Restructering Kernel folder before moving to higher half kernel

The boot up process will be changed somewhat dramatically, therefor a
restructering of the kernel seems as a good starting point.

src/kernel/Memory/paging.cpp

@@ -0,0 +1,170 @@
+#include "paging.h"
+PageDirectoryEntry kernel_directory[MAX_DIRECTORY_ENTRIES]__attribute__((aligned(4096)));
+
+PageTableEntry first_page_table[MAX_PAGE_TABLE_ENTRIES]__attribute__((aligned(4096)));
+
+void IdentityMap (){
+        printf("\nInit paging\n");
+    // The basics as explained by wiki.osdev.org
+
+    // Set all page_directories to not present
+    int i = 0;
+    while ( i < 1024)
+    {
+        kernel_directory[i] = 0x2;
+        i++;
+    }
+
+
+    // map 4 megabytes 
+    unsigned int j ;
+    for( j = 0;  j < 1024; j++ )
+    {
+        first_page_table[j] = (j * 0x1000) | 3 ;
+        
+        //Attributes: 
+        //Supervisor Level ,
+        //read/write,
+        //present,
+        
+
+    }
+
+    // Put the page table in the page directory 
+    // attributes: supervisor level, read/write, present;
+    kernel_directory[0] = ((unsigned int)first_page_table) | 3;
+
+    printf("Init paging DONE\n");
+}
+
+void InitializePaging()
+{
+    /*
+        Initial kernel page directory
+         set all page tables to not present
+    */
+    for (int i = 0; i < MAX_DIRECTORY_ENTRIES; i++)
+    {
+        kernel_directory[i] = 0x2;
+    }
+
+    // BIOS Address Identity mapping 
+    // Identity map the first 8MiB ... Physical addresses 0x00000000 to 0x007A1200
+    PHYSICAL_ADDRESS BIOSAddr = 0x00000000;
+    PHYSICAL_ADDRESS BIOSAddr_Max = 0x800000;
+
+    // How many PDE's do we need
+    uint8_t NUM_PDE = BIOSAddr_Max / (4 * 1024 * 1024);
+
+    printf("The first 8MiB require %d Page Directory Entries\n", NUM_PDE);
+/*
+    for( int i = 0; i < NUM_PDE; i++)
+    {
+        // setup a page table 
+        PageTableEntry pagetable[MAX_PAGE_TABLE_ENTRIES] = PhysicalMemory::allocate_block(); // TODO :: Physical memory manager functions should be available here.
+
+        for(int j = 0; j < MAX_PAGE_TABLE_ENTRIES; j++)
+        {
+            pagetable[j] = ( j  *  4096 ) | 3;
+        }
+
+        // add page table as page directory entry 
+        kernel_directory[i] =  ( (unsigned int) pagetable ) | 3;
+    }
+*/
+    //  map the kernel space 
+    VIRTUAL_ADDRESS Vaddr = KERNEL_VRT_MEMORY_BEGIN;
+    PHYSICAL_ADDRESS KernelAddr = kernel_begin;
+    PHYSICAL_ADDRESS KernelEndAddr = kernel_end;
+
+    uint32_t KernelSizeInBytes = (KernelEndAddr - KernelAddr);
+    printf("Kernel is 0x%x bytes\n", KernelSizeInBytes);
+    NUM_PDE = KernelSizeInBytes / (4 * 1024* 1024);
+    printf("Kernel requires %d Page Directory Entries\n", NUM_PDE);
+
+/*
+    for(int i = 0; i < NUM_PDE; i++)
+    {
+        PageTableEntry pageTable [MAX_PAGE_TABLE_ENTRIES] = PhysicalMemory::allocate_block();
+
+        for(int j = 0; j < MAX_PAGE_TABLE_ENTRIES; j++)
+        {
+            pageTable[j] = ( j * 4096) | 3; // NOTE: Check if page is actually supposed to be present
+        }
+
+        // TODO: Calculate Page Directory index 
+        
+
+
+    }
+    */
+
+    
+
+
+    // Identity map VGA memory
+    // Calc which PDE adn 
+    
+}
+
+
+void AllocatePage(VIRTUAL_ADDRESS vaddr, PageDirectoryEntry& page_directory)
+{
+
+}
+
+void FreePage(VIRTUAL_ADDRESS vaddr , PageDirectoryEntry& page_directory)
+{
+
+}
+
+void Map ( PHYSICAL_ADDRESS paddr, VIRTUAL_ADDRESS vaddr, PageDirectoryEntry& page_directory)
+{
+
+
+
+}
+
+void Unmap(VIRTUAL_ADDRESS vaddr, PageDirectoryEntry& page_directory)
+{
+    // NOTE: I will implement lazy unmapping for now 
+    
+}
+
+void Enable()
+{ 
+
+    //TODO: Write  protect will not be turned on 
+    // for the moment altough according to the intel
+    // developer manual this should happen.
+
+    uint32_t CR0;
+    
+    CR0 =  GetCR0();
+    printf("PG bit = %d \n" , GET_PG_BIT(CR0));
+
+    printf("Load into CR3 address: 0x%x\n", (uint32_t)(&kernel_directory[0]));
+    loadPageDirectory(&kernel_directory[0]);
+    enablePaging();
+
+    printf("Paging enabled!\n");
+
+
+    CR0 = GetCR0();
+    uint32_t CR4 = GetCR4();
+    printf("PG bit = %d\n" , GET_PG_BIT(CR0) );
+    printf("PAE bit = %d\n", GET_PAE_BIT(CR4));
+
+    if(GET_PAE_BIT(CR4) == 0){
+        printf("Using 32bit paging\n");
+
+        if(GET_PSE_BIT(CR4) == 0 ){
+            printf("Page size is 4KiB\n");
+        } else { 
+            printf("Page size is 4MiB\n");
+        }
+    }  else {
+        printf("Using some extended version for paging\n");
+    }
+
+}