public void CreateGDT() { new Comment(this, "BEGIN - Create GDT"); var xGDT = new List <byte>(); // Null Segment - Selector 0x00 // Not used, but required by many emulators. xGDT.AddRange(new byte[8] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }); // Code Segment mGdCode = (byte)xGDT.Count; xGDT.AddRange(GdtDescriptor(0x00000000, 0xFFFFFFFF, true)); // Data Segment - Selector mGdData = (byte)xGDT.Count; xGDT.AddRange(GdtDescriptor(0x00000000, 0xFFFFFFFF, false)); DataMembers.Add(new DataMember("_NATIVE_GDT_Contents", xGDT.ToArray())); XS.Comment("Tell CPU about GDT"); var xGdtPtr = new UInt16[3]; // Size of GDT Table - 1 xGdtPtr[0] = (UInt16)(xGDT.Count - 1); DataMembers.Add(new DataMember("_NATIVE_GDT_Pointer", xGdtPtr)); new Mov { DestinationRef = ElementReference.New("_NATIVE_GDT_Pointer"), DestinationIsIndirect = true, DestinationDisplacement = 2, SourceRef = ElementReference.New("_NATIVE_GDT_Contents") }; XS.Set(XSRegisters.EAX, "_NATIVE_GDT_Pointer"); XS.LoadGdt(XSRegisters.EAX, isIndirect: true); XS.Comment("Set data segments"); XS.Set(XSRegisters.EAX, mGdData); XS.Set(XSRegisters.DS, XSRegisters.AX); XS.Set(XSRegisters.ES, XSRegisters.AX); XS.Set(XSRegisters.FS, XSRegisters.AX); XS.Set(XSRegisters.GS, XSRegisters.AX); XS.Set(XSRegisters.SS, XSRegisters.AX); XS.Comment("Force reload of code segment"); new JumpToSegment { Segment = mGdCode, DestinationLabel = "Boot_FlushCsGDT" }; XS.Label("Boot_FlushCsGDT"); new Comment(this, "END - Create GDT"); }
public override void AssembleNew(Assembler aAssembler, object aMethodInfo) { XS.ClearInterruptFlag(); XS.Set(XSRegisters.EAX, "_NATIVE_GDT_Pointer"); XS.LoadGdt(XSRegisters.EAX, isIndirect: true); XS.Set(XSRegisters.EAX, XSRegisters.CR0); XS.Or(XSRegisters.AL, 1); XS.Set(XSRegisters.CR0, XSRegisters.EAX); XS.JumpToSegment(0x08, "PMode"); XS.Label("PMode"); }