Filling pixels isn't a rare corner case. I'm going to switch to a dense
rather than sparse representation for pixels, but callers will have to
explicitly request the additional memory.
We now have a couple of protections:
- if we get close to running out of space in the trace we drop in an
error
- if we run out of space in the trace we stop trying to append
- if there are errors we cancel future evaluations
This is already much nicer. You can't do much on the Mu computer, but at
least it gracefully gives up and shows its limitations. On my computer
the Mu shell tries to run computations for about 20s before giving up.
That seems at the outer limit of what interactivity supports. If things
take too long, test smaller chunks.
Among other things, we turned off the trace to significantly speed up the
debug cycle.
State as of https://merveilles.town/@akkartik/106079258606146213
Ohhh, as I save the commit I notice a big problem: I've been editing the
disk image directly because writes to the Mu disk lose indentation. But
I've been forgetting that the state in the Mu disk needs to be pre-evaluated.
So function bindings need extra parens for the environment. The `pixel`
calls in the previous commit message are the first statement in the body,
and they aren't actually considered part of the body right now. No wonder
they don't run.
There are lots of other problems, but this will clarify a lot.
I tried building a function to draw a horizontal line across the screen.
Here's what I have in data.txt:
(
(globals . (
(horline . (fn () (screen y)
(horline_1 screen y 0 (width screen))))
(horline_1 . (fn () (screen y lo hi)
(if (>= lo hi)
()
((fn ()
(pixel screen lo y 12)
(horline_1 screen y (+ lo 1) hi))))))
))
(sandbox . (horline_1 screen 0 0 20))
)
$ dd if=/dev/zero of=data.img count=20160
$ cat data.txt |dd of=data.img conv=notrunc
$ ./translate shell/*.mu && qemu-system-i386 -hda disk.img -hdb data.img
Result: I can't call (horline screen 0) over a fake screen of width 40.
Some stream overflows somewhere after all the tweaks to various fixed-size
buffers scattered throughout the app. Calling horline_1 gets to a 'hi'
column of 20, but not to 30.
Tested by inserting a call into the shell, but we can't leave it in because
every test ends up clobbering the disk. So it's now time to think about
a testable interface for the disk.
Baremetal is now the default build target and therefore has its sources
at the top-level. Baremetal programs build using the phase-2 Mu toolchain
that requires a Linux kernel. This phase-2 codebase which used to be at
the top-level is now under the linux/ directory. Finally, the phase-2 toolchain,
while self-hosting, has a way to bootstrap from a C implementation, which
is now stored in linux/bootstrap. The bootstrap C implementation uses some
literate programming tools that are now in linux/bootstrap/tools.
So the whole thing has gotten inverted. Each directory should build one
artifact and include the main sources (along with standard library). Tools
used for building it are relegated to sub-directories, even though those
tools are often useful in their own right, and have had lots of interesting
programs written using them.
A couple of things have gotten dropped in this process:
- I had old ways to run on just a Linux kernel, or with a Soso kernel.
No more.
- I had some old tooling for running a single test at the cursor. I haven't
used that lately. Maybe I'll bring it back one day.
The reorg isn't done yet. Still to do:
- redo documentation everywhere. All the README files, all other markdown,
particularly vocabulary.md.
- clean up how-to-run comments at the start of programs everywhere
- rethink what to do with the html/ directory. Do we even want to keep
supporting it?
In spite of these shortcomings, all the scripts at the top-level, linux/
and linux/bootstrap are working. The names of the scripts also feel reasonable.
This is a good milestone to take stock at.
Kartik K. Agaram