using System;
using System.Linq;
using Cosmos.Assembler;
using Cosmos.Assembler.x86;

namespace Cosmos.Debug.DebugStub {
	public class Screen : Cosmos.Assembler.Code {

		public Screen(Assembler.Assembler aAssembler) : base(aAssembler) {}

		public override void Assemble() {
			new Comment("X#: Group DebugStub");

			new Comment("X#: procedure Cls {");
			new Label("DebugStub_Cls");

			new Comment("VidBase");

			new Comment("X#: ESI = $B8000");
			new Mov{ DestinationReg = RegistersEnum.ESI, SourceValue = 0xB8000 };

			new Comment("X#: BeginLoop:");
			new Label("DebugStub_Cls_BeginLoop");

			new Comment("Text");

			new Comment("X#: AL = $00");
			new Mov{ DestinationReg = RegistersEnum.AL, SourceValue = 0x00 };

			new Comment("X#: ESI[0] = AL");
			new Mov{ DestinationReg = RegistersEnum.ESI, DestinationIsIndirect = true, DestinationDisplacement = 0, SourceReg = RegistersEnum.AL };

			new Comment("X#: ESI++");
			new INC { DestinationReg = RegistersEnum.ESI };

			new Comment("Colour");

			new Comment("X#: AL = $0A");
			new Mov{ DestinationReg = RegistersEnum.AL, SourceValue = 0x0A };

			new Comment("X#: ESI[0] = AL");
			new Mov{ DestinationReg = RegistersEnum.ESI, DestinationIsIndirect = true, DestinationDisplacement = 0, SourceReg = RegistersEnum.AL };

			new Comment("X#: ESI++");
			new INC { DestinationReg = RegistersEnum.ESI };

			new Comment("End of Video Area");

			new Comment("VidBase + 25 * 80 * 2 = B8FA0");

			new Comment("X#: If ESI < $B8FA0 goto BeginLoop");
			new Compare { DestinationReg = RegistersEnum.ESI, SourceValue = 0xB8FA0 };
			new ConditionalJump { Condition = ConditionalTestEnum.LessThan, DestinationLabel = "DebugStub_Cls_BeginLoop" };

			new Comment("X#: }");
			new Label("DebugStub_Cls_Exit");
			new Return();

			new Comment("X#: procedure DisplayWaitMsg {");
			new Label("DebugStub_DisplayWaitMsg");

			new Comment("http://wiki.osdev.org/Text_UI");

			new Comment("Later can cycle for x changes of second register:");

			new Comment("http://wiki.osdev.org/Time_And_Date");

			new Comment("X#: ESI = @..DebugWaitMsg");
			new Mov { DestinationReg = RegistersEnum.ESI , SourceRef = Cosmos.Assembler.ElementReference.New("DebugWaitMsg") };

			new Comment("VidBase");

			new Comment("X#: EDI = $B8000");
			new Mov{ DestinationReg = RegistersEnum.EDI, SourceValue = 0xB8000 };

			new Comment("10 lines down, 20 cols in (10 * 80 + 20) * 2)");

			new Comment("X#: EDI + 1640");
			new Add { DestinationReg = RegistersEnum.EDI, SourceValue = 1640 };

			new Comment("Read and copy string till 0 terminator");

			new Comment("X#: ReadChar:");
			new Label("DebugStub_DisplayWaitMsg_ReadChar");

			new Comment("X#: AL = ESI[0]");
			new Mov{ DestinationReg = RegistersEnum.AL, SourceReg = RegistersEnum.ESI, SourceIsIndirect = true, SourceDisplacement = 0 };

			new Comment("X#: if AL = 0 exit");
			new Compare { DestinationReg = RegistersEnum.AL, SourceValue = 0 };
			new ConditionalJump { Condition = ConditionalTestEnum.Zero, DestinationLabel = "DebugStub_DisplayWaitMsg_Exit" };

			new Comment("X#: ESI++");
			new INC { DestinationReg = RegistersEnum.ESI };

			new Comment("X#: EDI[0] = AL");
			new Mov{ DestinationReg = RegistersEnum.EDI, DestinationIsIndirect = true, DestinationDisplacement = 0, SourceReg = RegistersEnum.AL };

			new Comment("X#: EDI + 2");
			new Add { DestinationReg = RegistersEnum.EDI, SourceValue = 2 };

			new Comment("X#: Goto ReadChar");
			new Jump { DestinationLabel = "DebugStub_DisplayWaitMsg_ReadChar" };

			new Comment("X#: }");
			new Label("DebugStub_DisplayWaitMsg_Exit");
			new Return();

		}
	}
}