BITS 16
CPU 8086

org 0x7000

_start:
    jmp main

hexdigits:
    db "0123456789abcdef"

putc:
    push bx
    push bp
    mov ah, 0x0e
    xor bh, bh
    int 0x10
    pop bp
    pop bx
    ret

printnibble:
    push si
    push bx
    mov si, hexdigits
    xor bh, bh
    mov bl, al
    and bl, 0xf
    mov al, cs:[si+bx]
    call putc
    pop bx
    pop si
    ret

printi8:
    push bx
    mov bl, al
    mov cl, 4
    shr al, cl 
    call printnibble
    mov al, bl
    call printnibble
    pop bx
    ret

printi16:
    push bx
    mov bx, ax
    mov al, ah
    call printi8
    mov al, bl
    call printi8
    pop bx
    ret
    
main:
    mov bp, sp
    mov si, [bp+4]
    mov si, [si]
    mov ax, [si]
    call printi16
    mov al, 0x0d
    call putc
    mov al, 0x0a
    call putc
    retf 2