Software in Avionic

Hey guys, I'm trying to understand the software side of avionics systems.Specifically, I’m curious about:

• Which programming languages are commonly used in avionics (C, C++, Ada, Assembly, etc.)?
• What languages are typically used in systems like HUDs and MFDs?
• Are RTOS-based systems usually written in C/C++?
• Is Assembly still used in low-level avionics firmware today?

I’m at beginner level and trying to build a solid roadmap, so any guidance or resource recommendations would be greatly appreciated.