Efficient software is easy-to-understand software that runs faster and requires less code.

Software Development Strategies

1. Top-Down Development This is an approach to programming which relates to understandability and the use of functions. Essentially, it is an approach that starts with the broad overview (the “top”) and then moves (“down”) to the details. Using such an approach, you first write the main program (the main() function in C). In doing so, you make liberal use of functions that you have yet to write and assume that later on you will write them and that they will perform in specified ways. For example, if your final application needs a printing device, during development call a (at that moment non-existent) printf() function with a pointer to the desired message. If you need an A-D reading, during early development assume some function will exist to return the reading when called. Once you’ve written the main program, the “down” of “top-down” consists of writing the first level of functions. These in turn may use other functions, which you will also write later. Finally, you write the detailed drivers—the most basic functions. (If you would like to see an example of this 3-level programming, start with Figure 21.1 on page 236 and then follow the code in the rest of that chapter.) Continue reading →