io.s

global outb
global inb

; outb - send a byte to an I/O port
; stack: [esp + 8] the data byte
;        [esp + 4] the I/O port
;        [esp    ] return address
outb:
    mov al, [esp + 8]    ; put data in al register
    mov dx, [esp + 4]    ; put address of I/O port in dx register
    out dx, al
    ret

; inb - returns a byte from the given I/O port
; stack: [esp + 4] The address of the I/O port
;        [esp    ] The return address
inb:
    mov dx, [esp + 4]       ; put address of I/O port in dx register
    in  al, dx              ; read a byte from the I/O port in al register
    ret