PC-88 z80asmでキー入力

inkey1.asm

; z88dk / PC-88 mon
; z80asm -b -l inkey1.asm

tvram   equ     $f3c8

        org     $b000
start:
        ld      a, $0c          ; cls
        rst     $18             ; OUTIO
.loop
        ; キー入力
        ld      a, (dir)
        ld      b, a

        in      a, ($0a)        ; 左キー
        and     $04
        jr      nz, skip1
        dec     b
.skip1
        in      a, ($08)        ; 右キー
        and     $04
        jr      nz, skip2
        inc     b
.skip2
        ld      a, b
        and     $3f             ; 0～63
        ld      (dir), a

        call    WaitVBlank

        ; クリア
        ld      hl, tvram+120*5
        ld      b, 80
        ld      a, $20          ; ' '
.cls
        ld      (hl), a
        inc     hl
        djnz    cls

        ; 描画
        ld      hl, tvram+120*5
        ld      a, (dir)
        ld      b, a
        ld      a, $8e
.cont
        dec     b
        jp      m, break
        ld      (hl), a
        inc     hl
        jr      cont
.break
        jr      loop

WaitVBlank:
        in      a, ($40)
        and     $20
        jr      nz, WaitVBlank
.wait
        in      a, ($40)
        and     $20
        jr      z, wait
        ret

dir:    defb    $20