Installed headers relicensing and cleanup

[lttng-ust.git] / libringbuffer / vatomic.h

diff --git a/libringbuffer/vatomic.h b/libringbuffer/vatomic.h
new file mode 100644 (file)
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--- /dev/null
+++ b/libringbuffer/vatomic.h
@@ -0,0 +1,81 @@
+#ifndef _LINUX_RING_BUFFER_VATOMIC_H
+#define _LINUX_RING_BUFFER_VATOMIC_H
+
+/*
+ * linux/ringbuffer/vatomic.h
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * 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.
+ */
+
+#include <assert.h>
+#include <urcu/uatomic.h>
+
+/*
+ * Same data type (long) accessed differently depending on configuration.
+ * v field is for non-atomic access (protected by mutual exclusion).
+ * In the fast-path, the ring_buffer_config structure is constant, so the
+ * compiler can statically select the appropriate branch.
+ * local_t is used for per-cpu and per-thread buffers.
+ * atomic_long_t is used for globally shared buffers.
+ */
+union v_atomic {
+       long a; /* accessed through uatomic */
+       long v;
+};
+
+static inline
+long v_read(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a)
+{
+       assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+       return uatomic_read(&v_a->a);
+}
+
+static inline
+void v_set(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a,
+          long v)
+{
+       assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+       uatomic_set(&v_a->a, v);
+}
+
+static inline
+void v_add(const struct lttng_ust_lib_ring_buffer_config *config, long v, union v_atomic *v_a)
+{
+       assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+       uatomic_add(&v_a->a, v);
+}
+
+static inline
+void v_inc(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a)
+{
+       assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+       uatomic_inc(&v_a->a);
+}
+
+/*
+ * Non-atomic decrement. Only used by reader, apply to reader-owned subbuffer.
+ */
+static inline
+void _v_dec(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a)
+{
+       --v_a->v;
+}
+
+static inline
+long v_cmpxchg(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a,
+              long old, long _new)
+{
+       assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+       return uatomic_cmpxchg(&v_a->a, old, _new);
+}
+
+#endif /* _LINUX_RING_BUFFER_VATOMIC_H */