#define BREAK     0x01
#define MODIFIER  0x02
#define SHIFT_L   0x04
#define SHIFT_R   0x08
#define ALTGR     0x10
/* 追加 BEGIN */
#define ALT       0x20
#define CTRL      0x40
/* 追加 END */

static char get_iso8859_code(void)
{
  static uint8_t state = 0;
  static uint8_t sState = 0;　// 追加
  uint8_t s;
  char c;

  while (1) {
    s = get_scan_code();
    if (!s) return 0;
    if (s == 0xF0) {
      state |= BREAK;
    } else if (s == 0xE0) {
      state |= MODIFIER;
    } else {
      if (state & BREAK) {
        if (s == 0x12) {
          state &= ~SHIFT_L;
        } else if (s == 0x59) {
          state &= ~SHIFT_R;
        } else if (s == 0x11 && (state & MODIFIER)) {
          state &= ~ALTGR;
        }
        // CTRL, ALT & WIN keys could be added
        // but is that really worth the overhead?
        state &= ~(BREAK | MODIFIER);
        continue;
      }
      if (s == 0x12) {
        state |= SHIFT_L;
        sState |= SHIFT_L; // 追加
        continue;
      /* 追加 BEGIN */
      } else if (s == 0x11) {
        sState |= ALT;
        continue;
      } else if (s == 0x14) {
        sState |= CTRL;
        continue;
      /* 追加 END */
      } else if (s == 0x59) {
        state |= SHIFT_R;
        sState |= SHIFT_R; // 追加
        continue;
      } else if (s == 0x11 && (state & MODIFIER)) {
        state |= ALTGR;
        sState |= ALTGR; // 追加
      }
      c = 0;
      if (state & MODIFIER) {
        switch (s) {
//        case 0x70: c = PS2_INSERT;      break;
//        case 0x6C: c = PS2_HOME;        break;
//        case 0x7D: c = PS2_PAGEUP;      break;
          case 0x71: c = PS2_DELETE;      break;
//        case 0x69: c = PS2_END;         break;
//        case 0x7A: c = PS2_PAGEDOWN;    break;
          case 0x75: c = PS2_UPARROW;     break;
          case 0x6B: c = PS2_LEFTARROW;   break;
          case 0x72: c = PS2_DOWNARROW;   break;
          case 0x74: c = PS2_RIGHTARROW;  break;
          case 0x4A: c = '/';             break;
          case 0x5A: c = PS2_ENTER;       break;
          default: break;
        }
      } else if (state & ALTGR) {
        // [右ALT]+[カナ/かな]キーが押された
        if (s == 0x13) {
          kana_f = ~kana_f ;
          if (kana_f == 0) {
            keymap = &PS2Keymap_JP ;      // 日本語キーマップに戻す
          } else {
            keymap = &PS2Keymap_KANA ;    // カタカナキーマップにする
          }
          c = PS2_KANA ; // この行をコメントにすればキーコードは返りません
        }
      } else if (state & (SHIFT_L | SHIFT_R)) {
        if (s < PS2_KEYMAP_SIZE)
          c = pgm_read_byte(keymap->shift + s);
      } else {
        if (s < PS2_KEYMAP_SIZE)
          c = pgm_read_byte(keymap->noshift + s);
      }
      state &= ~(BREAK | MODIFIER);
      if (c) {
        /* 追加 BEGIN */
        if (sState & 0x40) {
          c &= 0x1F;
          sState = 0;  
        }
        /* 追加 END */
        return c;
      }
    }
  }
}