Specifications

CHAPTER 2: DESIGN ENTRY
USING ALTERA MEGAFUNCTIONS
ALTERA CORPORATION INTRODUCTION TO QUARTUS II ■ 51
Altera recommends that you use the MegaWizard Plug-In Manager to
instantiate megafunctions and create custom megafunction variations. The
wizard provides a graphical interface for customizing and parameterizing
megafunctions, and ensures that you set all megafunction parameters
correctly.
Instantiation in Verilog HDL & VHDL
You can use the MegaWizard Plug-In Manager to create a megafunction or
a custom megafunction variation. The MegaWizard Plug-In Manager then
creates a Verilog HDL or VHDL wrapper file that contains an instance of the
megafunction, which you can then use in your design. For VHDL
megafunctions, the MegaWizard Plug-In Manager also creates a
Component Declaration File.
Using the Port & Parameter Definition
You can instantiate the megafunction directly in your Verilog HDL or VHDL
design by calling the function like any other module or component. In
VHDL, you also need to use a Component Declaration.
Inferring Megafunctions
Quartus II Analysis & Synthesis automatically recognizes certain types of
HDL code and infers the appropriate megafunction. The Quartus II software
uses inference because Altera megafunctions are optimized for Altera
devices, and performance may be better than standard HDL code. For some
architecture-specific features, such as RAM and DSP blocks, you must use
Altera megafunctions.
The Quartus II software maps the following logic to megafunctions during
synthesis:
■ Counters
■ Adders/Subtractors
■ Multipliers
■ Multiply-accumulators and multiply-adders
■ RAM
■ Shift registers