#include "kernel.h"

enum PAGE_PTE_FLAGS {
 
    I86_PTE_PRESENT		=	1,		//0000000000000000000000000000001
    I86_PTE_WRITABLE		=	2,		//0000000000000000000000000000010
    I86_PTE_USER		=	4,		//0000000000000000000000000000100
    I86_PTE_WRITETHOUGH		=	8,		//0000000000000000000000000001000
    I86_PTE_NOT_CACHEABLE	=	0x10,		//0000000000000000000000000010000
    I86_PTE_ACCESSED		=	0x20,		//0000000000000000000000000100000
    I86_PTE_DIRTY		=	0x40,		//0000000000000000000000001000000
    I86_PTE_PAT			=	0x80,		//0000000000000000000000010000000
    I86_PTE_CPU_GLOBAL		=	0x100,		//0000000000000000000000100000000
    I86_PTE_LV4_GLOBAL		=	0x200,		//0000000000000000000001000000000
    I86_PTE_FRAME		=	0x7FFFF000 	//1111111111111111111000000000000
};

enum PAGE_PDE_FLAGS {
 
    I86_PDE_PRESENT		=	1,		//0000000000000000000000000000001
    I86_PDE_WRITABLE		=	2,		//0000000000000000000000000000010
    I86_PDE_USER		=	4,		//0000000000000000000000000000100
    I86_PDE_PWT			=	8,		//0000000000000000000000000001000
    I86_PDE_PCD			=	0x10,		//0000000000000000000000000010000
    I86_PDE_ACCESSED		=	0x20,		//0000000000000000000000000100000
    I86_PDE_DIRTY		=	0x40,		//0000000000000000000000001000000
    I86_PDE_4MB			=	0x80,		//0000000000000000000000010000000
    I86_PDE_CPU_GLOBAL		=	0x100,		//0000000000000000000000100000000
    I86_PDE_LV4_GLOBAL		=	0x200,		//0000000000000000000001000000000
    I86_PDE_FRAME		=	0x7FFFF000 	//1111111111111111111000000000000
};

//! page table entry
typedef uint32_t pt_entry;

//! a page directery entry
typedef uint32_t pd_entry;

////

//! virtual address
typedef uint32_t virtual_addr;
typedef uint32_t physical_addr;

typedef uint8_t bool;
 
//! i86 architecture defines 1024 entries per table--do not change
#define PAGES_PER_TABLE 1024
#define PAGES_PER_DIR	1024

#define PAGE_DIRECTORY_INDEX(x) (((x) >> 22) & 0x3ff)
#define PAGE_TABLE_INDEX(x) (((x) >> 12) & 0x3ff)
#define PAGE_GET_PHYSICAL_ADDRESS(x) (*x & ~0xfff)

//! page table represents 4mb address space
#define PTABLE_ADDR_SPACE_SIZE 0x400000

//! directory table represents 4gb address space
#define DTABLE_ADDR_SPACE_SIZE 0x100000000

//! page sizes are 4k
#define PAGE_SIZE 4096
 
//! page table
struct ptable {
 
    pt_entry m_entries[PAGES_PER_TABLE];
};
 
//! page directory
struct pdirectory {
 
    pd_entry m_entries[PAGES_PER_DIR];
};

void 		pt_entry_add_attrib (pt_entry* e, uint32_t attrib)
{
}
void 		pt_entry_del_attrib (pt_entry* e, uint32_t attrib)
{
}
void 		pt_entry_set_frame (pt_entry* e , physical_addr addr)
{
}
bool 		pt_entry_is_present (pt_entry e)
{
    return 1;
}
bool 		pt_entry_is_writable (pt_entry e)
{
    return 1;
}
physical_addr	pt_entry_pfn (pt_entry e)
{
    return 1;
}

void		pd_entry_add_attrib (pd_entry* e, uint32_t attrib)
{
}

void		pd_entry_del_attrib (pd_entry* e, uint32_t attrib)
{
}
void		pd_entry_set_frame (pd_entry* e, physical_addr add)
{
}
bool		pd_entry_is_present (pd_entry e)
{
    return 1;
}
bool		pd_entry_is_user (pd_entry e)
{
    return 1;
}

bool		pd_entry_is_4mb (pd_entry e)
{
    return 1;
}

bool		pd_entry_is_writable (pd_entry e)
{
    return 1;
}

physical_addr	pd_entry_pfn (pd_entry e)
{
    return 1;
}

void		pd_entry_enable_global (pd_entry e)
{
}

uint8_t vmmngr_alloc_page (pt_entry* e) 
{
 
	//! allocate a free physical frame
	void* p = pmmngr_alloc_block ();
	if (!p)
		return 0;
 
	//! map it to the page
	pt_entry_set_frame (e, (physical_addr)p);
	pt_entry_add_attrib (e, I86_PTE_PRESENT);

	return 1;
}

void vmem_init()
{

}