Show HN: Xcc700: Self-hosting mini C compiler for ESP32 (Xtensa) in 700 lines

A compiler you can fully grasp and tweak, on a modern platform where small is still cool. Basic features, not too entrenched, easy to morph into your language of choice. Reusable ELF writer, and a basic Xtensa bytecodes emitter. Possibly useful for hotfixes, CI, quick test/debug turnaround on esp32. ./xcc700 xcc700.c -o xcc700.elf [ xcc700 ] BUILD COMPLETED > OK > IN : 700 Lines / 7977 Tokens > SYM : 69 Funcs / 91 Globals > REL : 152 Literals / 1027 Patches > MEM : 1041 B .rodata / 17120 B .bss > OUT : 27735 B .text / 33300 B ELF [ 40 ms ] >> 17500 Lines/sec << Note: that timing is from esp32-s3. Timings on Mac/POSIX will be reported 1000x slower than they are, as on esp32 ticks are millisecond, and on POSIX microsecond, but there is no adjustment here. xcc700_demo10s.mov . Several options: A. Compile with gcc xcc700.c and run it on your computer as a cross-compiler. It is fairly portable, tested on Mac x86_64 and arm64. B. Compile for esp32 using xtensa-gcc or xcc700 from the option A (yes it can compile and cross-compile itself). Or grab the gcc-compiled version here: xcc700.elf (16kB) . Run with ESP-IDF elf_loader . C. Adapt the source code and call it as a function in your firmware. C features: minimum required to write something like this compiler. While loop, if/then/else, limited support for int/char/pointers/arrays, function calls and definitions, basic arithmetic and bitwise operators. Single source .c file as input, single REL ELF file as output. The output files can be run directly by the ESP-IDF elf_loader component, which links them on load via relocation table to anything you have exposed in your firmware: newlib libc, LVGL, your custom functions, anything you like. Just declare the functions you use. The rest of the C: for/do, include/define, long/float/double, struct/union/typedef, switch/case, array initializers, .data section, multi-line comments, too much to list. Many features are implemented only partially. E.g. you can have .bss globals but not global initializers; ++/-- are only supported in prefix position, assignment as statement not expression, types are mostly not checked, etc. Error handling and reporting. It is wildly optimistic, enforces nothing, has only a few error checks, and will crash in spectacular and unexpected ways on the most trivial errors. Optimization. It treats the Xtensa CPU as a stack machine, with no attempt at register allocation, and no benefit from the sliding window. It is a major sacrifice of performance for simplicity. GCC-compiled: 16kB, 17,500 lines/s; self-compiled: 33kB, 3,900 lines/s. Miss a feature? Just fork it! With a working foundation in only 700 lines, it is fairly easy to get started. This is free software under MIT License, see LICENSE . While I do not believe the world needs another C99 implementation, and do not intend to add features here, I am dead curious to see where the other creative minds can take a tiny self-hosting compiler on esp32. If you organize hackathons, or assign coursework,...

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