Like I said, we haven’t done anything about it yet. As for the correct values, use the C/C++ standard for everything. For divide by zero, return NaR(undefinedValueNaR).
Things are tricky when the domain is signed and either or both arguments are negative; see https://en.wikipedia.org/wiki/Modulo_operation. Currently we do not have a mode argument in the spec for these ops, but we probably should; the natural candidate is the roundingCode attribute that FP ops use. The integral result would then be the value produced by an infinitely precise FP divide operation followed by the FP integerize operation, plus the Euclidean rule for the remainder. As far as I can see the available rounding codes provide all the sign rules demanded by the various languages listed in the Wikipedia article, plus some (nearest-ties-to-even for example) that don’t seem to be used.
I suggest that you see how far you get in unsigned, and when that gets through the specializer (you’ll write in genAsm) then we can revisit signed and decide whether to use roundingCode, a new attribute, or roundingCode with some enumerates faulting as undefined.
It’s OK to post your code here, although I’d suggest starting anew topic. Other readers/posters may chime in on your efforts; please be polite. When you have something that you believe works then either we will have published access to the tool chain for all or (if that’s still not done) we can NDA and let you use our servers.