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

/*******************************
 * Useful routines			   *
 *******************************/
void PagingInitialize(uint32 kernel_used)
{
	Log("Mem", "Virtual memory manager initialization started. End of kernel = 0x%x\n", kernel_used);
	PageDirectory* kernelPd = (PageDirectory*) kmalloc_a(sizeof(PageDirectory));
	memset(kernelPd, 0, sizeof(PageDirectory));

	CurrentDirectory = kernelPd;
	KernelDirectory = kernelPd;

	uint32 i;
	for (i = 0; i < kernel_used; i+=0x1000)
		MemPhAllocFrame(PagingGetPage(i, 1, kernelPd), 0, 0);

	Log("Mem", "Identity mapped first 0x%x bytes.\n", kernel_used);

	for (i = KERNEL_HEAP_START; i < KERNEL_HEAP_END; i+=0x1000)
		MemPhAllocFrame(PagingGetPage(i, 1, kernelPd), 1, 1);

	Log("Mem", "Mapped kernel space.\n");

	PagingSwitchPageDirectory (kernelPd);
}

void PagingSwitchPageDirectory (PageDirectory* dir)
{
	CurrentDirectory = dir;
	asm volatile ("mov %0, %%cr3":: "r"(&dir->TablesPhysical));

	uint32 cr0;
	asm volatile ("mov %%cr0, %0": "=r"(cr0));
	cr0 |= 0x80000000;
	asm volatile ("mov %0, %%cr0":: "r"(cr0));

	Log("Mem", "Enabled paging.\n");
}

Page* PagingGetPage(uint32 addr, uint8 make, PageDirectory* dir)
{
	addr >>= 12;

	uint32 tableIndex = addr >> 10;

	if (dir->Tables[tableIndex])
		return &dir->Tables[tableIndex]->Pages[addr&0x3ff];

	else if (make)
	{
		uint32 temp;
		dir->Tables[tableIndex] = (PageTable*)kmalloc_ap(sizeof(PageTable), &temp);
		memset (dir->Tables[tableIndex], 0, 0x1000);
		dir->TablesPhysical[tableIndex] = temp | 0x7;
		return &dir->Tables[tableIndex]->Pages[addr&0x3ff];
	}

	else return 0;
}