1 files changed, 141 insertions, 0 deletions
diff --git a/src/common/atomic.h b/src/common/atomic.h
new file mode 100644
index 0000000..17cd4e5
--- /dev/null
+++ b/src/common/atomic.h
@@ -0,0 +1,141 @@
+/*  Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+/*!
+ * \file atomic.h
+ *
+ * \author Marek Vavrusa <marek.vavrusa@nic.cz>
+ *
+ * \brief Compatibility layer for atomic operations.
+ *
+ * Supports both __atomic and __sync legacy code.
+ * Based on the code bits from queue by Rusty Russel <rusty@rustcorp.com.au>.
+ *
+ * \addtogroup common_lib
+ * @{
+ */
+
+#ifndef _KNOTD_ATOMIC_H_
+#define _KNOTD_ATOMIC_H_
+
+#include <stdbool.h>
+#if defined(__ATOMIC_SEQ_CST)  /* GCC4.7+ supports C11 atomics. */
+
+static inline unsigned int read_once(unsigned int *ptr, int memmodel)
+{
+	return __atomic_load_n(ptr, memmodel);
+}
+
+static inline void *read_ptr(void **ptr, int memmodel)
+{
+	return __atomic_load_n(ptr, memmodel);
+}
+
+static inline void store_once(unsigned int *ptr, unsigned int val, int memmodel)
+{
+	__atomic_store_n(ptr, val, memmodel);
+}
+
+static inline void store_ptr(void **ptr, void *val, int memmodel)
+{
+	__atomic_store_n(ptr, val, memmodel);
+}
+
+static inline void atomic_inc(unsigned int *val, int memmodel)
+{
+	__atomic_add_fetch(val, 1, memmodel);
+}
+
+static inline void atomic_dec(unsigned int *val, int memmodel)
+{
+	__atomic_sub_fetch(val, 1, memmodel);
+}
+
+static inline bool compare_and_swap(unsigned int *ptr,
+	                            unsigned int old, unsigned int nval, int memmodel)
+{
+	return __atomic_compare_exchange_n(ptr, &old, nval, false,
+					   memmodel, memmodel);
+}
+
+#else /* Legacy __sync interface */
+
+#if defined(__i386__) || defined(__i686__) || defined(__amd64__)
+static inline void mb(void) /* mfence compatible */
+{
+	asm volatile ("mfence" : : : "memory");
+}
+#else                       /* last resort for other architectures */
+static inline void mb(void)
+{
+	__sync_synchronize();
+}
+#endif
+
+/* Define as full barrier. */
+#undef __ATOMIC_SEQ_CST
+#undef __ATOMIC_RELAXED
+#undef __ATOMIC_ACQUIRE
+#undef __ATOMIC_RELEASE
+#define __ATOMIC_SEQ_CST 1
+#define __ATOMIC_RELAXED 1
+#define __ATOMIC_ACQUIRE 1
+#define __ATOMIC_RELEASE 0
+
+static inline unsigned int read_once(unsigned int *ptr, int memmodel)
+{
+	return __sync_fetch_and_add(ptr, 0);
+}
+
+static inline void *read_ptr(void **ptr, int memmodel)
+{
+	return __sync_fetch_and_add(ptr, 0);
+}
+
+static inline void store_once(unsigned int *ptr, unsigned int val, int memmodel)
+{
+	*(volatile unsigned int *)ptr = val;
+	if (memmodel)
+		mb();
+}
+
+static inline void store_ptr(void **ptr, void *val, int memmodel)
+{
+	*(void * volatile *)ptr = val;
+	if (memmodel)
+		mb();
+}
+
+static inline void atomic_inc(unsigned int *val, int memmodel)
+{
+	__sync_fetch_and_add(val, 1);
+}
+
+static inline void atomic_dec(unsigned int *val, int memmodel)
+{
+	__sync_fetch_and_sub(val, 1);
+}
+
+static inline bool compare_and_swap(unsigned int *ptr,
+                                    unsigned int old, unsigned int nval, int memmodel)
+{
+	return __sync_bool_compare_and_swap(ptr, old, nval);
+}
+
+#endif
+
+#endif /* _KNOTD_ATOMIC_H_ */
+
+/*! @} */