X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=methods.mtask.tex;h=db317820b360f8e7c2b87bc974b1488ab1ee27d4;hb=047ee8a13310ba90d01934827cb17c680b32a4b5;hp=a35883a596e5944f5afa91da706fdfee1cd007b3;hpb=d118ff9d857683084065145df45135ef6fa06711;p=msc-thesis1617.git

diff --git a/methods.mtask.tex b/methods.mtask.tex
index a35883a..db31782 100644
--- a/methods.mtask.tex
+++ b/methods.mtask.tex
@@ -36,21 +36,55 @@ instance isExpr Expr
 \end{lstlisting}
 
 \section{Semantics}
-\gls{mTask} do not behave like functions but more like
-\gls{iTasks}-\glspl{Task}. When an \gls{mTask} is created it returns immediatly
-and the \gls{Task} will be executed sometime in the future. \glspl{Task} can
-run at an interval and they can start other tasks.
-\todo{Meer uitwijden over de mTask semantiek}
+The \gls{C}-backend of the \gls{mTask}-system has an engine that is generated
+alongside the code for the \glspl{Task}. This engine will execute the
+\glspl{mTask} according to certain rules and semantics.
+\glspl{mTask} do not behave like functions but more like
+\gls{iTasks}-\glspl{Task}. An \gls{mTask} is queued when either his timer runs
+out or when it is started by another \gls{mTask}. When an \gls{mTask} is
+queued it does not block the execution but it will return immediately while
+the actual \gls{Task} will be executed some time in the future.
+
+The \gls{iTasks}-backend simulates the \gls{C}-backend and thus uses the same
+semantics. This engine expressed in pseudocode is listed as
+Algorithm~\ref{lst:engine}. All the \glspl{Task} are inspected on their waiting
+time. When the waiting time has not passed the delta is subtracted and they are
+pushed to the end of the queue. When the waiting has has surpassed they are
+executed. When a \gls{mTask} wants to queue another \gls{mTask} it can just
+append it to the queue.
+
+\begin{algorithm}[H]
+	\KwData{\textbf{queue} queue$[]$, \textbf{time} $t, t_p$}
+
+	$t\leftarrow\text{now}()$\;
+	\Begin{
+		\While{true}{
+			$t_p\leftarrow t$\;
+			$t\leftarrow\text{now}()$\;
+			\If{notEmpty$($queue$)$}{
+				$task\leftarrow \text{queue.pop}()$\;
+				$task$.wait $-= t-t_p$\;
+				\eIf{$task.wait>t_0$}{
+					queue.append$(task)$\;
+				}{
+					run\_task$(task)$\;
+				}
+			}
+		}
+	}
+	\caption{Engine pseudocode for the \gls{C}- and
+		\gls{iTasks}-backends}\label{lst:engine}
+\end{algorithm}
 
 \section{Expressions}
 Expressions in the \gls{mTask}-\gls{EDSL} are divided into two types, namely
 boolean expressions and arithmetic expressions. The class of arithmetic
 language constructs also contains the function \CI{lit} that lifts a
 host-language value in to the \gls{EDSL} domain. All standard arithmetic
-functions are included but are omitted for brevity. Moreover the class
-restrictions are only shown in the first functions and are later omitted. Both
-the boolean expression and arithmetic expression classes are shown in
-Listing~\ref{lst:arithbool}.
+functions are included in the \gls{EDSL} but are omitted in the example for
+brevity. Moreover, the class restrictions are only shown in the first functions
+and omitted in subsequent funcitons. Both the boolean expression and arithmetic
+expression classes are shown in Listing~\ref{lst:arithbool}.
 
 \begin{lstlisting}[language=Clean,label={lst:arithbool},
 	caption={Basic classes for expressions}]
@@ -69,13 +103,13 @@ class boolExpr v where
 \section{Control flow}
 Looping of \glspl{Task} happens because \glspl{Task} are launched at regular
 intervals or relaunch themselves. Therefore there is no need for loop control
-flow functionality such as \CI{While} or \CI{For} constructions. The main
-control flow is the sequence operator and the \CI{If} statement. Both are shown
-in Listing~\ref{lst:control}. The first class of \CI{If} statements describe
-the regular if statement. The expressions given can have any role. The
-functional dependency on \CI{s} determines the return type of the statement.
-The sequence operator is very straightforward and just ties the two expressions
-together in sequence.
+flow functionality such as \emph{while} or \emph{for} constructions. The main
+control flow is the sequence operator and the \emph{if} statement. Both are
+shown in Listing~\ref{lst:control}. The first class of \emph{If} statements
+describe the regular \emph{if} statement. The expressions given can have any
+role. The functional dependency on \CI{s} determines the return type of the
+statement.  The sequence operator is very straightforward and just ties the two
+expressions together in sequence.
 
 \begin{lstlisting}[%
 	language=Clean,label={lst:control},caption={Control flow operators}]
@@ -118,7 +152,7 @@ class assign v where
 \end{lstlisting}
 
 A way of storing data in \glspl{mTask} is using \glspl{SDS}. \glspl{SDS} serve
-as variables in the \gls{mTask} and will keep their value across executions.
+as variables in the \gls{mTask} and maintain their value across executions.
 The classes associated with \glspl{SDS} are listed in
 Listing~\ref{lst:sdsclass}. The \CI{Main} class is introduced to box an
 \gls{mTask} and make it recognizable by the type system.
@@ -134,11 +168,11 @@ class sds v where
 
 \section{Example mTask}
 \todo{Also explain semantics about running tasks}
-Some example \glspl{mTask} using almost all of the functionality are show in
+Some example \glspl{mTask} using almost all of the functionality are shown in
 Listing~\ref{lst:exmtask}. The \glspl{mTask} shown in the example do not belong
 to a particular view and therefore are of the type \CI{View t r}. The
 \CI{blink} \gls{mTask} show the classic \emph{Arduino} \emph{Hello World!}
-application that blinks a certain LED every interval. The \CI{thermostat}
+application that blinks a certain LED at each interval. The \CI{thermostat}
 \gls{mTask} will enable a digital pin powering a cooling fan when the analog
 pin representing a temperature sensor is too high. \CI{thermostat`} shows the
 same program but now using the assignment style \gls{GPIO}.