Merge pull request #2090 from FearlessTobi/port-4599

Port citra-emu/citra#4244 and citra-emu/citra#4599: Changes to BitField

10 files changed, 337 insertions, 134 deletions

diff --git a/src/common/bit_field.h b/src/common/bit_field.h
index 7433c39ba..8e35c463f 100644
--- a/src/common/bit_field.h
+++ b/src/common/bit_field.h
@@ -34,6 +34,7 @@
 #include <limits>
 #include <type_traits>
 #include "common/common_funcs.h"
+#include "common/swap.h"
 
 /*
  * Abstract bitfield class
@@ -108,7 +109,7 @@
  * symptoms.
  */
 #pragma pack(1)
-template <std::size_t Position, std::size_t Bits, typename T>
+template <std::size_t Position, std::size_t Bits, typename T, typename EndianTag = LETag>
 struct BitField {
 private:
     // UnderlyingType is T for non-enum types and the underlying type of T if
@@ -121,7 +122,11 @@ private:
     // We store the value as the unsigned type to avoid undefined behaviour on value shifting
     using StorageType = std::make_unsigned_t<UnderlyingType>;
 
+    using StorageTypeWithEndian = typename AddEndian<StorageType, EndianTag>::type;
+
 public:
+    BitField& operator=(const BitField&) = default;
+
     /// Constants to allow limited introspection of fields if needed
     static constexpr std::size_t position = Position;
     static constexpr std::size_t bits = Bits;
@@ -170,7 +175,7 @@ public:
     }
 
     constexpr FORCE_INLINE void Assign(const T& value) {
-        storage = (storage & ~mask) | FormatValue(value);
+        storage = (static_cast<StorageType>(storage) & ~mask) | FormatValue(value);
     }
 
     constexpr T Value() const {
@@ -182,7 +187,7 @@ public:
     }
 
 private:
-    StorageType storage;
+    StorageTypeWithEndian storage;
 
     static_assert(bits + position <= 8 * sizeof(T), "Bitfield out of range");
 
@@ -193,3 +198,6 @@ private:
     static_assert(std::is_trivially_copyable_v<T>, "T must be trivially copyable in a BitField");
 };
 #pragma pack()
+
+template <std::size_t Position, std::size_t Bits, typename T>
+using BitFieldBE = BitField<Position, Bits, T, BETag>;
diff --git a/src/common/swap.h b/src/common/swap.h
index 0e219747f..b3eab1324 100644
--- a/src/common/swap.h
+++ b/src/common/swap.h
@@ -17,6 +17,8 @@
 
 #pragma once
 
+#include <type_traits>
+
 #if defined(_MSC_VER)
 #include <cstdlib>
 #elif defined(__linux__)
@@ -170,7 +172,7 @@ struct swap_struct_t {
     using swapped_t = swap_struct_t;
 
 protected:
-    T value = T();
+    T value;
 
     static T swap(T v) {
         return F::swap(v);
@@ -605,52 +607,154 @@ struct swap_double_t {
     }
 };
 
-#if COMMON_LITTLE_ENDIAN
-using u16_le = u16;
-using u32_le = u32;
-using u64_le = u64;
+template <typename T>
+struct swap_enum_t {
+    static_assert(std::is_enum_v<T>);
+    using base = std::underlying_type_t<T>;
+
+public:
+    swap_enum_t() = default;
+    swap_enum_t(const T& v) : value(swap(v)) {}
+
+    swap_enum_t& operator=(const T& v) {
+        value = swap(v);
+        return *this;
+    }
+
+    operator T() const {
+        return swap(value);
+    }
+
+    explicit operator base() const {
+        return static_cast<base>(swap(value));
+    }
 
-using s16_le = s16;
-using s32_le = s32;
-using s64_le = s64;
+protected:
+    T value{};
+    // clang-format off
+    using swap_t = std::conditional_t<
+        std::is_same_v<base, u16>, swap_16_t<u16>, std::conditional_t<
+        std::is_same_v<base, s16>, swap_16_t<s16>, std::conditional_t<
+        std::is_same_v<base, u32>, swap_32_t<u32>, std::conditional_t<
+        std::is_same_v<base, s32>, swap_32_t<s32>, std::conditional_t<
+        std::is_same_v<base, u64>, swap_64_t<u64>, std::conditional_t<
+        std::is_same_v<base, s64>, swap_64_t<s64>, void>>>>>>;
+    // clang-format on
+    static T swap(T x) {
+        return static_cast<T>(swap_t::swap(static_cast<base>(x)));
+    }
+};
 
