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\chapter{Bytecode instruction set}%
\label{chp:bytecode_instruction_set}%
This appendix describeds the semantics of the byte code instruction set of \gls{MTASK} (see \cref{chp:implementation}).
The byte code instructions are of variable length and automatically encoded and decoded using generic programming (see \cref{sec:ccodegen}).
\Cref{tbl:bc_notation} shows the notation convention.
\Cref{tbl:instr_task} shows the semantics of all major byte code instructions, shorthand instructions and auxiliary peripherals have been omitted for brevity but have the analogous semantics as their counterparts.

\begin{table}
	\caption{Notation convention for the byte code semantics.}%
	\label{tbl:bc_notation}
	\centering
	\begin{tabular}{lll}
		\toprule
		variable & meaning & \textnumero{}bytes\\
		\midrule
		$fp$ & frame pointer & 2\\
		$sp$ & stack pointer & 2\\
		$pc$ & program counter & 2\\
		$l$ & label & 2\\
		\midrule
		$w_r$ & return width & 1\\
		$w_a$ & argument width & 1\\
		$i$ & \gls{SDS} or sensor id & 1\\
		$n$ & number & 1\\
		$d$ & depth & 1\\
		\bottomrule
	\end{tabular}
\end{table}

\begin{landscape}
	\begin{longtable}[c]{lllll}
		\caption{Semantics for the bytecode instructions\label{tbl:instr_task}}\\
		\toprule
		Instruction & Arguments & Semantics & $sp$ & $pc$\\
		\midrule
		\endfirsthead%
		\caption{Semantics for the bytecode instructions (cont.)}\\
		\toprule
		Instruction & Arguments & Semantics & $sp$ & $pc$\\
		\midrule
		\endhead%
		\bottomrule
		\endfoot%
		\bottomrule
		\endlastfoot%
		\texttt{push}     & $n~b_0\ldots b_n$   & $st[sp+i] = s[i]$ {\bf for all} $i\in\{0..n\}$                            & $sp+n$           & $pc+2+n$\\
		\texttt{pop}      & $n$                 & & $sp\shortminus{}n$           & $pc+2$\\
		\texttt{rot}      & $d~n$               & $rotate\:(d, n)$                              & $sp$             & $pc+3$\\
		\texttt{dup}      &                     & $st[sp] = st[sp\shortminus{}1]$                           & $sp+1$           & $pc+1$\\
		\midrule
		\texttt{jumpF}    & $l$                 & & $sp\shortminus{}1$ & $\left\{\begin{array}{ll} pc+1 & \textrm{\bf if } st[sp\shortminus{}1]\\l & \textrm{\bf otherwise}\end{array}\right.$\\
		\texttt{jump}     & $l$                 & & $sp\shortminus{}1$ & $l$\\
		\texttt{jumpSR}   & $w_a~l$             & $st[sp\shortminus{}w_a\shortminus{}1]=pc+2$ & & $l$\\
		\texttt{tailCall} & $w_{a_1}~w_{a_2}~l$ & $rotate\:(w_{a_1}+3+w_{a_2},w_{a_2})$         & $fp$             & $jl$\\
						  &                     & $fp = fp\shortminus{}w_{a_1}+w_{a_2}$\\
						  &                     & \multicolumn{3}{p{.75\textwidth}}{{\bf where} $w_{a_1}$ is the width of the current function and $w_{a_2}$ the width of the called function}\\
		\texttt{arg}      & $n$                 & $st[sp] = st[fp\shortminus{}1\shortminus{}n]$ & $sp+1$\\
		\texttt{return}   & $w_r~w_a$           & $st[fp\shortminus{}w_a\shortminus{}3+i] = st[fp+1]$ & $st[fp\shortminus{}w_a\shortminus{}3+w_r]$ & $st[fp\shortminus{}w_a\shortminus{}1]$\\
					      &                     & {\bf for all} $i\in\{0..w_r\}$\\
					      &                     & $fp = st[fp\shortminus{}w_a\shortminus{}2]$\\
		\texttt{pushPtrs} &                     & $st[sp] = sp$                                 & $sp+3$           & $pc+1$\\
						  &                     & $st[sp+1] = fp$\\
		                  &                     & $st[sp+2] = 0$\\
		\midrule
		\texttt{unOp}     &                     & $st[sp\shortminus{}1] = \diamond{}st[sp\shortminus{}1]$ {\bf for all} $\diamond\in\{\neg\}$               & $sp$             & $pc+1$\\
		\texttt{binOp}    &                     & $st[sp\shortminus{}2] = st[sp\shortminus{}2] \mathbin{\oplus} st[sp\shortminus{}1]$         & $sp\shortminus{}1$           & $pc+1$\\
						  &                     & \multicolumn{3}{l}{{\bf for all} $\oplus\in\{+, \shortminus{}, *, /, \wedge, \vee, \equiv, \not\equiv, \leq, \geq, <, >\}$}\\
