using System;
using CPUx86 = Cosmos.Assembler.x86;

namespace Cosmos.IL2CPU.X86.IL
{
    /// <summary>
    /// Converts the value on top of the evaluation stack to float32.
    /// </summary>
    [Cosmos.IL2CPU.OpCode(ILOpCode.Code.Conv_R4)]
    public class Conv_R4 : ILOp
    {
        public Conv_R4(Cosmos.Assembler.Assembler aAsmblr)
            : base(aAsmblr)
        {
        }

        public override void Execute(MethodInfo aMethod, ILOpCode aOpCode)
        {
            var xSource = aOpCode.StackPopTypes[0];
            var xSourceIsFloat = TypeIsFloat(xSource);
            var xSourceSize = SizeOfType(xSource);
            switch (xSourceSize)
            {
                case 1:
                case 2:
                    {
                        new CPUx86.SSE.ConvertSI2SS { DestinationReg = CPUx86.Registers.XMM0, SourceReg = CPUx86.Registers.ESP, SourceIsIndirect = true };
                        new CPUx86.SSE.MoveSS { DestinationReg = CPUx86.Registers.ESP, DestinationIsIndirect = true, SourceReg = CPUx86.Registers.XMM0 };
                        break;
                    }
                case 4:
                    {
                        if (!xSourceIsFloat)
                        {
                            if (IsIntegerSigned(xSource))
                            {
                                new CPUx86.SSE.ConvertSI2SS { DestinationReg = CPUx86.Registers.XMM0, SourceReg = CPUx86.Registers.ESP, SourceIsIndirect = true };
                                new CPUx86.SSE.MoveSS { DestinationReg = CPUx86.Registers.ESP, DestinationIsIndirect = true, SourceReg = CPUx86.Registers.XMM0 };
                            }
                            else
                            {
#if false
                                /*
                                 * x86 assembler generated by GCC 4.86 with SSE2 arch enforced:
                                 * uint2float:
                                 *
                                 * LCPI0_0:
	                             *   .quad	4841369599423283200     # double 4503599627370496
	                             *
                                 *	push	ebp
	                             *  mov	ebp, esp
	                             *  sub	esp, 8
	                             *  mov	eax, dword ptr [ebp + 8]
	                             *  mov	dword ptr [ebp - 4], eax
	                             *  movsd	xmm0, qword ptr [.LCPI0_0]
	                             *  movaps	xmm1, xmm0
	                             *  movd	xmm2, eax
	                             *  por	xmm2, xmm1
	                             *  subsd	xmm2, xmm0
	                             *  cvtsd2ss	xmm0, xmm2
	                             *  movss	dword ptr [ebp - 8], xmm0
                                 *  ; Why moving the value on x87 registers after having avoided to touch them until now? Maybe is the x87 calling convention
                                 *  ; but we follow the .NET calling convention so we should push the result directly onto the stack
	                             *  fld	dword ptr [ebp - 8]
	                             *  add	esp, 8
	                             *  pop	ebp
	                             *  ret
                                 *      
                                 *  Let's to write it in the Cosmos dialect...
                                 */
                                new CPUx86.Push { DestinationReg = CPUx86.Registers.EBP };
                                new CPUx86.Mov { DestinationReg = CPUx86.Registers.EBP, SourceReg = CPUx86.Registers.ESP };
                                new CPUx86.Sub { DestinationReg = CPUx86.Registers.ESP, SourceValue = 8 };
                                new CPUx86.Mov { DestinationReg = CPUx86.Registers.EAX, SourceReg = CPUx86.Registers.EBP + 8};
                                new CPUx86.Mov { DestinationReg = CPUx86.Registers.EBP - 4, SourceReg = CPUx86.Registers.EAX };
                                /* Magic number */
                                new CPUx86.SSE.MoveSD { DestinationReg = CPUx86.Registers.XMM0, SourceValue = 4841369599423283200 };
