I’m not exactly sure where that snippet comes from, but I believe those values are forced into integers. The probably have decimals because they were produced by swarming years ago honestly.
Remember that this encoder is going to play a part in a larger encoding. To know if w is too large within n, you really need to know the combined n and how much space the sub-encoding takes up. 
Also, check out this cyclic encoder display I’m working on (not sure how long that link will be valid). In this viz, n = bits and w = range. I’m going to try and explain the concept of buckets with this visual soon.