-using float_le = float;
-using double_le = double;
+struct SwapTag {}; // Use the different endianness from the system
+struct KeepTag {}; // Use the same endianness as the system
 
-using u64_be = swap_struct_t<u64, swap_64_t<u64>>;
-using s64_be = swap_struct_t<s64, swap_64_t<s64>>;
+template <typename T, typename Tag>
+struct AddEndian;
 
-using u32_be = swap_struct_t<u32, swap_32_t<u32>>;
-using s32_be = swap_struct_t<s32, swap_32_t<s32>>;
+// KeepTag specializations
 
-using u16_be = swap_struct_t<u16, swap_16_t<u16>>;
-using s16_be = swap_struct_t<s16, swap_16_t<s16>>;
+template <typename T>
+struct AddEndian<T, KeepTag> {
+    using type = T;
+};
 
-using float_be = swap_struct_t<float, swap_float_t<float>>;
-using double_be = swap_struct_t<double, swap_double_t<double>>;
-#else
+// SwapTag specializations
+
+template <>
+struct AddEndian<u8, SwapTag> {
+    using type = u8;
+};
+
+template <>
+struct AddEndian<u16, SwapTag> {
+    using type = swap_struct_t<u16, swap_16_t<u16>>;
+};
+
+template <>
+struct AddEndian<u32, SwapTag> {
+    using type = swap_struct_t<u32, swap_32_t<u32>>;
+};
 
-using u64_le = swap_struct_t<u64, swap_64_t<u64>>;
-using s64_le = swap_struct_t<s64, swap_64_t<s64>>;
+template <>
+struct AddEndian<u64, SwapTag> {
+    using type = swap_struct_t<u64, swap_64_t<u64>>;
+};
+
+template <>
+struct AddEndian<s8, SwapTag> {
+    using type = s8;
+};
 
-using u32_le = swap_struct_t<u32, swap_32_t<u32>>;
-using s32_le = swap_struct_t<s32, swap_32_t<s32>>;
+template <>
+struct AddEndian<s16, SwapTag> {
+    using type = swap_struct_t<s16, swap_16_t<s16>>;
+};
 
-using u16_le = swap_struct_t<u16, swap_16_t<u16>>;
-using s16_le = swap_struct_t<s16, swap_16_t<s16>>;
+template <>
+struct AddEndian<s32, SwapTag> {
+    using type = swap_struct_t<s32, swap_32_t<s32>>;
+};
+
+template <>
+struct AddEndian<s64, SwapTag> {
+    using type = swap_struct_t<s64, swap_64_t<s64>>;
+};
+
+template <>
+struct AddEndian<float, SwapTag> {
+    using type = swap_struct_t<float, swap_float_t<float>>;
+};
+
+template <>
+struct AddEndian<double, SwapTag> {
+    using type = swap_struct_t<double, swap_double_t<double>>;
+};
+
+template <typename T>
+struct AddEndian<T, SwapTag> {
+    static_assert(std::is_enum_v<T>);
+    using type = swap_enum_t<T>;
+};
 
-using float_le = swap_struct_t<float, swap_float_t<float>>;
-using double_le = swap_struct_t<double, swap_double_t<double>>;
+// Alias LETag/BETag as KeepTag/SwapTag depending on the system
+#if COMMON_LITTLE_ENDIAN
 
-using u16_be = u16;
-using u32_be = u32;
-using u64_be = u64;
+using LETag = KeepTag;
+using BETag = SwapTag;
 
-using s16_be = s16;
-using s32_be = s32;
-using s64_be = s64;
+#else
 
-using float_be = float;
-using double_be = double;
+using BETag = KeepTag;
+using LETag = SwapTag;
 
