externals: Update boost to 1.72 and add Boost Context

boost/context/windows/protected_fixedsize_stack.hpp

@@ -0,0 +1,87 @@
+
+//          Copyright Oliver Kowalke 2014.
+// 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)
+
+#ifndef BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
+#define BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H
+
+extern "C" {
+#include <windows.h>
+}
+
+#include <cmath>
+#include <cstddef>
+#include <new>
+
+#include <boost/config.hpp>
+
+#include <boost/context/detail/config.hpp>
+#include <boost/context/stack_context.hpp>
+#include <boost/context/stack_traits.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+
+template< typename traitsT >
+class basic_protected_fixedsize_stack {
+private:
+    std::size_t     size_;
+
+public:
+    typedef traitsT traits_type;
+
+    basic_protected_fixedsize_stack( std::size_t size = traits_type::default_size() ) BOOST_NOEXCEPT_OR_NOTHROW :
+        size_( size) {
+    }
+
+    stack_context allocate() {
+        // calculate how many pages are required
+        const std::size_t pages(        
+            static_cast< std::size_t >(
+                std::ceil(
+                    static_cast< float >( size_) / traits_type::page_size() ) ) );
+        // add one page at bottom that will be used as guard-page
+        const std::size_t size__ = ( pages + 1) * traits_type::page_size();
+
+        void * vp = ::VirtualAlloc( 0, size__, MEM_COMMIT, PAGE_READWRITE);
+        if ( ! vp) throw std::bad_alloc();
+
+        DWORD old_options;
+#if defined(BOOST_DISABLE_ASSERTS)
+        ::VirtualProtect(
+            vp, traits_type::page_size(), PAGE_READWRITE | PAGE_GUARD /*PAGE_NOACCESS*/, & old_options);
+#else
+        const BOOL result = ::VirtualProtect(
+            vp, traits_type::page_size(), PAGE_READWRITE | PAGE_GUARD /*PAGE_NOACCESS*/, & old_options);
+        BOOST_ASSERT( FALSE != result);
+#endif
+
+        stack_context sctx;
+        sctx.size = size__;
+        sctx.sp = static_cast< char * >( vp) + sctx.size;
+        return sctx;
+    }
+
+    void deallocate( stack_context & sctx) BOOST_NOEXCEPT_OR_NOTHROW {
+        BOOST_ASSERT( sctx.sp);
+
+        void * vp = static_cast< char * >( sctx.sp) - sctx.size;
+        ::VirtualFree( vp, 0, MEM_RELEASE);
+    }
+};
+
+typedef basic_protected_fixedsize_stack< stack_traits > protected_fixedsize_stack;
+
+}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_PROTECTED_FIXEDSIZE_H