Give flags to the the paging structures

src/mem.c

@@ -3,16 +3,17 @@
 */
 
 #include "mem.h"
+#include "serial.h"
 
 // page_directory is currently defined once and should not be touched
 // later. It must be page aligned for the MMU to read properly
-uint32_t page_directory[1024] __attribute__((aligned(4096)));
+page_directory_entry page_directory[1024] __attribute__((aligned(4096)));
 
 // page_table_one is the first page table, and at the beginning the
 // only page table in the page directory
-uint32_t page_table_one[1024] __attribute__((aligned(4096)));
+page_table_entry page_table_one[1024] __attribute__((aligned(4096)));
 
-uint32_t* initiate_directory() {
+page_directory_entry* initiate_directory() {
     // set each entry to not present
     int i;
     for(i = 0; i < 1024; i++)
@@ -22,13 +23,14 @@ uint32_t* initiate_directory() {
         //   Write Enabled: It can be both read from and written to
         //     (this is the 2 bit)
         //   Not Present: The page table is not present
-        page_directory[i] = 0x00000002;
+        page_directory[i] = 0;
+        page_directory[i] |= PAGE_WRITABLE;
     }
 
     return page_directory;
 }
 
-void initiate_page_table(uint32_t* page_dir) {
+void initiate_page_table(page_directory_entry* page_dir) {
     // holds the physical address where we want to start mapping these pages to.
     // in this case, we want to map these pages to the very beginning of memory.
     unsigned int i;
@@ -39,9 +41,13 @@ void initiate_page_table(uint32_t* page_dir) {
         // As the address is page aligned, it will always leave 12 bits zeroed.
         // Those bits are used by the attributes:
         //    -> supervisor level, read/write, present.
-        page_table_one[i] = (i * 0x1000) | 3;
+        page_table_one[i] = 0;
+        page_table_one[i] |= i << 12;
+        page_table_one[i] |= PAGE_WRITABLE | PAGE_PRESENT;
     }
 
     // attributes: supervisor level, read/write, present
-    page_dir[0] = ((unsigned int)page_table_one) | 3;
+    page_dir[0] = (uint32_t) page_table_one;
+    page_dir[0] |= PAGE_WRITABLE | PAGE_PRESENT;
+
 }

src/mem.h

@@ -2,13 +2,31 @@
   mem.h
 */
 
-#pragma once
+#ifndef _MEM_INC
+#define _MEM_INT
+
+#include <stdbool.h>
 #include <stdint.h>
 
+// Flags for pages directory entries and table entries
+#define PAGE_PRESENT        0x1
+#define PAGE_WRITABLE       0x2
+#define PAGE_USER           0x4
+#define PAGE_WRITE_THROUGH  0x8
+#define PAGE_CACHE_DISABLED 0x10
+#define PAGE_ACCESSED       0x20
+#define PAGE_DIRTY          0x80
+#define PAGE_SIZE_FLAG      0x80
+
+typedef uint32_t page_directory_entry;
+typedef uint32_t page_table_entry;
+
 // These two are defined in the assembly file paging.asm
-extern void loadPageDirectory(uint32_t*);
+extern void loadPageDirectory(page_directory_entry*);
 extern void enablePaging();
 
 // Defined in the file mem.c
-uint32_t* initiate_directory();
- void initiate_page_table(uint32_t* page_dir);
+page_directory_entry* initiate_directory();
+void initiate_page_table(page_directory_entry* page_dir);
+
+#endif