this doesn't use any libraries (not even the standard C library) and use two syscalls (open / mmap) to output to the Linux framebuffer device (fbdev), this also doesn't use shell / compression stub so it is a 'pure' standalone 256 bytes ELF
prototyped first with my software graphics library
requirements:
- 32 bits /dev/fb0 (framebuffer) with supported resolution
- high quality: the framebuffer should be set to display resolution
how to run:
- switch to console with Ctrl+Alt+F2 (Ctrl+Alt+F1 to switch back to X)
- check /dev/fb0 is writable to you (or launch with sudo to bypass this step)
- check /dev/fb0 current resolution with fbset tool
clearbefore running the program (not mandatory)- run the appropriate binary
permission issue: add current user to either 'tty' or 'video' group or use 'sudo'
change graphical terminal resolution:
- check supported resolution with "vbeinfo" in GRUB command prompt
- "GRUB_GFXMODE=WxH" in /etc/default/grub (where W/H is a value)
- sudo update-grub
didn't test resolutions others than 1920x1080 so may have issues.
the goal was to test doing something midly interesting in 256b in C on Linux without compression stub / shell script, it use CORDIC based algorithm to output some kind of additive background stars
must be run at night with big display for best contrast ! (it is rather meh as a screenshot and couldn't capture fb0) here is a phone video
with compression stub + truncation this goes to 239 bytes, the ELF header is roughly taking half the size, without the header the program code is ~80 bytes
code by grz built with GCC v7.5.0
greetings to all sizecoders
12/03/2021