There is no such called code

There is no such thing called Code

There is no such thing called ubuntu, fedora software - Only linux softwares

There no such thing called linux or windows softwares - Only softwares

There is no such thing called softwares - Only source code

There is no such thing called source code - Only specifications and protocols

There is no such thing called programming language - Only syntax and semantics

There is no such thing called compilers - Only translators

There is no such called linux, minix, windows, mac - Only resource managers

There is no such thing called processor - Only instruction set

In the era of open source, there is no such thing at all. You want to develop a software for Operating system X, there is already similar -opens source- software is available for Operating system Y. You just have to compile it on operating system X. If it does not compile, you may need to tweak it a little bit. If it still does not compile, write it from scratch.

You want port a device driver from linux to other OSes, read the code and write it according to how the concerned OS handles drivers.

There is no real code, Only Knowledge and requirements. everything else imaginary.