  }
  n=objalloc(c);
  if(n==VOIDLINK) Throw("Error creating object");
  o=objects[n];
  o->x=x;
  o->y=y;
  o->image=im;

      }
    }
  }
  return v;
}

static int move_to(Uint32 from,Uint32 n,Uint32 x,Uint32 y) {
  Uint32 k,m;
  int i,xx,yy;
  Object*o;
  Object*p;
  Value v;
  if(n==VOIDLINK || (objects[n]->oflags&OF_DESTROYED) || n==control_obj) return 0;
  o=objects[n];
  if(lastimage_processing) Throw("Can't move during animation processing");
  if(x<1 || y<1 || x>pfwidth || y>pfheight) return 0;
  if(v_bool(send_message(from,n,MSG_MOVING,NVALUE(x),NVALUE(y),NVALUE(0)))) return 0;
  if(classes[o->class]->cflags&CF_PLAYER) {
    m=lastobj;
    while(m!=VOIDLINK) {
      if(v_bool(send_message(n,m,MSG_PLAYERMOVING,NVALUE(x),NVALUE(y),OVALUE(from)))) return 0;
      m=objects[m]->prev;
    }
  }
  if(!(o->oflags&OF_BIZARRO) && (i=classes[o->class]->collisionLayers) && (xx=collisions_at(x,y)&i)) {
    if((i=collide_with(xx,n,x,y,o->class))&0x01) {
      if(i&0x8000) {
        m=subst_obj;
        v=destroy(n,m,5);
        if(v.t) return 0;
        k=x_create(m,subst_class,x,y,o->dir,CVALUE(o->class),NVALUE(o->image),OVALUE(n));
        if(k!=VOIDLINK) {
          objects[m]->replacement=objects[n]->replacement=OVALUE(k);
          destroy(m,n,6);
          o->distance+=abs(x-o->x)+abs(y-o->y);
          return 1;
        }
        return 0;
      }
      return i&0x04?1:0;
    }
  }
  pfunlink(n);
  if(!(o->oflags&((classes[o->class]->cflags&CF_COMPATIBLE?OF_VISUALONLY:0)|OF_STEALTHY|OF_BIZARRO))) {
    for(i=25;i>=0;i--) {
      xx=o->x+Xbit(i); yy=o->y+Ybit(i);
      if(xx<1 || xx>pfwidth || yy<1 || yy>pfheight) continue;
      m=playfield[xx+yy*64-65];