                                new CPUx86.SSE.MoveAPS { DestinationReg = CPUx86.Registers.XMM1, SourceReg = CPUx86.Registers.XMM0 };
                                new CPUx86.Mov { DestinationReg = CPUx86.Registers.XMM2, SourceReg = CPUx86.Registers.EAX };
                                new CPUx86.SSE.Por { DestinationReg = CPUx86.Registers.XMM2, SourceReg = CPUx86.Registers.XMM1 };
                                new CPUx86.SSE.SubSD { DestinationReg = CPUx86.Registers.XMM2, SourceReg = CPUx86.Registers.XMM0 };
                                new CPUx86.SSE.ConvertSD2SS { DestinationReg = CPUx86.Registers.XMM0, SourceReg = CPUx86.Registers.XMM2 };
                                new CPUx86.SSE.MoveSS { DestinationReg = CPUx86.Registers.EBP - 8, SourceReg = CPUx86.Registers.XMM0 };
                                //new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue = 8 };
                                //new CPUx86.x87.FloatLoad { DestinationReg = CPUx86.Registers.EBP - 8, Size = 32 };
                                // Let's try to avoid the x87 fld instruction in EPB - 8 there is the result already!
                                new CPUx86.Mov { DestinationReg = CPUx86.Registers.ESP, SourceReg = CPUx86.Registers.EBP - 8 };
                                //new CPUx86.Add { DestinationReg = CPUx86.Registers.ESP, SourceValue = 8 };
                                new CPUx86.Pop { DestinationReg = CPUx86.Registers.EBP };
#endif
                                throw new NotImplementedException("Cosmos.IL2CPU.x86->IL->Conv_R4.cs->Conversion of UInt32 to Float is not yet implemented!");
                             }
                         }
                         break;
                     }
                 case 8:
                     {
                         if (xSourceIsFloat)
                         {
                             new CPUx86.SSE.ConvertSD2SS { SourceReg = CPUx86.Registers.ESP, DestinationReg = CPUx86.Registers.XMM0, SourceIsIndirect = true };
                             new CPUx86.SSE.MoveSS { SourceReg = CPUx86.Registers.XMM0, DestinationReg = CPUx86.Registers.ESP, DestinationIsIndirect = true };
                         }
                         else
                         {
                             if (IsIntegerSigned(xSource))
                             {
                                 /*
                                  * Again there is no SSE instruction in x86 to do this conversion as we need a 64 Bit register to do this! So we are forced
                                  * to use the legacy x87 FPU to do this operation. In x64 the SSE instruction ConvertSIQ2SS should exist.
                                  */
                                new CPUx86.x87.IntLoad { DestinationReg = CPUx86.Registers.ESP, Size = 64, DestinationIsIndirect = true };
                                new CPUx86.x87.FloatStoreAndPop { DestinationReg = CPUx86.Registers.ESP, Size = 32, DestinationIsIndirect = true };
                               
                                //throw new NotImplementedException("Cosmos.IL2CPU.x86->IL->Conv_R4.cs->Conversion of Int64 to Float is not yet implemented!");
                            }
                            else
                            {
                                throw new NotImplementedException("Cosmos.IL2CPU.x86->IL->Conv_R4.cs->Conversion of UInt64 to Float is not yet implemented!");
                            }
                        }

                        // Why I need to do all this Pop / Pop / Pushing or I get stack corruption? The result in the stack as expected so?
                        new CPUx86.Pop { DestinationReg = CPUx86.Registers.EAX };
                        new CPUx86.Pop { DestinationReg = CPUx86.Registers.ECX };
                        new CPUx86.Push { DestinationReg = CPUx86.Registers.EAX };

                        break;
                    }
                default:
                    //EmitNotImplementedException( Assembler, GetServiceProvider(), "Conv_U4: SourceSize " + xStackItem.Size + " not supported!", mCurLabel, mMethodInformation, mCurOffset, mNextLabel );
                    throw new NotImplementedException();
            }
        }
    }
}