io.s

global inb
global outb
global load_idt

section .text

; Read byte from I/O port: inb(port)
inb:
 mov dx, [esp + 4] ; Get port number from stack argument
 in al, dx ; Read byte into AL register
 ret ; Return value in AL

; Write byte to I/O port: outb(port, value)
outb:
 mov dx, [esp + 4] ; Get port number
 mov al, [esp + 8] ; Get value to write
 out dx, al ; Send byte to hardware port
 ret

; Load Interrupt Descriptor Table pointer: load_idt(idtp_address)
load_idt:
 mov edx, [esp + 4] ; Get address of IDT pointer
 lidt [edx] ; Execute x86 LIDT instruction
 sti ; Enable hardware interrupts
 ret