If this implementation had existed in the 1980s, the C standard would have a rule that different tokens hashing to the same 16-bit value invoke undefined behavior, and optimizing compilers in the 2000s would simply optimize such tokens away to a no-op. ;)
RodgerTheGreat 18 hours ago [-]
"you don't have -wTokenHashCollision enabled! it's your own foolish ignorance that triggered UB; the spec is perfectly clear!"
fredrikholm 9 hours ago [-]
Hey stop it with the ad hominems!
xorvoid 22 hours ago [-]
Too real! LMAO
mati365 1 days ago [-]
Oh, it looks like my X86-16 boot sector C compiler that I made recently [1]. Writing boot sector games has a nostalgic magic to it, when programming was actually fun and showed off your skills. It's a shame that the AI era has terribly devalued these projects.
Er, what? The article describes a compiler for a not-quite-C programming language which fits entirely in 512B. Your project, if I see this correctly, can optionally produce code meant to execute as boot sector.
Both interesting projects, but other than the words 'boot sector', 'C' and 'compiler', I don't see a similarity.
w4yai 16 hours ago [-]
> when programming was actually fun and showed off your skills
Oh no. Now more people are able to do what I do. I'm not special anymore.
mlsu 16 hours ago [-]
Seems like this is facetious but to me, “I’m not special” is a pretty valid thing to be sad about.
tgv 15 hours ago [-]
The two dos in "do what I do" do absolutely not carry the same meaning.
xorvoid 1 days ago [-]
I may be the author.. enjoy! It was an absolute blast making this!
veltas 1 days ago [-]
This is very nice. I'm currently writing a minimalist C compiler although my goal isn't fitting in a boot sector, it's more targeted at 8-bit systems with a lot more room than that.
This is a great demonstration of how simple the bare bones of C are, which I think is one reason I and many others find it so appealing despite how Spartan it is. C really evolved from B which was a demake of Fortran, if Ken Thompson is to be trusted.
JamesTRexx 1 days ago [-]
Would and how much would it shrink when if, while, and for were replaced by the simple goto routine? (after all, in assembly there is only jmp and no other fancy jump instruction (I assume) ).
And PS, it's "chose your own adventure". :-)
I love minimalism.
SAI_Peregrinus 1 days ago [-]
What fancy jumps are present in assembly depends on the CPU architecture. But there are always conditional jumps, like JNZ that jumps if the Zero flag isn't set.
MobiusHorizons 13 hours ago [-]
The “fancy jump” is the branch instruction. As far as I know all ISAs have them. Even rv32i which is famously minimal has several branch instructions in addition to two forms of unconditional jump. Branches are typically used to construct if / for / while as well as && and || (because of short circuiting) and ternary (although some architectures may have special instructions for that that may or may not be faster than branches depending on the exact model). Without it you would have to use computed goto with a destination address computed without conditional execution using constant time techniques.
dzaima 21 hours ago [-]
It only does if & while, not for. A goto in a single-pass thing would need separate handling for forwards vs backwards jumps, which involves keeping track of data per name (in a form where you can tell when it's not yet set; whereas if/while data is freely held in recursion stack). And you'd still need to handle at least `if ( expr ) goto foo;` to do any conditionals at all.
direwolf20 21 hours ago [-]
It's "choose your own adventure"
globalnode 21 hours ago [-]
thats the most important thing i noticed about the article, apart from the forth tokenising ideas.
einpoklum 1 days ago [-]
An interesting use case - for the compiler as-is or for the essentiall idea of barely-C - might be in bootstrapping chains, i.e. starting from tiny platform-specific binaries one could verify the disassembly of, and gradually building more complex tools, interpreters, and compiler, so that eventually you get to something like a version of GCC and can then build an entire OS distribution.
(Why does the referenced short story remind me of "There Is No Antimemetics Division"?)
wzbtoolbox 12 hours ago [-]
This is the kind of project that reminds you how far removed modern development is from the actual machine. We pile abstractions on abstractions until "Hello World" needs 200MB of node_modules, and then someone fits a C compiler in 512 bytes.
Not saying we should all write boot sector code, but reading through projects like this is genuinely humbling. Great educational resource too.
lock1 5 hours ago [-]
This kind of comment reminds me of how broad "software development" is.
On other HN posts, they're stating something like "software development is dead", "LLM as a compiler", "Do you read compiled assembly?", and so on.
While some other posts like this contain huge mechanical sympathy and literally r/w the assembly directly.
riedel 1 days ago [-]
Beautiful, but make sure to quickly add 2023 to the title.
