Inner Interpreter Works!

Progress update on my standalone forth- the inner interpreter works! I can compile primitive words and the threaded interpreter will run them to completion. If I start out with QUIT on the return stack, with some word's execution token (the location of its array of function pointers) in the IP register of the virtual machine (meaning the IP variable of a struct) and call next then the word will run and the program will block waiting for user input. This is because QUIT clears the return stack and starts the outer interpreter. The outer interpreter needs work, and I'm trying to get word lookup, compilation, and interpretation working.

Right now a word is arranged in memory like so- last_word, flags, length, characters..., function pointers..., exit.

The last_word is a pointer to the previous word in the dictionary of words. This means that each definition is linked to the last, up to the very first, which is linked to NULL. The characters are actually held in a cell length (4 bytes) for convenience. I'm willing to throw away memory for this system because I expect to use less than a single percent of my 2 gigs, so space is not a problem. If I packed them tighter than I would want to align the function pointers to 4 bytes, which would mean calculation the length of the word's name mod 4 and adding that many unused bytes at the end of the characters part of the definition. This is simply more work to save some bytes.

I'm working on getting numbers and words to be recognized and for words to be looked up and compiled or run. After that I will be able to extend the dictionary beyond a couple of single words and get this project on its feet. I'm hoping to also look into doing a preemptive round robin threading mechanism, as well as multiple terminals, a block file system, and a text editor. Big plans!