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\section{Introduction}
\begin{frame}
\sectionpage
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Representations of (digital) Circuits}
\begin{frame}[t]{\subsecname}
\begin{itemize}
\item Graphical
\begin{itemize}
\item \alert<1>{Schematic Diagram}
\item \alert<2>{Physical Layout}
\end{itemize}
\bigskip
\item Non-graphical
\begin{itemize}
\item \alert<3>{Netlists}
\item \alert<4>{Hardware Description Languages (HDLs)}
\end{itemize}
\end{itemize}
\bigskip
\begin{block}{Definition:
\only<1>{Schematic Diagram}%
\only<2>{Physical Layout}%
\only<3>{Netlists}%
\only<4>{Hardware Description Languages (HDLs)}}
\only<1>{
Graphical representation of the circtuit topology. Circuit elements
are represented by symbols and electrical connections by lines. The gometric
layout is for readability only.
}%
\only<2>{
The actual physical geometry of the device (PCB or ASIC manufracturing masks).
This is the final product of the design process.
}%
\only<3>{
A list of circuit elements and a list of connections. This is the raw circuit
topology.
}%
\only<4>{
Computer languages (like programming languages) that can be used to describe
circuits. HDLs are much more powerful in describing huge circuits than
schematic diagrams.
}%
\end{block}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Levels of Abstraction for Digital Circuits}
\begin{frame}[t]{\subsecname}
\begin{itemize}
\item \alert<1>{System Level}
\item \alert<2>{High Level}
\item \alert<3>{Behavioral Level}
\item \alert<4>{Register-Transfer Level (RTL)}
\item \alert<5>{Logical Gate Level}
\item \alert<6>{Physical Gate Level}
\item \alert<7>{Switch Level}
\end{itemize}
\bigskip
\begin{block}{Definition:
\only<1>{System Level}%
\only<2>{High Level}%
\only<3>{Behavioral Level}%
\only<4>{Register-Transfer Level (RTL)}%
\only<5>{Logical Gate Level}%
\only<6>{Physical Gate Level}%
\only<7>{Switch Level}}
\only<1>{
Overall view of the circuit: E.g. block-diagrams or instruction-set architecture descriptions
}%
\only<2>{
Functional implementation of circuit in high-level programming language (C, C++, SystemC, Matlab, Python, etc.).
}%
\only<3>{
Cycle-accurate description of circuit in hardware description language (Verilog, VHDL, etc.).
}%
\only<4>{
List of registers (flip-flops) and logic functions that calculate the next state from the previous one. Usually
a netlist utilizing high-level cells such as adders, multiplieres, multiplexer, etc.
}%
\only<5>{
Netlist of single-bit registers and basic logic gates (such as AND, OR,
NOT, etc.). Popular form: And-Inverter-Graphs (AIGs) with pairs of primary
inputs and outputs for each register bit.
}%
\only<6>{
Netlist of cells that actually are available on the target architecture
(such as CMOS gates in an ASCI or LUTs in an FPGA). Optimized for
area and/or and/or speed (static timing or number of logic levels).
}%
\only<7>{
Netlist of individual transistors.
}%
\end{block}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Digital Circuit Synthesis}
\begin{frame}{\subsecname}
Synthesis Tools (such as Yosys) can transform HDL code to circuits:
\bigskip
\begin{center}
\begin{tikzpicture}[scale=0.8, every node/.style={transform shape}]
\tikzstyle{lvl} = [draw, fill=MyBlue, rectangle, minimum height=2em, minimum width=15em]
\node[lvl] (sys) {System Level};
\node[lvl] (hl) [below of=sys] {High Level};
\node[lvl] (beh) [below of=hl] {Behavioral Level};
\node[lvl] (rtl) [below of=beh] {Register-Transfer Level (RTL)};
\node[lvl] (lg) [below of=rtl] {Logical Gate Level};
\node[lvl] (pg) [below of=lg] {Physical Gate Level};
\node[lvl] (sw) [below of=pg] {Switch Level};
\draw[dotted] (sys.east) -- ++(1,0) coordinate (sysx);
\draw[dotted] (hl.east) -- ++(1,0) coordinate (hlx);
\draw[dotted] (beh.east) -- ++(1,0) coordinate (behx);
\draw[dotted] (rtl.east) -- ++(1,0) coordinate (rtlx);
\draw[dotted] (lg.east) -- ++(1,0) coordinate (lgx);
\draw[dotted] (pg.east) -- ++(1,0) coordinate (pgx);
\draw[dotted] (sw.east) -- ++(1,0) coordinate (swx);
\draw[gray,|->] (sysx) -- node[right] {System Design} (hlx);
\draw[|->|] (hlx) -- node[right] {High Level Synthesis (HLS)} (behx);
\draw[->|] (behx) -- node[right] {Behavioral Synthesis} (rtlx);
\draw[->|] (rtlx) -- node[right] {RTL Synthesis} (lgx);
\draw[->|] (lgx) -- node[right] {Logic Synthesis} (pgx);
\draw[gray,->|] (pgx) -- node[right] {Cell Library} (swx);
\draw[dotted] (behx) -- ++(4,0) coordinate (a);
\draw[dotted] (pgx) -- ++(4,0) coordinate (b);
\draw[|->|] (a) -- node[right] {Yosys} (b);
\end{tikzpicture}
\end{center}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{What Yosys can and can't do}
\begin{frame}{\subsecname}
Things Yosys can do:
\begin{itemize}
\item Read and process (most of) modern Verilog-2005 code.
