#ifndef KERNEL_VM_OBJECT_H_
#define KERNEL_VM_OBJECT_H_

#include <kernel/locks.h>
#include <kernel/object.h>

#define VM_OBJECT_NAME_MAX 64

enum vm_object_flags {
	/* the memory behind this vm-object wasn't allocated by us, and
	 * therefore shouldn't be freed by us */
	VMO_IN_PLACE = 0x01u,
};

struct vm_object {
	struct object vo_base;

	char vo_name[VM_OBJECT_NAME_MAX];
	enum vm_object_flags vo_flags;

	/* queue of struct vm_region_mapping */
	struct queue vo_mappings;

	/* memory protection flags. mappings of this vm_object can only use
	 * a subset of the flags set in this mask. */
	vm_prot_t vo_prot;

	/* btree of vm_pages that have been allocated to this vm_object.
	 * vm_page->p_vmo_offset and the size of each page is the bst key. */
	struct btree vo_pages;
	/* total length of the vm_object in bytes. */
	size_t vo_size;
};

extern kern_status_t vm_object_type_init(void);
extern struct vm_object *vm_object_cast(struct object *obj);

/* create a vm_object with the specified length in bytes and protection flags.
 * the length will be automatically rounded up to the nearest vm_object page
 * order size. the actual page frames themselves won't be allocated until
 * they are mapped and accessed. */
extern struct vm_object *vm_object_create(
	const char *name,
	size_t name_len,
	size_t data_len,
	vm_prot_t prot);

/* create a vm_object that represents the specified range of physical memory.
 * the length will be automatically rounded up to the nearest vm_object page
 * order size.
 * NOTE this function assumes that the physical memory has already been
 * reserved, and is not in use by any other kernel component. */
extern struct vm_object *vm_object_create_in_place(
	const char *name,
	size_t name_len,
	phys_addr_t base,
	size_t data_len,
	vm_prot_t prot);

extern struct vm_page *vm_object_get_page(
	const struct vm_object *vo,
	off_t offset);

extern struct vm_page *vm_object_alloc_page(
	struct vm_object *vo,
	off_t offset,
	enum vm_page_order size);

extern kern_status_t vm_object_read(
	struct vm_object *vo,
	void *dst,
	off_t offset,
	size_t count,
	size_t *nr_read);
extern kern_status_t vm_object_write(
	struct vm_object *vo,
	const void *dst,
	off_t offset,
	size_t count,
	size_t *nr_written);
extern kern_status_t vm_object_copy(
	struct vm_object *dst,
	off_t dst_offset,
	struct vm_object *src,
	off_t src_offset,
	size_t count,
	size_t *nr_copied);

DEFINE_OBJECT_LOCK_FUNCTION(vm_object, vo_base)

#endif