From f27a28b58c75241c96c49aa1cbc066faa0cbdd4f Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Sun, 5 Nov 2023 21:34:19 +1000
Subject: [PATCH] CDImage: Use ByteSwap()

---
 src/common/bitutils.h | 88 +++++++++++++++++++++++++++++++------------
 src/util/cd_image.cpp |  5 ++-
 2 files changed, 66 insertions(+), 27 deletions(-)

diff --git a/src/common/bitutils.h b/src/common/bitutils.h
index 3461e06e5..dd253412f 100644
--- a/src/common/bitutils.h
+++ b/src/common/bitutils.h
@@ -2,22 +2,26 @@
 // SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
 
 #pragma once
+
 #include "types.h"
 
+#include <cstdint>
+#include <type_traits>
+
 #ifdef _MSC_VER
-#include <intrin.h>
+#include <stdlib.h>
 #endif
 
 // Zero-extending helper
 template<typename TReturn, typename TValue>
-ALWAYS_INLINE constexpr TReturn ZeroExtend(TValue value)
+ALWAYS_INLINE static constexpr TReturn ZeroExtend(TValue value)
 {
   return static_cast<TReturn>(static_cast<typename std::make_unsigned<TReturn>::type>(
     static_cast<typename std::make_unsigned<TValue>::type>(value)));
 }
 // Sign-extending helper
 template<typename TReturn, typename TValue>
-ALWAYS_INLINE constexpr TReturn SignExtend(TValue value)
+ALWAYS_INLINE static constexpr TReturn SignExtend(TValue value)
 {
   return static_cast<TReturn>(
     static_cast<typename std::make_signed<TReturn>::type>(static_cast<typename std::make_signed<TValue>::type>(value)));
@@ -25,97 +29,97 @@ ALWAYS_INLINE constexpr TReturn SignExtend(TValue value)
 
 // Type-specific helpers
 template<typename TValue>
-ALWAYS_INLINE constexpr u16 ZeroExtend16(TValue value)
+ALWAYS_INLINE static constexpr u16 ZeroExtend16(TValue value)
 {
   return ZeroExtend<u16, TValue>(value);
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u32 ZeroExtend32(TValue value)
+ALWAYS_INLINE static constexpr u32 ZeroExtend32(TValue value)
 {
   return ZeroExtend<u32, TValue>(value);
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u64 ZeroExtend64(TValue value)
+ALWAYS_INLINE static constexpr u64 ZeroExtend64(TValue value)
 {
   return ZeroExtend<u64, TValue>(value);
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u16 SignExtend16(TValue value)
+ALWAYS_INLINE static constexpr u16 SignExtend16(TValue value)
 {
   return SignExtend<u16, TValue>(value);
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u32 SignExtend32(TValue value)
+ALWAYS_INLINE static constexpr u32 SignExtend32(TValue value)
 {
   return SignExtend<u32, TValue>(value);
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u64 SignExtend64(TValue value)
+ALWAYS_INLINE static constexpr u64 SignExtend64(TValue value)
 {
   return SignExtend<u64, TValue>(value);
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u8 Truncate8(TValue value)
+ALWAYS_INLINE static constexpr u8 Truncate8(TValue value)
 {
   return static_cast<u8>(static_cast<typename std::make_unsigned<decltype(value)>::type>(value));
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u16 Truncate16(TValue value)
+ALWAYS_INLINE static constexpr u16 Truncate16(TValue value)
 {
   return static_cast<u16>(static_cast<typename std::make_unsigned<decltype(value)>::type>(value));
 }
 template<typename TValue>
-ALWAYS_INLINE constexpr u32 Truncate32(TValue value)
+ALWAYS_INLINE static constexpr u32 Truncate32(TValue value)
 {
   return static_cast<u32>(static_cast<typename std::make_unsigned<decltype(value)>::type>(value));
 }
 
 // BCD helpers
-ALWAYS_INLINE constexpr u8 BinaryToBCD(u8 value)
+ALWAYS_INLINE static constexpr u8 BinaryToBCD(u8 value)
 {
   return ((value / 10) << 4) + (value % 10);
 }
-ALWAYS_INLINE constexpr u8 PackedBCDToBinary(u8 value)
+ALWAYS_INLINE static constexpr u8 PackedBCDToBinary(u8 value)
 {
   return ((value >> 4) * 10) + (value % 16);
 }
-ALWAYS_INLINE constexpr u8 IsValidBCDDigit(u8 digit)
+ALWAYS_INLINE static constexpr u8 IsValidBCDDigit(u8 digit)
 {
   return (digit <= 9);
 }
-ALWAYS_INLINE constexpr u8 IsValidPackedBCD(u8 value)
+ALWAYS_INLINE static constexpr u8 IsValidPackedBCD(u8 value)
 {
   return IsValidBCDDigit(value & 0x0F) && IsValidBCDDigit(value >> 4);
 }
 
