You'll need a file, wordlist.txt, containing one word per line, no spaces etc.

Build using make

canonize and gather (and the system sort utility) are used to generate a file
containing the letterbanks in readable form.

gentables uses this to create a pre-built graph of all possible letterbanks in tables.h

letterbank lets you look up the letterbanks for any word.

letterswaps are built on the fly - the code to do this is far from efficent, but
modern computers are so fast now that the level of complexity needed to code what
previously would have been expected for this task is just not worth the effort...
a day of programming versus twenty or thirty seconds of runtime? No contest!