The best way to read it is close to how it executes. Following the call graph. Find the definitions of data types (if they exist properly) or functions which o

The best way to read it is close to how it executes. Following the call graph. Find the definitions of data types (if they exist properly) or functions which operate on a looser data type (like if the data is a raw integer array but the program utilizes a suite of functions for manipulating and accessing that array in a more structured way). Identify either the entry point ("main") or some point of interest and work down and up the call graph to understand what's happening. Most code is not written, outside scripts and often not even then, to be executed linearly. No reason to force linearity into reading the code either.