org 0x1000

prhex = $c174
putchar = $c45e
putstr = $c01b

PUBLIC _main
_main:
    in      a,($81)
    set     0,a
    out     ($81),a

    ld      a,($42)
    ld      ($d0a0),a

    jp      ASMPC


    ld      a,$40
    ld      ($d77f),a

    ld      hl,613
main_loop:
    push    hl
    call    putstr
    BYTE    "abc"
    BYTE    "\0"
    pop     hl
    dec     hl
    ld      a,l
    or      h
    jp      nz,main_loop

back:
    call    uart_rx
    cp      $61
    jp      z,log
    ld      c,a
    call    putchar
    jp      back

    jp      ASMPC

log:
    ld      a,($ffd5)
    call    prhex
    ld      a,($ffd4)
    call    prhex
    jp      back

delay:
    push    de
    ld      de,$0000
delay_loop:
    dec     de
    ld      a,d
    or      e
    jr      nz,delay_loop

    pop     de
    ret

uart_rx:
    in      a,($b1)
    and     $01
    jr      z,uart_rx
    in      a,($b0)
    ret

uart_tx:
    in      a,($b1)
    and     $04
    jr      z,uart_tx
    ld      a,c
    out     ($b0),a
    ret