/*
 * AUTOMATIC COMPACTING OBJECT HEAP SYSTEM
 *
 * Allows one to create one of two basic heap objects:  an array of bytes and
 * a vector of object pointers.  The heap will automatically compact memory
 * to a new heap area.  To keep your code correct, each object variable must
 * be registered.  Each object also allows for 7 bits of 'type' data.
 *
*/ 
#ifndef _MEM_H
#define _MEM_H



/* TUNEABLE PARAMETERS FOR THE COMPACTING GARBAGE COLLECTOR.
 */
#define INCREMENT_HEAP_SIZE 0x100000
#define DECREMENT_HEAP_SIZE 0x000100



#include "globals.h"



/* REGISTERS
 */
extern OBJ r0, r1, r2, r3, r4, r5, r6, r7,
           r8, r9, ra, rb, rc, rd, re, rf,
           stack;
extern OBJ *sp;



typedef U32 desc_t; /* CLASS (2bits) ID (6) AND SIZE (24) */

#define DESC_SIZE sizeof(desc_t) 


/* TWO BITS FOR OBJECT CLASS
   SIX BITS FOR OBJECT ID
 */
#define DESC_TYPE_MASK   0xff000000
#define DESC_LENGTH_MASK 0x00ffffff

#define TYPE_CLASS_MASK  0xc0
#define TYPE_ID_MASK     0x3f

#define ARRAY_CLASS  0x00
#define DIRTY_CLASS  0x40
#define VECTOR_CLASS 0x80
#define STACK_CLASS  0xc0

#define MAKE_ARRAY_TYPE(i)  (ARRAY_CLASS |(i))
#define MAKE_DIRTY_TYPE(i)  (DIRTY_CLASS |(i))
#define MAKE_VECTOR_TYPE(i) (VECTOR_CLASS|(i))
#define MAKE_STACK_TYPE(i)  (STACK_CLASS |(i))

//#define SHADOW_TYPE     (VECTOR_CLASS | TYPE_ID_MASK)
#define SHADOW_TYPE     0xff

#define MAKE_DESC(t,l) (((t)<<24)|(l))



#define ary_to_size(l) ((3+(l))&-sizeof(OBJ))
#define vec_to_size(l) ((l)*sizeof(OBJ))



void obj_type_set (OBJ o, U8 t); /* MUTATE AN OBJECTS TYPE */
U8  obj_type (OBJ o); /* RETURNS 8BIT TYPE (CLASS | ID) */
U32 obj_len  (OBJ o); /* RETURNS NUMBER OF ELEMENTS IN OBJECT */



/* THIS MUST BE CALLED BEFORE USAGE OF THIS LIBRARY
 */
void mem_init (void);



U32 mem_heap_size   (void);
U32 mem_heap_count  (void);
U32 mem_heap_free   (void);
U32 mem_heap_gccount(void);
void mem_heap_inc_dirtycount(void);


/* RETURNS THE ADDRESS OF AN ARRAY/VECTOR ELEMENT.
 */
U8*   mem_ary_ref (OBJ o, U32 r);
void* mem_drt_clnr(OBJ o);        /* RETURNS ADDRESS OF OBJECT CLEANER */
void* mem_drt_ref (OBJ o, U32 r); /* RETURNS ADDRESS OF DIRTY C OBJECT */
OBJ*  mem_vec_ref (OBJ o, U32 r);
OBJ*  mem_stk_ref (OBJ o, U32 r);



/* RETURNS ELEMENT OF THE ARRAY/VECTOR.
 */
U8  mem_ary_obj (OBJ o, U32 r);
OBJ mem_vec_obj (OBJ o, U32 r);
OBJ mem_stk_obj (OBJ o, U32 r);
U32 mem_stk_count (OBJ o);



/* MUTATE AN OBJECT ARRAY/VECTOR ENTRY.
 */
void mem_ary_set  (OBJ o, U32 r, U8 p);
void mem_vec_set  (OBJ o, U32 r, OBJ p);

void stack_push (OBJ o);
OBJ  stack_pop  (void);
OBJ  stack_peek (U32 I);



/* CREATE NEW OBJECTS IN THE HEAP
 */
void mem_obj_new (desc_t desc, U32 size);
void mem_obj_new_static (desc_t desc, U32 size);

#define mem_new_ary(t,l)    (mem_obj_new(MAKE_DESC(t,l),ary_to_size(l)))

#define mem_new_static(t,l) (mem_obj_new_static(MAKE_DESC(t,l),ary_to_size(l)))

#define mem_new_drt(t,l)    (mem_obj_new(MAKE_DESC(t,sizeof(void*)+l),ary_to_size(sizeof(void*)+l)),mem_heap_inc_dirtycount())

#define mem_new_vec(t,l)    (mem_obj_new(MAKE_DESC(t,l),vec_to_size(l)))

/* THE FIRST ITEM IN A STACK (VECTOR) IS U32 REPRESENTING OBJECT COUNT*/
#define mem_new_stk(t,l)    (mem_obj_new(MAKE_DESC(t,l),vec_to_size(l)))



/* SWAP STACK WITH ACC
 */
void mem_swap_stack (void);



/* FORCE GARBAGE COLLECTION.  PASSED SIZE OF DESIRED OBJECT SIZE FOR NEXT NEW.
 */
void mem_gc (U32 desired);



/* DEVELOPMENT DEBUGGING AIDS.
 */
void mem_heap_info (void);
void mem_stats_dump (void);
void mem_heap_obj_dump (OBJ o);
/*void mem_obj_dump (OBJ o);*/



#endif