NAME
    DoIO -- perform an I/O command and wait for completion

SYNOPSIS
    error = DoIO(iORequest)
    D0           A1

    BYTE DoIO(struct iorequest *);

FUNCTION
    This function requests a device driver to perform the I/O command
    specified in the I/O request.  This function will always wait until
    the I/O request is fully complete.

    DoIO() handles all the details, including Quick I/O, waiting for
    the request, and removing the reply message, etc..

IMPLEMENTATION
    This function first tries to complete the IO via the "Quick I/O"
    mechanism.  The io_Flags field is always set to IOF_QUICK (0x01)
    before the internal device call.

    The LN_TYPE field is used internally to flag completion.  Active
    requests have type NT_MESSAGE.  Requests that have been replied
    have type NT_REPLYMSG.  It is illegal to start IO using a
    still active iorequest, or a request with type nt_replymsg.

INPUTS
    iORequest - pointer to an iorequest initialized by opendevice()

RESULTS
    error - a sign-extended copy of the io_Error field of the
            iorequest.  most device commands require that the error
            return be checked.

SEE ALSO
    sendio, checkio, waitio, abortio, amiga.lib/beginio