fix alu: bit negate

1 files changed, 4 insertions, 3 deletions

diff --git a/nandgame/hack_alu.sv b/nandgame/hack_alu.sv
index 267b4a7..6d66a08 100644
--- a/nandgame/hack_alu.sv
+++ b/nandgame/hack_alu.sv
@@ -42,12 +42,13 @@ logic [(DATA_WIDTH-1):0] x1, x2, y1, y2, res1, res2 /* verilator public */;
 // logic [(DATA_WIDTH-1):0] int_result_arith;
 // logic [(DATA_WIDTH-1):0] int_result_logic;
 
+// bit-wise negation
 assign x1 = zx ? 0 : X_in;
 assign y1 = zy ? 0 : Y_in;
-assign x2 = nx ? -x1 : x1;
-assign y2 = ny ? -y1 : y1;
+assign x2 = nx ? ~x1 : x1;
+assign y2 = ny ? ~y1 : y1;
 assign res1 = f_arith_nlogic_in ? (x2 + y2) : (x2 & y2);
-assign res2 = neg_out ? -res1 : res1;
+assign res2 = neg_out ? ~res1 : res1;
 assign result_out = res2;
 assign zero_out = result_out == 0;
 assign negate_out = result_out[DATA_WIDTH-1] == 1;