3 files changed, 17 insertions, 10 deletions
diff --git a/techlibs/ice40/arith_map.v b/techlibs/ice40/arith_map.v
index 65f28c585..26b24db9e 100644
--- a/techlibs/ice40/arith_map.v
+++ b/techlibs/ice40/arith_map.v
@@ -44,10 +44,18 @@ module _80_ice40_alu (A, B, CI, BI, X, Y, CO);
 
 	genvar i;
 	generate for (i = 0; i < Y_WIDTH; i = i + 1) begin:slice
-		\$__ICE40_FULL_ADDER carry (
+		\$__ICE40_CARRY_WRAPPER #(
+			//    A[0]: 1010 1010 1010 1010
+			//    A[1]: 1100 1100 1100 1100
+			//    A[2]: 1111 0000 1111 0000
+			//    A[3]: 1111 1111 0000 0000
+			.LUT(16'b 0110_1001_1001_0110)
+		) fadd (
 			.A(AA[i]),
 			.B(BB[i]),
 			.CI(C[i]),
+			.I0(1'b0),
+			.I3(C[i]),
 			.CO(CO[i]),
 			.O(Y[i])
 		);
diff --git a/techlibs/ice40/cells_map.v b/techlibs/ice40/cells_map.v
index 511b7f6c6..0c10c9ac4 100644
--- a/techlibs/ice40/cells_map.v
+++ b/techlibs/ice40/cells_map.v
@@ -63,7 +63,8 @@ endmodule
 `endif
 
 `ifndef NO_ADDER
-module \$__ICE40_FULL_ADDER (output CO, O, input A, B, CI);
+module \$__ICE40_CARRY_WRAPPER (output CO, O, input A, B, CI, I0, I3);
+  parameter LUT = 0;
   SB_CARRY carry (
     .I0(A),
     .I1(B),
@@ -72,13 +73,9 @@ module \$__ICE40_FULL_ADDER (output CO, O, input A, B, CI);
   );
   \$lut #(
     .WIDTH(4),
-    //    A[0]: 1010 1010 1010 1010
-    //    A[1]: 1100 1100 1100 1100
-    //    A[2]: 1111 0000 1111 0000
-    //    A[3]: 1111 1111 0000 0000
-    .LUT(16'b 0110_1001_1001_0110)
-  ) adder (
-    .A({CI,B,A,1'b0}),
+    .LUT(LUT)
+  ) lut (
+    .A({I3,B,A,I0}),
     .Y(O)
   );
 endmodule
diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index 93d5dcbd4..8f4a0f377 100644
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -293,8 +293,10 @@ struct SynthIce40Pass : public ScriptPass
 		{
 			if (nocarry)
 				run("techmap");
-			else
+			else {
+				run("ice40_wrapcarry");
 				run("techmap -map +/techmap.v -map +/ice40/arith_map.v");
+			}
 			if (retime || help_mode)
 				run(abc + " -dff", "(only if -retime)");
 			run("ice40_opt");