All over the Mu code I reflexively initialize all variables just to keep
unsafe SubX easy to debug. However I don't really need to do this for safe
Mu code, since the type- and memory-safety already ensures we can't read
from streams beyond what we've written to them. For now I'll continue mostly
with the same approach, but with one exception for streams of bytes.
Mu programs often emit traces, and in doing so they often use temporary
streams of bytes that can get quite long. I'm hoping avoiding initializing
KBs of data all over the place will measurably speed up the Mu shell.
I spent a while building a little keyboard scancode printer:
$ ./translate ex1.mu && qemu-system-i386 disk.img
..and wondering why up-arrow was 0x48 in hex but 724 in decimal. I ended
up paranoidly poking at a bunch of crap (though there _is_ a cool chromatography-based
debugging technique in 126write-int-decimal.subx) before I realized:
- 724 just has one extra digit over the correct answer
- the 0xe0 scan code is a 3-digit number in decimal -- and the final digit is '4'
There's nothing actually wrong.
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