						  &                     & \multicolumn{3}{l}{similar for \cleaninline{Real} and \cleaninline{Long} variants}\\
		\texttt{cast}\textsubscript{f-t}     &  & $st[sp\shortminus{}1] = cast_{f\shortminus{}-t} (st[sp\shortminus{}1])$ & $sp$ & $pc+1$\\
						  &                     & \multicolumn{3}{l}{{\bf for all} $f,t\in\{Int, Real, Long\}$}\\
%		\pagebreak
		\texttt{mkTask}   & \texttt{Stable\textsubscript{n}} & $st[sp\shortminus{}n\shortminus{}1] = node (stable,$              & $sp\shortminus{}n+1$ & $pc+2$\\
						  &                                  & $\qquad\qquad st[sp\shortminus{}1], \ldots, st[sp\shortminus{}n\shortminus{}1])$\\
		\texttt{mkTask}   & \texttt{Unstable\textsubscript{n}} & $st[sp\shortminus{}n\shortminus{}1] = node (unstable,$          & $sp\shortminus{}n+1$ & $pc+2$\\
						  &                                  & $\qquad\qquad st[sp\shortminus{}1], \ldots, st[sp\shortminus{}n\shortminus{}1])$\\
		\midrule
		\texttt{mkTask}   & \texttt{ReadD}          & $st[sp\shortminus{}1] = node (readd, st[sp\shortminus{}1])$                 & $sp$      & $pc+2$\\
		\texttt{mkTask}   & \texttt{ReadA}          & $st[sp\shortminus{}1] = node (reada, st[sp\shortminus{}1])$                 & $sp$      & $pc+2$\\
		\texttt{mkTask}   & \texttt{WriteD}         & $st[sp\shortminus{}2] = node (writed, st[sp\shortminus{}1], st[sp\shortminus{}2])$    & $sp\shortminus{}1$ & $pc+2$\\
		\texttt{mkTask}   & \texttt{WriteA}         & $st[sp\shortminus{}2] = node (writea, st[sp\shortminus{}1], st[sp\shortminus{}2])$    & $sp\shortminus{}1$ & $pc+2$\\
		\texttt{mkTask}   & \texttt{WriteD}         & $st[sp\shortminus{}2] = node (writed, st[sp\shortminus{}1], st[sp\shortminus{}2])$    & $sp\shortminus{}1$ & $pc+2$\\
		\texttt{mkTask}   & \texttt{PinMode}        & $st[sp\shortminus{}2] = node (pinmode, st[sp\shortminus{}1], st[sp\shortminus{}2])$   & $sp\shortminus{}1$ & $pc+2$\\
		\midrule
		\texttt{mkTask}   & \texttt{Repeat}         & $st[sp] = node (repeat, st[sp\shortminus{}1])$              & $sp$   & $pc+2$\\
		\texttt{mkTask}   & \texttt{Delay}          & $st[sp] = node (delay, st[sp\shortminus{}1])$               & $sp$   & $pc+2$\\
		\texttt{mkTask}   & \texttt{And}            & $st[sp\shortminus{}1] = node (and, st[sp\shortminus{}1], st[sp\shortminus{}2])$       & $sp\shortminus{}1$ & $pc+2$\\
		\texttt{mkTask}   & \texttt{Or}             & $st[sp\shortminus{}1] = node (and, st[sp\shortminus{}1], st[sp\shortminus{}2])$       & $sp\shortminus{}1$ & $pc+2$\\
		\texttt{mkTask}   & \texttt{Step} $f$ $w_a$ & $st[sp] = node (step, st[sp\shortminus{}1], f, w)$          & $sp$   & $pc+5$\\
		\midrule
		\texttt{mkTask}   & \texttt{SdsGet} $i$     & $st[sp+1]   = node (sdsget, i)$                   & $sp+1$ & $pc+3$\\
		\texttt{mkTask}   & \texttt{SdsSet} $i$     & $st[sp\shortminus{}1] = node (sdsset, st[sp\shortminus{}1], i)$           & $sp$   & $pc+3$\\
		\texttt{mkTask}   & \texttt{SdsUpd} $i$ $l$ & $st[sp+1] = node (sdsset, i, l)$                  & $sp+1$ & $pc+5$\\
		\midrule
		\texttt{mkTask}   & \texttt{Interrupt}      & $st[sp\shortminus{}2] = node (interrupt, st[sp\shortminus{}1], st[sp\shortminus{}2])$ & $sp\shortminus{}1$ & $pc+2$\\
		\texttt{mkTask}   & \texttt{RateLimit}      & $st[sp\shortminus{}1] = node (ratelimit, st[sp\shortminus{}1])$           & $sp$   & $pc+2$\\
		\texttt{mkTask}   & \texttt{TuneRate}       & $st[sp\shortminus{}1] = node (tunerate,  st[sp\shortminus{}1], st[sp\shortminus{}2])$           & $sp\shortminus{}1$   & $pc+2$\\
		\midrule
		\texttt{mkTask}   & \texttt{DHTTemp} $i$    & $st[sp+1] = node (dhttemp, i)$                    & $sp+1$ & $pc+3$\\
		\texttt{mkTask}   & \texttt{DHTHumid} $i$   & $st[sp+1] = node (dhthumid, i)$                   & $sp+1$ & $pc+3$\\
	\end{longtable}
\end{landscape}

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