DiscIO: Move magic constants for discs to DiscUtils

Source/Core/DiscIO/DirectoryBlob.cpp

@@ -28,6 +28,7 @@
 #include "Core/Boot/DolReader.h"
 #include "Core/IOS/ES/Formats.h"
 #include "DiscIO/Blob.h"
+#include "DiscIO/DiscUtils.h"
 #include "DiscIO/VolumeWii.h"
 #include "DiscIO/WiiEncryptionCache.h"
 
@@ -653,8 +654,8 @@ void DirectoryBlobPartition::SetDiscHeaderAndDiscType(std::optional<bool> is_wii
   }
   else
   {
-    m_is_wii = Common::swap32(&m_disc_header[0x18]) == 0x5d1c9ea3;
-    const bool is_gc = Common::swap32(&m_disc_header[0x1c]) == 0xc2339f3d;
+    m_is_wii = Common::swap32(&m_disc_header[0x18]) == WII_DISC_MAGIC;
+    const bool is_gc = Common::swap32(&m_disc_header[0x1c]) == GAMECUBE_DISC_MAGIC;
     if (m_is_wii == is_gc)
       ERROR_LOG_FMT(DISCIO, "Couldn't detect disc type based on {}", boot_bin_path);
   }

Source/Core/DiscIO/DiscUtils.cpp

@@ -130,10 +130,9 @@ u64 GetBiggestReferencedOffset(const Volume& volume)
   // This can happen when certain programs that create WBFS files scrub the entirety of
   // the Masterpiece partitions in Super Smash Bros. Brawl without removing them from
   // the partition table. https://bugs.dolphin-emu.org/issues/8733
-  constexpr u32 WII_MAGIC = 0x5D1C9EA3;
   const auto it =
       std::remove_if(partitions.begin(), partitions.end(), [&](const Partition& partition) {
-        return volume.ReadSwapped<u32>(0x18, partition) != WII_MAGIC;
+        return volume.ReadSwapped<u32>(0x18, partition) != WII_DISC_MAGIC;
       });
   partitions.erase(it, partitions.end());
 

Source/Core/DiscIO/DiscUtils.h

@@ -22,6 +22,9 @@ constexpr u64 SL_DVD_R_SIZE = 4707319808;  // Wii RVT-R
 constexpr u64 DL_DVD_SIZE = 8511160320;    // Wii retail
 constexpr u64 DL_DVD_R_SIZE = 8543666176;  // Wii RVT-R
 
+constexpr u32 GAMECUBE_DISC_MAGIC = 0xC2339F3D;
+constexpr u32 WII_DISC_MAGIC = 0x5D1C9EA3;
+
 constexpr u32 PARTITION_DATA = 0;
 constexpr u32 PARTITION_UPDATE = 1;
 constexpr u32 PARTITION_CHANNEL = 2;  // Mario Kart Wii, Wii Fit, Wii Fit Plus, Rabbids Go Home

Source/Core/DiscIO/FileSystemGCWii.cpp

@@ -232,9 +232,9 @@ FileSystemGCWii::FileSystemGCWii(const VolumeDisc* volume, const Partition& part
 {
   u8 offset_shift;
   // Check if this is a GameCube or Wii disc
-  if (volume->ReadSwapped<u32>(0x18, partition) == u32(0x5D1C9EA3))
+  if (volume->ReadSwapped<u32>(0x18, partition) == WII_DISC_MAGIC)
     offset_shift = 2;  // Wii file system
-  else if (volume->ReadSwapped<u32>(0x1c, partition) == u32(0xC2339F3D))
+  else if (volume->ReadSwapped<u32>(0x1c, partition) == GAMECUBE_DISC_MAGIC)
     offset_shift = 0;  // GameCube file system
   else
     return;  // Invalid partition (maybe someone removed its data but not its partition table entry)

Source/Core/DiscIO/Volume.cpp

@@ -20,6 +20,7 @@
 
 #include "Core/IOS/ES/Formats.h"
 #include "DiscIO/Blob.h"
+#include "DiscIO/DiscUtils.h"
 #include "DiscIO/Enums.h"
 #include "DiscIO/VolumeDisc.h"
 #include "DiscIO/VolumeGC.h"
@@ -87,14 +88,10 @@ std::map<Language, std::string> Volume::ReadWiiNames(const std::vector<char16_t>
 
 static std::unique_ptr<VolumeDisc> CreateDisc(std::unique_ptr<BlobReader>& reader)
 {
-  // Check for Wii
-  const std::optional<u32> wii_magic = reader->ReadSwapped<u32>(0x18);
-  if (wii_magic == u32(0x5D1C9EA3))
+  if (reader->ReadSwapped<u32>(0x18) == WII_DISC_MAGIC)
     return std::make_unique<VolumeWii>(std::move(reader));
 
-  // Check for GC
-  const std::optional<u32> gc_magic = reader->ReadSwapped<u32>(0x1C);
-  if (gc_magic == u32(0xC2339F3D))
+  if (reader->ReadSwapped<u32>(0x1C) == GAMECUBE_DISC_MAGIC)
     return std::make_unique<VolumeGC>(std::move(reader));
 
   // No known magic words found

Source/Core/DiscIO/VolumeVerifier.cpp

@@ -523,12 +523,11 @@ bool VolumeVerifier::CheckPartition(const Partition& partition)
   bool invalid_header = false;
   bool blank_contents = false;
   std::vector<u8> disc_header(0x80);
-  constexpr u32 WII_MAGIC = 0x5D1C9EA3;
   if (!m_volume.Read(0, disc_header.size(), disc_header.data(), partition))
   {
     invalid_header = true;
   }
-  else if (Common::swap32(disc_header.data() + 0x18) != WII_MAGIC)
+  else if (Common::swap32(disc_header.data() + 0x18) != WII_DISC_MAGIC)
   {
     for (size_t i = 0; i < disc_header.size(); i += 4)
     {