/*
 * _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