 #endif
+
+// Aliases for LE types
+using u16_le = AddEndian<u16, LETag>::type;
+using u32_le = AddEndian<u32, LETag>::type;
+using u64_le = AddEndian<u64, LETag>::type;
+
+using s16_le = AddEndian<s16, LETag>::type;
+using s32_le = AddEndian<s32, LETag>::type;
+using s64_le = AddEndian<s64, LETag>::type;
+
+template <typename T>
+using enum_le = std::enable_if_t<std::is_enum_v<T>, typename AddEndian<T, LETag>::type>;
+
+using float_le = AddEndian<float, LETag>::type;
+using double_le = AddEndian<double, LETag>::type;
+
+// Aliases for BE types
+using u16_be = AddEndian<u16, BETag>::type;
+using u32_be = AddEndian<u32, BETag>::type;
+using u64_be = AddEndian<u64, BETag>::type;
+
+using s16_be = AddEndian<s16, BETag>::type;
+using s32_be = AddEndian<s32, BETag>::type;
+using s64_be = AddEndian<s64, BETag>::type;
+
+template <typename T>
+using enum_be = std::enable_if_t<std::is_enum_v<T>, typename AddEndian<T, BETag>::type>;
+
+using float_be = AddEndian<float, BETag>::type;
+using double_be = AddEndian<double, BETag>::type;
diff --git a/src/core/hle/ipc.h b/src/core/hle/ipc.h
index 455d1f346..fae54bcc7 100644
--- a/src/core/hle/ipc.h
+++ b/src/core/hle/ipc.h
@@ -39,10 +39,10 @@ struct CommandHeader {
     union {
         u32_le raw_low;
         BitField<0, 16, CommandType> type;
-        BitField<16, 4, u32_le> num_buf_x_descriptors;
-        BitField<20, 4, u32_le> num_buf_a_descriptors;
-        BitField<24, 4, u32_le> num_buf_b_descriptors;
-        BitField<28, 4, u32_le> num_buf_w_descriptors;
+        BitField<16, 4, u32> num_buf_x_descriptors;
+        BitField<20, 4, u32> num_buf_a_descriptors;
+        BitField<24, 4, u32> num_buf_b_descriptors;
+        BitField<28, 4, u32> num_buf_w_descriptors;
     };
 
     enum class BufferDescriptorCFlag : u32 {
@@ -53,28 +53,28 @@ struct CommandHeader {
 
     union {
         u32_le raw_high;
-        BitField<0, 10, u32_le> data_size;
+        BitField<0, 10, u32> data_size;
         BitField<10, 4, BufferDescriptorCFlag> buf_c_descriptor_flags;
-        BitField<31, 1, u32_le> enable_handle_descriptor;
+        BitField<31, 1, u32> enable_handle_descriptor;
     };
 };
 static_assert(sizeof(CommandHeader) == 8, "CommandHeader size is incorrect");
 
 union HandleDescriptorHeader {
     u32_le raw_high;
-    BitField<0, 1, u32_le> send_current_pid;
-    BitField<1, 4, u32_le> num_handles_to_copy;
-    BitField<5, 4, u32_le> num_handles_to_move;
+    BitField<0, 1, u32> send_current_pid;
+    BitField<1, 4, u32> num_handles_to_copy;
+    BitField<5, 4, u32> num_handles_to_move;
 };
 static_assert(sizeof(HandleDescriptorHeader) == 4, "HandleDescriptorHeader size is incorrect");
 
 struct BufferDescriptorX {
     union {
-        BitField<0, 6, u32_le> counter_bits_0_5;
-        BitField<6, 3, u32_le> address_bits_36_38;
-        BitField<9, 3, u32_le> counter_bits_9_11;
-        BitField<12, 4, u32_le> address_bits_32_35;
-        BitField<16, 16, u32_le> size;
+        BitField<0, 6, u32> counter_bits_0_5;
+        BitField<6, 3, u32> address_bits_36_38;
+        BitField<9, 3, u32> counter_bits_9_11;
+        BitField<12, 4, u32> address_bits_32_35;
+        BitField<16, 16, u32> size;
     };
 
     u32_le address_bits_0_31;
@@ -103,10 +103,10 @@ struct BufferDescriptorABW {
     u32_le address_bits_0_31;
 
     union {
-        BitField<0, 2, u32_le> flags;
-        BitField<2, 3, u32_le> address_bits_36_38;
-        BitField<24, 4, u32_le> size_bits_32_35;
-        BitField<28, 4, u32_le> address_bits_32_35;
+        BitField<0, 2, u32> flags;
+        BitField<2, 3, u32> address_bits_36_38;
+        BitField<24, 4, u32> size_bits_32_35;
+        BitField<28, 4, u32> address_bits_32_35;
     };
 
