// vmm.c
// Author: Josh Holtrop
// Date: 09/30/03

PageDirectory	*vmm_PDBR = 0;
dword	vmm_first_virtual_address = 0;


void	vmm_init()
{
	if(!(vmm_PDBR = mm_palloc(1, PID_KERNEL)))
	{
		printf("ERROR! COULD NOT ALLOCATE PAGE FOR INITIAL PAGE DIRECTORY!!\n");
		halt();
	}
	dword address = 0;
	PageTable *tmp;
	int pde;
	int pte;
	for (pde = 0; pde<1024; pde++)
	{
		for (pte = 0; pte<1024; pte++)
		{
			if (pte == 0)
			{
				if (!(tmp = mm_palloc(1, PID_KERNEL)))
				{
					printf("ERROR! Page could not be allocated for PDE %d, PTE %d!\n", pde, pte);
					halt();
				}
				vmm_PDBR->pageTables[pde] = ((dword)tmp | 0x00000003);	//present, read/write, supervisor priviledge
			}
			tmp = (PageTable *)((vmm_PDBR->pageTables[pde]) & 0xFFFFF000);	//mask out address of page table
			tmp->page[pte] = (address | 0x00000003);	//present, read/write, supervisor priviledge
			address += 4096;
			if (address >= mm_totalmem)
				pte = pde = 2000;
		}
	}

	//we also need to map in the video framebuffer memory:
	dword framebuffer_end = video_mode.PhysBasePtr + video_mode.BitsPerPixel/8 * video_mode.XResolution * video_mode.YResolution;	//framebuffer size in bytes
	address = video_mode.PhysBasePtr;
	if (address != 0)	//we do have a graphics buffer
	{
		pde = (address & 0xFFC00000) >> 22;
		pte = (address & 0x003FF000) >> 12;
		if (pte != 0)
			vmm_PDBR->pageTables[pde] = (dword)mm_palloc(1, PID_KERNEL) | 0x03; 	//present, read/write, supervisor priviledge
		for ( ; pde<1024; pde++) 	//top 10 bits are page directory index
		{
			for ( ; pte<1024; pte++)	//next 10 bits page table index
		 		{
				if (pte == 0)
				{
					if (!(tmp = mm_palloc(1, PID_KERNEL)))
					{
						printf("ERROR! Page could not be allocated for PDE %d, PTE %d!\n", pde, pte);
						halt();
					}
					vmm_PDBR->pageTables[pde] = ((dword)tmp | 0x00000003);	//present, read/write, supervisor priviledge
				}
				tmp = (PageTable *)((vmm_PDBR->pageTables[pde]) & 0xFFFFF000);	//mask out address of page table
				tmp->page[pte] = (address | 0x00000003);	//present, read/write, supervisor priviledge
				address += 4096;
				if (address >= framebuffer_end)
					pte = pde = 2000;
			 }
			 pte = 0;
		}
	}
}


void	*malloc(dword bytes)
{


}



int	free(void *ptr)
{




}