Aufgabe 4: Kontextwechsel

Preserved interrupt context.

After an interrupt was triggered, the core first saves the basic context (current code- & stack segment, instruction & stack pointer and the status flags register) and looks up the handling function for the vector using the IDT. In StuBS for each vector an own interrupt_entry_VECTOR function (written in assembly in interrupt/handler.asm) was registered during boot by kernel_init(), which all save the scratch registers on the stack before calling the C++ function interrupt_handler(). The high-level handler gets a pointer to the part of the stack which corresponds to the InterruptContext structure as second parameter. After returning from the high-level handler, the previous state is restored from this context (scratch register in assembly and basic context while executing iret) so it can continue transparently at the previous position.