Compare that to the C compiler in 100,000 lines written by Claude in two weeks for $20,000 (I think was posted on HN just yesterday)
vidarh 1 days ago [-]
It's a fun comparison, but with the notable difference that that one can compile the Linux kernel and generate code for multiple different architectures, while this one can only compile a small proportion of valid C. It's a great project, but it's not so much a C compiler, as a compiler for a subset of C that allows all programs this compiler can compile to also be compiled by an actual C compiler, but not vice versa.
d_silin 1 days ago [-]
But can it compile "Hello, World" example from its own README.md?
And it doesn't for the compiler in question either. As long as the headers exist in the places it looks for them. No compiler magically knows where the headers are if you haven't placed them in the right location
Retr0id 23 hours ago [-]
stddef.h (et al) should be shipped by the compiler itself, and so it should know where it is. But they rely on gcc for it, hence it doesn't always know where to look. Seems totally fine for a prototype.
vidarh 23 hours ago [-]
Especially given they're not shipping anything. The GCC binaries can't find misplaced or not installed headers either.
josefx 3 hours ago [-]
Shipping GPL headers that explicitly state that they are part of GCC with a creative commons licensed compiler would probably make a lot of people rather unhappy, possibly even lawyers.
d_silin 23 hours ago [-]
Would you accept the same quality of implementation from a human team?
dzaima 21 hours ago [-]
I've certainly encountered clang & gcc not finding or just not having header files a good couple times. Mostly around cross-compilation, but there was a period of time for which clang++ just completely failed to find any C++ headers on my system.
fooker 20 hours ago [-]
Yes, clang is famously in this category.
If you copy the clang binary to a random place in your filesystem, it will fail to compile programs that include standard headers.
vidarh 23 hours ago [-]
A compiler that can't magically know how to find headers that don't exist in the expected directory?
Yes, that is the case for pretty much every compiler. I suppose you could build the headers into the binary, but nobody does that.
tekne 21 hours ago [-]
Consider: content-addressed headers.
vidarh 10 hours ago [-]
Then you might as well embed the headers, since in that case you can't update the compiler and headers separately anyway.
Noticed the part where the exact instructions from the Readme were followed and it didn't work?
vidarh 11 hours ago [-]
So we're down to a missing or unclear description of a dependency in a README - note following the instructions worked for others -, from implications the compiler didn't work.
mojuba 21 hours ago [-]
Well I'm pretty sure the author can make a compliant C compiler in a few more sectors.
vidarh 7 hours ago [-]
I mean we know it can be done in little space, given the many tiny C compilers. I think what is most interesting about this one is exactly the creative shortcuts. It's an interesting design space for e.g. bootstrapping to impose extra restrictions.
1 days ago [-]
5 hours ago [-]
shikaan 13 hours ago [-]
Such a great read! Reminds me of the bootsector OS I made some time ago[^1]
The way hashing is used for tokens and for making a pseudo symbol table is such an elegant idea.
fix4fun 1 days ago [-]
I think the same. Really nice project and good trick with hashing tokens.
PS. There left 21 bytes (21 * 0x00 - from 0x01e0 to 0x01fd). Maybe something can be packed there ;)
avadodin 12 hours ago [-]
I actually "shipped" a parser using the symbols' hash(as the only identifier) for a test tool once. Hopefully, the users never used enough symbols to collide 32-bits.
benj111 7 hours ago [-]
I've had the idea before. Was never quite brave enough to do it. It's elegant until it isn't....
drob518 2 hours ago [-]
Brilliant! I love the stealing of Forth ideas to power this. Forth’s minimalism is highly underrated.
alittlebee 3 hours ago [-]
This is really beautiful (I feel like this sort of project is outsider art), thank you for sharing.
kreelman 17 hours ago [-]
There seems to be a good amount of interest for a boot sector compiler!!
If you're running on Linux, adjust the qemu call to use alsa rather than coreaudio.
I generated a pull request for this on Github. If the author is happy enough with my verbose shell scripting style :-) it might get included.
hgs3 4 hours ago [-]
Great read. It would be neat to see a mini operating system under 1 kb of code.
fooker 20 hours ago [-]
This is so cool!
Fun fact, Tiny C Compiler was derived from such a C compiler submitted to the the International Obfuscated C Code Contest.
Meh, I did an entire awk interpreter in two lines:
#!/bin/sh
echo "awk: bailing out" >&2
zahlman 13 hours ago [-]
> Big Insight #2 is that atoi() behaves as a (bad) hash function on ordinary text. It consumes characters and updates a 16-bit integer.
I could have sworn I remembered atoi() being defined to return 0 for invalid input (i.e. text not representing an integer in base ten).
