float下位8bitってどれだ？
[StructLayout(LayoutKind.Explicit)]
struct floatUnion
{
[FieldOffset(0)]
public System.Single floatValue;

[FieldOffset(0)]
public System.Byte b0;
[FieldOffset(1)]
public System.Byte b1;
[FieldOffset(2)]
public System.Byte b2;
[FieldOffset(3)]
public System.Byte b3;
｝