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