ecp5: Improve mapping of $alu when BI is used

Signed-off-by: David Shah <dave@ds0.me>

diff --git a/techlibs/ecp5/arith_map.v b/techlibs/ecp5/arith_map.v
index eb79476018ed07db8bf5f562bf8d33dd19053439..17bde049754396cc2a7c01f0e3acb1a729c2b9fc 100644 (file)
--- a/techlibs/ecp5/arith_map.v
+++ b/techlibs/ecp5/arith_map.v
@@ -50,20 +50,21 @@ module _80_ecp5_alu (A, B, CI, BI, X, Y, CO);
 
        wire [Y_WIDTH2-1:0] AA = A_buf;
        wire [Y_WIDTH2-1:0] BB = BI ? ~B_buf : B_buf;
+       wire [Y_WIDTH2-1:0] BX = B_buf;
        wire [Y_WIDTH2-1:0] C = {CO, CI};
        wire [Y_WIDTH2-1:0] FCO, Y1;
 
        genvar i;
        generate for (i = 0; i < Y_WIDTH2; i = i + 2) begin:slice
                CCU2C #(
-                       .INIT0(16'b0110011010101010),
-                       .INIT1(16'b0110011010101010),
+                       .INIT0(16'b1001011010101010),
+                       .INIT1(16'b1001011010101010),
                        .INJECT1_0("NO"),
                        .INJECT1_1("NO")
           ) ccu2c_i (
                        .CIN(C[i]),
-                       .A0(AA[i]), .B0(BB[i]), .C0(1'b0), .D0(1'b1),
-                       .A1(AA[i+1]), .B1(BB[i+1]), .C1(1'b0), .D1(1'b1),
+                       .A0(AA[i]), .B0(BX[i]), .C0(BI), .D0(1'b1),
+                       .A1(AA[i+1]), .B1(BX[i+1]), .C1(BI), .D1(1'b1),
                        .S0(Y[i]), .S1(Y1[i]),
                        .COUT(FCO[i])
                );