/*
 * memory-vi.c
 *
 *  Created on: Aug 23, 2011
 *      Author: Tiberiu
 */
#include <memory-add.h>
#include <stdio.h>

/*******************************
 * Data						   *
 *******************************/
PageDirectory* CurrentDirectory;
PageDirectory* KernelDirectory;

void PagingEnable()
{
	uint32 tmp;
	asm volatile ("mov %%cr0, %0" : "=r"(tmp));
	tmp |= 0x80000000;
	asm volatile ("mov %0, %%cr0" : : "r"(tmp));
}

void PagingDisable()
{
	uint32 tmp;
	asm volatile ("mov %%cr0, %0" : "=r"(tmp));
	tmp &= 0x7FFFFFFF;
	asm volatile ("mov %0, %%cr0" : : "r"(tmp));
}

void PagingSwitchDirectory(PageDirectory* dir)
{
	CurrentDirectory = dir;
	asm volatile ("mov %0, %%cr3" : : "r"(dir->PhysicalAddr));
}

void PagingFlushTlb ()
{
	uint32 tmp;
	asm volatile ("mov %%cr3, %0" : "=r"(tmp));
	asm volatile ("mov %0, %%cr3" : : "r" (tmp));
}

void PagingInitialize(uint32* kernelEnd)
{
	// Create the kernel page directory
	PageDirectory* kdir = kmalloc_a(sizeof(PageDirectory));
	memset(kdir, 0, sizeof(PageDirectory));

	KernelDirectory = kdir;

	// Set up physical address of PDEs.
	kdir->PhysicalAddr = (uint32) kdir->TablesPhysical;

	// Identity map the kernel
	uint32 i = 0;
	while (i <= *kernelEnd + 1024)
	{
		PagingMapPage(i, i, PageWriteable, kdir);
		i += 0x1000;
	}

	// Reserve the identity mapped blocks
	MemPhReserveBlocks(0x0, *kernelEnd);

	PagingSwitchDirectory(kdir);
	PagingEnable();
}

void PagingMapPage (uint32 phys, uint32 virt, uint32 flags, PageDirectory* pd)
{
	// Calculate pde and pte
	uint32 pde = virt >> 22;
	uint32 pte = (virt >> 12) & 0x3ff;

	phys &= 0xFFFFF000;	// Make sure address is page aligned
	flags &= 0xFFF;		// Make sure flags don't overflow

	// See if page table exists
	if (!pd->Tables[pde])
	{
		// No? allocate it
		uint32 ph;
		PageTable* pt = kmalloc_ap(sizeof(PageTable), &ph);
		memset(pt, 0, sizeof(PageTable));

		pd->Tables[pde] = pt;
		pd->TablesPhysical[pde] = ph | 0x7;
	}

	// Set up the page
	pd->Tables[pde]->Pages[pte] = phys | flags | 0x1; // Present, and flags

	// If it is the current directory, flush the tlb to notice the change
	if (pd == CurrentDirectory) PagingFlushTlb();
}

void PagingUnmapPage (uint32 virt, PageDirectory* pd)
{
	// Calculate pde and pte
	uint32 pde = virt >> 22;
	uint32 pte = (virt >> 12) & 0x3ff;

	if (!pd->Tables[pde] || !pd->Tables[pde]->Pages[pte]) return;

	// Get physical address
	uint32 phys = pd->Tables[pde]->Pages[pte] & PageFrame;

	// Free page
	pd->Tables[pde]->Pages[pte] = 0;
	MemPhFreeBlock(phys);

	// If it is the current directory, flush the tlb to notice the change
	if (pd == CurrentDirectory) PagingFlushTlb();
}

uint32 PagingGetPhysical (uint32 virt, PageDirectory* pd)
{
	// Calculate pde and pte
	uint32 pde = virt >> 22;
	uint32 pte = (virt >> 12) & 0x3ff;

	// Not mapped
	if (!pd->Tables[pde] || !pd->Tables[pde]->Pages[pte]) return NULL;

	return (pd->Tables[pde]->Pages[pte] & PageFrame);
}