The Designer's Guide to VHDL, 3rd Edition

Chapter 9. Predefined and Standard Packages

In this chapter, we look at several predefined and standard packages, which provide types and operators for use in VHDL models. While we could define all of the data types and operations we need for a given model, we can greatly increase our productivity by reusing the standard packages. Moreover, simulation and synthesis tools often have optimized, built-in implementations of the operations from these packages.

The Predefined Packages standard and env

In previous chapters, we have introduced numerous predefined types and operators. We can use them in our VHDL models without having to write type declarations or subprogram definitions for them. These predefined items all come from a special package called ...