/*
 * ISA 563, Spring 2011
 * Copyleft by Muhammad Abdulla
 */

#include <stdio.h>
#include <assert.h>

#include "stack3.h"

struct S
{
   int stack[MAX];
   int stack_idx;
}; 

void stack_init(Stack *s)
{
   s->stack_idx = 0;
}

void stack_push(Stack *s, int item)
{
   if ( s->stack_idx < MAX ) {
      s->stack[(s->stack_idx)++] = item;
   } else {
      fprintf(stderr, "stack is full, returning.\n");
   }
}

int stack_pop(Stack *s)
{
   if ( s->stack_idx > 0 ) {
      return s->stack[--(s->stack_idx)]; 
   } else {
      fprintf(stderr, "stack is empty, returning -1.\n");
      return -1;
   }
}

int stack_empty(Stack *s)
{
   return s->stack_idx > 0 ? 0 : 1;
}

int stack_full(Stack *s)
{
   return s->stack_idx < MAX ? 0 : 1;
}