#include <main.h>
#include <paging.h>
#include <console.h>

uint32_t *page_directory;
uint32_t *page_tables[1024];

void set_page_directory(uint32_t page_directory)
{
	asm volatile("mov %0, %%cr3":: "b"(page_directory));
}

void enable_paging()
{
	unsigned int cr0;
	asm volatile("mov %%cr0, %0": "=b"(cr0));
	cr0 |= CR0_ENABLE_PAGING;
	asm volatile("mov %0, %%cr0":: "b"(cr0));
}

void paging_map_4kb(uint32_t vmem, uint32_t pmem)
{
	uint32_t pdEntry = vmem >> 22;
	uint32_t ptEntry = (vmem >> 12) % 1024;
	
	//kprintf("[ PAGING ] Mapping PDEntry: %d, PTEntry: %d\n     Wert in der PageTable: 0x%x\n", pdEntry, ptEntry, pmem | FLAG_PRESENT | FLAG_WRITEABLE | FLAG_ACCESS);
	
	((uint32_t*)(page_directory[pdEntry] & ~(FLAG_PRESENT | FLAG_WRITEABLE | FLAG_ACCESS | FLAG_WT_CACHE | FLAG_NO_CACHE | FLAG_PT_USED | FLAG_WRITTEN | FLAG_4MB_PAGES | FLAG_KEEP_TLB)))[ptEntry] = pmem | FLAG_PRESENT | FLAG_WRITEABLE | FLAG_ACCESS;
	
	asm volatile("invlpg %0"::"m"(*(char*)vmem));
}

/// Mappt [size] Seiten von der angegebenen physischen Adresse in die angegebene virtuelle Adresse
void paging_map_physical(uint32_t vmem, uint32_t pmem, uint32_t size)
{
	unsigned int i;
	for(i = 0; i < size; i++)
	{
		paging_map_4kb(vmem + (i * 0x1000), pmem + (i * 0x1000));
	}
}

void init_paging()
{
	page_directory = pmm_alloc();
	
	//kprintf("[ PAGING ] Page directory is located at 0x%x\n", page_directory);
	
	unsigned int i;
	for(i = 0; i < 1024; i++)
	{
		page_tables[i] = pmm_alloc();
		page_directory[i] = (uint32_t)page_tables[i] | FLAG_PRESENT | FLAG_WRITEABLE | FLAG_ACCESS;
		//kprintf("[ PAGING ] Page table %d is located at 0x%x\n", i, page_tables[i]);
	}
	
	paging_map_physical(0, 0, 4096);
	
	set_page_directory((uint32_t)page_directory);
	//kprintf("[ PAGING ] Page directory set\n");
	//enable_paging();
	//kprintf("[ PAGING ] Paging enabled\n");
}