unsigned int
*get_page_directory (void)
{
    return (unsigned int *)0x9c000;
}

void
add_page (unsigned int v_addr, unsigned int p_addr)
{
    int offset = v_addr / (4096*1024);
    int i;
    unsigned int *page_directory = get_page_directory();//Make sure that this address is properly page aligned
    unsigned int *page_table = page_directory + (1024 * (offset+1));
    for (i=0;i<1024;i++) {
            page_table[i] = p_addr | 3; // attributes: supervisor level, read/write, present.
            p_addr = p_addr + 4096; //advance the address to the next page boundary
    }
    page_directory[offset] = page_table;
    page_directory[offset] |= 3;// attributes: supervisor level, read/write, present
}

void
page_initialize (void)
{
    unsigned int *page_directory = get_page_directory();//Make sure that this address is properly page aligned
    //set each entry to not present
    int i = 0;
    for (i = 0; i < 1024; i++) {
        //attribute: supervisor level, read/write, not present.
        page_directory[i] = 0 | 2;
    }

    add_page(0, 0);
    add_page(0x400000, 0x400000);
    add_page(0x800000, 0x800000);
    add_page(0xC00000, 0xC00000);
    add_page(0xFD000000, 0xFD000000);


    __asm__ volatile("mov %0, %%cr3":: "b"(page_directory));
    //reads cr0, switches the "paging enable" bit, and writes it back.
    unsigned int cr0;
    asm volatile("mov %%cr0, %0": "=b"(cr0));
    cr0 |= 0x80000000;
    asm volatile("mov %0, %%cr0":: "b"(cr0));

}