From 680affd1fea519a288a1d6e20d77c3404031c260 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Thu, 25 May 2023 19:56:04 +1000
Subject: [PATCH] Common: Add ByteSwap.h

Provides a C++23-like std::byteswap implementation.
---
 common/ByteSwap.h                     | 56 +++++++++++++++++++++++++++
 common/CMakeLists.txt                 |  1 +
 common/common.vcxproj                 |  1 +
 common/common.vcxproj.filters         |  3 ++
 tests/ctest/common/CMakeLists.txt     |  1 +
 tests/ctest/common/byteswap_tests.cpp | 26 +++++++++++++
 6 files changed, 88 insertions(+)
 create mode 100644 common/ByteSwap.h
 create mode 100644 tests/ctest/common/byteswap_tests.cpp

diff --git a/common/ByteSwap.h b/common/ByteSwap.h
new file mode 100644
index 0000000000..b1196a3773
--- /dev/null
+++ b/common/ByteSwap.h
@@ -0,0 +1,56 @@
+/*  PCSX2 - PS2 Emulator for PCs
+ *  Copyright (C) 2023  PCSX2 Dev Team
+ *
+ *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
+ *  of the GNU Lesser General Public License as published by the Free Software Found-
+ *  ation, either version 3 of the License, or (at your option) any later version.
+ *
+ *  PCSX2 is distributed in the hope that 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 PCSX2.
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <type_traits>
+
+#ifdef _MSC_VER
+#include <stdlib.h>
+#endif
+
+template <typename T>
+T ByteSwap(T value)
+{
+	if constexpr (std::is_signed_v<T>)
+	{
+		return static_cast<T>(ByteSwap(std::make_unsigned_t<T>(value)));
+	}
+	else if constexpr (std::is_same_v<T, std::uint16_t>)
+	{
+#ifdef _MSC_VER
+		return _byteswap_ushort(value);
+#else
+		return __builtin_bswap16(value);
+#endif
+	}
+	else if constexpr (std::is_same_v<T, std::uint32_t>)
+	{
+#ifdef _MSC_VER
+		return _byteswap_ulong(value);
+#else
+		return __builtin_bswap32(value);
+#endif
+	}
+	else if constexpr (std::is_same_v<T, std::uint64_t>)
+	{
+#ifdef _MSC_VER
+		return _byteswap_uint64(value);
+#else
+		return __builtin_bswap64(value);
+#endif
+	}
+}
diff --git a/common/CMakeLists.txt b/common/CMakeLists.txt
index eeee867614..f679aaff7e 100644
--- a/common/CMakeLists.txt
+++ b/common/CMakeLists.txt
@@ -64,6 +64,7 @@ target_sources(common PRIVATE
 	AlignedMalloc.h
 	Assertions.h
 	boost_spsc_queue.hpp
+	ByteSwap.h
 	Console.h
 	CrashHandler.h
 	DynamicLibrary.h
diff --git a/common/common.vcxproj b/common/common.vcxproj
index 14d76822a2..291418bf61 100644
--- a/common/common.vcxproj
+++ b/common/common.vcxproj
@@ -104,6 +104,7 @@
     <ClInclude Include="Align.h" />
     <ClInclude Include="AlignedMalloc.h" />
     <ClInclude Include="BitCast.h" />
+    <ClInclude Include="ByteSwap.h" />
     <ClInclude Include="CrashHandler.h" />
     <ClInclude Include="DynamicLibrary.h" />
     <ClInclude Include="Easing.h" />
diff --git a/common/common.vcxproj.filters b/common/common.vcxproj.filters
index 19e1d6b590..ab75569ef9 100644
--- a/common/common.vcxproj.filters
+++ b/common/common.vcxproj.filters
@@ -351,6 +351,9 @@
     <ClInclude Include="FileSystem.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="ByteSwap.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <Filter Include="Source Files">
diff --git a/tests/ctest/common/CMakeLists.txt b/tests/ctest/common/CMakeLists.txt
index 80d10dd400..7d2c00d27f 100644
--- a/tests/ctest/common/CMakeLists.txt
+++ b/tests/ctest/common/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_pcsx2_test(common_test
+	byteswap_tests.cpp
 	path_tests.cpp
 	string_util_tests.cpp
 	x86emitter/codegen_tests.cpp
diff --git a/tests/ctest/common/byteswap_tests.cpp b/tests/ctest/common/byteswap_tests.cpp
new file mode 100644
index 0000000000..501c94b117
--- /dev/null
+++ b/tests/ctest/common/byteswap_tests.cpp
@@ -0,0 +1,26 @@
+/*  PCSX2 - PS2 Emulator for PCs
+ *  Copyright (C) 2023 PCSX2 Dev Team
+ *
+ *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
+ *  of the GNU Lesser General Public License as published by the Free Software Found-
+ *  ation, either version 3 of the License, or (at your option) any later version.
+ *
+ *  PCSX2 is distributed in the hope that 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 PCSX2.
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "common/Pcsx2Defs.h"
+#include "common/ByteSwap.h"
+#include <gtest/gtest.h>
+
+TEST(ByteSwap, ByteSwap)
+{
+	ASSERT_EQ(ByteSwap(static_cast<u16>(0xabcd)), 0xcdabu);
+	ASSERT_EQ(ByteSwap(static_cast<u32>(0xabcdef01)), 0x01efcdabu);
+	ASSERT_EQ(ByteSwap(static_cast<u64>(0xabcdef0123456789ULL)), 0x8967452301efcdabu);
+	ASSERT_EQ(ByteSwap(static_cast<s32>(0x80123456)), 0x56341280);
+}