From 8dca8d486e945eb5883e6757f711011ed23aa5ba Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Wed, 17 Jul 2019 12:44:52 -0700
Subject: [PATCH] Fix mul2dsp signedness

---
 techlibs/common/mul2dsp.v | 80 +++++++++++++++++++--------------------
 1 file changed, 38 insertions(+), 42 deletions(-)

diff --git a/techlibs/common/mul2dsp.v b/techlibs/common/mul2dsp.v
index d19599620..7344bc5fe 100644
--- a/techlibs/common/mul2dsp.v
+++ b/techlibs/common/mul2dsp.v
@@ -34,49 +34,45 @@ module \$mul (A, B, Y);
 	output [Y_WIDTH-1:0] Y;
 
 	generate
-        localparam add_sign_A = `DSP_A_SIGNEDONLY && !A_SIGNED;
-        localparam add_sign_B = `DSP_B_SIGNEDONLY && !B_SIGNED;
-        if (add_sign_A || add_sign_B) begin
-            if (add_sign_A && add_sign_B)
-                wire [1:0] dummy;
-            else
-                wire dummy;
-			\$mul #(
-				.A_SIGNED(1),
-				.B_SIGNED(1),
-				.A_WIDTH(A_WIDTH + (add_sign_A ? 1 : 0)),
-				.B_WIDTH(B_WIDTH + (add_sign_B ? 1 : 0)),
-				.Y_WIDTH(Y_WIDTH + (add_sign_A ? 1 : 0) + (add_sign_B ? 1 : 0))
-			) _TECHMAP_REPLACE_ (
-				.A(add_sign_A ? {1'b0, A} : A),
-				.B(add_sign_B ? {1'b0, B} : B),
-				.Y({dummy, Y})
-			);
+        if (`DSP_A_SIGNEDONLY && `DSP_B_SIGNEDONLY && !A_SIGNED) begin
+		wire [1:0] dummy;
+		\$mul #(
+			.A_SIGNED(1),
+			.B_SIGNED(1),
+			.A_WIDTH(A_WIDTH + 1),
+			.B_WIDTH(B_WIDTH + 1),
+			.Y_WIDTH(Y_WIDTH + 2)
+		) _TECHMAP_REPLACE_ (
+			.A({1'b0, A}),
+			.B({1'b0, B}),
+			.Y({dummy, Y})
+		);
         end
-		else if (A_WIDTH >= B_WIDTH)
-			\$__mul_gen #(
-				.A_SIGNED(A_SIGNED),
-				.B_SIGNED(B_SIGNED),
-				.A_WIDTH(A_WIDTH),
-				.B_WIDTH(B_WIDTH),
-				.Y_WIDTH(Y_WIDTH)
-			) _TECHMAP_REPLACE_ (
-				.A(A),
-				.B(B),
-				.Y(Y)
-			);
-		else
-			\$__mul_gen #(
-				.A_SIGNED(B_SIGNED),
-				.B_SIGNED(A_SIGNED),
-				.A_WIDTH(B_WIDTH),
-				.B_WIDTH(A_WIDTH),
-				.Y_WIDTH(Y_WIDTH)
-			) _TECHMAP_REPLACE_ (
-				.A(B),
-				.B(A),
-				.Y(Y)
-			);
+	// NB: A_SIGNED == B_SIGNED == 0 from here
+	else if (A_WIDTH >= B_WIDTH)
+		\$__mul_gen #(
+			.A_SIGNED(A_SIGNED),
+			.B_SIGNED(B_SIGNED),
+			.A_WIDTH(A_WIDTH),
+			.B_WIDTH(B_WIDTH),
+			.Y_WIDTH(Y_WIDTH)
+		) _TECHMAP_REPLACE_ (
+			.A(A),
+			.B(B),
+			.Y(Y)
+		);
+	else
+		\$__mul_gen #(
+			.A_SIGNED(B_SIGNED),
+			.B_SIGNED(A_SIGNED),
+			.A_WIDTH(B_WIDTH),
+			.B_WIDTH(A_WIDTH),
+			.Y_WIDTH(Y_WIDTH)
+		) _TECHMAP_REPLACE_ (
+			.A(B),
+			.B(A),
+			.Y(Y)
+		);
 	endgenerate
 endmodule
 
-- 
2.30.2