iop_readb
retval = (iop_readb(iop, IOP_ADDR_ALIVE) == 0xFF);
msg->reply[i] = iop_readb(iop, offset);
if (msg && iop_readb(iop, IOP_ADDR_SEND_STATE + chan) == IOP_MSG_IDLE)
msg->message[i] = iop_readb(iop, offset);
state = iop_readb(iop, IOP_ADDR_SEND_STATE + i);
state = iop_readb(iop, IOP_ADDR_RECV_STATE + i);