Properly implement unsigned conversion

Author: Sebmaster

lib/index.js

@@ -61,6 +61,12 @@ function createNumberConversion(bitLength, typeOpts) {
 
         if (!typeOpts.unsigned && x >= moduloBound) {
             return x - moduloVal;
+        } else if (typeOpts.unsigned) {
+            if (x < 0) {
+              x += moduloVal;
+            } else if (x === -0) { // don't return negative zero
+              return 0;
+            }
         }
 
         return x;