public static ReadOnlySpan <U> Cast <[Primitive] T, [Primitive] U>(this ReadOnlySpan <T> slice)
where T : struct
where U : struct
{
int countOfU;
/// This comparison is a jittime constant
if (PtrUtils.SizeOf <T>() > PtrUtils.SizeOf <U>())
{
IntPtr count = PtrUtils.CountOfU <T, U>((uint)slice.Length);
unsafe
{
// We can't compare IntPtrs, so have to resort to pointer comparison
bool fits = (byte *)count <= (byte *)int.MaxValue;
Contract.Requires(fits);
countOfU = (int)count.ToPointer();
}
}
else
{
countOfU = slice.Length * PtrUtils.SizeOf <T>() / PtrUtils.SizeOf <U>();
}
object obj = slice.Object;
UIntPtr offset = slice.Offset;
if (countOfU == 0)
{
obj = null;
offset = (UIntPtr)0;
}
return(new ReadOnlySpan <U>(obj, offset, countOfU));
}