diff --git a/CAS.h b/CAS.h
new file mode 100644
index 0000000..536dfa9
--- /dev/null
+++ b/CAS.h
@@ -0,0 +1,152 @@
+#ifndef _CAS_H
+#define _CAS_H
+
+/* Atomic operations for lock-free data structures.
+ * We operate on machine words and use size_t as a type.
+ * CAS stands for Compare And Swap, the most common operation. */
+
+/* The API was inspired by the Linux kernel */
+
+#if defined(__INTEL_COMPILER) || (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 1))
+#define USE_BUILTINS
+#endif
+
+/* *x += val; */
+static inline void atomic_add(size_t* x,size_t val) {
+#ifdef USE_BUILTINS
+  __sync_add_and_fetch(x,val);
+#elif defined(__i386__)
+  asm volatile ("lock; addl %1, %0" : "+m" (*x) : "ir" (val) );
+#elif defined(__x86_64__)
+  asm volatile ("lock; addq %1, %0" : "+m" (*x) : "ir" (val) );
+#else
+#error architecture not supported and gcc too old, edit CAS.h
+#endif
+}
+
+/* return *x += val; */
+static inline size_t atomic_add_return(size_t* x,size_t val) {
+#ifdef USE_BUILTINS
+  __sync_add_and_fetch(x,val);
+#elif defined(__i386__)
+  size_t i = val;
+  asm volatile ("lock; xaddl %1, %0" : "+m" (*x), "+r" (val) :: "memory" );
+  return i + val;
+#elif defined(__x86_64__)
+  size_t i = val;
+  asm volatile ("lock; xaddq %1, %0" : "+m" (*x), "+r" (val) :: "memory" );
+  return i + val;
+#else
+#error architecture not supported and gcc too old, edit CAS.h
+#endif
+}
+
+static inline void atomic_inc(size_t* x) {
+#ifdef __i386__
+  asm volatile ("lock; incl %0" : "+m" (*x) );
+#elif defined(__x86_64__)
+  asm volatile ("lock; incq %0" : "+m" (*x) );
+#else
+  atomic_add(x,1);
+#endif
+}
+
+static inline size_t atomic_inc_return(size_t* x) {
+  return atomic_add_return(x,1);
+}
+
+static inline void atomic_dec(size_t* x) {
+#ifdef __i386__
+  asm volatile ("lock; decl %0" : "+m" (*x) );
+#elif defined(__x86_64__)
+  asm volatile ("lock; decq %0" : "+m" (*x) );
+#else
+  atomic_add(x,-1);
+#endif
+}
+
+static inline size_t atomic_dec_return(size_t* x) {
+  return atomic_add_return(x,-1);
+}
+
+/* *x |= val; */
+static inline void atomic_or(volatile size_t* x,size_t val) {
+#ifdef USE_BUILTINS
+  __sync_or_and_fetch(x,val);
+#elif defined(__i386__)
+  asm volatile ("lock; orl %1, %0" : "+m" (*x) : "r" (val) );
+#elif defined(__x86_64__)
+  asm volatile ("lock; orq %1, %0" : "+m" (*x) : "r" (val) );
+#else
+#error architecture not supported and gcc too old, edit CAS.h
+#endif
+}
+
+/* *x &= val; */
+static inline void atomic_and(volatile size_t* x,size_t val) {
+#ifdef USE_BUILTINS
+  __sync_and_and_fetch(x,val);
+#elif defined(__i386__)
+  asm volatile ("lock; andl %1, %0" : "+m" (*x) : "r" (val) );
+#elif defined(__x86_64__)
+  asm volatile ("lock; andq %1, %0" : "+m" (*x) : "r" (val) );
+#else
+#error architecture not supported and gcc too old, edit CAS.h
+#endif
+}
+
+/* if (*x == oldval) { *x=newval; return 1; } else return 0; */
+static inline int compare_and_swap(volatile size_t* x,size_t oldval,size_t newval) {
+#ifdef USE_BUILTINS
+  __sync_bool_compare_and_swap(x,oldval,newval);
+#elif defined(__i386__)
+  char result;
+  asm volatile ("lock; cmpxchgl %3, %0; setz %1" : "=m"(*x), "=q" (result) : "m" (*x), "r" (newval), "a" (oldval) : "memory");
+  return result;
+#elif defined(__x86_64__)
+  char result;
+  asm volatile ("lock; cmpxchgq %3, %0; setz %1" : "=m"(*x), "=q" (result) : "m" (*x), "r" (newval), "a" (oldval) : "memory");
+  return result;
+#else
+#error architecture not supported and gcc too old, edit CAS.h
+#endif
+}
+
+/* Optimization barrier */
+/* The "volatile" is due to gcc bugs */
+#define barrier() __asm__ __volatile__("": : :"memory")
+
+#if defined(__i386__) || defined(__x86_64__)
+
+#define mb()	asm volatile("mfence":::"memory")
+#define rmb()	asm volatile("lfence":::"memory")
+#define wmb()	asm volatile("sfence":::"memory")
+
+/* Atomic operations are already serializing on x86 */
+#define smp_mb__before_atomic_dec()	barrier()
+#define smp_mb__after_atomic_dec()	barrier()
+#define smp_mb__before_atomic_inc()	barrier()
+#define smp_mb__after_atomic_inc()	barrier()
+
+#elif defined(__powerpc__)
+
+#define mb()	asm volatile("sync":::"memory")
+#define rmb()	asm volatile("sync":::"memory")
+#define wmb()	asm volatile("sync":::"memory")
+
+#define smp_mb__before_atomic_dec()     mb()
+#define smp_mb__after_atomic_dec()      mb()
+#define smp_mb__before_atomic_inc()     mb()
+#define smp_mb__after_atomic_inc()      mb()
+
+#elif defined(USE_BUILTINS)
+
+#define mb()	__sync_synchronize()
+#define rmb()	__sync_synchronize()
+#define wmb()	__sync_synchronize()
+
+#endif
+
+#undef USE_BUILTINS
+
+#endif