initial commit

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diff --git a/src/atomic_ptr.hpp b/src/atomic_ptr.hpp
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--- /dev/null
+++ b/src/atomic_ptr.hpp
@@ -0,0 +1,189 @@
+/*
+    Copyright (c) 2007-2009 FastMQ Inc.
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the Lesser GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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
+    Lesser GNU General Public License for more details.
+
+    You should have received a copy of the Lesser GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef __ZS_ATOMIC_PTR_HPP_INCLUDED__
+#define __ZS_ATOMIC_PTR_HPP_INCLUDED__
+
+#include "platform.hpp"
+
+#if defined ZS_FORCE_MUTEXES
+#define ZS_ATOMIC_PTR_MUTEX
+#elif (defined __i386__ || defined __x86_64__) && defined __GNUC__
+#define ZS_ATOMIC_PTR_X86
+#elif 0 && defined __sparc__ && defined __GNUC__
+#define ZS_ATOMIC_PTR_SPARC
+#elif defined ZS_HAVE_WINDOWS
+#define ZS_ATOMIC_PTR_WINDOWS
+#elif defined ZS_HAVE_SOLARIS
+#define ZS_ATOMIC_PTR_SOLARIS
+#else
+#define ZS_ATOMIC_PTR_MUTEX
+#endif
+
+#if defined ZS_ATOMIC_PTR_MUTEX
+#include "mutex.hpp"
+#elif defined ZS_ATOMIC_PTR_WINDOWS
+#include "windows.hpp"
+#elif defined ZS_ATOMIC_PTR_SOLARIS
+#include <atomic.h>
+#endif
+
+namespace zs
+{
+
+    //  This class encapsulates several atomic operations on pointers.
+
+    template <typename T> class atomic_ptr_t
+    {
+    public:
+
+        //  Initialise atomic pointer
+        inline atomic_ptr_t ()
+        {
+            ptr = NULL;
+        }
+
+        //  Destroy atomic pointer
+        inline ~atomic_ptr_t ()
+        {
+        }
+
+        //  Set value of atomic pointer in a non-threadsafe way
+        //  Use this function only when you are sure that at most one
+        //  thread is accessing the pointer at the moment.
+        inline void set (T *ptr_)
+        {
+            this->ptr = ptr_;
+        }
+
+        //  Perform atomic 'exchange pointers' operation. Pointer is set
+        //  to the 'val' value. Old value is returned.
+        inline T *xchg (T *val_)
+        {
+#if defined ZS_ATOMIC_PTR_WINDOWS
+            return (T*) InterlockedExchangePointer (&ptr, val_);
+#elif defined ZS_ATOMIC_PTR_SOLARIS
+            return (T*) atomic_swap_ptr (&ptr, val_);
+#elif defined ZS_ATOMIC_PTR_X86
+            T *old;
+            __asm__ volatile (
+                "lock; xchg %0, %2"
+                : "=r" (old), "=m" (ptr)
+                : "m" (ptr), "0" (val_));
+            return old;
+#elif defined ZS_ATOMIC_PTR_SPARC
+            T* newptr = val_;
+            volatile T** ptrin = &ptr;
+            T* tmp;
+            T* prev;
+            __asm__ __volatile__(
+                "ld [%4], %1\n\t"
+                "1:\n\t"
+                "mov %0, %2\n\t"
+                "cas [%4], %1, %2\n\t"
+                "cmp %1, %2\n\t"
+                "bne,a,pn %%icc, 1b\n\t"
+                "mov %2, %1\n\t"
+                : "+r" (newptr), "=&r" (tmp), "=&r" (prev), "+m" (*ptrin)
+                : "r" (ptrin)
+                : "cc");
+            return prev;
+#elif defined ZS_ATOMIC_PTR_MUTEX
+            sync.lock ();
+            T *old = (T*) ptr;
+            ptr = val_;
+            sync.unlock ();
+            return old;
+#else
+#error
+#endif
+        }
+
+        //  Perform atomic 'compare and swap' operation on the pointer.
+        //  The pointer is compared to 'cmp' argument and if they are
+        //  equal, its value is set to 'val'. Old value of the pointer
+        //  is returned.
+        inline T *cas (T *cmp_, T *val_)
+        {
+#if defined ZS_ATOMIC_PTR_WINDOWS
+            return (T*) InterlockedCompareExchangePointer (
+                (volatile PVOID*) &ptr, val_, cmp_);
+#elif defined ZS_ATOMIC_PTR_SOLARIS
+            return (T*) atomic_cas_ptr (&ptr, cmp_, val_);
+#elif defined ZS_ATOMIC_PTR_X86
+            T *old;
+            __asm__ volatile (
+                "lock; cmpxchg %2, %3"
+                : "=a" (old), "=m" (ptr)
+                : "r" (val_), "m" (ptr), "0" (cmp_)
+                : "cc");
+            return old;
+#elif defined ZS_ATOMIC_PTR_SPARC
+            volatile T** ptrin = &ptr;
+            volatile T* prev = ptr;
+            __asm__ __volatile__(
+                "cas [%3], %1, %2\n\t"
+                : "+m" (*ptrin)
+                : "r" (cmp_), "r" (val_), "r" (ptrin)
+                : "cc");
+            return prev;
+#elif defined ZS_ATOMIC_PTR_MUTEX
+            sync.lock ();
+            T *old = (T*) ptr;
+            if (ptr == cmp_)
+                ptr = val_;
+            sync.unlock ();
+            return old;
+#else
+#error
+#endif
+        }
+
+    private:
+
+        volatile T *ptr;
+#if defined ZS_ATOMIC_PTR_MUTEX
+        mutex_t sync;
+#endif
+
+        atomic_ptr_t (const atomic_ptr_t&);
+        void operator = (const atomic_ptr_t&);
+    };
+
+}
+
+//  Remove macros local to this file.
+#if defined ZS_ATOMIC_PTR_WINDOWS
+#undef ZS_ATOMIC_PTR_WINDOWS
+#endif
+#if defined ZS_ATOMIC_PTR_SOLARIS
+#undef ZS_ATOMIC_PTR_SOLARIS
+#endif
+#if defined ZS_ATOMIC_PTR_X86
+#undef ZS_ATOMIC_PTR_X86
+#endif
+#if defined ZS_ATOMIC_PTR_SPARC
+#undef ZS_ATOMIC_PTR_SPARC
+#endif
+#if defined ZS_ATOMIC_PTR_MUTEX
+#undef ZS_ATOMIC_PTR_MUTEX
+#endif
+
+#endif