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serialwait.tex

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+\subsection{Serial Wait}
+This module is a very SINQ specific function. At SINQ, serial devices are
+controlled through a serial port server program running on a Macintosh PC.
+This program blocks, if the serial device is very slow. This blocks the
+Macintosh as well as the SICS server. This module solves this problem. It
+does so using the following logic:
+
+The command to execute is sent with a zero timeout.
+
+A special sics task, the SerialPoller, is started to monitor the device.
+
+The routine issuing the command waits for the SerialPoller to finish. If
+somebody issues new commands while this is going on, an error must be
+returned.
+
+The SerialPoller sends commands of zero length and with a zero timeout to
+the Macintosh. Usually the reply will be a ?TMO because no data is
+available. If data becomes available, two situations have to be handled:
+In the first case all data was read including the terminator. Then a reply
+without a ?TMO will be returned. If there is a slight delay in getting all
+the data, a ?TMO followed by data bytes is returned. In that case the data
+has to be appended to the data buffer. Then a null command with a sensible
+timeout is sent. If a new timeout comes in on that onew, there is an error.
+Else the data is appended to the data already read and we are finished. 
+
+It has been choosen to implement this logic separatly from the serialsinq
+stuff as it interacts very much with rest of SICS.
+
+Just one function is exported:
+\begin{flushleft} \small
+\begin{minipage}{\linewidth} \label{scrap1}
+\verb@"serialwait.h"@ {\footnotesize ? }$\equiv$
+\vspace{-1ex}
+\begin{list}{}{} \item
+\mbox{}\verb@@\\
+\mbox{}\verb@/*--------------------------------------------------------------------------@\\
+\mbox{}\verb@                          S E R I A L W A I T@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@  Executes a command on a serial port and waits for replies coming@\\
+\mbox{}\verb@  along by polling with null commands.@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@  copyright: see copyright.h@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@  Mark Koennecke, June 1998@\\
+\mbox{}\verb@---------------------------------------------------------------------------*/@\\
+\mbox{}\verb@#ifndef SERIALSICSWAIT@\\
+\mbox{}\verb@#define SERIALSICSWAIT@\\
+\mbox{}\verb@#include "sics.h"@\\
+\mbox{}\verb@#include "hardsup/serialsinq.h"@\\
+\mbox{}\verb@  int SerialSicsExecute(void **pData, char *pCommand, char *pReply, @\\
+\mbox{}\verb@                        int iBufLen);@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@#endif@\\
+\mbox{}\verb@@$\diamond$
+\end{list}
+\vspace{-2ex}
+\end{minipage}\\[4ex]
+\end{flushleft}
+Parameters and return values are the same as defined for the
+SerialWriteRead function.
+
+I am not sure if this facility works as expected. I think there was a
+problem with crosstalk on the serial line.  
+