nexus: Fix arith_map CO signal.

Fixes #3187.

diff --git a/techlibs/nexus/arith_map.v b/techlibs/nexus/arith_map.v
index 9a1fedfc81a71e7c68529a9a6521752a6bfb22c1..81ab7ba54721062a930fa17acb3534565a5689b9 100644 (file)
--- a/techlibs/nexus/arith_map.v
+++ b/techlibs/nexus/arith_map.v
@@ -90,7 +90,7 @@ module _80_nexus_alu (A, B, CI, BI, X, Y, CO);
 
                assign CO[i] = (AA[i] && BB[i]) || ((Y[i] ^ AA[i] ^ BB[i]) && (AA[i] || BB[i]));
                if (i+1 < Y_WIDTH) begin
-                       assign CO[i + 1] = (AA[i] && BB[i]) || ((Y[i] ^ AA[i] ^ BB[i]) && (AA[i] || BB[i]));
+                       assign CO[i + 1] = (AA[i + 1] && BB[i + 1]) || ((Y[i + 1] ^ AA[i + 1] ^ BB[i + 1]) && (AA[i + 1] || BB[i + 1]));
                        assign Y[i+1] = Y1[i];
                end
        end endgenerate