이 정도면 어떨까요?

void Disp_operation(void) {
  
 // if(Disp_timer>0) return;  
  //Disp_timer =1;

    if(LED_timer>0) return;
  LED_timer=1;

      DIGM = 1<<icounter;
        ////////////////////////////
        if(icounter == 3){
          if(blink_flag >0 && blink_flag < 9){
   //           if(LED_timer>0) return;
              
              LED_timer = 800;
                if(LEDST[blink_flag-1]==1){ //LED OFF
                Led_one = Led_one & ~(1<<(blink_flag-1));//ON   
                SEGM = Led_one;}
                else if(LEDST[blink_flag-1]==0) { //LED ON
                Led_one = Led_one | (1<<(blink_flag-1));//OFF
                SEGM = Led_one;}                
          }
          else {
            SEGM = Led_one; }
        }
        //////////////////////////////  
        else if(icounter == 7){
          if(blink_flag >8){
     //         if(LED_timer>0) return;
              
              LED_timer = 800;
                if(LEDST[blink_flag-1]==1){ //LED OFF
                Led_two = Led_two & ~(1<<(blink_flag-9));//ON   
                SEGM = Led_two;}
                else if(LEDST[blink_flag-1]==0) { //LED ON
                Led_two = Led_two | (1<<(blink_flag-9));//OFF
                SEGM = Led_two;}                
          }
          else {
            SEGM = Led_two; }
        }
        ////////////////////////////////
        else{SEGM =fnd_data[icounter];}
   ++icounter;
   if(icounter ==8) icounter=0;
}