--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/imgtools/imglib/boostlibrary/boost/thread/pthread/once.hpp	Tue Oct 27 16:36:35 2009 +0000
@@ -0,0 +1,90 @@
+#ifndef BOOST_THREAD_PTHREAD_ONCE_HPP
+#define BOOST_THREAD_PTHREAD_ONCE_HPP
+
+//  once.hpp
+//
+//  (C) Copyright 2007-8 Anthony Williams 
+//
+//  Distributed under the Boost Software License, Version 1.0. (See
+//  accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/thread/detail/config.hpp>
+
+#include <pthread.h>
+#include <boost/assert.hpp>
+#include "pthread_mutex_scoped_lock.hpp"
+#include <boost/thread/pthread/pthread_mutex_scoped_lock.hpp>
+#include <boost/cstdint.hpp>
+
+#include <boost/config/abi_prefix.hpp>
+
+namespace boost
+{
+
+    struct once_flag
+    {
+        boost::uintmax_t epoch;
+    };
+
+    namespace detail
+    {
+        BOOST_THREAD_DECL boost::uintmax_t& get_once_per_thread_epoch();
+        BOOST_THREAD_DECL extern boost::uintmax_t once_global_epoch;
+        BOOST_THREAD_DECL extern pthread_mutex_t once_epoch_mutex;
+        BOOST_THREAD_DECL extern pthread_cond_t once_epoch_cv;
+    }
+    
+#define BOOST_ONCE_INITIAL_FLAG_VALUE 0
+#define BOOST_ONCE_INIT {BOOST_ONCE_INITIAL_FLAG_VALUE}
+
+
+    // Based on Mike Burrows fast_pthread_once algorithm as described in
+    // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2444.html
+    template<typename Function>
+    void call_once(once_flag& flag,Function f)
+    {
+        static boost::uintmax_t const uninitialized_flag=BOOST_ONCE_INITIAL_FLAG_VALUE;
+        static boost::uintmax_t const being_initialized=uninitialized_flag+1;
+        boost::uintmax_t const epoch=flag.epoch;
+        boost::uintmax_t& this_thread_epoch=detail::get_once_per_thread_epoch();
+        
+        if(epoch<this_thread_epoch)
+        {
+            pthread::pthread_mutex_scoped_lock lk(&detail::once_epoch_mutex);
+
+            while(flag.epoch<=being_initialized)
+            {
+                if(flag.epoch==uninitialized_flag)
+                {
+                    flag.epoch=being_initialized;
+                    try
+                    {
+                        pthread::pthread_mutex_scoped_unlock relocker(&detail::once_epoch_mutex);
+                        f();
+                    }
+                    catch(...)
+                    {
+                        flag.epoch=uninitialized_flag;
+                        BOOST_VERIFY(!pthread_cond_broadcast(&detail::once_epoch_cv));
+                        throw;
+                    }
+                    flag.epoch=--detail::once_global_epoch;
+                    BOOST_VERIFY(!pthread_cond_broadcast(&detail::once_epoch_cv));
+                }
+                else
+                {
+                    while(flag.epoch==being_initialized)
+                    {
+                        BOOST_VERIFY(!pthread_cond_wait(&detail::once_epoch_cv,&detail::once_epoch_mutex));
+                    }
+                }
+            }
+            this_thread_epoch=detail::once_global_epoch;
+        }
+    }
+}
+
+#include <boost/config/abi_suffix.hpp>
+
+#endif