1 files changed, 60 insertions, 0 deletions
diff --git a/kernel/inc/gdt.h b/kernel/inc/gdt.h
new file mode 100644
index 0000000..06388a9
--- /dev/null
+++ b/kernel/inc/gdt.h
@@ -0,0 +1,60 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#ifndef GDT_H
+#define GDT_H
+
+#include <def.h>
+
+#define GDT_SUPER_CODE_OFFSET 0x08 // Super (kernel) code segment offset in GDT
+#define GDT_SUPER_DATA_OFFSET 0x10 // Super (kernel) data segment offset in GDT
+#define GDT_USER_CODE_OFFSET 0x1b // User code segment offset in GDT (with ring3 mask)
+#define GDT_USER_DATA_OFFSET 0x23 // User data segment offset in GDT (with ring3 mask)
+
+struct gdt_entry {
+	u16 limit_low;
+	u16 base_low;
+	u8 base_middle;
+	u8 access;
+	u8 granularity;
+	u8 base_high;
+} PACKED;
+
+struct gdt_ptr {
+	u16 limit;
+	void *base;
+} PACKED;
+
+struct tss_entry {
+	u32 prev_tss;
+	u32 esp0;
+	u32 ss0;
+	u32 esp1;
+	u32 ss1;
+	u32 esp2;
+	u32 ss2;
+	u32 cr3;
+	u32 eip;
+	u32 eflags;
+	u32 eax;
+	u32 ecx;
+	u32 edx;
+	u32 ebx;
+	u32 esp;
+	u32 ebp;
+	u32 esi;
+	u32 edi;
+	u32 es;
+	u32 cs;
+	u32 ss;
+	u32 ds;
+	u32 fs;
+	u32 gs;
+	u32 ldt;
+	u16 trap;
+	u16 iomap_base;
+} PACKED;
+
+void gdt_install(void);
+void tss_set_stack(u32 ss, u32 esp);
+
+#endif