MobiusHorizons 6 hours ago [-]
That would be true of one using a libc, but in a boot sector, you only have the bios, so the atoi being referenced is the one defined in c near the beginning of the article
zahlman 4 hours ago [-]
Ah, I somehow skipped over that exact code block on first read.
userbinator 18 hours ago [-]
C-subset, to be precise; but microcomputer C compilers were in the tens of KB range, for one that can actually compile real C.
DeathArrow 15 hours ago [-]
For me is not interesting because it fits in 512 bytes, it's interesting because it's very simple. I think it would be a great introduction to learning about compilers.
SeanSullivan86 1 days ago [-]
Why is it called a C Compiler if it's a subset of C?
userbinator 14 hours ago [-]
[flagged]
perching_aix 10 hours ago [-]
Why is your visceral reaction is to frame it as a quest for truth versus a great suppression of truth? Everything alright up there?
Literal second sentence in the article, in case it wasn't incredibly obvious to people anyways:
> It supports a subset of C that is large enough to write real and interesting programs.
I'm all for more boring headlines, but this characterization is ridiculous.
userbinator 2 hours ago [-]
I've had enough of headlines that overpromise and underdeliver. It's essentially false advertising. It's not like the word "subset" would put it over the length limit.
wbsun 17 hours ago [-]
Nice, now you can dd it to your boot sector and ... Wait, it is 2026, there are 1000 ways of booting and memory mapping on so-called unified ARM architecture @,@
NooneAtAll3 1 days ago [-]
> I wrote a fairly straight-forward and minimalist lexer and it took >150 lines of C code
was it supposed to be "<150"?
owalt 1 days ago [-]
They're saying the naive implementation was more than 150 lines of C code (300-450 bytes), i.e. too big.
EGreg 23 hours ago [-]
Reminds me of Allegro SizeHack where we made games in 10KB - but we were using C and Allegro library!
[1] https://github.com/Mati365/ts-c-compiler
Both interesting projects, but other than the words 'boot sector', 'C' and 'compiler', I don't see a similarity.
Oh no. Now more people are able to do what I do. I'm not special anymore.
This is a great demonstration of how simple the bare bones of C are, which I think is one reason I and many others find it so appealing despite how Spartan it is. C really evolved from B which was a demake of Fortran, if Ken Thompson is to be trusted.
And PS, it's "chose your own adventure". :-) I love minimalism.
Examples:
https://github.com/cosinusoidally/mishmashvm/
and https://github.com/cosinusoidally/tcc_bootstrap_alt/
(Why does the referenced short story remind me of "There Is No Antimemetics Division"?)
Not saying we should all write boot sector code, but reading through projects like this is genuinely humbling. Great educational resource too.
On other HN posts, they're stating something like "software development is dead", "LLM as a compiler", "Do you read compiled assembly?", and so on.
While some other posts like this contain huge mechanical sympathy and literally r/w the assembly directly.
Discussed at the time: https://news.ycombinator.com/item?id=36064971
SectorC: A C Compiler in 512 bytes - https://news.ycombinator.com/item?id=36064971 - May 2023 (80 comments)
https://github.com/anthropics/claudes-c-compiler/issues/1
Most people think they are more capable than they actually are.
From https://news.ycombinator.com/item?id=46920922 discussion.
If you copy the clang binary to a random place in your filesystem, it will fail to compile programs that include standard headers.
Yes, that is the case for pretty much every compiler. I suppose you could build the headers into the binary, but nobody does that.
Maybe it's time to equip it with a C compiler...
[1]: https://github.com/shikaan/osle
PS. There left 21 bytes (21 * 0x00 - from 0x01e0 to 0x01fd). Maybe something can be packed there ;)
If you're running on Linux, adjust the qemu call to use alsa rather than coreaudio.
I generated a pull request for this on Github. If the author is happy enough with my verbose shell scripting style :-) it might get included.
Fun fact, Tiny C Compiler was derived from such a C compiler submitted to the the International Obfuscated C Code Contest.
https://www.ioccc.org/2001/bellard/index.html
https://xorvoid.com/otcc_deobfuscated.html https://github.com/xorvoid/otcc_deobfuscated
I could have sworn I remembered atoi() being defined to return 0 for invalid input (i.e. text not representing an integer in base ten).
Literal second sentence in the article, in case it wasn't incredibly obvious to people anyways:
> It supports a subset of C that is large enough to write real and interesting programs.
I'm all for more boring headlines, but this characterization is ridiculous.
was it supposed to be "<150"?
https://www.oocities.org/trentgamblin/sizehack/entries.html#...
And anyway, isn't that kind of missing the point. 512 bytes isn't much. Your comment is nearly a 5th of that budget.
Or you know, just didn't get hung up on the blatantly obvious thing not being explicitly disclaimed right in the title, only in the preamble?