/*
 * _heap.h
 *
 * Ullrich von Bassewitz, 1998-06-03, 2004-12-19
 *
 */



#ifndef __HEAP_H
#define __HEAP_H



/* Structure that preceeds a user block in most cases. 
 * The aligned_malloc function may generate blocks where the start pointer
 * and size are splitted to handle a memory hole that is needed for 
 * alignment.
 */
struct usedblock {
    unsigned            size;
    struct usedblock*   start;
};

/* Space needed for administering used blocks */
#define HEAP_ADMIN_SPACE        sizeof (struct usedblock)

/* The data type used to implement the free list.
 * Beware: Field order is significant!
 */                                                      
struct freeblock {
    unsigned 		size;
    struct freeblock*  	next;
    struct freeblock*  	prev;
};



/* Variables that describe the heap */
extern unsigned*       	  _heaporg;     /* Bottom of heap */
extern unsigned*  	  _heapptr;	/* Current top */
extern unsigned*  	  _heapend;	/* Upper limit */
extern struct freeblock*  _heapfirst;	/* First free block in list */
extern struct freeblock*  _heaplast;	/* Last free block in list */



/* End of _heap.h */

#endif



