This arithmetic technique is often called wraparound, and anyone who's done even a smattering of low-level programming is familiar with it. Conversely, in saturation mode the result of an operation that would cause an overflow or an underflow is set to the range limit for the data type instead of rolling over. For example, if you add two unsigned, single-byte numbers whose sum is greater than 255, the saturation result is simply 255. To a layman, the benefits of saturation might not be obvious. Saturation mode allows you to complete this task without having to correct for wraparound, thus increasing the performance of the operation.
Similar benefits occur in other data processing algorithms as well.
Now that you've been exposed to some of the features of MMX Technology, you might be wondering how you should take advantage of it. As we see it, you have three options. First, you can do nothing. Not every application will benefit from MMX Technology. If the performance of your application does not rely on computation-intensive algorithms, you probably don't need to worry about incorporating MMX instructions into your code.