\item Perform all kinds of operations on netlist (RTL, Logic, Gate).
\item Perform logic optimiziations and gate mapping with ABC\footnote[frame]{\url{http://www.eecs.berkeley.edu/~alanmi/abc/}}.
\end{itemize}
\bigskip
Things Yosys can't do:
\begin{itemize}
\item Process high-level languages such as C/C++/SystemC.
\item Create physical layouts (place\&route).
\end{itemize}
\bigskip
A typical flow combines Yosys with with a low-level implementation tool, such
as Qflow\footnote[frame]{\url{http://opencircuitdesign.com/qflow/}} for ASIC designs.
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Yosys Data- and Control-Flow}
\begin{frame}{\subsecname}
A (usually short) synthesis script controlls Yosys.
This scripts contain three types of commands:
\begin{itemize}
\item {\bf Frontends}, that read input files (usually Verilog).
\item {\bf Passes}, that perform transformation on the design in memory.
\item {\bf Backends}, that write the design in memory to a file (various formats are available, e.g. Verilog, BLIF, EDIF, SPICE, BTOR, etc.).
\end{itemize}
\bigskip
\begin{center}
\begin{tikzpicture}[scale=0.6, every node/.style={transform shape}]
\path (-1.5,3) coordinate (cursor);
\draw[-latex] ($ (cursor) + (0,-1.5) $) -- ++(1,0);
\draw[fill=orange!10] ($ (cursor) + (1,-3) $) rectangle node[rotate=90] {Frontend} ++(1,3) coordinate (cursor);
\draw[-latex] ($ (cursor) + (0,-1.5) $) -- ++(1,0);
\draw[fill=green!10] ($ (cursor) + (1,-3) $) rectangle node[rotate=90] {Pass} ++(1,3) coordinate (cursor);
\draw[-latex] ($ (cursor) + (0,-1.5) $) -- ++(1,0);
\draw[fill=green!10] ($ (cursor) + (1,-3) $) rectangle node[rotate=90] {Pass} ++(1,3) coordinate (cursor);
\draw[-latex] ($ (cursor) + (0,-1.5) $) -- ++(1,0);
\draw[fill=green!10] ($ (cursor) + (1,-3) $) rectangle node[rotate=90] {Pass} ++(1,3) coordinate (cursor);
\draw[-latex] ($ (cursor) + (0,-1.5) $) -- ++(1,0);
\draw[fill=orange!10] ($ (cursor) + (1,-3) $) rectangle node[rotate=90] {Backend} ++(1,3) coordinate (cursor);
\draw[-latex] ($ (cursor) + (0,-1.5) $) -- ++(1,0);
\path (-3,-0.5) coordinate (cursor);
\draw (cursor) -- node[below] {HDL} ++(3,0) coordinate (cursor);
\draw[|-|] (cursor) -- node[below] {Internal Format (RTLIL)} ++(8,0) coordinate (cursor);
\draw (cursor) -- node[below] {Netlist} ++(3,0);
\path (-3,3.5) coordinate (cursor);
\draw[-] (cursor) -- node[above] {High-Level} ++(3,0) coordinate (cursor);
\draw[-] (cursor) -- ++(8,0) coordinate (cursor);
\draw[->] (cursor) -- node[above] {Low-Level} ++(3,0);
\end{tikzpicture}
\end{center}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Example Synthesis Script}
\begin{frame}[t]{\subsecname}
\setbeamercolor{alerted text}{fg=white,bg=red}
\begin{minipage}[t]{6cm}
\tt\scriptsize
\# read design\\
\boxalert<1>{read\_verilog mydesign.v}\\
\boxalert<2>{hierarchy -check -top mytop}
\medskip
\# the high-level stuff\\
\boxalert<3>{proc}; \boxalert<4>{opt}; \boxalert<5>{memory}; \boxalert<6>{opt}; \boxalert<7>{fsm}; \boxalert<8>{opt}
