1 files changed, 54 insertions, 0 deletions
diff --git a/kern/atomic.h b/kern/atomic.h
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index 00000000..00da1645
--- /dev/null
+++ b/kern/atomic.h
@@ -0,0 +1,54 @@
+/* Copyright (C) 2017 Free Software Foundation, Inc.
+   Contributed by Agustina Arzille <avarzille@riseup.net>, 2017.
+
+   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 2 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/>.
+*/
+
+#ifndef _KERN_ATOMIC_H_
+#define _KERN_ATOMIC_H_   1
+
+/* Atomically compare *PTR with EXP and set it to NVAL if they're equal.
+ * Evaluates to a boolean, indicating whether the comparison was successful.*/
+#define __atomic_cas_helper(ptr, exp, nval, mo)   \
+  ({   \
+     typeof(exp) __e = (exp);   \
+     __atomic_compare_exchange_n ((ptr), &__e, (nval), 0,   \
+       __ATOMIC_##mo, __ATOMIC_RELAXED);   \
+   })
+
+#define atomic_cas_acq(ptr, exp, nval)   \
+  __atomic_cas_helper (ptr, exp, nval, ACQUIRE)
+
+#define atomic_cas_rel(ptr, exp, nval)   \
+  __atomic_cas_helper (ptr, exp, nval, RELEASE)
+
+#define atomic_cas_seq(ptr, exp, nval)   \
+  __atomic_cas_helper (ptr, exp, nval, SEQ_CST)
+
+/* Atomically exchange the value of *PTR with VAL, evaluating to
+ * its previous value. */
+#define __atomic_swap_helper(ptr, val, mo)   \
+  __atomic_exchange_n ((ptr), (val), __ATOMIC_##mo)
+
+#define atomic_swap_acq(ptr, val)   \
+  __atomic_swap_helper (ptr, val, ACQUIRE)
+
+#define atomic_swap_rel(ptr, val)   \
+  __atomic_swap_helper (ptr, val, RELEASE)
+
+#define atomic_swap_seq(ptr, val)   \
+  __atomic_swap_helper (ptr, val, SEQ_CST)
+
+#endif