FP conversion from smaller-sized FP numbers to larger-sized ones is needed: FP32->FP64, FP16->FP64, FP16->FP32. unit tests also needed, with full (comprehensive) coverage.
https://git.libre-riscv.org/?p=ieee754fpu.git;a=commitdiff;h=1b91f4639aee04ecabd24126675a752f53523298 unit tests functional.