TABLE OF CONTENTS The trick to writing any useful library of source code is to build a solid foundation and work outward from it. First, a problem along with allowable solution parameters should be identified and analyzed. In this particular case, the inability to accommodate multiple precision integers is the problem. Furthermore, the solution must be written as portable source code that is reasonably efficient across several different computer platforms.
After a foundation is formed, the remainder of the library can be designed and implemented in a hierarchical fashion. That is, to implement the lowest level dependencies first and work toward the most abstract functions last. For example, before implementing a modular exponentiation algorithm, one would implement a modular reduction algorithm. By building outward from a base foundation instead of using a parallel design methodology, you end up with a project that is highly modular. Being highly modular is a desirable property of any project as it often means the resulting product has a small footprint and updates are easy to perform.
Usually, when I start a project I will begin with the header files. I define the data types I think I will need and prototype the initial functions that are not dependent on other functions (within the library). After I implement these base functions, I prototype more dependent functions and implement them. The process repeats until I implement all the functions I require. For example, in the case of LibTomMath, I implemented functions such as mp_init() well before...
