Programming Embedded Systems in C and C++

139

Chapter 10

In this chapter:

• Increasing Code

Efficiency

• Decreasing Code Size

• Reducing Memory

Usage

• Limiting the Impact

of C++

10

10. Optimizing Your

Code

Things should be made as simple as possible,

but not any simpler.

—Albert Einstein

Though getting the software to work correctly seems like the logical last step for a

project, this is not always the case in embedded systems development. The need

for low-cost versions of our products drives hardware designers to provide just

barely enough memory and processing power to get the job done. Of course, dur-

ing the software development phase of the project it is more important to get the

program to work correctly. And toward that end there are usually one or more

“development” boards around, each with additional memory, a faster processor, or

both. These boards are used to get the software working correctly, and then the

final phase of the project becomes code optimization. The goal of this final step is

to make the working program run on the lower-cost “production” version of the

hardware.

Increasing Code Efficiency

Some degree of code optimization is provided by all modern C and C++ compil-

ers. However, most of the optimization techniques that are performed by a com-

piler involve a tradeoff between execution speed and code size. Your program can

be made either faster or smaller, but not both. In fact, an improvement in one of

these areas can have a ...