d66

6 ms·

1.
by d66 1y ago
It wouldn't be idiomatic Uxntal but there's a relatively simple modification where load/store is from RAM space but jump/pc is from ROM space. For a subset of existing programs it would work fine, although the assembler
2.
by d66 1y ago
That's a fair point. A few of us have been discussing a modified Varvara spec that limits the system to a smaller amount of memory (e.g. 32k, 16k, or 8k). I think with a spec like that it would unlock many implementations that are not
3.
by d66 1y ago
I'm not sure that's true. I have an eZ80-based emulator for the AgonLight2 that is already running well enough to run some real (console-based) ROMs: https://git.phial.org/d6/uxn-ez80/ (I'm new to e
4.
by d66 2y ago
There's no requirement that stacks grow upwards in Varvara. If your stacks grew downwards then you could use LE instructions to operate on 16-bit values on the stack. You'd still need to support loading from BE memory into the LE
5.
by d66 3y ago
yes, that is the actual construction: the disjunction data type only supports a lhs and rhs, so that is the only possible way to represent it. i wrote it the way i did for clarity in the comments.
6.
by d66 3y ago
negation (~α): strings not matched by α difference (α - β): strings matched by α but not β intersection (α & β): strings matched by α and β exclusive-or (α ^ β): strings matched by α or β but not both inclusion (α > β):
7.
by d66 3y ago
you're right. inclusion/intersection/etc. aren't actually computed via DFA but instead are computed directly on the regular expression representation itself. and large disjunctions (with 256 branches) are what is very he
8.
by d66 3y ago
the library uses a fairly simple data representation where x{m,n} is compiled using conjunction and disjunction. so x{1,4} ends up being represented as x|xx|xxx|xxxx. this simplifies the code for testing equality and inclusion, since logica
9.
by d66 3y ago
interesting! what would [ab]* be? for computing an ordinal number the only real difficulty is how to handle kleene star: given ord(X) how do we calculate ord(X*)? but as you probably noticed i'm a bit out of my depth when dealing with
10.
by d66 3y ago
expressions like (...){1,256} are very heavyweight and the scala JS code ends up timing out or crashing the browser. if you replace that with (...)+ then it seems to work (at least for me). smaller expressions like (...){1,6} should be fine
11.
by d66 3y ago
normally you would use an ordinal number [1] to label individual elements of an infinite set while using a cardinal number [2] to measure the size of the set. i believe the cardinality of a set of words from a finite alphabet (with more tha
12.
by d66 3y ago
the page actually does give these. for α := [a-z]{2,4} the page gives |α| = 475228. however, as others have pointed out any non-trivial use of the kleene star means the result will be ∞. in this case the page will list numbers that roughly