/*
 *      extcode:        resolve Atari-ST extended character codes
 *                      encoding the proper sequences into emacs
 *                      printable character specifications
 *
 *      Completely rewritten by Mike
 */

int extcode(sk, sc, key)
unsigned int sk;        /* Shift keys from event */
unsigned int sc;        /* ST scancode */
unsigned int key;       /* GEMDOS translation of the key */
{
  unsigned int code;    /* Build up special function code */
           int shift;   /* CAPS LOCK flag doesn't come from EVENT_MULTI */

  sc    &= 0xff;
  code  =  0;
#ifdef __GNUC__
  shift = Getshift();
#else
  shift = Getshift(-1);
#endif

  if (key)              /* Everything that returns a character */
  {
    if (key > 0x1a)     /* None of Ctrl-A to Ctrl-Z */
    {
      switch ((sc << 8) | key)
      {
        case 0x4b34 :           /* Shift cursor left */
          code = SPEC;
          key  = 'A';
          break;
        case 0x4d36 :           /* Shift cursor right */
          code = SPEC;
          key  = 'E';
          break;
        case 0x5032 :           /* Shift cursor down */
          code = SPEC;
          key  = 'V';
          break;
        case 0x4838 :           /* Shift cursor up */
          code = SPEC;
          key  = 'Z';
          break;
        case 0x5230 :           /* Shift insert */
          code = SPEC;
          key  = 'I';
          break;
        case 0x4737 :           /* Clr */
          code = SPEC;
          key  = '>';
          break;
        case 0x537f :
          code = SPEC;
          if (shift & 3)        /* Shift Del */
            key = 'd';
          else                  /* Del */
            key = 'D';
          break;
        default :
          if (sk & K_ALT)
          {
            switch (key)
            {
              case '\\' :
              case '@'  :
              case '{'  :
              case '}'  :
              case '['  :
              case ']'  :
                break;
              default   :
                code |= ALTD;
            }
          }
      }
    }
  }
  else                  /* All non character keys */
  {
    if (sc >= 0x54 && sc <= 0x5d)       /* Shifted function keys */
    {
      code =  SHFT;
      sc   -= 0x54 - 0x3b;
    }
    if (sc >= 0x3b && sc <= 0x44)       /* Function keys */
    {
      code |= SPEC;
      if (sk & K_ALT)
        code |= ALTD;
      else if (sk & K_CTRL)
        code |= CTRL;
      key = sc - 0x3b + '1';
      if (key == '9' + 1)
        key = '0';
    }
    else
    {
      if (sk & K_ALT)                   /* Alt pressed? */
      {
        code = ALTD;
        key  = kt->caps[sc];
        if (key < 'A' || key > 'Z')     /* Bogus key combination */
        {
          code = CTRL;
          key  = '@';
        }
      }
      else
      {
        code = SPEC;
        switch (sc)
        {
          case 0x4b :           /* Cursor left */
            key = 'B';
            break;
          case 0x73 :           /* Ctrl cursor left */
            code |= CTRL;
            key  =  'B';
            break;
          case 0x4d :           /* Cursor right */
            key = 'F';
            break;
          case 0x74 :           /* Ctrl cursor right */
            code |= CTRL;
            key  =  'F';
            break;
          case 0x50 :
            if (sk & K_CTRL)    /* Ctrl cursor down */
            {
              code |= CTRL;
              key  = 'V';
            }
            else                /* Cursor down */
              key = 'N';
            break;
          case 0x48 :
            if (sk & K_CTRL)    /* Ctrl cursor up */
            {
              code |= CTRL;
              key  =  'Z';
            }
            else                /* Cursor up */
              key = 'P';
            break;
          case 0x52 :           /* Insert */
            key = 'C';
            break;
          case 0x47 :           /* Home */
            key = '<';
            break;
          case 0x77 :           /* Ctrl home */
            code |= CTRL;
            key  =  'D';
            break;
          case 0x62 :           /* Help */
            key = 'H';
            break;
          case 0x61 :           /* Undo */
            key = 'X';
            break;
          default   :           /* Bogus key combination */
            code = CTRL;
            key  = '@';
        }
      }
    }
  }

  if (code)             /* Enter a special key */
  {
    in_put(0);
    in_put(code >> 8);
    in_put(key);
  }
  else                  /* Enter a normal key */
    in_put(key);
}