\medskip
\# mapping to internal cell library\\
\boxalert<9>{techmap}; \boxalert<10>{opt}
\bigskip
\it continued\dots
\end{minipage}
\begin{minipage}[t]{5cm}
\tt\scriptsize
\# mapping flip-flops to mycells.lib\\
\boxalert<11>{dfflibmap -liberty mycells.lib}
\medskip
\# mapping logic to mycells.lib\\
\boxalert<12>{abc -liberty mycells.lib}
\medskip
\# cleanup\\
\boxalert<13>{clean}
\medskip
\# write synthesized design\\
\boxalert<14>{write\_verilog synth.v}
\end{minipage}
\vskip1cm
\begin{block}{Command: \tt
\only<1>{read\_verilog mydesign.v}%
\only<2>{hierarchy -check -top mytop}%
\only<3>{proc}%
\only<4>{opt}%
\only<5>{memory}%
\only<6>{opt}%
\only<7>{fsm}%
\only<8>{opt}%
\only<9>{techmap}%
\only<10>{opt}%
\only<11>{dfflibmap -liberty mycells.lib}%
\only<12>{abc -liberty mycells.lib}%
\only<13>{clean}%
\only<14>{write\_verilog synth.v}}
\only<1>{
TBD
}%
\only<2>{
TBD
}%
\only<3>{
TBD
}%
\only<4>{
TBD
}%
\only<5>{
TBD
}%
\only<6>{
TBD
}%
\only<7>{
TBD
}%
\only<8>{
TBD
}%
\only<9>{
TBD
}%
\only<10>{
TBD
}%
\only<11>{
TBD
}%
\only<12>{
TBD
}%
\only<13>{
TBD
}%
\only<14>{
TBD
}%
\end{block}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Running the Synthesis Script}
\begin{frame}[fragile]{\subsecname{} -- Verilog Source: \tt counter.v}
\lstinputlisting[xleftmargin=1cm, language=Verilog]{PRESENTATION_Intro/counter.v}
\end{frame}
\begin{frame}[fragile]{\subsecname{} -- Cell Library: \tt mycells.lib}
\begin{columns}
\column[t]{5cm}
\lstinputlisting[basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, language=liberty, lastline=20]{PRESENTATION_Intro/mycells.lib}
\column[t]{5cm}
\lstinputlisting[basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, language=liberty, firstline=21]{PRESENTATION_Intro/mycells.lib}
\end{columns}
\end{frame}
\begin{frame}[t, fragile]{\subsecname{} -- Step 1/4}
\begin{verbatim}
read_verilog counter.v
hierarchy -check -top counter
\end{verbatim}
\vfill
\includegraphics[width=\linewidth,trim=0 0cm 0 0cm]{PRESENTATION_Intro/counter_00.pdf}
\end{frame}
\begin{frame}[t, fragile]{\subsecname{} -- Step 2/4}
\begin{verbatim}
proc; opt; memory; opt; fsm; opt
\end{verbatim}
\vfill
\includegraphics[width=\linewidth,trim=0 0cm 0 0cm]{PRESENTATION_Intro/counter_01.pdf}
\end{frame}
\begin{frame}[t, fragile]{\subsecname{} -- Step 3/4}
\begin{verbatim}
techmap; opt
\end{verbatim}
\vfill
\includegraphics[width=\linewidth,trim=0 0cm 0 0cm]{PRESENTATION_Intro/counter_02.pdf}
\end{frame}
\begin{frame}[t, fragile]{\subsecname{} -- Step 4/4}
\begin{verbatim}
dfflibmap -liberty mycells.lib
abc -liberty mycells.lib
clean
\end{verbatim}
\vfill
\includegraphics[width=\linewidth,trim=0 0cm 0 0cm]{PRESENTATION_Intro/counter_03.pdf}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{More Yosys Commands}
\begin{frame}[fragile]{\subsecname{} 1/3}
Command reference:
\begin{itemize}
\item Use ``{\tt help}'' for a command list and ``{\tt help \it command}'' for details.
