@code{*@var{expected}}. If equal, the operation is a @emph{read-modify-write}
operation that writes @var{desired} into @code{*@var{ptr}}. If they are not
equal, the operation is a @emph{read} and the current contents of
-@code{*@var{ptr}} is written into @code{*@var{expected}}. @var{weak} is true
-for weak compare_exchange, and false for the strong variation. Many targets
+@code{*@var{ptr}} are written into @code{*@var{expected}}. @var{weak} is true
+for weak compare_exchange, which may fail spuriously, and false for
+the strong variation, which never fails spuriously. Many targets
only offer the strong variation and ignore the parameter. When in doubt, use
the strong variation.
-True is returned if @var{desired} is written into
-@code{*@var{ptr}} and the operation is considered to conform to the
+If @var{desired} is written into @code{*@var{ptr}} then true is returned
+and memory is affected according to the
memory order specified by @var{success_memorder}. There are no
restrictions on what memory order can be used here.
-False is returned otherwise, and the operation is considered to conform
+Otherwise, false is returned and memory is affected according
to @var{failure_memorder}. This memory order cannot be
@code{__ATOMIC_RELEASE} nor @code{__ATOMIC_ACQ_REL}. It also cannot be a
stronger order than that specified by @var{success_memorder}.
compiler may also ignore this parameter.
@smallexample
-if (_atomic_always_lock_free (sizeof (long long), 0))
+if (__atomic_always_lock_free (sizeof (long long), 0))
@end smallexample
@end deftypefn