VideoCommon: Expose SamplerState to shaders

The benefit to exposing this over the raw BP state is that adjustments Dolphin makes, such as LOD biases from arbitrary mipmap detection, will work properly.

Source/Core/VideoCommon/RenderState.h

@@ -145,30 +145,16 @@ union BlendingState
   u32 hex;
 };
 
-union SamplerState
+struct SamplerState
 {
-  using StorageType = u64;
-
-  enum class Filter : StorageType
-  {
-    Point,
-    Linear
-  };
-
-  enum class AddressMode : StorageType
-  {
-    Clamp,
-    Repeat,
-    MirroredRepeat
-  };
-
   void Generate(const BPMemory& bp, u32 index);
 
   SamplerState() = default;
   SamplerState(const SamplerState&) = default;
   SamplerState& operator=(const SamplerState& rhs)
   {
-    hex = rhs.hex;
+    tm0.hex = rhs.tm0.hex;
+    tm1.hex = rhs.tm1.hex;
     return *this;
   }
   SamplerState(SamplerState&&) = default;
@@ -179,22 +165,54 @@ union SamplerState
     return *this;
   }
 
-  bool operator==(const SamplerState& rhs) const { return hex == rhs.hex; }
+  bool operator==(const SamplerState& rhs) const { return Hex() == rhs.Hex(); }
   bool operator!=(const SamplerState& rhs) const { return !operator==(rhs); }
-  bool operator<(const SamplerState& rhs) const { return hex < rhs.hex; }
-  BitField<0, 1, Filter> min_filter;
-  BitField<1, 1, Filter> mag_filter;
-  BitField<2, 1, Filter> mipmap_filter;
-  BitField<3, 2, AddressMode> wrap_u;
-  BitField<5, 2, AddressMode> wrap_v;
-  BitField<7, 16, s64> lod_bias;  // multiplied by 256
-  BitField<23, 8, u64> min_lod;   // multiplied by 16
-  BitField<31, 8, u64> max_lod;   // multiplied by 16
-  BitField<39, 1, u64> anisotropic_filtering;
+  bool operator<(const SamplerState& rhs) const { return Hex() < rhs.Hex(); }
 
-  StorageType hex;
+  constexpr u64 Hex() const { return tm0.hex | (static_cast<u64>(tm1.hex) << 32); }
+
+  // Based on BPMemory TexMode0/TexMode1, but with slightly higher precision and some
+  // simplifications
+  union TM0
+  {
+    // BP's mipmap_filter can be None, but that is represented here by setting min_lod and max_lod
+    // to 0
+    BitField<0, 1, FilterMode> min_filter;
+    BitField<1, 1, FilterMode> mag_filter;
+    BitField<2, 1, FilterMode> mipmap_filter;
+    // Guaranteed to be valid values (i.e. not 3)
+    BitField<3, 2, WrapMode> wrap_u;
+    BitField<5, 2, WrapMode> wrap_v;
+    BitField<7, 1, LODType> diag_lod;
+    BitField<8, 16, s32> lod_bias;         // multiplied by 256, higher precision than normal
+    BitField<24, 1, bool, u32> lod_clamp;  // TODO: This isn't currently implemented
+    BitField<25, 1, bool, u32> anisotropic_filtering;  // TODO: This doesn't use the BP one yet
+    u32 hex;
+  };
+  union TM1
+  {
+    // Min is guaranteed to be less than or equal to max
+    BitField<0, 8, u32> min_lod;  // multiplied by 16
+    BitField<8, 8, u32> max_lod;  // multiplied by 16
+    u32 hex;
+  };
+
+  TM0 tm0;
+  TM1 tm1;
 };
 
+namespace std
+{
+template <>
+struct hash<SamplerState>
+{
+  std::size_t operator()(SamplerState const& state) const noexcept
+  {
+    return std::hash<u64>{}(state.Hex());
+  }
+};
+}  // namespace std
+
 namespace RenderState
 {
 RasterizationState GetInvalidRasterizationState();