#include <stdio.h>
#include <stdlib.h>
#define TLIST_CONTENT int
#define TRUE 1
#define FALSE 0
#define BOOLEAN short

struct slist {
  struct stlistitem *head, *tail;
  int elem_count;
};

typedef struct slist tlist;

struct stlistitem {
  struct stlistitem *next, *previous;
  TLIST_CONTENT *content;
};

typedef struct stlistitem tlistitem;

tlist *tlist_init();
void tlist_add(tlist *list, TLIST_CONTENT *content);
void tlist_free(tlist *list);
tlistitem *_tlist_new_item();

int main(int argc, char *argv[]) {
  tlist *a;
  TLIST_CONTENT value1, value2;
  value1 = 99;
  value2 = 88;
  a = tlist_init();
  tlist_add(a,&value1);
  tlist_add(a,&value2);
  printf("%d\n", *(a->head->next->content));
  printf("%d\n", *(a->head->next->next->content));
  tlist_free(a);
}

tlist *tlist_init() {
  tlist *l;
  l = (tlist *)malloc(sizeof(tlist));
  tlistitem *head;
  head = _tlist_new_item();
  l->head = head;
  l->tail = l->head;
  l->elem_count = 0;
  return l;
}

void tlist_add(tlist *list, TLIST_CONTENT *content) {
  tlistitem *new_item, *temp;
  new_item = (tlistitem *)malloc(sizeof(tlistitem));
  list->tail->next = new_item;
  new_item->previous = list->tail;
  new_item->next = NULL;
  new_item->content = content;
  list->tail = new_item;
  list->elem_count++;
}

tlistitem *_tlist_new_item() {
  tlistitem *item;
  item = (tlistitem *)malloc(sizeof(tlistitem));
  item->previous = NULL;
  item->next = NULL;
  item->content = NULL;
  return item;
}

tlistitem *tlist_get_head(tlist *list) {
  return list->head->next;
}

tlistitem *tlist_get_tail(tlist *list) {
  return list->tail;
}

tlistitem *tlist_get_next(tlistitem *item) {
  return item->next;
}

tlistitem *tlist_get_previous(tlistitem *item) {
  return item->previous;
}

BOOLEAN tlist_is_tail(tlist *list, tlistitem *item) {
  return (item == (list->tail));
}

BOOLEAN tlist_is_head(tlist *list, tlistitem *item) {
  return (item == (list->head));
}


void tlist_free_item(tlistitem *item) {
  free(item->next);
  item->next = NULL;
  free(item->previous);
  item->previous = NULL;
  free(item);
  item = NULL;
}

void tlist_free(tlist *list) {
  tlistitem *item = tlist_get_tail(list);
  tlistitem *prev;
  if(item != NULL) {
    prev = tlist_get_previous(item);
    while(!tlist_is_head(list,item)) {
      tlist_free_item(item);
      item = prev;
	prev = tlist_get_previous(item);
    }
  }
  free(list);
}