NAME
    SCI_Poll - Check for arriving messages in polling mode

C Syntax
    #include <sci.h>
    int SCI_Poll(int timeout)

INPUT PARAMETERS
    timeout
        Timeout if no message arrives in timeout milliseconds, <0 means no timeout (IN).

DESCRIPTION
    This subroutine is used to check for arriving messages in polling mode. If a new
    message is arrived, user-registered handler in sci_info_t will be called to handle 
    the message, otherwise a timeout will occur after timeout milliseconds elapsed.

    If timeout is set to a negative value, no timeout will occur, and SCI_Poll can only
    return when a new message arrived or errors occurred.

    For more information, please refer to SCI's online documents.

EXAMPLE
        {
                int pollFd, extFd, maxFd;
                fd_set fdSet;
                SCI_Query(POLLING_FD, &pollFd);
                ...
                FD_ZERO(&fdSet);
                FD_SET(pollFd, &fdSet);
                FD_SET(extFd, &fdSet);
                maxFd = (pollFd > extFd) ? pollFd : extFd;
                select(maxFd+1, &fdSet, 0, 0, NULL);
                if (FD_ISSET(pollFd, &fdSet)) {
                        SCI_Poll(-1);
                }
                if (FD_ISSET(extFd, &fdSet)) {
                        ...
                }
        }

ERRORS
    All SCI routines return an error value.

    SCI_ERR_UNINTIALIZED
        Uninitialized SCI execution environment
    SCI_ERR_INVALID_CALLER
        Can only be called in the front end
    SCI_ERR_MODE
        Can only be used in polling mode
    SCI_ERR_POLL_INVALID
        Invalid polling calls
    SCI_ERR_POLL_TIMEOUT
        A polling timeout occurs after timeout milliseconds elapsed

SEE ALSO
    SCI_Bcast(3)
    SCI_Upload(3)