indicates whether the changed bit was set _BEFORE_ the atomic bit
operation.
-WARNING! It is incredibly important that the value be a boolean,
-ie. "0" or "1". Do not try to be fancy and save a few instructions by
-declaring the above to return "long" and just returning something like
-"old_val & mask" because that will not work.
+
+.. warning::
+ It is incredibly important that the value be a boolean, ie. "0" or "1".
+ Do not try to be fancy and save a few instructions by declaring the
+ above to return "long" and just returning something like "old_val &
+ mask" because that will not work.
For one thing, this return value gets truncated to int in many code
paths using these interfaces, so on 64-bit if the bit is set in the