     VAddr Address() const {
@@ -128,8 +128,8 @@ struct BufferDescriptorC {
     u32_le address_bits_0_31;
 
     union {
-        BitField<0, 16, u32_le> address_bits_32_47;
-        BitField<16, 16, u32_le> size;
+        BitField<0, 16, u32> address_bits_32_47;
+        BitField<16, 16, u32> size;
     };
 
     VAddr Address() const {
@@ -167,8 +167,8 @@ struct DomainMessageHeader {
         struct {
             union {
                 BitField<0, 8, CommandType> command;
-                BitField<8, 8, u32_le> input_object_count;
-                BitField<16, 16, u32_le> size;
+                BitField<8, 8, u32> input_object_count;
+                BitField<16, 16, u32> size;
             };
             u32_le object_id;
             INSERT_PADDING_WORDS(2);
diff --git a/src/core/hle/service/hid/controllers/debug_pad.h b/src/core/hle/service/hid/controllers/debug_pad.h
index 929035034..e584b92ec 100644
--- a/src/core/hle/service/hid/controllers/debug_pad.h
+++ b/src/core/hle/service/hid/controllers/debug_pad.h
@@ -41,20 +41,20 @@ private:
     struct PadState {
         union {
             u32_le raw{};
-            BitField<0, 1, u32_le> a;
-            BitField<1, 1, u32_le> b;
-            BitField<2, 1, u32_le> x;
-            BitField<3, 1, u32_le> y;
-            BitField<4, 1, u32_le> l;
-            BitField<5, 1, u32_le> r;
-            BitField<6, 1, u32_le> zl;
-            BitField<7, 1, u32_le> zr;
-            BitField<8, 1, u32_le> plus;
-            BitField<9, 1, u32_le> minus;
-            BitField<10, 1, u32_le> d_left;
-            BitField<11, 1, u32_le> d_up;
-            BitField<12, 1, u32_le> d_right;
-            BitField<13, 1, u32_le> d_down;
+            BitField<0, 1, u32> a;
+            BitField<1, 1, u32> b;
+            BitField<2, 1, u32> x;
+            BitField<3, 1, u32> y;
+            BitField<4, 1, u32> l;
+            BitField<5, 1, u32> r;
+            BitField<6, 1, u32> zl;
+            BitField<7, 1, u32> zr;
+            BitField<8, 1, u32> plus;
+            BitField<9, 1, u32> minus;
+            BitField<10, 1, u32> d_left;
+            BitField<11, 1, u32> d_up;
+            BitField<12, 1, u32> d_right;
+            BitField<13, 1, u32> d_down;
         };
     };
     static_assert(sizeof(PadState) == 0x4, "PadState is an invalid size");
@@ -62,7 +62,7 @@ private:
     struct Attributes {
         union {
             u32_le raw{};
-            BitField<0, 1, u32_le> connected;
+            BitField<0, 1, u32> connected;
         };
     };
     static_assert(sizeof(Attributes) == 0x4, "Attributes is an invalid size");
diff --git a/src/core/hle/service/hid/controllers/npad.h b/src/core/hle/service/hid/controllers/npad.h
index 18c7a94e6..4ff50b3cd 100644
--- a/src/core/hle/service/hid/controllers/npad.h
+++ b/src/core/hle/service/hid/controllers/npad.h
@@ -39,13 +39,13 @@ public:
         union {
             u32_le raw{};
 
-            BitField<0, 1, u32_le> pro_controller;
-            BitField<1, 1, u32_le> handheld;
-            BitField<2, 1, u32_le> joycon_dual;
-            BitField<3, 1, u32_le> joycon_left;
-            BitField<4, 1, u32_le> joycon_right;
+            BitField<0, 1, u32> pro_controller;
+            BitField<1, 1, u32> handheld;
+            BitField<2, 1, u32> joycon_dual;
+            BitField<3, 1, u32> joycon_left;
+            BitField<4, 1, u32> joycon_right;
 
