The Ulam spiral is a graphical depiction of a set of prime numbers devised by the mathematician Stanislaw Ulam. To quote the Wiki, it’s constructed by writing the positive integers in a square spiral and specially marking the prime numbers. The outcome is a square with distinct diagonal, horizontal, and vertical lines. This post will walk through the development of a Ulam spiral visualization tool. Creating a Ulam Spiral Take a look at the 4x4 Ulam spiral below:...
The Caesar Cipher (CC) is a classic symmetric key algorithm dating back to the time of Julius Caesar. If you are new to cryptography, the Caesar Cipher is a great first crypto algorithm to learn. This post will walk through the details of implementing a CC encrypt/decrypt function. You’ll then get a look at the internals of a CC code cracker. Algorithm Description There are four key ingredients to a Caesar Cipher:...
Have you implemented a shared pointer class in C++? If you have, did you do it in an interview setting? You might be familiar with the STL shared_ptr and the fact that many implementations of shared_ptr use reference counting to manage the lifetime of a dynamically allocated object. That said, if you’ve never thought about or tried to actually implement the concept itself, doing so in an interview is a tall order....
This is the second installment in a series of posts where I share notes taken while reading an interesting book or article. This post includes the notes made while reading “Linux Driver Development for Embedded Processors” by Alberto Liberal de los Rios. Notes weren’t taken for every chapter so keep in mind that the book actually covers more topics than what’s shown here. If you are considering buying the book, you might want to checkout this review before buying....
This is the first installment in a series of posts where I share notes taken while reading an interesting book or article. This post includes the notes made while reading a series of articles by Ulrich Drepper titled “What Every Programmer Should Know About Memory”. Part 1: Introduction There are a number of different computer architectures each with their own tradeoffs. The commodity HW setup has the CPUs attached via a Frontside Bus (FSB) to a Northbridge and indirectly via the Northbridge to a Southbridge....
Do you remember when you first learned about recursion? The thought triggered a memory from an old CS101 Java course. The textbook had some fractal triangle thing made with only 20 lines of code. At the time, it was a confusing 20 lines of code. A quick search on Google for “fractal triangle recursion” led straight to the Sierpinski triangle. A Sierpinski triangle generator with an ncurses visualization is a fun afternoon project....
If you’ve worked in a large C++ codebase within the last couple of years, you’ve probably come across the GoogleTest unit testing framework. Chances are you’ve also encountered everyone’s favorite build generator: CMake. In this article, you will see two options for integrating GoogleTest into your next CMake project. The content that follows is largely a condensed version of the tips found in “An Introduction to Modern CMake”. This post summarizes the bits relevant to using CMake with GoogleTest to act as a quick reference when setting up future projects....
If you grind old Advent of Code problems, you might notice a particular style of problem crop up more than once. The people of Reddit refer to their solutions as a variation of Conway’s Game of Life (GoL). Wikipedia has a great article on GoL. The animations are eye catching. The Wiki serves as motivation for a terminal app that visualizes GoL simulations. Rules of the Game What are the GoL rules?...
You ever come across one of those ASMR programming videos? This video where the developer programs a terminal display with a couple of spinning cubes is neat. This video is the motivation for the development of a ncurses application that renders a user controlled 3D cube. Perspective Projection and Rotation Matrices So how do you take an object in 3D space and visualize it in 2D space? The answer is perspective projection....
If you’re familiar with the kbhell application, you might realize that kbhell is about 90% of the way to being a keylogger. Why not finish the job and write a proper, cross platform keylogger that captures a victim’s every keystroke (for science reasons, of course)? The Requirements So there’s the obvious requirement of capturing user keystrokes. When you think about the fact that keyboards have different layouts, there are different language sets, etc....