From 32e3cff46afbc33a8a2bac4f28f5f83837d04d78 Mon Sep 17 00:00:00 2001
From: Sam Hocevar <sam@hocevar.net>
Date: Tue, 5 Feb 2013 02:08:48 +0000
Subject: [PATCH] sys: Atomic template class for thread-safe and potentially
 lockless structures.

---
 src/Makefile.am      |  3 +-
 src/lol/sys/atomic.h | 77 ++++++++++++++++++++++++++++++++++++++++++++
 src/lol/sys/sys.h    |  3 +-
 src/lolcore.vcxproj  |  1 +
 test/Makefile.am     |  2 +-
 5 files changed, 83 insertions(+), 3 deletions(-)
 create mode 100644 src/lol/sys/atomic.h

diff --git a/src/Makefile.am b/src/Makefile.am
index d178b96c..60d0c929 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -42,7 +42,8 @@ liblol_headers = \
     lol/math/remez.h lol/math/math.h lol/math/geometry.h \
     \
     lol/sys/sys.h \
-    lol/sys/init.h lol/sys/file.h lol/sys/thread.h lol/sys/timer.h \
+    lol/sys/init.h lol/sys/file.h lol/sys/thread.h lol/sys/atomic.h \
+    lol/sys/timer.h \
     \
     lol/image/image.h \
     lol/image/color.h \
diff --git a/src/lol/sys/atomic.h b/src/lol/sys/atomic.h
new file mode 100644
index 00000000..8412b57c
--- /dev/null
+++ b/src/lol/sys/atomic.h
@@ -0,0 +1,77 @@
+//
+// Lol Engine
+//
+// Copyright: (c) 2010-2013 Sam Hocevar <sam@hocevar.net>
+//   This program is free software; you can redistribute it and/or
+//   modify it under the terms of the Do What The Fuck You Want To
+//   Public License, Version 2, as published by Sam Hocevar. See
+//   http://www.wtfpl.net/ for more details.
+//
+
+#if !defined __LOL_SYS_ATOMIC_H__
+#define __LOL_SYS_ATOMIC_H__
+
+namespace lol
+{
+
+/*
+ * TODO: we should use real atomic stuff here.
+ */
+template<typename T> class Atomic
+{
+public:
+    inline Atomic(T const &value) : m_value(value) {}
+
+    operator T() const
+    {
+        return m_value;
+    }
+
+    inline T operator =(T const &value)
+    {
+        m_mutex.Lock();
+        m_value = value;
+        m_mutex.Unlock();
+    }
+
+    inline T operator++(int)
+    {
+        m_mutex.Lock();
+        T ret = m_value++;
+        m_mutex.Unlock();
+        return ret;
+    }
+
+    inline T& operator++()
+    {
+        m_mutex.Lock();
+        T ret = ++m_value;
+        m_mutex.Unlock();
+        return ret;
+    }
+
+    inline T operator--(int)
+    {
+        m_mutex.Lock();
+        T ret = m_value--;
+        m_mutex.Unlock();
+        return ret;
+    }
+
+    inline T& operator--()
+    {
+        m_mutex.Lock();
+        T ret = --m_value;
+        m_mutex.Unlock();
+        return ret;
+    }
+
+private:
+    Mutex m_mutex; /* FIXME: this shouldn't be needed */
+    T m_value;
+};
+
+} /* namespace lol */
+
+#endif // __LOL_SYS_ATOMIC_H__
+
diff --git a/src/lol/sys/sys.h b/src/lol/sys/sys.h
index 32755422..a43705ef 100644
--- a/src/lol/sys/sys.h
+++ b/src/lol/sys/sys.h
@@ -11,9 +11,10 @@
 #if !defined __LOL_SYS_SYS_H__
 #define __LOL_SYS_SYS_H__
 
+#include <lol/sys/thread.h>
+#include <lol/sys/atomic.h>
 #include <lol/sys/init.h>
 #include <lol/sys/file.h>
-#include <lol/sys/thread.h>
 #include <lol/sys/timer.h>
 
 #endif // __LOL_SYS_SYS_H__
diff --git a/src/lolcore.vcxproj b/src/lolcore.vcxproj
index b50fd910..a331606e 100644
--- a/src/lolcore.vcxproj
+++ b/src/lolcore.vcxproj
@@ -606,6 +606,7 @@
     <ClInclude Include="lol\math\real.h" />
     <ClInclude Include="lol\math\remez.h" />
     <ClInclude Include="lol\math\vector.h" />
+    <ClInclude Include="lol\sys\atomic.h" />
     <ClInclude Include="lol\sys\file.h" />
     <ClInclude Include="lol\sys\init.h" />
     <ClInclude Include="lol\sys\sys.h" />
diff --git a/test/Makefile.am b/test/Makefile.am
index 7b08e889..0d97201f 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -23,7 +23,7 @@ testsuite_SOURCES = testsuite.cpp \
     unit/vector.cpp unit/matrix.cpp unit/half.cpp unit/trig.cpp \
     unit/build.cpp unit/real.cpp unit/image.cpp unit/quat.cpp unit/cmplx.cpp \
     unit/array.cpp unit/rotation.cpp unit/string.cpp unit/map.cpp \
-    unit/color.cpp
+    unit/color.cpp unit/atomic.cpp
 testsuite_CPPFLAGS = @LOL_CFLAGS@
 testsuite_LDFLAGS = $(top_builddir)/src/liblol.a @LOL_LIBS@
 testsuite_DEPENDENCIES = $(top_builddir)/src/liblol.a