Cosmos/source/Compiler/Indy.IL2CPU.X86/IL/x86/Bgt_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.Bgt_Un)]
	public class Bgt_Un: Op {
		public readonly string TargetLabel;
		public readonly string CurInstructionLabel;
        private string mNextLabel;
	    private string mCurLabel;
	    private uint mCurOffset;
	    private MethodInformation mMethodInformation;

		public Bgt_Un(ILReader aReader, MethodInformation aMethodInfo)
			: base(aReader, aMethodInfo) {
			TargetLabel = GetInstructionLabel(aReader.OperandValueBranchPosition);
			CurInstructionLabel = GetInstructionLabel(aReader);
             mMethodInformation = aMethodInfo;
		    mCurOffset = aReader.Position;
		    mCurLabel = IL.Op.GetInstructionLabel(aReader);
            mNextLabel = IL.Op.GetInstructionLabel(aReader.NextPosition);
		}
		public override void DoAssemble() {
			if (Assembler.StackContents.Peek().IsFloat)
			{
                EmitNotSupportedException(Assembler, GetServiceProvider(), "Floats not yet supported!", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                return;
			}
			var rightTop = Assembler.StackContents.Pop();
			var leftBottom = Assembler.StackContents.Pop();
			int xSize = Math.Max(rightTop.Size, leftBottom.Size);
			if (xSize > 8)
			{
                EmitNotSupportedException(Assembler, GetServiceProvider(), "StackSize>8 not supported", mCurLabel, mMethodInformation, mCurOffset, mNextLabel);
                return;
			}

			string BaseLabel = CurInstructionLabel + "__";
			string LabelTrue = BaseLabel + "True";
			string LabelFalse = BaseLabel + "False";

			if (xSize <= 4)
			{
                new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
				new CPUx86.Compare{DestinationReg=CPUx86.Registers.EAX, SourceReg=CPUx86.Registers.ESP, SourceIsIndirect=true};
                new CPUx86.ConditionalJump { Condition = CPUx86.ConditionalTestEnum.Below, 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.ConditionalJump{Condition=CPUx86.ConditionalTestEnum.Above,DestinationLabel = TargetLabel };
                return;
			}

			throw new NotSupportedException();
		}
	}
}