Rendering text atop baremetal

Mu can now render text atop baremetal x86.

Try clicking around from http://akkartik.github.io/mu/html/apps/ex5.mu.html

The boot-up machine code reads a few sectors from disk, configures a keyboard handler, and loads a bitmap font (2KB for ASCII, with the option for more).

I use GNU Unifont. I believe that means Mu is now GPL v2. So stated. IANAL and I try not to think about software IP. But a font? Copyright seems reasonable there.

Next up: a text editor!

https://github.com/akkartik/mu

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Towards running Mu without Linux

All Mu really needs so far is to print to screen and read from the keyboard. Here's a 2-minute video about achieving that:

https://archive.org/details/akkartik-2min-2020-12-24

It seems such a small thing. But I needed lots of help, as you can see from the additions to my credits.

Merry Christmas to all! What a beautiful world.

Project page: https://github.com/akkartik/mu

More context: https://mastodon.social/@akkartik/104896128141863951

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Editing functions in the Mu shell

https://archive.org/details/akkartik-2min-2020-12-06

Long delay since my last video. Printing floating-point numbers is really hard. I'm still half-assing it.

As a follow-up to my previous post, I'm tightening focus to two threads:

1. These Mu shell experiments, and
2. An extremely skeletal OS to drop the Linux kernel dependency.

Deprioritized for now:

1. Other processors: RISCV, ARM, RPi, etc.
2. Graphics, mouse, etc. Device priorities for the OS are disk then ethernet.

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Feeling low today.

Damn hands are acting up again. RSI. Perhaps I should give up on Advent.

Mu's compromises:

• Just one instruction set. New processors need reworking. And I have RSI.
• Text mode. Hopefully a graphics stack can slot in underneath without needing rework.
• No pointer device. Apps are starting to make this assumption. Adding a mouse will require rework. And I have RSI.

:/ Constraints I consider "temporary" are perhaps not.

Want less. — The Buddha

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#adventofcode in Mu

I seem to be settling into a pattern of solving these on alternate days. Late for one round, early for the next.

Day 4 solutions (spoiler alert):

http://akkartik.github.io/mu/html/apps/advent2020/4a.mu.html

http://akkartik.github.io/mu/html/apps/advent2020/4b.mu.html (utterly ghastly)

2.5 hours. 2 machine-code bugs found, 1 new (terribly named) library primitive added: https://github.com/akkartik/mu/commit/18d5bab2b66

Day 5 solutions:

http://akkartik.github.io/mu/html/apps/advent2020/5a.mu.html

http://akkartik.github.io/mu/html/apps/advent2020/5b.mu.html

30 minutes. No new Mu bugs found.

Project page: https://github.com/akkartik/mu

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Advent of code in Mu

Day 2 solutions (spoiler alert): 2a 2b.

40 minutes. No new Mu bugs found, no machine-code hacking was needed.

Day 3 solution

60 minutes. Lost 11 minutes debugging a silly mistake (see commit log)

No new Mu bugs found, no machine-code hacking was needed.

Project page: https://github.com/akkartik/mu

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Advent of code in Mu

http://akkartik.github.io/mu/html/linux/apps/advent2020/1a.mu.html Day 1 part 1 solution (don't click if you don't want to be spoiled):

Took me about 40 minutes. In the process, I had to:

• Fix a bug in reading lines from stdin into streams
• Start trailing newlines when parsing ints from streams
• Implement `find` in an array

We'll see how long I can keep this up. Linear scans will soon not cut it.

Day 1 part 2 (same deal, same spoiler alert, just more brute force): http://akkartik.github.io/mu/html/apps/advent2020/1b.mu.html

Part 1 took 40 minutes and part 2 took 18. Therefore I'm getting better at this.

Project page: https://github.com/akkartik/mu

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I'm trying to come up with a notation for the rotate (circular shift) operation:

https://stackoverflow.com/questions/32785998/symbol-for-bitwise-circular-shifts

Kinda surprising that there isn't a standard answer yet, given how common it is in cryptography, and how much of a workhorse it is in the ARM instruction set.

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The Mu shell, compiling down to a subset of 32-bit x86 machine code, then to a Linux ELF binary, packaged up with just a Linux kernel and nothing else, running on a Linux console emulated on Qemu, on a Thinkpad T420s running 64-bit Linux.

Just another 27 million lines of C to take out (Linux kernel), and I'll have a decent computing stack.

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I'm also thinking today about what it would take to fork Mu for the Raspberry Pi. It uses ARM processors, a 64-bit instruction since the Pi 3 which was released in 2015. The 64-bit ISA looks quite nice, but it's incompatible with the Pi 1 and Pi 2. Contrast x86, where 64-bit is quite compatible with 32-bit, but grotesque as a result, with bits for a register scattered across multiple bytes. So I might make the opposite choice to x86 and support just the 64-bit ISA. Thoughts?

https://developer.arm.com/documentation/den0024/a

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Screenception

Visualizing programs with side-effects in a postfix shell with a live-updating text-mode environment. Built all the way up from machine code without any dependencies (except an x86 processor and Linux kernel).

https://archive.org/details/akkartik-2min-2020-11-12

Project page: https://github.com/akkartik/mu

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