CHAPTER FOUR

Coding Style: Best-Known Method for Synthesis

Coding style plays a very important role for an ASIC design flow. “Bad” HDL (either Verilog or VHDL) code does not allow efficient optimization during synthesis. Logic that is generated from synthesis tools depends highly on the code that is written. A badly formed code would generally create bad logic. As the saying goes, “garbage in, garbage out.”

There are certain general guidelines to follow when it comes to coding style. By following these guidelines, a constant, good coding style can be attained. By having a good coding style, synthesis results are optimal.

4.1 NAMING CONVENTION

For a design project, a good naming convention is necessary. Naming convention is normally the most overlooked guideline when coding in HDL. Having a well-defined naming convention does not seem to sound important, but not having one can cause a lot of problems in the later stages of design, especially during the fullchip integration. It would be difficult for the designer to connect all the signals between modules of a fullchip if the signal names do not match.

By defining a naming convention, a set of rules is applied when the designer names the ports of a module. If each module in fullchip is based on the same set of naming rules, then it becomes much easier to connect these signals together in the fullchip level.

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FIGURE 4.1. Diagram showing ...

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