The IEEE library is the standardised collection of logic and
arithmetic packages that every conforming VHDL tool provides.
Defined in Clauses 16.6 through 16.11 of IEEE Std 1076-2019, it
builds on the predefined types of STD.STANDARD and is
the home of STD_LOGIC, the synthesisable
SIGNED / UNSIGNED arithmetic, the real
and complex math packages, and the fixed and floating-point types.
