PRODUCT  :  Borland C++                            NUMBER  :  717
  VERSION  :  2.0
       OS  :  DOS
     DATE  :  October 19, 1993                         PAGE  :  1/1

    TITLE  :  Getting Amount of Available Memory on the Far Heap




  /************************************************************************
      Purpose:
          This function will determine how much memory is available
          on the far heap.

      Usage:
          To use this function you must put the statement:
               extern unsigned long heapsize(void);
          within the scope of the calling function.

      Method:
          The memory available on the far heap is computed by
          determining the sum of the freed blocks of memory and
          adding that amount to the value returned by coreleft().

  ***********************************************************************/
  #include <alloc.h>
  #include <stdio.h>

  unsigned long heapsize(void)
  {
     unsigned long i = 0;    /* Return variable */
     struct farheapinfo hi;  /* Value returned from farheapwalk */
     hi.ptr = NULL;          /* Set the beginning of farheapwalk*/

     if( farheapcheck() <= 0 )  /* Check for corrupted heap */
        return (-1L);

     while( farheapwalk(&hi) == _HEAPOK ) /* Walk the heap and sum
                                             size of free blocks */
          if( hi.in_use == 0 )
             i += hi.size;

     i += farcoreleft();  /* Check for amount of free memory from
                             the highest allocated block to the end
                             of DOS */
     return i;
  }

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