Reversi Blog Posts

I still haven't worked on my Reversi program since the last post. Instead, I did some web browsing and found a blog post by some one who wrote an Othello program in C#. He has several posts on the topic that look like they could be educational. I only had time to look over a couple of them. The Othello program part 2 post had an interesting trick on how to encode a position on the board. Instead of a coordinate pair such as 0,0 or 7,7, he transformed the location into a single offset 0-63 and then started the offset that from a letter to turn the description into an alphanumeric. Since it is text it could now be transmitted as part of a hyperlink.

My current system is not as simple. To turn the coordinate into text I used base64 encoding of a byte array. Each byte I separated into a low and high 4 bit number to get a board coordinate. Base64 uses 6 bits instead of all 8 bits. However it still needs to end on a byte boundary and is an extra call. The minimal amount of bits to describe a coordinate is 6 bits, so it could map to Base64 encoding. However, it seems like it would get complicated aligning a series of 6 bits numbers to byte boundaries so I didn't go to the trouble of doing so.

A calculation can describe a rough estimate of the savings. For a maximum of 60 moves that could be played the single offset method would simply describe it with 60 bytes. If encoding with 6 bits instead of 8 bits, that would result in 360 bits or 45 bytes. So a potential savings of 15 bytes at the end. It seems like a lot of complication for 15 bytes so I haven't done it yet, but there is a difference that could add up if this operation is done a lot. However, if one decides to just send back one move at a time the base64 encoding would actually take up more bytes than the single character encoding method.

This seems like a change of detail that I might have enough time to do over a weekend. However, I would still need tools to quantify the benefit of making a change to 6 bits, while the change from a pair of numbers to a single character is clearly simpler to work with and may be the way to go. Hopefully, reading his other Othello blog posts will encourage me to work on my project again.