Merge branch 'master' of git.martlubbers.net:msc-thesis1617

[msc-thesis1617.git] / mtaskext.examples.tex

diff --git a/mtaskext.examples.tex b/mtaskext.examples.tex
index 66c2466..d680072 100644 (file)
--- a/mtaskext.examples.tex
+++ b/mtaskext.examples.tex
@@ -1,15 +1,65 @@
-The thermostat example given previously in Listing~\ref{lst:exmtask} would be
-compiled to the following code. The left column indicates the
-position in the program memory.
-
-\begin{lstlisting}[caption={Thermostat bytecode},language=c]
- 1-2 : BCAnalogRead (Analog A0)
- 3-6 : BCPush (Int 50)
- 7   : BCGre
- 8-9 : BCJmpF 17                   //Jump to else
-10-12: BCPush (Bool 1)
-13-14: BCDigitalWrite (Digital D0)
-15-16: BCJmp 21                    //Jump to end of if
-17-19: BCPush (Bool 0)             //Else label
-20   : BCDigitalWrite (Digital D0)
+As an example for the bytecode compilation the following listing shows the
+thermostat example given in Listing~\ref{lst:exmtask} compiled to bytecode.
+The left column indicates the position in the program memory. The \CI{endif}
+label is resolved to an address outside of the program space. This is not a
+problem since this is included in the stopping condition of the interpreter.
+When the program counter exceeds the length of the program, the task
+terminates.
+
+\begin{lstlisting}[language=Clean,caption={Thermostat bytecode},language=c]
+ 0-1 : BCAnalogRead (Analog A0)
+ 2-5 : BCPush (Int 50)
+ 6   : BCGre
+ 7-8 : BCJmpF 17                   //Jump to else
+ 9-11: BCPush (Bool 1)
+12-13: BCDigitalWrite (Digital D0)
+14-15: BCJmp 21                    //Jump to endif
+16-18: BCPush (Bool 0)             //Else label
+19   : BCDigitalWrite (Digital D0)
+20   :                             //Endif label
+\end{lstlisting}
+
+The factorial function can be expressed as an \gls{mTask}-\gls{Task} and uses
+the \CI{sds} and the \CI{return} functionality. Typically this \gls{Task} is
+called with the \CI{OnInterval} scheduling strategy and will calculate the
+factorial after which is will return. The following listings shows the actual
+\gls{mTask} and the generated messages followed by the actual bytecode in a
+readable form.
+
+\begin{lstlisting}[language=Clean,caption={Factorial as an \gls{mTask}-\gls{Task}}]
+factorial :: Int -> Main (ByteCode () Stmt)
+factorial i = sds \y=i In
+       namedsds \x=1 Named "result" In
+       {main =
+               IF (y <=. lit 1) (
+                       pub x :. retrn
+               ) (
+                       x =. x *. y :. y =. y -. lit 1
+               )}
+
+//Generating the actual messages with:
+Start = fst $ toMessages (OnInterval 500) (factorial 5) zero
+
+//The output will be
+//[MTSds 2 (BCValue 5), MTSds 1 (BCValue 1), MTTask (OnInterval 500) ...]
+\end{lstlisting}
+
+\begin{lstlisting}[language=Clean,label={lst:actualbc},%
+       caption={The resulting bytecode for the factorial function},language=C]
+ 0-2 : BCSdsFetch 1
+ 3-6 : BCPush (Int 1)
+ 7   : BCLeq
+ 8-9 : BCJmpF 16                    //Jump to else
+10-12: BCSdsPublish 2 ("result")
+13   : BCReturn
+14-15: BCJmp 37                     //Jump to endif
+16-18: BCSdsFetch 2 ("result")      //Else label
+19-21: BCSdsFetch 1
+22   : BCMul
+23-25: BCSdsStore 2 ("result")
+26-28: BCSdsFetch 1
+29-32: BCPush (Int 1)
+33   : BCSub
+34-36: BCSdsStore 1
+37   :                               //Endif label
 \end{lstlisting}