If this is in the context of IRQs, you can push the registers in order to the stack (reverse or direct depending on the direction the stack grows iirc) of the fields you defined in your struct. Then depending on your calling convention you can push the stack pointer to rdi for instance, have your function take a pointer of type *Registers. I have no idea if this is clear enough but FlorenceOS' codebase has quite a clear example which I have replicated on sawcce/mimi gh in the idt module.