-            BitField<6, 1, u32_le> pokeball; // TODO(ogniK): Confirm when possible
+            BitField<6, 1, u32> pokeball; // TODO(ogniK): Confirm when possible
         };
     };
     static_assert(sizeof(NPadType) == 4, "NPadType is an invalid size");
@@ -150,43 +150,43 @@ private:
         union {
             u64_le raw{};
             // Button states
-            BitField<0, 1, u64_le> a;
-            BitField<1, 1, u64_le> b;
-            BitField<2, 1, u64_le> x;
-            BitField<3, 1, u64_le> y;
-            BitField<4, 1, u64_le> l_stick;
-            BitField<5, 1, u64_le> r_stick;
-            BitField<6, 1, u64_le> l;
-            BitField<7, 1, u64_le> r;
-            BitField<8, 1, u64_le> zl;
-            BitField<9, 1, u64_le> zr;
-            BitField<10, 1, u64_le> plus;
-            BitField<11, 1, u64_le> minus;
+            BitField<0, 1, u64> a;
+            BitField<1, 1, u64> b;
+            BitField<2, 1, u64> x;
+            BitField<3, 1, u64> y;
+            BitField<4, 1, u64> l_stick;
+            BitField<5, 1, u64> r_stick;
+            BitField<6, 1, u64> l;
+            BitField<7, 1, u64> r;
+            BitField<8, 1, u64> zl;
+            BitField<9, 1, u64> zr;
+            BitField<10, 1, u64> plus;
+            BitField<11, 1, u64> minus;
 
             // D-Pad
-            BitField<12, 1, u64_le> d_left;
-            BitField<13, 1, u64_le> d_up;
-            BitField<14, 1, u64_le> d_right;
-            BitField<15, 1, u64_le> d_down;
+            BitField<12, 1, u64> d_left;
+            BitField<13, 1, u64> d_up;
+            BitField<14, 1, u64> d_right;
+            BitField<15, 1, u64> d_down;
 
             // Left JoyStick
-            BitField<16, 1, u64_le> l_stick_left;
-            BitField<17, 1, u64_le> l_stick_up;
-            BitField<18, 1, u64_le> l_stick_right;
-            BitField<19, 1, u64_le> l_stick_down;
+            BitField<16, 1, u64> l_stick_left;
+            BitField<17, 1, u64> l_stick_up;
+            BitField<18, 1, u64> l_stick_right;
+            BitField<19, 1, u64> l_stick_down;
 
             // Right JoyStick
-            BitField<20, 1, u64_le> r_stick_left;
-            BitField<21, 1, u64_le> r_stick_up;
-            BitField<22, 1, u64_le> r_stick_right;
-            BitField<23, 1, u64_le> r_stick_down;
+            BitField<20, 1, u64> r_stick_left;
+            BitField<21, 1, u64> r_stick_up;
+            BitField<22, 1, u64> r_stick_right;
+            BitField<23, 1, u64> r_stick_down;
 
             // Not always active?
-            BitField<24, 1, u64_le> left_sl;
-            BitField<25, 1, u64_le> left_sr;
+            BitField<24, 1, u64> left_sl;
+            BitField<25, 1, u64> left_sr;
 
