[Question] Are bit shift functions available in structured text?

[Servostar]

While experimenting with ruSTy on some implementations for PRNGs, I came across this:

Seemingly, ruSTy does not support bitwise function defined in IEC 61131-3 (6.6.2.5.10). Am I mistaken about that?
What would be the best way to implement this? Perhaps an external library implementing these functions in C which is then added during link time. However, this would add an unnecessary function call.
Is there a way to have ruSTy/LLVM generate platform native bitshift functions?