Commit d32acd5f authored by phlo's avatar phlo

leaving hospital

parent e00d43bf
......@@ -46,21 +46,36 @@ In terms of memory ordering, the addition of a \emph{store buffer} allows stores
\subsection{Instructions}
To keep things simple, instructions are not stored in memory and labelled using the following attributes:
% not stored in memory
% simple format - unary at most
Instructions are stored separately for each processor and are therefore not contained in memory.
Our machine uses a radically reduced instruction set that contains only the most substantial operations.
To simplify the latter definition of operational semantics, instructions are labelled using the following attributes:
% To keep things simple, instructions are not stored in memory and labelled using the following attributes:
% Since we are not considering an actual implementation, the stream of instructions can be seen as hardwired to each of the processors.
\begin{itemize}
\item \textbf{accu} -- modifies accumulator contents
\item \textbf{mem} -- modifies CAS memory register contents
\item \textbf{modify} -- modifies a register's content (accu or mem)
% \item \textbf{accu} -- modifies accumulator contents
% \item \textbf{mem} -- modifies CAS memory register contents
\item \textbf{modify} -- modifies a register's content
\item \textbf{read} -- reads from memory
\item \textbf{write} -- writes to memory
\item \textbf{barrier} -- memory barrier - requires the store buffer to be flushed
\item \textbf{atomic} -- atomic operations (implies barrier)
\item \textbf{barrier} -- memory barrier% - requires the store buffer to be flushed
\item \textbf{atomic} -- atomic operation% (implies barrier)
\item \textbf{control} -- control flow operation
\end{itemize}
Due to the single register architecture, all instructions have at most one operand.
Two addressing modes are supported, direct and indirect, denoted by square brackets (e.g. \texttt{LOAD [adr]}).
\subsubsection{LOAD - Read from Memory}
\texttt{LOAD adr} loads the value at \texttt{adr} into \accu.
\subsubsection{STORE - Write to Memory}
\subsubsection{ADDI - Immediate Addition}
\paragraph{Syntax:} \texttt{ADDI val}
......
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