+\subsection{Shared Data Sources \& Assignment}
+Shared data sources must be acquired from the state and constructing one
+happens via multiple steps. First a fresh identifier is grabbed from the state.
+Then a \CI{BCShare} record is created with that identifier. A \CI{BCSdsFetch}
+instruction is written and the body is generated to finally add the share to
+the actual state with the value obtained from the function. The exact
+implementation is shown in Listing~\ref{lst:shareview}.
+
+\begin{lstlisting}[label={lst:shareview},%
+ caption={Bytecode view for \texttt{arith}}]
+freshshare = get >>= \st=:{freshl=[fr:frs]}->put {st & freshl=frs} >>| pure fr
+
+instance sds ByteCode where
+ sds f = {main = BC (freshshare
+ >>= \sdsi->pure {BCShare | sdsi=sdsi,sdsval=BCValue 0}
+ >>= \sds->pure (f (tell` [BCSdsFetch sds]))
+ >>= \(v In bdy)->modify (addSDS sds v)
+ >>| unBC (unMain bdy))
+ }
+ pub (BC x) = BC (censor (\[BCSdsFetch s]->[BCSdsPublish s]) x)
+
+addSDS sds v s = {s & sdss=[{sds & sdsval=BCValue v}:s.sdss]}
+\end{lstlisting}
+
+All assignable types compile to an \gls{RWST} that writes one instruction. For
+example, using an \gls{SDS} always results in an expression of the form
+\CI{sds \x=4 In ...}. The actual \CI{x} is the \gls{RWST} that always writes
+one \CI{BCSdsFetch} instruction with the correct \gls{SDS} embedded. When the
+call of the \CI{x} is not a read but an assignment, the instruction will be
+rewritten as a \CI{BCSdsStore}. The implementation for this is given in
+Listing~\ref{lst:assignmentview}.
+
+\begin{lstlisting}[label={lst:assignmentview},%
+ caption={Bytecode view implementation for assignment.}]
+instance assign ByteCode where
+ (=.) (BC v) (BC e) = BC (e >>| censor makeStore v)
+
+makeStore [BCSdsFetch i] = [BCSdsStore i]
+makeStore [BCDigitalRead i] = [BCDigitalWrite i]
+makeStore [...] = [...]
+\end{lstlisting}
+
+\section{Actual Compilation}
+All the previous functions are tied together with the \CI{toMessages} function.
+This function compiles the bytecode and transforms the \gls{Task} in a message.
+The \glspl{SDS} that were not already sent to the device are also placed in
+messages to be sent to the device. This functionality is listed in
+Listing~\ref{lst:compilation}. The compilation process consists of two steps.
+First the \gls{RWST} is executed, secondly the \emph{Jump} statements that jump
+to labels are transformed to jump to addresses. The translation of labels is
+possible in one sweep because no labels are reused. Reusing labels would not
+give a speed improvement since the labels are removed anyways in the end.
+
+\begin{lstlisting}[label={lst:compilation},%
+ caption={Actual compilation.}]
+bclength :: BC -> Int
+bclength (BCPush s) = 1 + size (toByteCode s)
+bclength ... = ...
+bclength x = 1 + consNum{|*|} x
+
+computeGotos :: [BC] Int -> ([BC], Map Int Int)
+computeGotos [] _ = ([], newMap)
+computeGotos [BCLab l:xs] i = appSnd ('DM'.put l i) (computeGotos xs i)
+computeGotos [x:xs] i = appFst (\bc->[x:bc]) (computeGotos xs (i + bclength x))
+
+toRealByteCode :: (ByteCode a b) BCState -> (String, BCState)
+toRealByteCode x s
+# (s, bc) = runBC x s
+# (bc, gtmap) = computeGotos bc 1
+= (concat (map (toString o toByteVal) (map (implGotos gtmap) bc)), s)
+
+toMessages :: MTaskInterval (Main (ByteCode a b)) BCState -> ([MTaskMSGSend], BCState)
+toMessages interval x oldstate
+# (bc, newstate) = toRealByteCode (unMain x) oldstate
+# newsdss = difference newstate.sdss oldstate.sdss
+= ([MTSds sdsi e\\{sdsi,sdsval=e}<-newsdss] ++ [MTTask interval bc], newstate)
+\end{lstlisting}
+
+\section{Example}
+The heating 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)
+\end{lstlisting}
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