Pica/Texture: Move part of ETC1 decoding to new file and cleanups

4 files changed, 159 insertions, 110 deletions

diff --git a/src/video_core/CMakeLists.txt b/src/video_core/CMakeLists.txt
index ecb424cfd..ad984cd94 100644
--- a/src/video_core/CMakeLists.txt
+++ b/src/video_core/CMakeLists.txt
@@ -15,6 +15,7 @@ set(SRCS
             shader/shader.cpp
             shader/shader_interpreter.cpp
             swrasterizer.cpp
+            texture/etc1.cpp
             texture/texture_decode.cpp
             vertex_loader.cpp
             video_core.cpp
@@ -44,6 +45,7 @@ set(HEADERS
             shader/shader.h
             shader/shader_interpreter.h
             swrasterizer.h
+            texture/etc1.h
             texture/texture_decode.h
             utils.h
             vertex_loader.h
diff --git a/src/video_core/texture/etc1.cpp b/src/video_core/texture/etc1.cpp
new file mode 100644
index 000000000..af60cde1e
--- /dev/null
+++ b/src/video_core/texture/etc1.cpp
@@ -0,0 +1,124 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+#include "common/bit_field.h"
+#include "common/color.h"
+#include "common/common_types.h"
+#include "common/math_util.h"
+#include "common/vector_math.h"
+#include "video_core/texture/etc1.h"
+
+namespace Pica {
+namespace Texture {
+
+namespace {
+
+constexpr std::array<u8[2], 8> etc1_modifier_table = {{
+    {2, 8}, {5, 17}, {9, 29}, {13, 42}, {18, 60}, {24, 80}, {33, 106}, {47, 183},
+}};
+
+union ETC1Tile {
+    u64 raw;
+
+    // Each of these two is a collection of 16 bits (one per lookup value)
+    BitField<0, 16, u64> table_subindexes;
+    BitField<16, 16, u64> negation_flags;
+
+    unsigned GetTableSubIndex(unsigned index) const {
+        return (table_subindexes >> index) & 1;
+    }
+
+    bool GetNegationFlag(unsigned index) const {
+        return ((negation_flags >> index) & 1) == 1;
+    }
+
+    BitField<32, 1, u64> flip;
+    BitField<33, 1, u64> differential_mode;
+
+    BitField<34, 3, u64> table_index_2;
+    BitField<37, 3, u64> table_index_1;
+
+    union {
+        // delta value + base value
+        BitField<40, 3, s64> db;
+        BitField<43, 5, u64> b;
+
+        BitField<48, 3, s64> dg;
+        BitField<51, 5, u64> g;
+
+        BitField<56, 3, s64> dr;
+        BitField<59, 5, u64> r;
+    } differential;
+
+    union {
+        BitField<40, 4, u64> b2;
+        BitField<44, 4, u64> b1;
+
+        BitField<48, 4, u64> g2;
+        BitField<52, 4, u64> g1;
+
+        BitField<56, 4, u64> r2;
+        BitField<60, 4, u64> r1;
+    } separate;
+
+    const Math::Vec3<u8> GetRGB(unsigned int x, unsigned int y) const {
+        int texel = 4 * x + y;
+
+        if (flip)
+            std::swap(x, y);
+
+        // Lookup base value
+        Math::Vec3<int> ret;
+        if (differential_mode) {
+            ret.r() = static_cast<int>(differential.r);
+            ret.g() = static_cast<int>(differential.g);
+            ret.b() = static_cast<int>(differential.b);
+            if (x >= 2) {
+                ret.r() += static_cast<int>(differential.dr);
+                ret.g() += static_cast<int>(differential.dg);
+                ret.b() += static_cast<int>(differential.db);
+            }
+            ret.r() = Color::Convert5To8(ret.r());
+            ret.g() = Color::Convert5To8(ret.g());
+            ret.b() = Color::Convert5To8(ret.b());
+        } else {
+            if (x < 2) {
+                ret.r() = Color::Convert4To8(static_cast<u8>(separate.r1));
+                ret.g() = Color::Convert4To8(static_cast<u8>(separate.g1));
+                ret.b() = Color::Convert4To8(static_cast<u8>(separate.b1));
+            } else {
+                ret.r() = Color::Convert4To8(static_cast<u8>(separate.r2));
+                ret.g() = Color::Convert4To8(static_cast<u8>(separate.g2));
+                ret.b() = Color::Convert4To8(static_cast<u8>(separate.b2));
+            }
+        }
+
+        // Add modifier
+        unsigned table_index =
+            static_cast<int>((x < 2) ? table_index_1.Value() : table_index_2.Value());
+
+        int modifier = etc1_modifier_table[table_index][GetTableSubIndex(texel)];
+        if (GetNegationFlag(texel))
+            modifier *= -1;
+
+        ret.r() = MathUtil::Clamp(ret.r() + modifier, 0, 255);
+        ret.g() = MathUtil::Clamp(ret.g() + modifier, 0, 255);
+        ret.b() = MathUtil::Clamp(ret.b() + modifier, 0, 255);
+
+        return ret.Cast<u8>();
+    }
+};
+
+} // anonymous namespace
+
+Math::Vec3<u8> SampleETC1Subtile(u64 value, unsigned int x, unsigned int y) {
+    ETC1Tile tile{value};
+    return tile.GetRGB(x, y);
+}
+
+} // namespace Texture
+} // namespace Pica
diff --git a/src/video_core/texture/etc1.h b/src/video_core/texture/etc1.h
new file mode 100644
index 000000000..e188b19df
--- /dev/null
+++ b/src/video_core/texture/etc1.h
@@ -0,0 +1,16 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+#include "common/vector_math.h"
+
+namespace Pica {
+namespace Texture {
+
+Math::Vec3<u8> SampleETC1Subtile(u64 value, unsigned int x, unsigned int y);
+
+} // namespace Texture
+} // namespace Pica
diff --git a/src/video_core/texture/texture_decode.cpp b/src/video_core/texture/texture_decode.cpp
index f13d6e577..f611a1aa9 100644
--- a/src/video_core/texture/texture_decode.cpp
+++ b/src/video_core/texture/texture_decode.cpp
@@ -8,8 +8,10 @@
 #include "common/color.h"
 #include "common/logging/log.h"
 #include "common/math_util.h"
+#include "common/swap.h"
 #include "common/vector_math.h"
 #include "video_core/pica.h"
+#include "video_core/texture/etc1.h"
 #include "video_core/texture/texture_decode.h"
 #include "video_core/utils.h"
 
