5 files changed, 80 insertions, 1 deletions
diff --git a/manual/PRESENTATION_ExAdv.tex b/manual/PRESENTATION_ExAdv.tex
index cf36d32c..483389d8 100644
--- a/manual/PRESENTATION_ExAdv.tex
+++ b/manual/PRESENTATION_ExAdv.tex
@@ -361,6 +361,44 @@ this is known to work well.
 \end{columns}
 \end{frame}
 
+\subsubsection{Handling constant inputs}
+
+\begin{frame}{\subsubsecname}
+\begin{itemize}
+\item The special parameters {\tt \_TECHMAP\_CONSTMSK\_\it <port-name>\tt \_} and
+{\tt \_TECHMAP\_CONSTVAL\_\it <port-name>\tt \_} can be used to handle constant
+input values to cells.
+\medskip
+\item The former contains 1-bits for all constant input bits on the port.
+\medskip
+\item The latter contains the constant bits or undef (x) for non-constant bits.
+\medskip
+\item Example use-cases:
+\begin{itemize}
+\item Converting arithmetic (for example multiply to shift)
+\item Identify constant addresses or enable bits in memory interfaces.
+\end{itemize}
+\end{itemize}
+\end{frame}
+
+\begin{frame}[t]{\subsubsecname{} -- Example}
+\vbox to 0cm{
+\vskip5.2cm
+\hskip6.5cm\includegraphics[width=5cm,trim=0 0cm 0 0cm]{PRESENTATION_ExAdv/mulshift.pdf}
+\vss
+}
+\vskip-0.6cm
+\begin{columns}
+\column[t]{6cm}
+\vskip-0.4cm
+\lstinputlisting[basicstyle=\ttfamily\fontsize{7pt}{8pt}\selectfont, language=verilog]{PRESENTATION_ExAdv/mulshift_map.v}
+\column[t]{4.2cm}
+\vskip-0.6cm
+\lstinputlisting[basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, frame=single, language=verilog]{PRESENTATION_ExAdv/mulshift_test.v}
+\lstinputlisting[basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, frame=single, language=ys, lastline=5]{PRESENTATION_ExAdv/mulshift_test.ys}
+\end{columns}
+\end{frame}
+
 \subsubsection{TBD}
 
 \begin{frame}{\subsubsecname}
diff --git a/manual/PRESENTATION_ExAdv/Makefile b/manual/PRESENTATION_ExAdv/Makefile
index 74f26327..3bbc239a 100644
--- a/manual/PRESENTATION_ExAdv/Makefile
+++ b/manual/PRESENTATION_ExAdv/Makefile
@@ -1,5 +1,5 @@
 
-all: select_01.pdf red_or3x1.pdf sym_mul.pdf mymul.pdf
+all: select_01.pdf red_or3x1.pdf sym_mul.pdf mymul.pdf mulshift.pdf
 
 select_01.pdf: select_01.v select_01.ys
 	../../yosys select_01.ys
@@ -13,3 +13,6 @@ sym_mul.pdf: sym_mul_*
 mymul.pdf: mymul_*
 	../../yosys mymul_test.ys
 
+mulshift.pdf: mulshift_*
+	../../yosys mulshift_test.ys
+
diff --git a/manual/PRESENTATION_ExAdv/mulshift_map.v b/manual/PRESENTATION_ExAdv/mulshift_map.v
new file mode 100644
index 00000000..4a3c2a06
--- /dev/null
+++ b/manual/PRESENTATION_ExAdv/mulshift_map.v
@@ -0,0 +1,26 @@
+module MYMUL(A, B, Y);
+    parameter WIDTH = 1;
+    input [WIDTH-1:0] A, B;
+    output reg [WIDTH-1:0] Y;
+
+    parameter _TECHMAP_CONSTVAL_A_ = WIDTH'bx;
+    parameter _TECHMAP_CONSTVAL_B_ = WIDTH'bx;
+
+    reg _TECHMAP_FAIL_;
+    wire [1023:0] _TECHMAP_DO_ = "proc; clean";
+
+    integer i;
+    always @* begin
+    	_TECHMAP_FAIL_ <= 1;
+        for (i = 0; i < WIDTH; i=i+1) begin
+            if (_TECHMAP_CONSTVAL_A_ === WIDTH'd1 << i) begin
+	        _TECHMAP_FAIL_ <= 0;
+                Y <= B << i;
+	    end
+            if (_TECHMAP_CONSTVAL_B_ === WIDTH'd1 << i) begin
+	        _TECHMAP_FAIL_ <= 0;
+                Y <= A << i;
+	    end
+	end
+    end
+endmodule
diff --git a/manual/PRESENTATION_ExAdv/mulshift_test.v b/manual/PRESENTATION_ExAdv/mulshift_test.v
new file mode 100644
index 00000000..4b975f41
--- /dev/null
+++ b/manual/PRESENTATION_ExAdv/mulshift_test.v
@@ -0,0 +1,5 @@
+module test (A, X, Y);
+input [7:0] A;
+output [7:0] X = A * 8'd 6;
+output [7:0] Y = A * 8'd 8;
+endmodule
diff --git a/manual/PRESENTATION_ExAdv/mulshift_test.ys b/manual/PRESENTATION_ExAdv/mulshift_test.ys
new file mode 100644
index 00000000..c5dac49e
--- /dev/null
+++ b/manual/PRESENTATION_ExAdv/mulshift_test.ys
@@ -0,0 +1,7 @@
+read_verilog mulshift_test.v
+hierarchy -check -top test
+
+techmap -map sym_mul_map.v \
+        -map mulshift_map.v;;
+
+show -prefix mulshift -format pdf -notitle -lib sym_mul_cells.v