globals
    integer eax=0
// stack
    integer stack_max=0
    integer array stack_free
    boolean array stack_used
    integer stack_free_max=0
// replace stack
    integer repstack_max=0
    integer array repstack
    boolean array repstack_used
    integer array repstack_pos
// Data arrays
    unit array units
// test
    unit eux=null
endglobals


function echo takes string s returns nothing
        call DisplayTextToPlayer(GetLocalPlayer(),0,0,s)
endfunction

function echoAdv takes string s returns nothing
        call DisplayTimedTextToPlayer(GetLocalPlayer(),0,0,99999999,s)
endfunction

function AddEffectTarget takes string s,widget w,string a returns nothing
    call DestroyEffect(AddSpecialEffectTarget(s,w,a))
endfunction


//#####
// Stack
function StackGetSlot takes nothing returns integer
  if stack_free_max>0 then
    set eax=stack_free[stack_free_max]
    set stack_used[eax]=true
    set stack_free_max=stack_free_max-1
    return eax
  else
    set stack_max=stack_max+1
  if stack_max>8190 then
    set stack_max=8190
    return 0
  else
    set stack_used[stack_max]=true
    return stack_max
  endif
  endif  
    return 0
endfunction

function StackFreeSlot takes integer i returns nothing
  if stack_used[i] then
    set stack_free_max=stack_free_max+1
    set stack_used[i]=false
    set stack_free[stack_free_max]=i
  endif
endfunction

//#####
// Replace Stack

function Repstack_Add takes integer i returns nothing
   if repstack_used[i]==false then
      set repstack_max=repstack_max+1
      set repstack_used[i]=true
      set repstack_pos[i]=repstack_max
      set repstack[repstack_max]=i
   endif
endfunction

function Repstack_Remove takes integer i returns nothing
   if repstack_used[i] then
      set repstack_used[i]=false
      set repstack[repstack_pos[i]]=repstack[repstack_max]
      set repstack_pos[repstack[repstack_max]]=repstack_pos[i]
      set repstack_max=repstack_max-1      
   endif
endfunction

//#####
// My Alg

function AddUnitX takes unit u returns integer
      local integer i=StackGetSlot()
      call Repstack_Add(i)
      set units[i]=u
      return i
endfunction

function RemoveUnitX takes integer i returns nothing
      call StackFreeSlot(i)
      call Repstack_Remove(i)
      set units[i]=null
endfunction