Library

Library

Libraries are the folders that contain one or more packages.

library library_name;
library IEEE;

There are two types of libraries.

1. Source Library

Source library contains:

• Standart package
• The packages which are defined by IEEE.
• Libraries which are created by FPGA vendors.
• Some libraries of units which are referenced in designs.

2. Work Library

It is he library that contains the generated VHDL code within the scope of a design.

In the following illustration, you can see the working library of ISE program and VHDL codes of this library generated during the design.

IEEE Library

IEEE library includes the following packages:

• IEEE.STD_LOGIC_1164 : Contains the std_logic  type and related functions.
• IEEE.STD_LOGIC_ARITH : Contains arithmetic functions.
• IEEE.STD_LOGIC_UNSIGNED : Contains unsigned arithmetic functions.
• IEEE.STD_LOGIC_SIGNED : Contains signed arithmetic functions.