/// <summary>
/// Unwinde code parsing is based on <a href="https://github.com/dotnet/coreclr/blob/master/src/jit/unwindamd64.cpp">src\jit\unwindamd64.cpp</a> DumpUnwindInfo
/// </summary>
public UnwindCode(byte[] image, ref int frameOffset, ref int offset)
{
CodeOffset = NativeReader.ReadByte(image, ref offset);
byte op = NativeReader.ReadByte(image, ref offset);
UnwindOp = (UnwindOpCodes)(op & 15);
OpInfo = (byte)(op >> 4);
OffsetLow = CodeOffset;
OffsetHigh = OpInfo;
FrameOffset = frameOffset;
switch (UnwindOp)
{
case UnwindOpCodes.UWOP_PUSH_NONVOL:
OpInfoStr = $"{(Registers)OpInfo}({OpInfo})";
break;
case UnwindOpCodes.UWOP_ALLOC_LARGE:
OpInfoStr = $"{OpInfo} - ";
if (OpInfo == 0)
{
OpInfoStr += "Scaled small";
NextFrameOffset = 8 * NativeReader.ReadUInt16(image, ref offset);
}
else if (OpInfo == 1)
{
OpInfoStr += "Unscaled large";
uint nextOffset = NativeReader.ReadUInt16(image, ref offset);
NextFrameOffset = (int)((uint)(NativeReader.ReadUInt16(image, ref offset) << 16) | nextOffset);
}
else
{
throw new BadImageFormatException();
}
break;
case UnwindOpCodes.UWOP_ALLOC_SMALL:
int opInfo = OpInfo * 8 + 8;
OpInfoStr = $"{opInfo}";
break;
case UnwindOpCodes.UWOP_SET_FPREG:
OpInfoStr = $"Unused({OpInfo})";
break;
case UnwindOpCodes.UWOP_SET_FPREG_LARGE:
{
OpInfoStr = $"Unused({OpInfo})";
uint nextOffset = NativeReader.ReadUInt16(image, ref offset);
nextOffset = ((uint)(NativeReader.ReadUInt16(image, ref offset) << 16) | nextOffset);
NextFrameOffset = (int)nextOffset * 16;
if ((NextFrameOffset & 0xF0000000) != 0)
{
throw new BadImageFormatException("Warning: Illegal unwindInfo unscaled offset: too large");
}
}
break;
case UnwindOpCodes.UWOP_SAVE_NONVOL:
{
OpInfoStr = $"{(Registers)OpInfo}({OpInfo})";
NextFrameOffset = NativeReader.ReadUInt16(image, ref offset) * 8;
}
break;
case UnwindOpCodes.UWOP_SAVE_NONVOL_FAR:
{
OpInfoStr = $"{(Registers)OpInfo}({OpInfo})";
uint nextOffset = NativeReader.ReadUInt16(image, ref offset);
NextFrameOffset = (int)((uint)(NativeReader.ReadUInt16(image, ref offset) << 16) | nextOffset);
}
break;
case UnwindOpCodes.UWOP_SAVE_XMM128:
{
OpInfoStr = $"XMM{OpInfo}({OpInfo})";
NextFrameOffset = (int)NativeReader.ReadUInt16(image, ref offset) * 16;
}
break;
case UnwindOpCodes.UWOP_SAVE_XMM128_FAR:
{
OpInfoStr = $"XMM{OpInfo}({OpInfo})";
uint nextOffset = NativeReader.ReadUInt16(image, ref offset);
NextFrameOffset = (int)((uint)(NativeReader.ReadUInt16(image, ref offset) << 16) | nextOffset);
}
break;
default:
throw new NotImplementedException(UnwindOp.ToString());
}
NextFrameOffset = frameOffset;
}
private static ushort PackUnwindOp(UnwindOp op, int prologOffset, int opInfo)
{
return((ushort)(prologOffset | ((int)op << 8) | (opInfo << 12)));
}