A library clause defines logical names for design libraries in the host environment.

Syntax:

library library_name, ... ; 

Description:

The library clause defines the logical names of design libraries, which are used by the design units. A library is an implementation-dependent storage facility for previously analyzed design units.

A VHDL library is usually implemented as a directory in the host file system. The library name is mapped to the pathname of that directory by the VHDL tool.

There are two predefined libraries, which are used implicitly in every design: Std and Work. The Std library contains the packages Standard and Textio. The Work library is a working library, where all user-created and analyzed design units are stored. Also user-specified packages are stored in the working library Work.

Example:

library IEEE;
library Work, IpCores; 

Notes:

• A library specified in a library clause of the primary design unit (entity, configuration or package) is visible in each secondary unit (architecture or package body) associated to it.
• Library Std need not to be specified. Both library packages are automatically included in every design unit.

See also:

Use