The Ulam spiral is a graphical depiction of a set of prime numbers devised by the mathematician Stanislaw Ulam1. 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 Cipher1 (CC) is a classic symmetric key2 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 review1 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....