\item Or run ``{\tt yosys -H}'' and ``{\tt yosys -h \it command}''.
\item Or go to \url{http://www.clifford.at/yosys/documentation.html}.
\end{itemize}
\bigskip
Commands for design navigation and investigation:
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont]
cd a shortcut for 'select -module <name>'
ls list modules or objects in modules
dump print parts of the design in ilang format
show generate schematics using graphviz
select modify and view the list of selected objects
\end{lstlisting}
\bigskip
Commands for executing scripts or entering interactive mode:
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont]
shell enter interactive command mode
history show last interactive commands
script execute commands from script file
tcl execute a TCL script file
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]{\subsecname{} 2/3}
Commands for reading and elaborating the design:
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont]
read_ilang read modules from ilang file
read_verilog read modules from verilog file
hierarchy check, expand and clean up design hierarchy
\end{lstlisting}
\bigskip
Commands for high-level synthesis:
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont]
proc translate processes to netlists
fsm extract and optimize finite state machines
memory translate memories to basic cells
opt perform simple optimizations
\end{lstlisting}
\bigskip
Commands for technology mapping:
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont]
techmap simple technology mapper
abc use ABC for technology mapping
dfflibmap technology mapping of flip-flops
hilomap technology mapping of constant hi- and/or lo-drivers
iopadmap technology mapping of i/o pads (or buffers)
flatten flatten design
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]{\subsecname{} 3/3}
Commands for writing the results:
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont]
write_blif write design to BLIF file
write_btor write design to BTOR file
write_edif write design to EDIF netlist file
write_ilang write design to ilang file
write_spice write design to SPICE netlist file
write_verilog write design to verilog file
\end{lstlisting}
\bigskip
Script-Commands for standard synthesis tasks:
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont]
synth_xilinx synthesis for Xilinx FPGAs
\end{lstlisting}
\bigskip
... and many many more.
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{More Verilog Examples}
\begin{frame}[fragile]{\subsecname{} 1/3}
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, language=Verilog]
module detectprime(a, y);
input [4:0] a;
output y;
integer i, j;
reg [31:0] lut;
initial begin
for (i = 0; i < 32; i = i+1) begin
lut[i] = i > 1;
for (j = 2; j*j <= i; j = j+1)
if (i % j == 0)
lut[i] = 0;
end
end
assign y = lut[a];
endmodule
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]{\subsecname{} 2/3}
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, language=Verilog]
module carryadd(a, b, y);
parameter WIDTH = 8;
input [WIDTH-1:0] a, b;
output [WIDTH-1:0] y;
genvar i;
generate
for (i = 0; i < WIDTH; i = i+1) begin:STAGE
wire IN1 = a[i], IN2 = b[i];
wire C, Y;
if (i == 0)
assign C = IN1 & IN2, Y = IN1 ^ IN2;
else
assign C = (IN1 & IN2) | ((IN1 | IN2) & STAGE[i-1].C),
Y = IN1 ^ IN2 ^ STAGE[i-1].C;
assign y[i] = Y;
end
endgenerate
endmodule
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]{\subsecname{} 3/3}
\begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{7pt}{8.5pt}\selectfont, language=Verilog]
module cam(clk, wr_enable, wr_addr, wr_data, rd_data, rd_addr, rd_match);
parameter WIDTH = 8;
parameter DEPTH = 16;
localparam ADDR_BITS = $clog2(DEPTH);
input clk, wr_enable;
input [ADDR_BITS-1:0] wr_addr;
input [WIDTH-1:0] wr_data, rd_data;
output reg [ADDR_BITS-1:0] rd_addr;
output reg rd_match;
integer i;
reg [WIDTH-1:0] mem [0:DEPTH-1];
always @(posedge clk) begin
rd_addr <= 'bx;
rd_match <= 0;
for (i = 0; i < DEPTH; i = i+1)
if (mem[i] == rd_data) begin
rd_addr <= i;
rd_match <= 1;
end
if (wr_enable)
mem[wr_addr] <= wr_data;
end
endmodule
\end{lstlisting}
\end{frame}
\subsection{Verification}
\begin{frame}{\subsecname{} -- VlogHammer}
TBD
\end{frame}
\begin{frame}{\subsecname{} -- yosys-bigsim}
TBD
\end{frame}
\subsection{Benefits of Open Source HDL Synthesis}
\begin{frame}{\subsecname}
TBD
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|