Detect GC region based on the actual region value

The county code isn't 100% reliable for detecting the region.
For instance, some games released in Korea have the country
code E even though they're region-locked to NTSC-J consoles.

This commit makes the GC disc region detection match the Wii
disc region detection (apart from the region value being in
a different place on the disc).

1 files changed, 10 insertions, 4 deletions

diff --git a/Source/Core/DiscIO/VolumeGC.cpp b/Source/Core/DiscIO/VolumeGC.cpp
index 1a89917812..5941af4a56 100644
--- a/Source/Core/DiscIO/VolumeGC.cpp
+++ b/Source/Core/DiscIO/VolumeGC.cpp
@@ -60,14 +60,20 @@ std::string VolumeGC::GetGameID(const Partition& partition) const
 
 Region VolumeGC::GetRegion() const
 {
-  const std::optional<u8> country_code = ReadSwapped<u8>(3, PARTITION_NONE);
-  return country_code ? RegionSwitchGC(*country_code) : Region::UNKNOWN_REGION;
+  const std::optional<u32> region_code = ReadSwapped<u32>(0x458, PARTITION_NONE);
+  return region_code ? static_cast<Region>(*region_code) : Region::UNKNOWN_REGION;
 }
 
 Country VolumeGC::GetCountry(const Partition& partition) const
 {
-  const std::optional<u8> country_code = ReadSwapped<u8>(3, partition);
-  return country_code ? CountrySwitch(*country_code) : Country::COUNTRY_UNKNOWN;
+  // The 0 that we use as a default value is mapped to COUNTRY_UNKNOWN and UNKNOWN_REGION
+  const u8 country_byte = ReadSwapped<u8>(3, partition).value_or(0);
+  const Region region = GetRegion();
+
+  if (RegionSwitchGC(country_byte) != region)
+    return TypicalCountryForRegion(region);
+
+  return CountrySwitch(country_byte);
 }
 
 std::string VolumeGC::GetMakerID(const Partition& partition) const