-            BitField<26, 1, u64_le> right_sl;
-            BitField<27, 1, u64_le> right_sr;
+            BitField<26, 1, u64> right_sl;
+            BitField<27, 1, u64> right_sr;
         };
     };
     static_assert(sizeof(ControllerPadState) == 8, "ControllerPadState is an invalid size");
@@ -200,12 +200,12 @@ private:
     struct ConnectionState {
         union {
             u32_le raw{};
-            BitField<0, 1, u32_le> IsConnected;
-            BitField<1, 1, u32_le> IsWired;
-            BitField<2, 1, u32_le> IsLeftJoyConnected;
-            BitField<3, 1, u32_le> IsLeftJoyWired;
-            BitField<4, 1, u32_le> IsRightJoyConnected;
-            BitField<5, 1, u32_le> IsRightJoyWired;
+            BitField<0, 1, u32> IsConnected;
+            BitField<1, 1, u32> IsWired;
+            BitField<2, 1, u32> IsLeftJoyConnected;
+            BitField<3, 1, u32> IsLeftJoyWired;
+            BitField<4, 1, u32> IsRightJoyConnected;
+            BitField<5, 1, u32> IsRightJoyWired;
         };
     };
     static_assert(sizeof(ConnectionState) == 4, "ConnectionState is an invalid size");
@@ -240,23 +240,23 @@ private:
     struct NPadProperties {
         union {
             s64_le raw{};
-            BitField<11, 1, s64_le> is_vertical;
-            BitField<12, 1, s64_le> is_horizontal;
-            BitField<13, 1, s64_le> use_plus;
-            BitField<14, 1, s64_le> use_minus;
+            BitField<11, 1, s64> is_vertical;
+            BitField<12, 1, s64> is_horizontal;
+            BitField<13, 1, s64> use_plus;
+            BitField<14, 1, s64> use_minus;
         };
     };
 
     struct NPadDevice {
         union {
             u32_le raw{};
-            BitField<0, 1, s32_le> pro_controller;
-            BitField<1, 1, s32_le> handheld;
-            BitField<2, 1, s32_le> handheld_left;
-            BitField<3, 1, s32_le> handheld_right;
-            BitField<4, 1, s32_le> joycon_left;
-            BitField<5, 1, s32_le> joycon_right;
-            BitField<6, 1, s32_le> pokeball;
+            BitField<0, 1, s32> pro_controller;
+            BitField<1, 1, s32> handheld;
+            BitField<2, 1, s32> handheld_left;
+            BitField<3, 1, s32> handheld_right;
+            BitField<4, 1, s32> joycon_left;
+            BitField<5, 1, s32> joycon_right;
+            BitField<6, 1, s32> pokeball;
         };
     };
 
diff --git a/src/core/hle/service/hid/controllers/touchscreen.h b/src/core/hle/service/hid/controllers/touchscreen.h
index 012b6e0dd..76fc340e9 100644
--- a/src/core/hle/service/hid/controllers/touchscreen.h
+++ b/src/core/hle/service/hid/controllers/touchscreen.h
@@ -33,8 +33,8 @@ private:
     struct Attributes {
         union {
             u32 raw{};
-            BitField<0, 1, u32_le> start_touch;
-            BitField<1, 1, u32_le> end_touch;
+            BitField<0, 1, u32> start_touch;
+            BitField<1, 1, u32> end_touch;
         };
     };
     static_assert(sizeof(Attributes) == 0x4, "Attributes is an invalid size");
diff --git a/src/core/hle/service/lm/lm.cpp b/src/core/hle/service/lm/lm.cpp
index 1f462e087..2a61593e2 100644
--- a/src/core/hle/service/lm/lm.cpp
+++ b/src/core/hle/service/lm/lm.cpp
@@ -42,7 +42,7 @@ private:
         union {
             BitField<0, 16, Flags> flags;
             BitField<16, 8, Severity> severity;
-            BitField<24, 8, u32_le> verbosity;
+            BitField<24, 8, u32> verbosity;
         };
         u32_le payload_size;
 
diff --git a/src/core/hle/service/nvdrv/devices/nvdevice.h b/src/core/hle/service/nvdrv/devices/nvdevice.h
index 0f02a1a18..4f6042b00 100644
--- a/src/core/hle/service/nvdrv/devices/nvdevice.h
+++ b/src/core/hle/service/nvdrv/devices/nvdevice.h
@@ -19,11 +19,11 @@ public:
     virtual ~nvdevice() = default;
     union Ioctl {
         u32_le raw;
-        BitField<0, 8, u32_le> cmd;
-        BitField<8, 8, u32_le> group;
-        BitField<16, 14, u32_le> length;
-        BitField<30, 1, u32_le> is_in;
-        BitField<31, 1, u32_le> is_out;
+        BitField<0, 8, u32> cmd;
+        BitField<8, 8, u32> group;
+        BitField<16, 14, u32> length;
+        BitField<30, 1, u32> is_in;
+        BitField<31, 1, u32> is_out;
     };
 
