\end{lstlisting}
\bigskip
-Note: Most synthesis script never switch to module context. But it is a very powerful
+Note: Most synthesis scripts never switch to module context. But it is a very powerful
tool for interactive design investigation.
\end{frame}
select w:reg_* # select all wires whose names start with reg_
select a:foobar # select all objects with the attribute foobar set
select a:foobar=42 # select all objects with the attribute foobar set to 42
-select A:blabla # select all module with the attribute blabla set
+select A:blabla # select all modules with the attribute blabla set
select foo/t:$add # select all $add cells from the module foo
\end{lstlisting}
\begin{frame}[fragile]{\subsubsecname}
When more than one selection expression is used in one statement they are
-pushed on a stack. At the final elements on the stack are combined into a union:
+pushed on a stack. The final elements on the stack are combined into a union:
\medskip
\begin{lstlisting}[xleftmargin=0.5cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, language=ys]
\begin{frame}[fragile]{\subsubsecname}
Sometime a selection can most easily described by a series of add/delete operations.
-For the commands {\tt select -add} and {\tt select -del} add or remove objects
+The commands {\tt select -add} and {\tt select -del} respectively add or remove objects
from the current selection instead of overwriting it.
\medskip
\item The special wires {\tt \_TECHMAP\_DO\_*} can be used to run Yosys scripts
in the context of the replacement module.
\medskip
-\item The wire that comes first in alphatecial oder is interprated as string (must
+\item The wire that comes first in alphabetical oder is interpreted as string (must
be connected to constants) that is executed as script. Then the wire is removed. Repeat.
\medskip
\item You can even call techmap recursively!
\item Interacting with custom commands.
\end{itemize}
\end{itemize}
+
+\scriptsize
+PROTIP: Commands such as {\tt shell}, {\tt show -pause}, and {\tt dump} can be use
+in the {\tt \_TECHMAP\_DO\_*} scripts for debugging map modules.
\end{frame}
\begin{frame}[t]{\subsubsecname{} -- Example}
\end{columns}
\end{frame}
-\subsubsection{TBD}
+\subsubsection{Handling shorted inputs}
\begin{frame}{\subsubsecname}
TBD
\end{frame}
+\subsubsection{Notes on using techmap}
+
+\begin{frame}{\subsubsecname}
+\begin{itemize}
+\item Don't use positional cell parameters in map modules.
+\medskip
+\item Don't try to implement basic logic optimization with techmap. \\
+{\small (So the OR-reduce using OR3X1 cells map was actually a bad example.)}
+\medskip
+\item You can use the {\tt \$\_\,\_}-prefix for internal cell types to avoid
+collisions with the user-namespace. But always use two underscores or the
+internal consistency checker will trigger on this cells.
+\medskip
+\item Techmap has two major use cases:
+\begin{itemize}
+\item Creating good logic-level representation of arithmetic functions. \\
+This also means using dedicated hardware resources such as half- and full-adder
+cells in ASICS or dedicated carry logic in FPGAs.
+\smallskip
+\item Mapping of coarse-grain resources such as block memory or DSP cells.
+\end{itemize}
+\end{itemize}
+\end{frame}
+
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Coarse-grain synthesis}
Read Verilog source file and convert to internal representation.
}%
\only<2>{
- Elaborate the design hierarchy. Should alsways be the first
+ Elaborate the design hierarchy. Should always be the first
command after reading the design.
}%
\only<3>{
\begin{frame}{\subsecname}
\begin{itemize}
\item Yosys is a powerful tool and framework for Verilog synthesis.
-\item Is uses a command-based interface and can be controlled by scripts.
+\item It uses a command-based interface and can be controlled by scripts.
\item By combining existing commands and implementing new commands Yosys can
be used in a wide range of application far beyond simple synthesis.
\end{itemize}
projects / yosys.git / commitdiff