Updated structure and added makefile

core/atomic.c

@@ -0,0 +1,49 @@
+/*
+ * This file is distributed as part of the SkySQL Gateway.  It 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,
+ * version 2.
+ *
+ * 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, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Copyright SkySQL Ab 2013
+ */
+
+/*
+ * atomic.c  - Implementation of atomic opertions for the gateway
+ *
+ * Revision History
+ *
+ * Date		Who		Description
+ * 10/06/13	Mark Riddoch	Initial implementation
+ *
+ */
+
+/*
+ * Implementation of an atomic add operation for the X86 processor.
+ * Adds a value to the contents of a location pointed to by the first parameter.
+ * The add operation is atomic and the return value is the value stored in the location
+ * prior to the operation. The number that is added may be signed, therefore atomic_subtract
+ * is merely an atomic add with a negative value.
+ *
+ * @param variable	Pointer the the variable to add to
+ * @param value		Value to be added
+ * @return		The value of *variable before the add occured
+ */
+int
+atomic_add(int *variable, int value)
+{
+	asm volatile(
+		"lock; xaddl %%eax, %2;"
+		:"=a" (value)
+		: "a" (value), "m" (*variable)
+		: "memory" );
+	return value;
+}