ants[index].counter_2 = RAND_RANGE(10, 100);

               // start animation
               Set_Animation_BOB(&ants[index], ants[index].varsI[ANT_INDEX_DIRECTION]);

               } break;

          case ANT_EATING:         // at a mnm eating it
               {
               // set state to eating
               ants[index].varsI[ANT_INDEX_AI_STATE] = ANT_EATING;

               // start eating the mnm indexed by var1 
               ants[index].varsI[ANT_INDEX_MNM_BEING_DEVOURED] = var1;

               // counters not used in this state

               } break;          

          case ANT_RESTING:        // sleeping :)
               {
               // set the ai state of ant
               ants[index].varsI[ANT_INDEX_AI_STATE] = ANT_RESTING;

               // set how long to rest
               ants[index].counter_1 = RAND_RANGE(50, 200);
              

               } break;

          case ANT_SEARCH_FOOD:    // hungry and searching for food
               {
               // set state to search for food
               ants[index].varsI[ANT_INDEX_AI_STATE]    = ANT_SEARCH_FOOD;

               // start off by scanning for food
               ants[index].varsI[ANT_INDEX_AI_SUBSTATE] = ANT_SEARCH_FOOD_S1_SCAN;

               // initialize targets tp 0
               ants[index].varsI[ANT_INDEX_FOOD_TARGET_X] = 0;
               ants[index].varsI[ANT_INDEX_FOOD_TARGET_Y] = 0;


               } break;

          case ANT_COMMUNICATING:  // talking to another ant  
               {

               // set the ai state of ant
               ants[index].varsI[ANT_INDEX_AI_STATE] = ANT_COMMUNICATING;

               // set how long to communicate
               ants[index].counter_1 = RAND_RANGE(60, 90);

               // when counter 2 hits 5 then exchange memory
               // thus about 5-10% of the memories will be exchanged
               ants[index].counter_2 = 0;

               } break;

          case ANT_DEAD:           // this guy is dead, got too hungry
               {
               // set the ai state of ant
               ants[index].varsI[ANT_INDEX_AI_STATE] = ANT_DEAD;

               // set direction
               ants[index].varsI[ANT_INDEX_DIRECTION] = ANT_ANIM_DEAD;
    
               // start animation
               Set_Animation_BOB(&ants[index], ants[index].varsI[ANT_INDEX_DIRECTION]);
 
               } break;

          default: break;

          } // end switch             

} // end Set_New_State


//////////////////////////////////////////////////////////////////////

void Move_Ants(void)
{
// this function moves all the ants and processes the ai

// up, right, down, left
static int ant_movements_x[4] = { 0,2,0,-2};
static int ant_movements_y[4] = {-2,0,2, 0};

static int clear_ilayer = 0; // tracks when to clear the input memory layer

int index;
int select_new_state = -1;

for (index=0; index < NUM_ANTS; index++)
    {
    // reset new state selector
    select_new_state = -1;

    // what state is ant in?
    switch(ants[index].varsI[ANT_INDEX_AI_STATE])
          {
           case ANT_WANDERING:      // moving around randomly
               {
               // in this state the ant selects random directions and then
               // walks for some period in that direction, if during the ants
               // walk, it stumbles across some food, then it will remember
               // the rough position of the food in int memory
               // burns 1 unit per cycle 

               // move the ant
               ants[index].x+=ant_movements_x[ants[index].varsI[ANT_INDEX_DIRECTION]];
               ants[index].y+=ant_movements_y[ants[index].varsI[ANT_INDEX_DIRECTION]];

               // test if ant is done with direction and needs a new one
               if (--ants[index].counter_2 < 0)
                  {
                  // set direction
                  ants[index].varsI[ANT_INDEX_DIRECTION] = RAND_RANGE(ANT_ANIM_UP, ANT_ANIM_LEFT);
    
                  // time in this new direction
                  ants[index].counter_2 = RAND_RANGE(10, 100);

                  // start animation
                  Set_Animation_BOB(&ants[index], ants[index].varsI[ANT_INDEX_DIRECTION]);

                  } // end if new direction

               // burn food
               ants[index].varsI[ANT_INDEX_HUNGER_LEVEL]++;

               // update memory with presence of food
               int ant_cell_x = ants[index].x / 30;
               int ant_cell_y = ants[index].y / 30;

