From 108b997ef27bf51b1505b835c8cda4723e4dab8d Mon Sep 17 00:00:00 2001
From: TuxSH <tuxsh@sfr.fr>
Date: Tue, 4 Feb 2020 01:24:16 +0000
Subject: [PATCH] libvapours: introduce BitsOf, Bits

---
 .../include/vapours/util/util_bitutil.hpp     | 77 +++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 libraries/libvapours/include/vapours/util/util_bitutil.hpp

diff --git a/libraries/libvapours/include/vapours/util/util_bitutil.hpp b/libraries/libvapours/include/vapours/util/util_bitutil.hpp
new file mode 100644
index 000000000..1a3063c0f
--- /dev/null
+++ b/libraries/libvapours/include/vapours/util/util_bitutil.hpp
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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 program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "../defines.hpp"
+#include "../types.hpp"
+
+namespace ams::util {
+
+    template <typename T>
+    class BitsOf {
+        private:
+            static_assert(std::is_integral<T>::value);
+
+            static constexpr ALWAYS_INLINE int GetLsbPos(T v) {
+                return __builtin_ctzll(static_cast<u64>(v));
+            }
+
+            T value;
+        public:
+            /* Note: GCC has a bug in constant-folding here. Workaround: wrap entire caller with constexpr. */
+            constexpr ALWAYS_INLINE BitsOf(T value = T(0u)) : value(value) {
+                /* ... */
+            }
+
+            constexpr ALWAYS_INLINE bool operator==(const BitsOf &other) const {
+                return this->value == other.value;
+            }
+
+            constexpr ALWAYS_INLINE bool operator!=(const BitsOf &other) const {
+                return this->value != other.value;
+            }
+
+            constexpr ALWAYS_INLINE int operator*() const {
+                return GetLsbPos(this->value);
+            }
+
+            constexpr ALWAYS_INLINE BitsOf &operator++() {
+                this->value &= ~(T(1u) << GetLsbPos(this->value));
+                return *this;
+            }
+
+            constexpr ALWAYS_INLINE BitsOf &operator++(int) {
+                BitsOf ret(this->value);
+                ++(*this);
+                return ret;
+            }
+
+            constexpr ALWAYS_INLINE BitsOf begin() const {
+                return *this;
+            }
+
+            constexpr ALWAYS_INLINE BitsOf end() const {
+                return BitsOf(T(0u));
+            }
+    };
+
+    template<typename T = u64, typename ...Args>
+    T CombineBits(Args... args) {
+        return (... | (T(1u) << args));
+    }
+
+}