Implement Interrupt Descriptor Table and Handlers

Simulate interrupt handling infrastructure in C.

Requirements:

• Define IDT_ENTRY structure matching x86 format
• Implement encode_idt_entry() with offset, selector, access byte
• Create handlers for: divide by zero (0), timer (32), keyboard (33), syscall (128)
• Implement register_interrupt_handler() to set handlers
• Simulate lidt by storing IDT base and limit
• Implement handle_interrupt() dispatcher that calls correct handler
• Show register save/restore sequence
• Print when each handler fires with interrupt number
• Show EOI (End of Interrupt) being sent for hardware interrupts

Test:

• Show IDT being populated
• Show divide by zero handler firing
• Show timer interrupt handler firing
• Show syscall handler (int 0x80) firing