               // this updates the i,jth memory cell in ant with info about food
               ants_mem[index].cell[ant_cell_x][ant_cell_y] =
                   ANT_MEMORY_RESIDUAL_RATE*ants_mem[index].cell[ant_cell_x][ant_cell_y] + 
                   (1-ANT_MEMORY_RESIDUAL_RATE)*Food_Near_Ant(ant_cell_x, ant_cell_y);

               // test if we are done with this state and need a new one?
               if (--ants[index].counter_1 < 0)                                        
                  {
                  // select either rest or wander, search will pre-empt with logic following
                  // if hungry, state, probability of state, must sum to 100
                  select_new_state = Select_State_Rand(ANT_WANDERING,     70,            
                                                       ANT_EATING,        0,                
                                                       ANT_RESTING,       30,              
                                                       ANT_SEARCH_FOOD,   0,           
                                                       ANT_COMMUNICATING, 0,         
                                                       ANT_DEAD,          0);                    
                   } // end if

   
               // test for pre-empt into communication mode
               for (int dialog_ant = 0; dialog_ant < NUM_ANTS; dialog_ant++)
                   {

                   // try and talk if this isn't the same ant just talked to and this ant
                   // is either resting or wandering
                   if ( ( (dialog_ant!=index) && (ants[index].varsI[ANT_INDEX_LAST_TALKED_WITH] != dialog_ant) ) &&
                        ((ants[dialog_ant].varsI[ANT_INDEX_AI_STATE] == ANT_RESTING) ||
                         (ants[dialog_ant].varsI[ANT_INDEX_AI_STATE] == ANT_WANDERING)) )
                        {
                        // are they close enough to talk?
                        if ((abs(ants[index].x - ants[dialog_ant].x) < 8)  &&
                            (abs(ants[index].y - ants[dialog_ant].y) < 8) )
                            {
                            // set both ants to communicate mode
                            Set_New_State(ANT_COMMUNICATING,index);              
                            Set_New_State(ANT_COMMUNICATING,dialog_ant);
                      
                            // set communicate partners for chat
                            ants[index].varsI[ANT_INDEX_LAST_TALKED_WITH]      = dialog_ant;
                            ants[dialog_ant].varsI[ANT_INDEX_LAST_TALKED_WITH] = index;

                            break;
                            } // end if
                              
                        } // end if

                   } // end for dialog_ant
 

               // test for pre-empt into search mode if hunger is 75% tolerance
               if (ants[index].varsI[ANT_INDEX_HUNGER_LEVEL] > (0.75*ants[index].varsI[ANT_INDEX_HUNGER_TOLERANCE]) )
                  {
                  select_new_state = ANT_SEARCH_FOOD;
                  } // end if                   

        

               } break;

          case ANT_EATING:         // at a mnm eating it
               {
               // in this state the ant is eating and at rest, the ant will
               // eat from a single mnm until it puts itself to 50% of its hunger tolerance
               // and then stop or if the food runs out it will stop
               // ants eat at a rate of 5 energy units per cycle 
               // burns 1 unit per cycle
         
               // eat the mnm up until its gone or the hunger level drops to 50%
                     
               // decrease food supply
               food[ants[index].varsI[ANT_INDEX_MNM_BEING_DEVOURED]].energy-=BITE_SIZE;

               // transfer to ant and decrease hunger level BITE_SIZE units 
               ants[index].varsI[ANT_INDEX_HUNGER_LEVEL]-=BITE_SIZE;

               // is food supply depleted?
               if (food[ants[index].varsI[ANT_INDEX_MNM_BEING_DEVOURED]].energy < 0)
                  {
                  food[ants[index].varsI[ANT_INDEX_MNM_BEING_DEVOURED]].energy = 0;

                  // transfer to search state or rest a sec
                  select_new_state = Select_State_Rand(ANT_WANDERING,     0,            
                                                       ANT_EATING,        0,                
                                                       ANT_RESTING,       30,              
                                                       ANT_SEARCH_FOOD,   70,           
                                                       ANT_COMMUNICATING, 0,         
                                                       ANT_DEAD,          0);  

