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1 files changed, 40 insertions, 0 deletions

diff --git a/cas.h b/cas.h
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+/*
+ * File     : cas.c
+ * Author   : Jérémy Zurcher  <jeremy@asynk.ch>
+ * Date     : 01/11/09 
+ * License  :
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining
+ *  a copy of this software and associated documentation files (the
+ *  "Software"), to deal in the Software without restriction, including
+ *  without limitation the rights to use, copy, modify, merge, publish,
+ *  distribute, sublicense, and/or sell copies of the Software, and to
+ *  permit persons to whom the Software is furnished to do so, subject to
+ *  the following conditions:
+ *  
+ *  The above copyright notice and this permission notice shall be
+ *  included in all copies or substantial portions of the Software.
+ *  
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+/* CMPXCHG8B m64   Compare EDX:EAX with m64. If equal, set ZF and load ECX:EBX into m64. Else, clear ZF and load m64 into EDX:EAX. */
+static inline unsigned int compare_and_swap(volatile unsigned long long *mem,
+                                            volatile unsigned long long old,
+                                            volatile unsigned long long new) {
+    char result;
+    __asm__ __volatile__("lock; cmpxchg8b %0; setz %1;"
+            : "=m"(*mem), "=q"(result)
+            : "m"(*mem), "d" ((unsigned long)(old>>32)), "a" ((unsigned long)old),
+            "c" ((unsigned long)(new>>32)), "b" ((unsigned long)new)
+            : "memory");
+    return (int)result;
+}
+