Listing 5. Read/Write Relays

unsigned char readRelay8(int iRelay8Address)
{
    /* Read Relay8 register and return the value */
    return(readb(iRelay8Address));
}

void writeRelay8(int iRelay8Address, unsigned char ucValues)
{
    /* Write Relay8 register with the values */
    writeb(ucValues, iRelay8Address);
}

// Excerpt from ioctl function:
    switch(cmd) {

    case RELAY8_IOC_READ_RELAYS:
        /* Read Relay8 relay values */
        ucRelayValues = readRelay8(relay8_base + RELAY8_CONTROL);
        if (copy_to_user((typeof(relay8_relayValues)) arg,
                         &ucRelayValues,
                         sizeof(relay8_relayValues))) {
            ret = -EFAULT;
        }
        break;

    case RELAY8_IOC_WRITE_RELAYS:
        /* Write Relay8 relay values */
        writeRelay8(relay8_base + RELAY8_CONTROL,
                    *(typeof(relay8_relayValues)) arg);
        break;

    default:
        ret = -ENOTTY;
    }