--- /dev/null
+/*
+ * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
+ * Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved.
+ * Copyright (c) 1999-2003 by Hewlett-Packard Company. All rights reserved.
+ *
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+ */
+
+/* FIXME: untested. */
+/* The relevant documentation appears to be at */
+/* http://publibz.boulder.ibm.com/epubs/pdf/dz9zr003.pdf */
+/* around page 5-96. Apparently: */
+/* - Memory references in general are atomic only for a single */
+/* byte. But it appears that the most common load/store */
+/* instructions also guarantee atomicity for aligned */
+/* operands of standard types. WE FOOLISHLY ASSUME that */
+/* compilers only generate those. If that turns out to be */
+/* wrong, we need inline assembly code for AO_load and */
+/* AO_store. */
+/* - A store followed by a load is unordered since the store */
+/* may be delayed. Otherwise everything is ordered. */
+/* - There is a hardware compare-and-swap (CS) instruction. */
+
+#include "../ordered_except_wr.h"
+#include "../all_aligned_atomic_load_store.h"
+
+#include "../test_and_set_t_is_ao_t.h"
+/* FIXME: Is there a way to do byte-sized test-and-set? */
+
+/* FIXME: AO_nop_full should probably be implemented directly. */
+/* It appears that certain BCR instructions have that effect. */
+/* Presumably they're cheaper than CS? */
+
+AO_INLINE int AO_compare_and_swap_full(volatile AO_t *addr,
+ AO_t old, AO_t new_val)
+{
+ int retval;
+ __asm__ __volatile__ (
+# ifndef __s390x__
+ " cs %1,%2,0(%3)\n"
+# else
+ " csg %1,%2,0(%3)\n"
+# endif
+ " ipm %0\n"
+ " srl %0,28\n"
+ : "=&d" (retval), "+d" (old)
+ : "d" (new_val), "a" (addr)
+ : "cc", "memory");
+ return retval == 0;
+}
+#define AO_HAVE_compare_and_swap_full
+
+/* FIXME: Add double-wide compare-and-swap for 32-bit executables. */