 // Boolean to integer
-ALWAYS_INLINE constexpr u8 BoolToUInt8(bool value)
+ALWAYS_INLINE static constexpr u8 BoolToUInt8(bool value)
 {
   return static_cast<u8>(value);
 }
-ALWAYS_INLINE constexpr u16 BoolToUInt16(bool value)
+ALWAYS_INLINE static constexpr u16 BoolToUInt16(bool value)
 {
   return static_cast<u16>(value);
 }
-ALWAYS_INLINE constexpr u32 BoolToUInt32(bool value)
+ALWAYS_INLINE static constexpr u32 BoolToUInt32(bool value)
 {
   return static_cast<u32>(value);
 }
-ALWAYS_INLINE constexpr u64 BoolToUInt64(bool value)
+ALWAYS_INLINE static constexpr u64 BoolToUInt64(bool value)
 {
   return static_cast<u64>(value);
 }
 
 // Integer to boolean
 template<typename TValue>
-ALWAYS_INLINE constexpr bool ConvertToBool(TValue value)
+ALWAYS_INLINE static constexpr bool ConvertToBool(TValue value)
 {
   return static_cast<bool>(value);
 }
 
 // Unsafe integer to boolean
 template<typename TValue>
-ALWAYS_INLINE bool ConvertToBoolUnchecked(TValue value)
+ALWAYS_INLINE static bool ConvertToBoolUnchecked(TValue value)
 {
   // static_assert(sizeof(uint8) == sizeof(bool));
   bool ret;
@@ -125,7 +129,7 @@ ALWAYS_INLINE bool ConvertToBoolUnchecked(TValue value)
 
 // Generic sign extension
 template<int NBITS, typename T>
-ALWAYS_INLINE constexpr T SignExtendN(T value)
+ALWAYS_INLINE static constexpr T SignExtendN(T value)
 {
   // http://graphics.stanford.edu/~seander/bithacks.html#VariableSignExtend
   constexpr int shift = 8 * sizeof(T) - NBITS;
@@ -134,7 +138,7 @@ ALWAYS_INLINE constexpr T SignExtendN(T value)
 
 /// Returns the number of zero bits before the first set bit, going MSB->LSB.
 template<typename T>
-ALWAYS_INLINE unsigned CountLeadingZeros(T value)
+ALWAYS_INLINE static unsigned CountLeadingZeros(T value)
 {
 #ifdef _MSC_VER
   if constexpr (sizeof(value) >= sizeof(u64))
@@ -161,7 +165,7 @@ ALWAYS_INLINE unsigned CountLeadingZeros(T value)
 
 /// Returns the number of zero bits before the first set bit, going LSB->MSB.
 template<typename T>
-ALWAYS_INLINE unsigned CountTrailingZeros(T value)
+ALWAYS_INLINE static unsigned CountTrailingZeros(T value)
 {
 #ifdef _MSC_VER
   if constexpr (sizeof(value) >= sizeof(u64))
@@ -183,3 +187,37 @@ ALWAYS_INLINE unsigned CountTrailingZeros(T value)
     return static_cast<unsigned>(__builtin_ctz(ZeroExtend32(value)));
 #endif
 }
+
+// C++23-like std::byteswap()
+template<typename T>
+ALWAYS_INLINE static 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/src/util/cd_image.cpp b/src/util/cd_image.cpp
index 12cc1f50e..aa9c3a7c6 100644
--- a/src/util/cd_image.cpp
+++ b/src/util/cd_image.cpp
@@ -3,6 +3,7 @@
 
 #include "cd_image.h"
 #include "common/assert.h"
+#include "common/bitutils.h"
 #include "common/error.h"
 #include "common/file_system.h"
 #include "common/log.h"
@@ -536,8 +537,8 @@ u16 CDImage::SubChannelQ::ComputeCRC(const Data& data)
   for (u32 i = 0; i < 10; i++)
     value = crc16_table[(value >> 8) ^ data[i]] ^ (value << 8);
 
-  value = ~value;
-  return (value >> 8) | (value << 8);
+  // Invert and swap
+  return ByteSwap(static_cast<u16>(~value));
 }
 
 bool CDImage::SubChannelQ::IsCRCValid() const