                                
                  } // end if

               // test if done eating?, i.e. hunger < 50% tolerance
               else
               if (ants[index].varsI[ANT_INDEX_HUNGER_LEVEL] < 
                   (0.50*ants[index].varsI[ANT_INDEX_HUNGER_TOLERANCE]) )
                  {
                  // switch to another state
                  select_new_state = Select_State_Rand(ANT_WANDERING,     50,            
                                                       ANT_EATING,        0,                
                                                       ANT_RESTING,       30,              
                                                       ANT_SEARCH_FOOD,   20,           
                                                       ANT_COMMUNICATING, 0,         
                                                       ANT_DEAD,          0);    


                  } // end if

               } break;          

          case ANT_RESTING:        // sleeping :)
               {
               // ant is simply resting and burns 1 unit per cycle                 

               // test if we are done with this state and need a new one?
               if (--ants[index].counter_1 < 0)                                        
                  {
                  // select either rest or wander, search will pre-empt with logic following
                  // if hungry, state, probability of state, must sum to 100
                  select_new_state = Select_State_Rand(ANT_WANDERING,     90,            
                                                       ANT_EATING,        0,                
                                                       ANT_RESTING,       10,              
                                                       ANT_SEARCH_FOOD,   0,           
                                                       ANT_COMMUNICATING, 0,         
                                                       ANT_DEAD,          0);                    
                 } // end if

               // burn food
               ants[index].varsI[ANT_INDEX_HUNGER_LEVEL]++;


               // test for pre-empt into search mode if hunger is 50% tolerance
               if (ants[index].varsI[ANT_INDEX_HUNGER_LEVEL] > (ants[index].varsI[ANT_INDEX_HUNGER_TOLERANCE] >> 1) )
                  {
                  select_new_state = ANT_SEARCH_FOOD;
                  } // end if    



               } break;

          case ANT_SEARCH_FOOD:    // hungry and searching for food
               {
               // in this state the ant is looking for food based on its memory
               // if the memory is blank then random walks
               // if the ant gets to a location and cant find any food where its
               // memory found some then the memory for that food location is degraded by 1
               // searching takes 2 units of energy per cycle

#if 0
               ants[index].varsI[ANT_INDEX_AI_STATE]    = ANT_SEARCH_FOOD;

               // start off by scanning for food
               ants[index].varsI[ANT_INDEX_AI_SUBSTATE] = ANT_SEARCH_FOOD_S1_SCAN;

               // initialize targets tp 0
               ants[index].varsI[ANT_INDEX_FOOD_TARGET_X] = 0;
               ants[index].varsI[ANT_INDEX_FOOD_TARGET_Y] = 0;

#endif

               // test substate
               switch(ants[index].varsI[ANT_INDEX_AI_SUBSTATE])
                     {     

                     case ANT_SEARCH_FOOD_S1_SCAN:
                          {
                          // this state is transient and doesn't persist, so
                          // no energy expended by it

                          // scan for a "hot" cell
                          float max_energy = 0;
                          int cell_x = 0, cell_y = 0;
                        
                          for (int index_x = 0; index_x < 16; index_x++)
                              for (int index_y = 0; index_y < 16; index_y++)
                                  // does this cell have more food?
                                  if (ants_mem[index].cell[index_x][index_y] > max_energy)
                                     {
                                     // update new max
                                     max_energy = ants_mem[index].cell[index_x][index_y]; 
                                     cell_x = index_x; cell_y = index_y;

                                     } // end if

                          // test max and see if we have a winner?
                          if (max_energy > 0)
                             {
                             // vector to this cell
                            ants[index].varsI[ANT_INDEX_AI_SUBSTATE] = ANT_SEARCH_FOOD_S3_VECTOR_2CELL;

                            // send to cell center
                            ants[index].varsI[ANT_INDEX_FOOD_TARGET_X] = 30*cell_x+15;
                            ants[index].varsI[ANT_INDEX_FOOD_TARGET_Y] = 30*cell_y+15;                              

                            // set counters to 0
                            ants[index].counter_1 = ants[index].counter_2 = 0;                           

                             } // end if
                           else
                              { 
                              // go into wander mode, no knowledge of food
                              // vector to this cell
                              ants[index].varsI[ANT_INDEX_AI_SUBSTATE] = ANT_SEARCH_FOOD_S2_WANDER;

                              // set counters 
                              ants[index].counter_1 = RAND_RANGE(100,150);
                              ants[index].counter_2 = 0;