SectorC: A C Compiler in 512 bytes
xorvoid.com115 points by valyala 5 hours ago
115 points by valyala 5 hours 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.
I may be the author.. enjoy! It was an absolute blast making this!
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.
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.
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.
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.
Examples:
It would be interesting to understand what non-toy programs can be coded in this subset of C. For example, could tcc be rewritten in this dialect?
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)
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.
The way hashing is used for tokens and for making a pseudo symbol table is such an elegant idea.
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 ;)
Lacking support for structs, I think this is too minimalistic to be called "a C compiler".
Beautiful, but make sure to quickly add 2023 to the title.
Discussed at the time: https://news.ycombinator.com/item?id=36064971
> I wrote a fairly straight-forward and minimalist lexer and it took >150 lines of C code
was it supposed to be "<150"?
They're saying the naive implementation was more than 150 lines of C code (300-450 bytes), i.e. too big.
Why is it called a C Compiler if it's a subset of C?
Nice. Very K&R-ish. Not a bad thing.