util: add atomic64

This introduces read/set accessors for int64_t and uint64_t.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20180910232752.31565-3-cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index de3e36f400..f6993a8fb1 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -450,4 +450,38 @@
     _oldn;                                                              \
 })
 
+/* Abstractions to access atomically (i.e. "once") i64/u64 variables */
+#ifdef CONFIG_ATOMIC64
+static inline int64_t atomic_read_i64(const int64_t *ptr)
+{
+    /* use __nocheck because sizeof(void *) might be < sizeof(u64) */
+    return atomic_read__nocheck(ptr);
+}
+
+static inline uint64_t atomic_read_u64(const uint64_t *ptr)
+{
+    return atomic_read__nocheck(ptr);
+}
+
+static inline void atomic_set_i64(int64_t *ptr, int64_t val)
+{
+    atomic_set__nocheck(ptr, val);
+}
+
+static inline void atomic_set_u64(uint64_t *ptr, uint64_t val)
+{
+    atomic_set__nocheck(ptr, val);
+}
+
+static inline void atomic64_init(void)
+{
+}
+#else /* !CONFIG_ATOMIC64 */
+int64_t  atomic_read_i64(const int64_t *ptr);
+uint64_t atomic_read_u64(const uint64_t *ptr);
+void atomic_set_i64(int64_t *ptr, int64_t val);
+void atomic_set_u64(uint64_t *ptr, uint64_t val);
+void atomic64_init(void);
+#endif /* !CONFIG_ATOMIC64 */
+
 #endif /* QEMU_ATOMIC_H */