This gives the maximum size of the stack at any given moment during the
execution of the program. It's useful to figure out if the stack gets
dangerously close to the heap.
That's my mega-commit you've all been waiting for.
The code for the shell share more routines with userspace apps than with kernel
units, because, well, its behavior is that of a userspace app, not a device
driver.
This created a weird situation with libraries and jump tables. Some routine
belonging to the `kernel/` directory felt weird there.
And then comes `apps/basic`, which will likely share even more code with the
shell. I was seeing myself creating huge jump tables to reuse code from the
shell. It didn't feel right.
Moreover, we'll probably want basic-like apps to optionnally replace the shell.
So here I am with this huge change in the project structure. I didn't test all
recipes on hardware yet, I will do later. I might have broken some...
But now, the structure feels better and the line between what belongs to
`kernel` and what belongs to `apps` feels clearer.
Instead of expecting a `USER_CODE` symbol to be set, we expect `.org` to be
set in all userspace glue code. This gives us more flexibility with regards to
how we manage that.
Moreover, instead of making `USER_RAMSTART` mandatory, we make it default to
the end of the binary, which is adequate in a majority of cases.
Will be useful for my upcoming mega-commit... :)
Most of register fiddling routines (which is now the only thing contained
in care.asm) are used by almost all userspace apps, often in inner loops.
That makes the penalty of using jump tables for those a bit too high.
Moreover, it burdens jump tables needlessly.
Because this unit is very small (now that string routines are out), it makes
sense to always include it in binaries.
There's a couple of bit fiddling instructions that didn't have their
IX/IY variant implemented yet and without this commit, each of them
would have required a special routine. Not anymore.
This was mostly lifted from my "tihello" example, but it required significant
adjustments.
This commit also introduces a font management system. A lot of fonts are
available online, but sources aren't always clear so to avoid copyright
landmines, I re-created my first 5x7 font from scratch.
As it is now, this resulting ROM gets "Collapse OS>" to be displayed on the
LCD screen. Much work still left to do.
ref #41
We use zasm's ability to use labels in .equ directive.
We didn't do it before because for a while, we were in between scas
and zasm (scas was used in automated tests) so we needed to use the
lowest common denominator: zasm doesn't have macros and scas can't
use labels in .equ directives.
This forced us to add this layer of indirection. But now that we are
completely cut from scas' dependency, we can use this nice zasm's
ability.
The goal is to avoid mixing those routines with "character devices"
(acia, vpd, kbd) which aren't block devices and have routines that
have different expectations.
This is a first step to fixing #64.
* Fix for tools/zasm.sh being dependent on readlink -f (an issue on macOS, preventing builds)
* Wrap zasm.sh shebang in /usr/bin/env ; remove comment about BSDs
I've tested RAM usage when self-assembling and there weren't as high
as I thought. zasm's defaults now use less than 0x1800 bytes of RAM,
making it possible, theoretically for now, for a Sega Master System
to assemble Collapse OS from within itself.
I'm about to split the global registry in two (labels and consts)
and the previous state of registry selection made things murky.
Now it's much better.
This hard-binds ed to the filesystem (I liked the idea of working
only with blockdevs though...), but this is necessary for the
upcoming `w` command. We need some kind of way to tell the
destination to write to truncate itself.
This only has a meaning in the filesystem, but it's necessary to
let the file know that its registered file size has possibly
shrunk.
I thought of alternatives that would have allowed me to keep ed
blkdev-centered, but they were all too hackish to my own taste.
Hence, this new hard-bind on files.
During expression parsing, if a local label was parsed, it would
select the local registry and keep that selection, making
subsequent global labels register in the wrong place.
I'm about to break compatibility with scas. Before I do that, I
need to adjusts tests. Instead of running scas to compare results,
we commit expected result as binaries directly in the repo.
This huge refactoring remove the Seek and Tell routine from blockdev
implementation requirements and change GetC and PutC's API so that they
take an address to read and write (through HL/DE) at each call.
The "PTR" approach in blockdev implementation was very redundant from
device to device and it made more sense to generalize. It's possible
that future device aren't "random access", but we'll be able to add more
device types later.
Another important change in this commit is that the "blockdev handle" is
now opaque. Previously, consumers of the API would happily call routines
directly from one of the 4 offsets. We can't do that any more. This
makes the API more solid for future improvements.
This change forced me to change a lot of things in fs, but overall,
things are now simpler. No more `FS_PTR`: the "device handle" now holds
the active pointer.
Lots, lots of changes, but it also feels a lot cleaner and solid.
What used to be `tools/emul/user.h` was in fact specific to zasm, so I
moved it there.
To avoid name confusion, I renamed what used to be kernel.h and user.h
to kernel-bin.h and user-bin.h.
Move load/save to blkdev_cmds and add a new "poke" builtin shell cmd
that is the mirror of "peek" and strictly uses stdio (no blkdev
involved).
This allows us to slim the minimal OS size but, more importantly, change
the behavior of "load" so that we don't expect GetC to block until Z is
set. This way, using "load X" with X being larger than the blkdev size
won't block forever.
This also brings our RC2014 minimal kernel below the 1K mark again.
The pgm module implements a shell hook so that when an unknown command
is typed, we look into the mounted filesystem and look for a file with
the same name as the command. If we find one, we load it in memory and
run it.
This allows us to break through the 64K limit for includes CFS in zasm,
a limit we were dangerously close to breaking. In fact, this commit
makes us go over that limit. Right in time!
To run a parseExpr on first pass would always return a false success
with dummy value because symbols are configured to always succeed on
first pass. This would make expressions like ".fill 0x38-$" so bad
things to labels because "0x38-$" wouldn't return the same thing on
first and second pass.
Revert to parsing literals and symbols after having scanned for
expressions and add a special case specifically for char literals (which
is why we scanned for literals and symbols first in the first place).
