Minimal C stack ADT

stack-node.c

typedef struct flt_stack_node
{
  void* value;
  struct flt_stack_node* prev;  
}flt_stack_node;

typedef struct flt_stack
{
  struct flt_stack_node* tail;  
  int n_entries;
}flt_stack;

int flt_stack_create(flt_stack** s)
{
  flt_stack* _s = (flt_stack*)flt_calloc(1,sizeof(flt_stack));
  if ( !_s ) return 0;  
  *s = _s;
  return 1;
}

void flt_stack_destroy(flt_stack** s)
{
  if ( !s || !*s ) return;
  flt_stack_clear(*s);
  flt_safefree(*s);
}

void flt_stack_clear(flt_stack* s)
{
  flt_stack_node *n, *pn;

  n=s->tail;
  while (n)
  {
    pn=n->prev;
    flt_free(n);
    n=pn;
  }
  s->tail=fltnull;
}

void flt_stack_push(flt_stack* s, void* value)
{
  flt_stack_node* sn = (flt_stack_node*)flt_malloc(sizeof(flt_stack_node));

  if ( !sn ) return;  
  ++s->n_entries;
  sn->value = value;
  sn->prev = s->tail;
  s->tail = sn;  
}

void* flt_stack_top(flt_stack* s)
{
  return (s->tail) ? s->tail->value : fltnull;
}

void* flt_stack_pop(flt_stack* s)
{
  flt_stack_node* prev=fltnull;
  void* v=fltnull;

  if ( s->tail )
  {
    v=s->tail->value;
    prev=s->tail->prev;
    flt_free(s->tail);
    s->tail=prev;
  }
  return v;
}