Implemented C x86 paging, removed C++ code

src/x86/mmgr.c

@@ -0,0 +1,121 @@
+#include "mmgr.h"
+#include "pageallocator.h"
+#include "string.h"
+#include "types/status.h"
+#include <stdint.h>
+
+const size_t page_size = 4096;
+
+const size_t page_bits = 12;
+
+struct page_table_entry_t
+{
+    uint32_t present : 1;
+
+	uint32_t rw : 1;
+
+	uint32_t usermode : 1;
+
+	uint32_t writeThrough : 1;
+
+	uint32_t cacheDisable : 1;
+
+	uint32_t accessed : 1;
+
+	uint32_t dirty : 1;
+
+	uint32_t pat : 1;
+
+	uint32_t global : 1;
+    
+	uint32_t shared : 1;
+
+	uint32_t ignored : 2;
+
+	uint32_t physicalAddress : 20;
+};
+
+struct page_table_entry_t *page_tables = (struct page_table_entry_t*) 0xFFC00000;
+
+struct page_table_entry_t *page_directory = (struct page_table_entry_t*) 0xFFFFF000;
+
+physaddr_t create_address_space(struct page_stack_t *page_stack)
+{
+    physaddr_t table = reserve_page(page_stack);
+    if(table == S_OUT_OF_MEMORY)
+    {
+        return S_OUT_OF_MEMORY;
+    }
+    struct page_table_entry_t buffer = page_directory[0];
+    page_directory[0] = table;
+    asm volatile("invlpg $0xFFC00000" ::: "memory");
+    memset((void*) page_tables, 0, 1022 * 4);
+    page_tables[1022] = page_directory[1022];
+    page_tables[1023] = page_directory[1023];
+    page_directory[0] = buffer;
+    asm volatile("invlpg $0xFFC00000" ::: "memory");
+    return table;
+}
+
+void load_address_space(physaddr_t table)
+{
+    asm volatile("mov %0, %%cr3"
+        :
+        : "r" (table)
+        : "memory");
+}
+
+int map_page(struct page_stack_t *page_stack, void *page, physaddr_t frame, int flags)
+{
+    if((size_t) page % page_size != 0 || frame % page_size != 0)
+    {
+        return S_OUT_OF_BOUNDS;
+    }
+    size_t table_index = (size_t) page / page_size;
+    size_t directory_index = table_index / (page_size / sizeof(struct page_table_entry_t));
+    if(!page_directory[directory_index].present)
+    {
+        physaddr_t new_table = reserve_page(page_stack);
+        if(new_table == S_OUT_OF_MEMORY)
+        {
+            return S_OUT_OF_MEMORY;
+        }
+        page_directory[directory_index] = new_table >> page_bits;
+        page_directory[directory_index].present = 1;
+        page_directory[directory_index].usermode = 0;
+        page_directory[directory_index].rw = 1;
+    }
+    page_tables[table_index] = frame >> 12;
+    page_tables[table_index].present = 1;
+    page_tables[table_index].usermode = 1;
+    page_tables[table_index].rw = 1;
+    asm volatile("invlpg (%0)"
+        :
+        : "r" (page)
+        : "memory");
+    return S_OK;
+}
+
+physaddr_t unmap_page(void *page)
+{
+    if((size_t) page % page_size != 0)
+    {
+        return S_OUT_OF_BOUNDS;
+    }
+    size_t table_index = (size_t) page / page_size;
+    size_t directory_index = table_index / (page_size / sizeof(struct page_table_entry_t));
+    if(!page_directory[directory_index].present || !page_tables[table_index].present)
+    {
+        return S_OUT_OF_BOUNDS;
+    }
+    else
+    {
+        physaddr_t frame = page_tables[table_index].physicalAddress << page_bits;
+        memset(&page_tables[table_index], 0, sizeof(struct page_table_entry_t));
+        asm volatile("invlpg (%0)"
+            :
+            : "r" (page)
+            : "memory");
+        return frame;
+    }
+}