7842 - new directory organization

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.

1 files changed, 34 insertions, 0 deletions

diff --git a/linux/tui.mu b/linux/tui.mu
new file mode 100644
index 00000000..c58a82c6
--- /dev/null
+++ b/linux/tui.mu
@@ -0,0 +1,34 @@
+# Test some primitives for text-mode.
+#
+# To run:
+#   $ ./translate_mu apps/tui.mu
+#   $ ./a.elf
+
+fn main -> _/ebx: int {
+  var nrows/eax: int <- copy 0
+  var ncols/ecx: int <- copy 0
+  nrows, ncols <- screen-size 0
+  enable-screen-grid-mode
+  move-cursor 0/screen, 5/row, 0x22/col
+  start-color 0/screen, 1/fg, 0x7a/bg
+  start-blinking 0/screen
+  print-string 0/screen, "Hello world!"
+  reset-formatting 0/screen
+  move-cursor 0/screen, 6/row, 0x22/col
+  print-string 0/screen, "tty dimensions: "
+  print-int32-hex 0/screen, nrows
+  print-string 0/screen, " rows, "
+  print-int32-hex 0/screen, ncols
+  print-string 0/screen, " rows\n"
+
+  print-string 0/screen, "press a key to see its code: "
+  enable-keyboard-immediate-mode
+  var x/eax: grapheme <- read-key-from-real-keyboard
+  enable-keyboard-type-mode
+  enable-screen-type-mode
+  print-string 0/screen, "You pressed "
+  var x-int/eax: int <- copy x
+  print-int32-hex 0/screen, x-int
+  print-string 0/screen, "\n"
+  return 0
+}