     /**
diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index 37f09ce5f..d0284bdf4 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_executable(tests
+    common/bit_field.cpp
     common/param_package.cpp
     common/ring_buffer.cpp
     core/arm/arm_test_common.cpp
diff --git a/src/tests/common/bit_field.cpp b/src/tests/common/bit_field.cpp
new file mode 100644
index 000000000..8ca1889f9
--- /dev/null
+++ b/src/tests/common/bit_field.cpp
@@ -0,0 +1,90 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <array>
+#include <cstring>
+#include <type_traits>
+#include <catch2/catch.hpp>
+#include "common/bit_field.h"
+
+TEST_CASE("BitField", "[common]") {
+    enum class TestEnum : u32 {
+        A = 0b10111101,
+        B = 0b10101110,
+        C = 0b00001111,
+    };
+
+    union LEBitField {
+        u32_le raw;
+        BitField<0, 6, u32> a;
+        BitField<6, 4, s32> b;
+        BitField<10, 8, TestEnum> c;
+        BitField<18, 14, u32> d;
+    } le_bitfield;
+
+    union BEBitField {
+        u32_be raw;
+        BitFieldBE<0, 6, u32> a;
+        BitFieldBE<6, 4, s32> b;
+        BitFieldBE<10, 8, TestEnum> c;
+        BitFieldBE<18, 14, u32> d;
+    } be_bitfield;
+
+    static_assert(sizeof(LEBitField) == sizeof(u32));
+    static_assert(sizeof(BEBitField) == sizeof(u32));
+    static_assert(std::is_trivially_copyable_v<LEBitField>);
+    static_assert(std::is_trivially_copyable_v<BEBitField>);
+
+    std::array<u8, 4> raw{{
+        0b01101100,
+        0b11110110,
+        0b10111010,
+        0b11101100,
+    }};
+
+    std::memcpy(&le_bitfield, &raw, sizeof(raw));
+    std::memcpy(&be_bitfield, &raw, sizeof(raw));
+
+    // bit fields: 11101100101110'10111101'1001'101100
+    REQUIRE(le_bitfield.raw == 0b11101100'10111010'11110110'01101100);
+    REQUIRE(le_bitfield.a == 0b101100);
+    REQUIRE(le_bitfield.b == -7); // 1001 as two's complement
+    REQUIRE(le_bitfield.c == TestEnum::A);
+    REQUIRE(le_bitfield.d == 0b11101100101110);
+
+    le_bitfield.a.Assign(0b000111);
+    le_bitfield.b.Assign(-1);
+    le_bitfield.c.Assign(TestEnum::C);
+    le_bitfield.d.Assign(0b01010101010101);
+    std::memcpy(&raw, &le_bitfield, sizeof(raw));
+    // bit fields: 01010101010101'00001111'1111'000111
+    REQUIRE(le_bitfield.raw == 0b01010101'01010100'00111111'11000111);
+    REQUIRE(raw == std::array<u8, 4>{{
+                       0b11000111,
+                       0b00111111,
+                       0b01010100,
+                       0b01010101,
+                   }});
+
+    // bit fields: 01101100111101'10101110'1011'101100
+    REQUIRE(be_bitfield.raw == 0b01101100'11110110'10111010'11101100);
+    REQUIRE(be_bitfield.a == 0b101100);
+    REQUIRE(be_bitfield.b == -5); // 1011 as two's complement
+    REQUIRE(be_bitfield.c == TestEnum::B);
+    REQUIRE(be_bitfield.d == 0b01101100111101);
+
+    be_bitfield.a.Assign(0b000111);
+    be_bitfield.b.Assign(-1);
+    be_bitfield.c.Assign(TestEnum::C);
+    be_bitfield.d.Assign(0b01010101010101);
+    std::memcpy(&raw, &be_bitfield, sizeof(raw));
+    // bit fields: 01010101010101'00001111'1111'000111
+    REQUIRE(be_bitfield.raw == 0b01010101'01010100'00111111'11000111);
+    REQUIRE(raw == std::array<u8, 4>{{
+                       0b01010101,
+                       0b01010100,
+                       0b00111111,
+                       0b11000111,
+                   }});
+}