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costa.tex

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+\subsection{The Command Stack}
+This is a helper class to the connection class. 
+Each connection to a client has a command stack associated with it. The
+command stack is a stack of command strings as generated by the SICS
+clients. Commands are added to the top of the command queue by the network
+ reader. Each time the task associated with a connection runs one command
+is popped from the command stack and executed. During execution the command
+stack must be locked in order to prevent commands being accepted by tasks
+busy waiting for some other process to finish. 
+
+Correspondingly, the interface to the command stack looks like this:
+
+\begin{flushleft} \small
+\begin{minipage}{\linewidth} \label{scrap1}
+$\langle$costaint {\footnotesize ?}$\rangle\equiv$
+\vspace{-1ex}
+\begin{list}{}{} \item
+\mbox{}\verb@@\\
+\mbox{}\verb@     typedef struct __costa *pCosta;@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@/*----------------------------- live & death ----------------------------*/@\\
+\mbox{}\verb@     pCosta CreateCommandStack(void);@\\
+\mbox{}\verb@     void   DeleteCommandStack(pCosta self);@\\
+\mbox{}\verb@     int    SetCommandStackMaxSize(pCosta self, int iNewSize);@\\
+\mbox{}\verb@/*----------------------------------------------------------------------*/@\\
+\mbox{}\verb@     int CostaTop(pCosta self, char *pCommand);@\\
+\mbox{}\verb@     int CostaBottom(pCosta self, char *pCommand);@\\
+\mbox{}\verb@     int CostaPop(pCosta self,char **pPtr);@\\
+\mbox{}\verb@/*----------------------------------------------------------------------*/@\\
+\mbox{}\verb@     void CostaLock(pCosta self);@\\
+\mbox{}\verb@     void CostaUnlock(pCosta self);@\\
+\mbox{}\verb@@$\diamond$
+\end{list}
+\vspace{-1ex}
+\footnotesize\addtolength{\baselineskip}{-1ex}
+\begin{list}{}{\setlength{\itemsep}{-\parsep}\setlength{\itemindent}{-\leftmargin}}
+\item Macro referenced in scrap ?.
+\end{list}
+\end{minipage}\\[4ex]
+\end{flushleft}
+Internally, two data structure need to be defined, the first for the 
+list implementing the command stack, the second for the command stack
+itself.
+
+\begin{flushleft} \small
+\begin{minipage}{\linewidth} \label{scrap2}
+$\langle$costadat {\footnotesize ?}$\rangle\equiv$
+\vspace{-1ex}
+\begin{list}{}{} \item
+\mbox{}\verb@@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@/*------------------------------------------------------------------------*/@\\
+\mbox{}\verb@  typedef struct __costa {@\\
+\mbox{}\verb@                          int iLock;@\\
+\mbox{}\verb@                          int iList;@\\
+\mbox{}\verb@                          int iMaxSize;@\\
+\mbox{}\verb@                          int iCount;@\\
+\mbox{}\verb@                         } Costa;@\\
+\mbox{}\verb@@$\diamond$
+\end{list}
+\vspace{-1ex}
+\footnotesize\addtolength{\baselineskip}{-1ex}
+\begin{list}{}{\setlength{\itemsep}{-\parsep}\setlength{\itemindent}{-\leftmargin}}
+\item Macro referenced in scrap ?.
+\end{list}
+\end{minipage}\\[4ex]
+\end{flushleft}
+\begin{flushleft} \small
+\begin{minipage}{\linewidth} \label{scrap3}
+\verb@"costa.h"@ {\footnotesize ? }$\equiv$
+\vspace{-1ex}
+\begin{list}{}{} \item
+\mbox{}\verb@@\\
+\mbox{}\verb@/*-------------------------------------------------------------------------@\\
+\mbox{}\verb@                             C O S T A@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@  A command stack implementation for SICS. To be used by each connection.@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@  Mark Koennecke, September 1997@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@  copyright: see implementation file.@\\
+\mbox{}\verb@@\\
+\mbox{}\verb@----------------------------------------------------------------------------*/@\\
+\mbox{}\verb@#ifndef SICSCOSTA@\\
+\mbox{}\verb@#define SICSCOSTA@\\
+\mbox{}\verb@@$\langle$costaint {\footnotesize ?}$\rangle$\verb@@\\
+\mbox{}\verb@#endif@\\
+\mbox{}\verb@@$\diamond$
+\end{list}
+\vspace{-2ex}
+\end{minipage}\\[4ex]
+\end{flushleft}
+\begin{flushleft} \small
+\begin{minipage}{\linewidth} \label{scrap4}
+\verb@"costa.i"@ {\footnotesize ? }$\equiv$
+\vspace{-1ex}
+\begin{list}{}{} \item
+\mbox{}\verb@@\\
+\mbox{}\verb@/*---------------------------------------------------------------------------@\\
+\mbox{}\verb@                          C O S T A@\\
+\mbox{}\verb@  Internal data structures for the command stack.@\\
+\mbox{}\verb@--------------------------------------------------------------------------*/@\\
+\mbox{}\verb@@$\langle$costadat {\footnotesize ?}$\rangle$\verb@@\\
+\mbox{}\verb@@$\diamond$
+\end{list}
+\vspace{-2ex}
+\end{minipage}\\[4ex]
+\end{flushleft}