/*
stack.c
Pedro Flynn - pflynn@microsoftsucks.org
*/

#include "stack.h"

struct stack* stack_create()
{
struct stack* new_stack;

new_stack = (struct stack*) malloc(sizeof(struct stack));

new_stack->s_size = 0;
new_stack->s_top = new_stack->s_bottom = NULL;

return new_stack;
	
}


int stack_push(struct stack* stack,const void* data)
{
struct stack_element* new_element;
	
new_element = (struct stack_element*) malloc(sizeof(struct stack_element));
new_element->se_data = (void*) data;

if(!stack->s_top)
	stack->s_bottom = new_element;

	new_element->se_next = stack->s_top;
	stack->s_top = new_element;
			
stack->s_size++;
return 0;
}

int stack_pop(struct stack* stack,void** data)
{
struct stack_element* element;	

if(!stack->s_size)
	return -1;

element = stack->s_top;
*data = (void*) element->se_data;

if(element->se_next)
	stack->s_top = element->se_next;
else
  stack->s_top = NULL;

free(element);
stack->s_size--;
return 0;
}

/* apenas debug */
void stack_print(struct stack* stack)
{
struct stack_element* element;
	
if(!stack->s_size)
	return;

element = stack->s_top;

do
fprintf(stdout,"%f\n",*((float*) element->se_data));
while(element = element->se_next);

}

int stack_empty(struct stack* stack)
{
void* data;

if(!stack->s_size)
	return -1;

while(!stack_pop(stack,&data))
free(data);

return 0;	
}

int stack_destroy(struct stack* stack)
{

stack_empty(stack);
	free(stack);

return 0;
}