/usr/share/doc/libopenusb-doc/html/function.openusbwait.html

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><H1
><A
NAME="function.openusbwait"
></A
><CODE
CLASS="function"
>openusb_wait, openusb_poll</CODE
></H1
><DIV
CLASS="refnamediv"
><A
NAME="AEN1340"
></A
><H2
>Name</H2
><CODE
CLASS="function"
>openusb_wait, openusb_poll</CODE
>&nbsp;--&nbsp;Wait for I/O request completion, Poll completion status of I/O request</DIV
><DIV
CLASS="refsynopsisdiv"
><A
NAME="AEN1344"
></A
><H2
>Synopsis</H2
><DIV
CLASS="funcsynopsis"
><P
></P
><A
NAME="AEN1345"
></A
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int32_t openusb_wait</CODE
>(uint32_t num_reqs, openusb_request_handle_t* handles, openusb_request_handle_t* handle);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int32_topenusb_poll</CODE
>(uint32_t num_reqs, openusb_request_handle_t* handles, openusb_request_handle_t* handle);</CODE
></P
><P
></P
></DIV
><P
></P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN1365"
></A
><H2
>Parameters</H2
><P
><CODE
CLASS="parameter"
> num_reqs </CODE
> Number of requests to wait/poll.</P
><P
><CODE
CLASS="parameter"
> handles </CODE
>  Array of request handles to wait/poll.</P
><P
><CODE
CLASS="parameter"
> handle </CODE
>  Completed request handle.</P
><P
></P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN1374"
></A
><H2
>Description</H2
><P
>&#13;
    <CODE
CLASS="function"
>openusb_wait()</CODE
> can be called to wait for completion on <CODE
CLASS="parameter"
>num_reqs
    </CODE
> of request handles. If one request was completed, <CODE
CLASS="function"
>openusb_wait</CODE
>
    will return its handle in <CODE
CLASS="parameter"
>handle</CODE
>. Otherwise, <CODE
CLASS="function"
>openusb_wait</CODE
>
    will block until one request gets completed.  
    </P
><P
>&#13;    <CODE
CLASS="function"
>openusb_poll()</CODE
> is different from <CODE
CLASS="function"
>openusb_wait</CODE
>. It
    checks if any request in <CODE
CLASS="parameter"
>handles</CODE
> has been completed. If there's one,
    <CODE
CLASS="function"
>openusb_poll</CODE
> will return this request's handle in <CODE
CLASS="parameter"
>handle</CODE
>.
    Otherwise, it returns immediately with <CODE
CLASS="parameter"
>handle</CODE
> set to NULL. No block at all.
    </P
><P
>&#13;    For both functions, caller should allocate an array of <CODE
CLASS="parameter"
>num_reqs</CODE
> elements
    for <CODE
CLASS="parameter"
>handles</CODE
> and set every element to the request handles to be checked.
    </P
><P
>If application has set callback in request when submitting it in <CODE
CLASS="function"
>openusb_xfer_aio
    </CODE
>, it should <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>NOT</I
></SPAN
> call the above functions to wait/poll that request.

    </P
><P
></P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN1396"
></A
><H2
>Return Value</H2
><P
><CODE
CLASS="function"
>openusb_wait</CODE
>(),  <CODE
CLASS="function"
>openusb_poll</CODE
>() returns 0 on success.
    Otherwise, a openusb error is returned. </P
><P
></P
><P
>OPENUSB_SUCCESS     No errors.</P
><P
>OPENUSB_BADARG         <CODE
CLASS="parameter"
>handles</CODE
> or <CODE
CLASS="parameter"
>handle</CODE
>
    				is not valid. Either they are NULL or some member of request is
				invalid.
    </P
><P
>OPENUSB_UNKNOWN_DEVICE     Can't find the device specified in request.</P
><P
>OPENUSB_PLATFORM_FAILURE   Unspecified kernel/driver failure</P
><P
>OPENUSB_NO_RESOURCES       Memory allocation failure</P
><P
>OPENUSB_IO_*               USB host controller errors</P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN1410"
></A
><H2
>See Also</H2
><P
></P
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libopenusb-doc 1.1.11-2 / usr / share / doc / libopenusb-doc / html / function.openusbwait.html
