com_dlbh
outb(COMPORT + com_dlbh, COMC_BPS(COMSPEED) >> 8);
if (sio_getreg(com, com_dlbh) != dlbh)
sio_setreg(com, com_dlbh, dlbh);
dlbh = inb(iobase + com_dlbh);
sp->dlbh = inb(iobase + com_dlbh);
outb(iobase + com_dlbh, dlbh);
if (sp->dlbh != inb(iobase + com_dlbh))
outb(iobase + com_dlbh, sp->dlbh);
outb(iobase + com_dlbh, divisor >> 8);
sio_setreg(com, com_dlbh, divisor >> 8);