Cosmos/source/Indy.IL2CPU/IL/x86/Blt_Un.cs

using System;
using System.IO;


using CPU = Indy.IL2CPU.Assembler;
using CPUx86 = Indy.IL2CPU.Assembler.X86;

namespace Indy.IL2CPU.IL.X86 {
	[OpCode(OpCodeEnum.Blt_Un)]
	public class Blt_Un: Op {
		public readonly string TargetLabel;
		public readonly string CurInstructionLabel;
		public Blt_Un(ILReader aReader, MethodInformation aMethodInfo)
			: base(aReader, aMethodInfo) {
			TargetLabel = GetInstructionLabel(aReader.OperandValueBranchPosition);
			CurInstructionLabel = GetInstructionLabel(aReader);
		}
		public override void DoAssemble() {
			if (Assembler.StackContents.Peek().IsFloat) {
				throw new Exception("Floats not yet supported!");
			}
			var rightTop = Assembler.StackContents.Pop();
			var leftBottom = Assembler.StackContents.Pop();
			int xSize = Math.Max(rightTop.Size, leftBottom.Size);
			if (xSize > 8) {
				throw new Exception("StackSize>8 not supported");
			}
			string BaseLabel = CurInstructionLabel + "__";
			string LabelTrue = BaseLabel + "True";
			string LabelFalse = BaseLabel + "False";
			if (xSize <= 4)
			{
                new CPUx86.Pop { DestinationReg = CPUx86.Registers.ECX };
				//if (xSize > 4)
				//{
				//    throw new NotImplementedException("long comprasion is not implemented");
				//    new CPUx86.Add("esp", "4");
				//}
                new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
				//if (xSize > 4)
				//{
				//    throw new NotImplementedException("long comprasion is not implemented");
				//    new CPUx86.Add("esp", "4");
				//}
                new CPUx86.Push { DestinationReg = CPUx86.Registers.ECX };
                new CPUx86.Compare { DestinationReg = CPUx86.Registers.EAX, SourceReg = CPUx86.Registers.ESP, SourceIsIndirect = true };
                new CPUx86.JumpIfLess { DestinationLabel = LabelTrue };
                new CPUx86.Jump { DestinationLabel = LabelFalse };
				new CPU.Label(LabelTrue);
                new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue = 4 };
                new CPUx86.Jump { DestinationLabel = TargetLabel };
				new CPU.Label(LabelFalse);
                new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue=4 };
				return;
			}

			if (xSize == 8)
			{
                new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
				new CPUx86.Pop{DestinationReg = CPUx86.Registers.EDX};
				//value2: EDX:EAX
                new CPUx86.Pop { DestinationReg = CPUx86.Registers.EBX };
                new CPUx86.Pop { DestinationReg = CPUx86.Registers.ECX };
                //value1: ECX:EBX
                new CPUx86.Sub { DestinationReg = CPUx86.Registers.EBX, SourceReg = CPUx86.Registers.EAX };
                new CPUx86.SubWithCarry { DestinationReg = CPUx86.Registers.ECX, SourceReg = CPUx86.Registers.EDX };
				//result = value1 - value2
                new CPUx86.JumpIfBelow { DestinationLabel = TargetLabel };
			}
			throw new NotSupportedException();
		}
	}
}