C++11 [ptr.align].
This should probably not be inline. But for now this avoids any ABI
changes.
* libstdc++-v3/testsuite/20_util/align/1.cc: New file.
* libstdc++-v3/include/std/memory (align): New function.
---
libstdc++-v3/include/std/memory | 35 +++++++++++++
libstdc++-v3/testsuite/20_util/align/1.cc | 82 +++++++++++++++++++++++++++++++
2 files changed, 117 insertions(+)
create mode 100644 libstdc++-v3/testsuite/20_util/align/1.cc
diff --git a/libstdc++-v3/include/std/memory b/libstdc++-v3/include/std/memory
index dafec0c..f9ae7b9 100644
--- a/libstdc++-v3/include/std/memory
+++ b/libstdc++-v3/include/std/memory
@@ -83,6 +83,41 @@
# if _GLIBCXX_USE_DEPRECATED
# include <backward/auto_ptr.h>
# endif
+
+/**
+ * @brief Fit aligned storage in buffer.
+ *
+ * [ptr.align]
+ *
+ * This function tries to fit __size storage with __alignment into
+ * the buffer __ptr of size __space bytes. If such a buffer fits
+ * then __ptr is changed to point to the storage and __space is
+ * reduced by the bytes needed to adjust the alignment.
+ *
+ * @param __alignment A fundamental or extended alignment value
+ of the desired storage.
+ * @param __size Size of the aligned storage.
+ * @param __ptr Pointer to a buffer of __space byte size.
+ * @param __space Size of the buffer pointed to by __ptr.
+ * @return the updated pointer if the aligned storage fits or
+ nullptr else.
+ */
+inline
+void*
+align(size_t __alignment, size_t __size, void*& __ptr, size_t& __space)
+{
+ const size_t __diff = __alignment -
+ reinterpret_cast<uintptr_t>(__ptr) % __alignment;
+ if (__diff + __size >= __space)
+ return nullptr;
+ else
+ {
+ __space -= __diff;
+ __ptr = static_cast<char*>(__ptr) + __diff;
+ return __ptr;
+ }
+}
+
#else
# include <backward/auto_ptr.h>
#endif
diff --git a/libstdc++-v3/testsuite/20_util/align/1.cc
b/libstdc++-v3/testsuite/20_util/align/1.cc
new file mode 100644
index 0000000..2e74806
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/align/1.cc
@@ -0,0 +1,82 @@
+// { dg-options " -std=gnu++11 " }
+
+// 2014-04-16 Rüdiger Sonderfeld <ruedi...@c-plusplus.de>
+
+// Copyright (C) 2014 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library 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 GNU
+// General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// C++11 [ptr.align] (20.6.5): std::align
+
+#include <memory>
+#include <cstdint>
+#include <testsuite_hooks.h>
+
+#ifndef _GLIBCXX_ASSERT
+# include <iostream>
+# define STRINGIZE2(x) #x
+# define STRINGIZE(x) STRINGIZE2(x)
+# define CHECK(a, op, b) \
+ do \
+ { \
+ if ( !( (a) op (b) ) ) \
+ { \
+ cerr << "Mismatch: " \
+ << STRINGIZE(a) \
+ << " (" << (a) << ") " \
+ << STRINGIZE(op) << ' ' \
+ << STRINGIZE(b) \
+ << " (" << (b) << ")\n"; \
+ } \
+ } while(false)
+#else
+# define CHECK(a, op, b) VERIFY( (a) op (b) )
+#endif
+
+void test01()
+{
+ using namespace std;
+ bool test __attribute__((unused)) = true;
+
+ size_t space = 100;
+ void* ptr = new char[space];
+ char* const orig_ptr = static_cast<char*>(ptr);
+ char* old_ptr = orig_ptr;
+ const size_t orig_space = space;
+ size_t old_space = space;
+ const size_t alignment = 16;
+ const size_t size = 10;
+ while( void* const r = align(alignment, size, ptr, space) )
+ {
+ CHECK( r, ==, ptr );
+ uintptr_t p = reinterpret_cast<uintptr_t>(ptr);
+ CHECK( p % alignment, ==, 0 );
+ char* const x = static_cast<char*>(ptr);
+ CHECK( x - old_ptr, ==, old_space - space );
+ CHECK( (void*)x, <, (void*)(orig_ptr + orig_space) );
+ CHECK( (void*)(x + size), <, (void*)(orig_ptr + orig_space) );
+ ptr = x + size;
+ old_ptr = x;
+ old_space = space;
+ space -= size;
+ }
+ delete [] orig_ptr;
+}
+
+int main()
+{
+ test01();
+}
--
1.9.2
