Explain the bit twiddling

johnmay · johnmay · commit 93a5c5e416f4 · 2021-02-06T12:02:49.000Z
diff --git a/base/core/src/main/java/org/openscience/cdk/stereo/AbstractStereo.java b/base/core/src/main/java/org/openscience/cdk/stereo/AbstractStereo.java
@@ -123,8 +123,8 @@ public int getGroupInfo() {
      * {@inheritDoc}
      */
     public void setGroupInfo(int grp) {
-        value &= ~IStereoElement.GRP_MASK;
-        value |= (grp & IStereoElement.GRP_MASK);
+        value &= ~IStereoElement.GRP_MASK; // clear existing hit bits
+        value |= (grp & IStereoElement.GRP_MASK); // set the new value ensure low bits aren't overwritten
     }
 
     /**
