Base bitfield class

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_