Cosmos/source/Cosmos.IL2CPU/IL/Shl.cs
2017-03-19 09:29:46 -05:00

74 lines
2.5 KiB
C#

using System;
using CPUx86 = Cosmos.Assembler.x86;
using Cosmos.Assembler;
using XSharp.Common;
using static XSharp.Common.XSRegisters;
namespace Cosmos.IL2CPU.X86.IL
{
[Cosmos.IL2CPU.OpCode( ILOpCode.Code.Shl )]
public class Shl : ILOp
{
public Shl( Cosmos.Assembler.Assembler aAsmblr )
: base( aAsmblr )
{
}
public override void Execute(_MethodInfo aMethod, ILOpCode aOpCode )
{
XS.Pop(XSRegisters.ECX); // shift amount
var xStackItem_ShiftAmount = aOpCode.StackPopTypes[0];
var xStackItem_Value = aOpCode.StackPopTypes[1];
var xStackItem_Value_Size = SizeOfType(xStackItem_Value);
#if DOTNETCOMPATIBLE
if (xStackItem_Value.Size == 4)
#else
if (xStackItem_Value_Size <= 4)
#endif
{
XS.ShiftLeft(XSRegisters.ESP, XSRegisters.CL, destinationIsIndirect: true, size: RegisterSize.Int32);
}
#if DOTNETCOMPATIBLE
else if (xStackItem_Value.Size == 8)
#else
else if (xStackItem_Value_Size <= 8)
#endif
{
string BaseLabel = GetLabel(aMethod, aOpCode) + ".";
string LowPartIsZero = BaseLabel + "LowPartIsZero";
string End_Shl = BaseLabel + "End_Shl";
// [ESP] is low part
// [ESP + 4] is high part
// move low part to eax
XS.Set(EAX, ESP, sourceIsIndirect: true);
XS.Compare(XSRegisters.CL, 32, size: RegisterSize.Byte8);
XS.Jump(CPUx86.ConditionalTestEnum.AboveOrEqual, LowPartIsZero);
// shift higher part
XS.ShiftLeftDouble(ESP, EAX, CL, destinationDisplacement: 4);
// shift lower part
// To retain the sign bit we must use ShiftLeftArithmetic and not ShiftLeft!
XS.ShiftLeftArithmetic(XSRegisters.ESP, XSRegisters.CL, destinationIsIndirect: true, size: RegisterSize.Int32);
XS.Jump(End_Shl);
XS.Label(LowPartIsZero);
// remove bits >= 32, so that CL max value could be only 31
XS.And(XSRegisters.CL, 0x1f, size: RegisterSize.Byte8);
// shift low part in EAX and move it in high part
// To retain the sign bit we must use ShiftLeftArithmetic and not ShiftLeft!
XS.ShiftLeftArithmetic(EAX, CL);
XS.Set(ESP, EAX, destinationDisplacement: 4);
// replace unknown low part with a zero, if <= 32
XS.Set(XSRegisters.ESP, 0, destinationIsIndirect: true);
XS.Label(End_Shl);
}
else
throw new NotSupportedException("A size bigger 8 not supported at Shl!");
}
}
}