From 145ee8fcc841c08587a11f0a0d768f5552816077 Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Thu, 2 Jan 2020 01:41:52 -0800
Subject: [PATCH] util: add BitPack

---
 .../libvapours/include/vapours/defines.hpp    |  6 +-
 libraries/libvapours/include/vapours/util.hpp |  1 +
 .../include/vapours/util/util_bitpack.hpp     | 87 +++++++++++++++++++
 3 files changed, 92 insertions(+), 2 deletions(-)
 create mode 100644 libraries/libvapours/include/vapours/util/util_bitpack.hpp

diff --git a/libraries/libvapours/include/vapours/defines.hpp b/libraries/libvapours/include/vapours/defines.hpp
index 9d0982a8b..629b3723f 100644
--- a/libraries/libvapours/include/vapours/defines.hpp
+++ b/libraries/libvapours/include/vapours/defines.hpp
@@ -42,6 +42,8 @@
 #define CONCATENATE_IMPL(S1, s2) s1##s2
 #define CONCATENATE(s1, s2) CONCATENATE_IMPL(s1, s2)
 
+#define BITSIZEOF(x) (sizeof(x) * CHAR_BIT)
+
 #ifdef __COUNTER__
 #define ANONYMOUS_VARIABLE(pref) CONCATENATE(pref, __COUNTER__)
 #else
@@ -55,8 +57,8 @@
                                                     probability;                                 \
                                                }))
 
-#define AMS_PREDICT_TRUE(expr, probability)  AMS_PREDICT(!!expr, 1, probability)
-#define AMS_PREDICT_FALSE(expr, probability) AMS_PREDICT(!!expr, 0, probability)
+#define AMS_PREDICT_TRUE(expr, probability)  AMS_PREDICT(!!(expr), 1, probability)
+#define AMS_PREDICT_FALSE(expr, probability) AMS_PREDICT(!!(expr), 0, probability)
 
 #define AMS_LIKELY(expr)   AMS_PREDICT_TRUE(expr, 1.0)
 #define AMS_UNLIKELY(expr) AMS_PREDICT_FALSE(expr, 1.0)
diff --git a/libraries/libvapours/include/vapours/util.hpp b/libraries/libvapours/include/vapours/util.hpp
index c35192e45..a3562c93a 100644
--- a/libraries/libvapours/include/vapours/util.hpp
+++ b/libraries/libvapours/include/vapours/util.hpp
@@ -20,6 +20,7 @@
 #include "util/util_alignment.hpp"
 #include "util/util_size.hpp"
 #include "util/util_fourcc.hpp"
+#include "util/util_bitpack.hpp"
 #include "util/util_scope_guard.hpp"
 #include "util/util_typed_storage.hpp"
 #include "util/util_intrusive_list.hpp"
diff --git a/libraries/libvapours/include/vapours/util/util_bitpack.hpp b/libraries/libvapours/include/vapours/util/util_bitpack.hpp
new file mode 100644
index 000000000..ccec50e98
--- /dev/null
+++ b/libraries/libvapours/include/vapours/util/util_bitpack.hpp
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2018-2019 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"
+
+namespace ams::util {
+
+    namespace impl {
+
+        template<typename IntegralStorageType>
+        class BitPack {
+            private:
+                static_assert(std::is_integral<IntegralStorageType>::value);
+                static_assert(std::is_unsigned<IntegralStorageType>::value);
+
+                template<size_t Index, size_t Count>
+                static constexpr inline IntegralStorageType Mask = [] {
+                    static_assert(Index < BITSIZEOF(IntegralStorageType));
+                    static_assert(0 < Count && Count <= BITSIZEOF(IntegralStorageType));
+                    static_assert(Index + Count <= BITSIZEOF(IntegralStorageType));
+
+                    return ((IntegralStorageType(1) << Count) - 1) << Index;
+                }();
+            public:
+                template<size_t _Index, size_t _Count, typename T>
+                struct Field {
+                    using Type = T;
+                    static constexpr size_t Index = _Index;
+                    static constexpr size_t Count = _Count;
+                    static constexpr size_t Next = Index + Count;
+
+                    using BitPackType = BitPack<IntegralStorageType>;
+
+                    static_assert(Mask<Index, Count> != 0);
+                    static_assert(std::is_integral<T>::value);
+                    static_assert(!std::is_same<T, bool>::value || Count == 1);
+                };
+            private:
+                IntegralStorageType value;
+            public:
+                constexpr ALWAYS_INLINE void Clear() {
+                    constexpr IntegralStorageType Zero = IntegralStorageType(0);
+                    this->value = Zero;
+                }
+
+                template<typename FieldType>
+                constexpr ALWAYS_INLINE typename FieldType::Type Get() const {
+                    static_assert(std::is_same<FieldType, Field<FieldType::Index, FieldType::Count, typename FieldType::Type>>::value);
+                    return static_cast<typename FieldType::Type>((this->value & Mask<FieldType::Index, FieldType::Count>) >> FieldType::Index);
+                }
+
+                template<typename FieldType>
+                constexpr ALWAYS_INLINE void Set(typename FieldType::Type field_value) {
+                    static_assert(std::is_same<FieldType, Field<FieldType::Index, FieldType::Count, typename FieldType::Type>>::value);
+                    constexpr IntegralStorageType FieldMask = Mask<FieldType::Index, FieldType::Count>;
+                    this->value &= ~FieldMask;
+                    this->value |= (static_cast<IntegralStorageType>(field_value) << FieldType::Index) & FieldMask;
+                }
+        };
+
+    }
+
+    using BitPack8  = impl::BitPack<u8>;
+    using BitPack16 = impl::BitPack<u16>;
+    using BitPack32 = impl::BitPack<u32>;
+    using BitPack64 = impl::BitPack<u64>;
+
+    static_assert(std::is_pod<BitPack8 >::value);
+    static_assert(std::is_pod<BitPack16>::value);
+    static_assert(std::is_pod<BitPack32>::value);
+    static_assert(std::is_pod<BitPack64>::value);
+
+}