From 2acee0859006b4eaa27c4c1b97c6c1a2d853f137 Mon Sep 17 00:00:00 2001
From: "Dr. Chat" <arkolbed@gmail.com>
Date: Sun, 19 Feb 2017 19:58:58 -0600
Subject: [PATCH] Base bitfield class

---
 src/xenia/base/bit_field.h              | 42 +++++++++++++++++++++++++
 src/xenia/base/debug_visualizers.natvis |  7 +++++
 2 files changed, 49 insertions(+)
 create mode 100644 src/xenia/base/bit_field.h

diff --git a/src/xenia/base/bit_field.h b/src/xenia/base/bit_field.h
new file mode 100644
index 000000000..a089775c9
--- /dev/null
+++ b/src/xenia/base/bit_field.h
@@ -0,0 +1,42 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2017 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_BASE_BIT_FIELD_H_
+#define XENIA_BASE_BIT_FIELD_H_
+
+#include <cstdint>
+#include <cstdlib>
+#include <type_traits>
+
+namespace xe {
+
+// Bitfield, where position starts at the LSB.
+template <typename T, size_t position, size_t n_bits>
+struct bf {
+  bf() = default;
+  inline operator T() const { return value(); }
+
+  inline T value() const {
+    return static_cast<T>((storage & mask()) >> position);
+  }
+
+  // For enum values, we strip them down to an underlying type.
+  typedef
+      typename std::conditional<std::is_enum<T>::value, std::underlying_type<T>,
+                                std::identity<T>>::type::type value_type;
+  inline value_type mask() const {
+    return (((value_type)~0) >> (8 * sizeof(value_type) - n_bits)) << position;
+  }
+
+  value_type storage;
+};
+
+}  // namespace xe
+
+#endif  // XENIA_BASE_BIT_FIELD_H_
\ No newline at end of file
diff --git a/src/xenia/base/debug_visualizers.natvis b/src/xenia/base/debug_visualizers.natvis
index b5077dfc6..e0022ed70 100644
--- a/src/xenia/base/debug_visualizers.natvis
+++ b/src/xenia/base/debug_visualizers.natvis
@@ -67,5 +67,12 @@
       {value}
     </DisplayString>
   </Type>
+  
+  <Type Name="xe::bf&lt;*&gt;">
+    <DisplayString>
+      <!-- (storage & mask()) >> position -->
+      {($T1)((storage &amp; ((((value_type)~0) &gt;&gt; (8 * sizeof(value_type) - $T3)) &lt;&lt; $T2)) &gt;&gt; $T2)}
+    </DisplayString>
+  </Type>
 
 </AutoVisualizer>