For very small platforms, where it's a struggle to have a C compiler because a "long int" of 32 bits is already a huge challenge to implement, let alone "long l

For very small platforms, where it's a struggle to have a C compiler because a "long int" of 32 bits is already a huge challenge to implement, let alone "long long int" - stop using high level languages. Figure out the few dozen machine code instructions you want for your program, write them down, review, translate to binary, done. For the bigger systems where that's not appropriate, you'll value a more expressive language. I recommend Rust particularly, even though Rust isn't available everywhere there's an excellent chance it covers every platform you actually care about.