working on virtual memory manager

1 files changed, 76 insertions, 0 deletions

diff --git a/kernel/vmem.c b/kernel/vmem.c
new file mode 100644
index 0000000..d434dee
--- /dev/null
+++ b/kernel/vmem.c
@@ -0,0 +1,76 @@
+#include "kernel.h"
+
+enum PAGE_PTE_FLAGS {
+ 
+    I86_PTE_PRESENT		=	1,		//0000000000000000000000000000001
+    I86_PTE_WRITABLE		=	2,		//0000000000000000000000000000010
+    I86_PTE_USER		=	4,		//0000000000000000000000000000100
+    I86_PTE_WRITETHOUGH		=	8,		//0000000000000000000000000001000
+    I86_PTE_NOT_CACHEABLE	=	0x10,		//0000000000000000000000000010000
+    I86_PTE_ACCESSED		=	0x20,		//0000000000000000000000000100000
+    I86_PTE_DIRTY		=	0x40,		//0000000000000000000000001000000
+    I86_PTE_PAT			=	0x80,		//0000000000000000000000010000000
+    I86_PTE_CPU_GLOBAL		=	0x100,		//0000000000000000000000100000000
+    I86_PTE_LV4_GLOBAL		=	0x200,		//0000000000000000000001000000000
+    I86_PTE_FRAME		=	0x7FFFF000 	//1111111111111111111000000000000
+};
+
+enum PAGE_PDE_FLAGS {
+ 
+    I86_PDE_PRESENT		=	1,		//0000000000000000000000000000001
+    I86_PDE_WRITABLE		=	2,		//0000000000000000000000000000010
+    I86_PDE_USER		=	4,		//0000000000000000000000000000100
+    I86_PDE_PWT			=	8,		//0000000000000000000000000001000
+    I86_PDE_PCD			=	0x10,		//0000000000000000000000000010000
+    I86_PDE_ACCESSED		=	0x20,		//0000000000000000000000000100000
+    I86_PDE_DIRTY		=	0x40,		//0000000000000000000000001000000
+    I86_PDE_4MB			=	0x80,		//0000000000000000000000010000000
+    I86_PDE_CPU_GLOBAL		=	0x100,		//0000000000000000000000100000000
+    I86_PDE_LV4_GLOBAL		=	0x200,		//0000000000000000000001000000000
+    I86_PDE_FRAME		=	0x7FFFF000 	//1111111111111111111000000000000
+};
+
+//! page table entry
+typedef uint32_t pt_entry;
+
+//! a page directery entry
+typedef uint32_t pd_entry;
+
+////
+
+//! virtual address
+typedef uint32_t virtual_addr;
+ 
+//! i86 architecture defines 1024 entries per table--do not change
+#define PAGES_PER_TABLE 1024
+#define PAGES_PER_DIR	1024
+
+#define PAGE_DIRECTORY_INDEX(x) (((x) >> 22) & 0x3ff)
+#define PAGE_TABLE_INDEX(x) (((x) >> 12) & 0x3ff)
+#define PAGE_GET_PHYSICAL_ADDRESS(x) (*x & ~0xfff)
+
+//! page table represents 4mb address space
+#define PTABLE_ADDR_SPACE_SIZE 0x400000
+
+//! directory table represents 4gb address space
+#define DTABLE_ADDR_SPACE_SIZE 0x100000000
+
+//! page sizes are 4k
+#define PAGE_SIZE 4096
+ 
+//! page table
+struct ptable {
+ 
+    pt_entry m_entries[PAGES_PER_TABLE];
+};
+ 
+//! page directory
+struct pdirectory {
+ 
+    pd_entry m_entries[PAGES_PER_DIR];
+};
+
+void vmem_init()
+{
+    scr_put_string_nl("todo: init paging");
+}