%define KBD_STATUS 0x1ffc
%define KBD_CODE 0x1ffe
%define VCD 0x2000

%define KBD_FLAG_IS_RELEASE 0x1

    mov rsp, 0x1000
    mov rbp, rsp

    ; setup vcd
    mov r0, VCD
    mov [0x700], r0
    lvcd 0x700

    ; setup kbd
    mov r0, KBD_STATUS
    mov [0x702], r0
    mov r0, KBD_CODE
    mov [0x704], r0
    mov r0, key_press_int
    mov [0x706], r0
    lkbd 0x702

    ; init counter
    mov r0, 0
    mov [0x600], r0

main_loop:
    hlt
    jmp main_loop
    
key_press_int:
    mov r0, [KBD_STATUS]
    and r0, r0, KBD_FLAG_IS_RELEASE
    jnz r0, .leave

    mov r0, [0x600]
    add r0, r0, VCD
    mov r1, [KBC_CODE]
    add r1, r1, 61
    mov byte [r0], r1

    mov r0, [0x600]
    add r0, r0, 1
    mov [0x600], r0

.leave:
    reti


; vim: syntax=nasm