2a55bfd375
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. |
||
|---|---|---|
| .. | ||
| cfsin | ||
| .gitignore | ||
| glue.asm | ||
| Makefile | ||
| README.md | ||
| user.h | ||
Assembling binaries
For a system to be able to self-reproduce, it needs to assemble source z80 assembly to binary.
Goals
Have a RC2014 assemble a Collapse OS kernel with its source living on a CFS on a SD card.
Gathering parts
- Same parts as the SD card recipe.
The zasm binary
To achieve our goal in this recipe, we'll need a zasm binary on the SD card.
This zasm binary needs to be compiled with the right jump offsets for the kernel
we build in this recipe. These offsets are in user.h and are closely in sync
with the configuration in glue.asm.
user.h is then included in apps/zasm/glue.asm.
The makefile in this recipe takes care of compiling zasm with the proper
user.h file and place it in cfsin/zasm
The userland source
The code we're going to compile is cfsin/hello.asm. As you can see, we also
include user.h in this source code or else ld hl, sAwesome would load the
wrong offset.
Because of this, the Makefile takes care of copying user.h in our filesystem.
Preparing the card and kernel
After running make, you'll end up with sdcard.cfs which you can load the
same way you did in the SD card recipe.
You will also have os.bin, which you can flash on your EEPROM the same way
you already did before.
Running it
Compiling and running hello.asm is done very much like in
the shell emulator:
Collapse OS
> sdci
> fson
> fopn 0 hello.asm
> fnew 1 dest
> fopn 1 dest
> zasm 1 2
> dest
Assembled from a RC2014
>
That RC2014 is starting to feel powerful now, right?
Test your hardware
Now that you have a fully functional filesystem that can load programs and run
them easily, you'll see that this recipe's CFS include a couple of programs
besides zasm. Among them, there's sdct that stress tests reading and
writing on the SD card and memt that stress tests RAM. You might be
interested in running them. Look at their description in apps/. All you need
to to do run them is to type their name.
Assembling the kernel
Now let's go for something a little more fun! Jiu-jitsu? No, you're not going to learn jiu-jitsu! You're going to assemble the kernel from within your RC2014!
The makefile doesn't prepare a CFS blob for this, let's learn to build that blob
yourself. First of all, we'll need to have what we already had in sdcard.cfs
because it has zasm and user.h. But we're going to add the contents of
the /kernel/ directory to it.
$ cp ../../../kernel/*.{h,asm} cfsin
You'll also need your glue file:
$ cp glue.asm cfsin
You're now ready to re-make your CFS:
$ rm sdcard.cfs && make
Now you can write this into your card and boot Collapse OS:
Collapse OS
> sdci
> fson
> fopn 0 glue.asm
> fnew 10 dest
> fopn 1 dest
> zasm 1 2 # This takes a while. About 7 minutes.
> sdcf # success! sdcf flushes SD card buffers to the card.
Now let's go verify that we assembled the right thing. Pop out the card and
plug it in your "modern" computer. Pipe the device directly through cfsunpack
to unpack the FS into a directory (it will stop reading when it stops seeing
CFS blocks):
$ sudo cat /dev/sdX | ../../../tools/cfspack/cfsunpack cfsout
$ cmp cfsout/dest ../os.bin
They're the same! Your RC2014 assembled a full Collapse OS kernel all by itself!