Add atomic primitives

Signed-off-by: Stephan Mueller <smueller@chronox.de>

lib/atomic.h

@@ -0,0 +1,215 @@
+/*
+ * Copyright (C) 2018, Stephan Mueller <smueller@chronox.de>
+ *
+ * License: see COPYING file in root directory
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
+ * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+#ifndef _ATOMIC_H
+#define _ATOMIC_H
+
+/*
+ * Atomic operations only work on:
+ *	GCC >= 4.1
+ *	Clang / LLVM
+ */
+
+/**
+ * Atomic type and operations equivalent to the Linux kernel.
+ */
+typedef struct {
+	volatile int counter;
+} atomic_t;
+
+/**
+ * Memory barrier
+ */
+static inline void mb(void)
+{
+	__sync_synchronize();
+}
+
+#define ATOMIC_INIT(i)  { (i) }
+
+/**
+ * Read atomic variable
+ * @param v atomic variable
+ * @return variable content
+ */
+static inline int atomic_read(const atomic_t *v)
+{
+	int i;
+
+	mb();	
+	i = ((v)->counter);
+	mb();
+
+	return i;
+}
+
+/**
+ * Set atomic variable
+ * @param i value to be set
+ * @param v atomic variable
+ */
+static inline void atomic_set(int i, atomic_t *v)
+{
+	mb();
+	((v)->counter) = i;
+	mb();
+}
+
+/**
+ * Atomic add operation
+ * @param i integer value to add
+ * @param v atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_add(int i, atomic_t *v)
+{
+	return __sync_add_and_fetch(&v->counter, i);
+}
+
+/**
+ * Atomic add value from variable and test for zero
+ * @param i integer value to add
+ * @param v atomic variable
+ * @return true if the result is zero, or false for all other cases.
+ */
+static inline int atomic_add_and_test(int i, atomic_t *v)
+{
+	return !(__sync_add_and_fetch(&v->counter, i));
+}
+
+/**
+ * Atomic increment by 1
+ * @param v atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_inc(atomic_t *v)
+{
+	return atomic_add(1, v);
+}
+
+/**
+ * Atomic increment and test for zero
+ * @param v pointer of type atomic_t
+ * @return true if the result is zero, or false for all other cases.
+ */
+static inline int atomic_inc_and_test(atomic_t *v)
+{
+	return atomic_add_and_test(1, v);
+}
+
+/**
+ * Atomic subtract operation
+ * @param i integer value to subtract
+ * @param v atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_sub(int i, atomic_t *v)
+{
+	return __sync_sub_and_fetch(&v->counter, i);
+}
+
+/**
+ * Atomic subtract value from variable and test for zero
+ * @param i integer value to subtract
+ * @param v atomic variable
+ * @return true if the result is zero, or false for all other cases.
+ */
+static inline int atomic_sub_and_test(int i, atomic_t *v)
+{
+	return !(__sync_sub_and_fetch(&v->counter, i));
+}
+
+/**
+ * Atomic decrement by 1
+ * @param v: atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_dec(atomic_t *v)
+{
+	return atomic_sub(1, v);
+}
+
+/**
+ * Atomic decrement by 1 and test for zero
+ * @param v atomic variable
+ * @return true if the result is zero, or false for all other cases.
+ */
+static inline int atomic_dec_and_test(atomic_t *v)
+{
+	return atomic_sub_and_test(1, v);
+}
+
+/**
+ * Atomic or operation
+ * @param i integer value to or
+ * @param v atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_or(int i, atomic_t *v)
+{
+	return __sync_or_and_fetch(&v->counter, i);
+}
+
+/**
+ * Atomic xor operation
+ * @param i integer value to xor
+ * @param v atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_xor(int i, atomic_t *v)
+{
+	return __sync_xor_and_fetch(&v->counter, i);
+}
+
+/**
+ * Atomic and operation
+ * @param i integer value to and
+ * @param v atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_and(int i, atomic_t *v)
+{
+	return __sync_and_and_fetch(&v->counter, i);
+}
+
+/**
+ * Atomic nand operation
+ * @param i integer value to nand
+ * @param v atomic variable
+ * @return variable content after operation
+ */
+static inline int atomic_nand(int i, atomic_t *v)
+{
+	return __sync_nand_and_fetch(&v->counter, i);
+}
+
+/**
+ * Atomic compare and exchange operation (if current value of atomic
+ * variable is equal to the old value, set the new value)
+ * @param v atomic variable
+ * @param old integer value to compare with
+ * @param new integer value to set atomic variable to
+ * @return true if comparison is successful and new was written
+ */
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+	return __sync_bool_compare_and_swap(&v->counter, old, new);
+}
+
+#endif