From 248fb1c6c08521bb2c1674b344c4ce8dde5197ab Mon Sep 17 00:00:00 2001
From: Joakim Gebart <joakim.gebart@eistec.se>
Date: Fri, 29 May 2015 02:37:35 +0200
Subject: [PATCH] sys/cpp11-compat: Add C++ runtime helpers

cppsupport.cpp contains functions which are necessary in order to use
some features of the C++ language, e.g. calling static constructors or
virtual functions.

TODO/Not implemented yet:
 - Test virtual functions
 - Handle exceptions (stack unwinding)
 - Run time type identification (RTTI)
---
 sys/Makefile.include            |   3 +
 sys/cpp11-compat/cppsupport.cpp | 147 ++++++++++++++++++++++++++++++++
 2 files changed, 150 insertions(+)
 create mode 100644 sys/cpp11-compat/cppsupport.cpp

diff --git a/sys/Makefile.include b/sys/Makefile.include
index 6ee00a8b96..cedc4c608a 100644
--- a/sys/Makefile.include
+++ b/sys/Makefile.include
@@ -30,6 +30,9 @@ endif
 
 ifneq (,$(filter cpp11-compat,$(USEMODULE)))
     USEMODULE_INCLUDES += $(RIOTBASE)/sys/cpp11-compat/include
+    # make sure cppsupport.o is linked explicitly because __dso_handle is not
+    # found if it is hidden away inside a static object.
+    export UNDEF += $(BINDIR)cpp11-compat/cppsupport.o
 endif
 
 ifneq (,$(filter ng_slip,$(USEMODULE)))
diff --git a/sys/cpp11-compat/cppsupport.cpp b/sys/cpp11-compat/cppsupport.cpp
new file mode 100644
index 0000000000..2274b7a305
--- /dev/null
+++ b/sys/cpp11-compat/cppsupport.cpp
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2015 Eistec AB
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup cpp11-compat
+ * @{
+ *
+ * @file
+ * @brief C++ runtime support functions
+ *
+ * Tested with GCC-4.9.2 and Clang-3.6
+ *
+ * @author  Joakim Gebart <joakim.gebart@eistec.se>
+ */
+
+#include <new>
+#include <cstddef>
+#include <cstdlib>
+
+extern "C" {
+#include "panic.h"
+}
+
+/**
+ * @brief DSO handle
+ *
+ * This symbol is used by dynamic shared objects to identify them, but it is
+ * somehow pulled in as a dependency by the compiler-generated global (static)
+ * constructor code.
+ */
+void *__dso_handle __attribute__((weak)) = NULL;
+
+/**
+ * @brief Definition of a pure virtual function
+ *
+ * Calling this function is an error.
+ */
+extern "C" void __cxa_pure_virtual ()
+{
+    core_panic(123, "PURE VIRTUAL CALL");
+}
+
+/**
+ * @brief Register a function to be called by exit or when a shared library is unloaded.
+ *
+ * Not really used on an embedded system where you pull the power to shut down
+ * the program.
+ *
+ * This is only called by code automatically generated by the C++ compiler.
+ *
+ * @return 0 on success
+ * @return non-zero on failure.
+ */
+extern "C" int __cxa_atexit (void (*) (void *), void *, void *)
+{
+    /* We just pretend everything is dandy. */
+    return 0;
+}
+
+namespace __gnu_cxx {
+/**
+ * @brief Override the G++ verbose termination handler
+ *
+ * The default implementation of __gnu_cxx::__verbose_terminate_handler comes
+ * with gcc and will print the name of unhandled exceptions to stderr before
+ * terminating the program. However, in order to get the name of the exceptions
+ * a large chunk of name demangling code is pulled in as well (several tens of
+ * kBytes!).
+ *
+ * @note Depending on the version of the compiler and what settings were used
+ * when building the toolchain __gnu_cxx::__verbose_terminate_handler may or may
+ * not be pulled in. std::abort may be used instead by default in some
+ * toolchains.
+ *
+ * @see http://www.webalice.it/fede.tft/cpp_on_microcontrollers_tricks/cpp_on_microcontrollers_tricks.html
+ */
+void __verbose_terminate_handler()
+{
+    core_panic(123, "UNHANDLED C++ EXCEPTION");
+}
+} /* namespace __gnu_cxx */
+
+/* Implementations of new and delete operators taken from public domain code
+ * at http://pastebin.com/7VKUuTJa (downloaded on Wed 24 Jun 2015 09:00:07 PM CEST)
+ * Author: Eric Agan
+ * The license text reads:
+ * > "Public domain, use however you wish.
+ * > "If you really need a license, consider it MIT."
+ */
+
+/* tinynew.cpp
+
+   Overrides operators new and delete
+   globally to reduce code size.
+
+   Public domain, use however you wish.
+   If you really need a license, consider it MIT:
+   http://www.opensource.org/licenses/mit-license.php
+
+   - Eric Agan
+     Elegant Invention
+ */
+
+void* operator new(std::size_t size) {
+    return std::malloc(size);
+}
+
+void* operator new[](std::size_t size) {
+    return std::malloc(size);
+}
+
+void operator delete(void* ptr) noexcept {
+    std::free(ptr);
+}
+
+void operator delete[](void* ptr) noexcept {
+    std::free(ptr);
+}
+
+/* Optionally you can override the 'nothrow' versions as well.
+   This is useful if you want to catch failed allocs with your
+   own debug code, or keep track of heap usage for example,
+   rather than just eliminate exceptions.
+ */
+
+void* operator new(std::size_t size, const std::nothrow_t&) noexcept {
+    return std::malloc(size);
+}
+
+void* operator new[](std::size_t size, const std::nothrow_t&) noexcept {
+    return std::malloc(size);
+}
+
+void operator delete(void* ptr, const std::nothrow_t&) noexcept {
+    std::free(ptr);
+}
+
+void operator delete[](void* ptr, const std::nothrow_t&) noexcept {
+    std::free(ptr);
+}
+
+/** @} */