/*-------------------------------------------------------------------*/
/* stack.c (Version 3: Data Modules)                                 */
/*-------------------------------------------------------------------*/

#include "stack.h"
#include <stdlib.h>
#include <assert.h>

static double *pdStackArray;
static int iStackTop;
static int iStackMaxSize;

void Stack_new(int iMaxSize)
/* Create a new Stack that is able to store iMaxSize items, each of 
   type double. */
{
   assert(iMaxSize > 0);
   pdStackArray = (double*)calloc(iMaxSize, sizeof(double));
   assert(pdStackArray != NULL);
   iStackTop = 0;
   iStackMaxSize = iMaxSize;
}

void Stack_free()
/* Free the Stack. */
{
   free(pdStackArray);
}

void Stack_push(double dItem)
/* Push dItem onto the Stack. */
{
   assert(iStackTop < iStackMaxSize);
   pdStackArray[iStackTop] = dItem;
   ++iStackTop;
}

double Stack_pop()
/* Pop the Stack, and return the popped item. */
{
   assert(iStackTop > 0);
   --iStackTop;
   return pdStackArray[iStackTop];
}

int Stack_empty()
/* Return 1 (TRUE) iff the Stack is empty. */
{
   return iStackTop == 0;
}

int Stack_full()
/* Return 1 (TRUE) iff the Stack is full. */
{
   return iStackTop == iStackMaxSize;
}