@@ -177,127 +179,32 @@ Math::Vec4<u8> LookupTexelInTile(const u8* source, unsigned int x, unsigned int
     case Regs::TextureFormat::ETC1:
     case Regs::TextureFormat::ETC1A4: {
         bool has_alpha = (info.format == Regs::TextureFormat::ETC1A4);
+        size_t subtile_size = has_alpha ? 16 : 8;
 
         // ETC1 further subdivides each 8x8 tile into four 4x4 subtiles
         constexpr unsigned int subtile_width = 4;
         constexpr unsigned int subtile_height = 4;
 
         unsigned int subtile_index = (x / subtile_width) + 2 * (y / subtile_height);
-        size_t subtile_size = has_alpha ? 16 : 8;
+        x %= subtile_width;
+        y %= subtile_height;
 
-        // TODO(yuriks): Use memcpy instead of reinterpret_cast
-        const u64* source_ptr = reinterpret_cast<const u64*>(source + subtile_index * subtile_size);
+        const u8* subtile_ptr = source + subtile_index * subtile_size;
 
-        u64 alpha = 0xFFFFFFFFFFFFFFFF;
+        u8 alpha = 255;
         if (has_alpha) {
-            alpha = *source_ptr;
-            source_ptr++;
+            u64_le packed_alpha;
+            memcpy(&packed_alpha, subtile_ptr, sizeof(u64));
+            subtile_ptr += sizeof(u64);
+
+            alpha = Color::Convert4To8((packed_alpha >> (4 * (x * subtile_width + y))) & 0xF);
         }
 
-        union ETC1Tile {
-            // Each of these two is a collection of 16 bits (one per lookup value)
-            BitField<0, 16, u64> table_subindexes;
-            BitField<16, 16, u64> negation_flags;
-
-            unsigned GetTableSubIndex(unsigned index) const {
-                return (table_subindexes >> index) & 1;
-            }
-
-            bool GetNegationFlag(unsigned index) const {
-                return ((negation_flags >> index) & 1) == 1;
-            }
-
-            BitField<32, 1, u64> flip;
-            BitField<33, 1, u64> differential_mode;
-
-            BitField<34, 3, u64> table_index_2;
-            BitField<37, 3, u64> table_index_1;
-
-            union {
-                // delta value + base value
-                BitField<40, 3, s64> db;
-                BitField<43, 5, u64> b;
-
-                BitField<48, 3, s64> dg;
-                BitField<51, 5, u64> g;
-
-                BitField<56, 3, s64> dr;
-                BitField<59, 5, u64> r;
-            } differential;
-
-            union {
-                BitField<40, 4, u64> b2;
-                BitField<44, 4, u64> b1;
-
-                BitField<48, 4, u64> g2;
-                BitField<52, 4, u64> g1;
-
-                BitField<56, 4, u64> r2;
-                BitField<60, 4, u64> r1;
-            } separate;
-
-            const Math::Vec3<u8> GetRGB(int x, int y) const {
-                int texel = 4 * x + y;
-
-                if (flip)
-                    std::swap(x, y);
-
-                // Lookup base value
-                Math::Vec3<int> ret;
-                if (differential_mode) {
-                    ret.r() = static_cast<int>(differential.r);
-                    ret.g() = static_cast<int>(differential.g);
-                    ret.b() = static_cast<int>(differential.b);
-                    if (x >= 2) {
-                        ret.r() += static_cast<int>(differential.dr);
-                        ret.g() += static_cast<int>(differential.dg);
-                        ret.b() += static_cast<int>(differential.db);
-                    }
-                    ret.r() = Color::Convert5To8(ret.r());
-                    ret.g() = Color::Convert5To8(ret.g());
-                    ret.b() = Color::Convert5To8(ret.b());
-                } else {
-                    if (x < 2) {
-                        ret.r() = Color::Convert4To8(static_cast<u8>(separate.r1));
-                        ret.g() = Color::Convert4To8(static_cast<u8>(separate.g1));
-                        ret.b() = Color::Convert4To8(static_cast<u8>(separate.b1));
-                    } else {
-                        ret.r() = Color::Convert4To8(static_cast<u8>(separate.r2));
-                        ret.g() = Color::Convert4To8(static_cast<u8>(separate.g2));
-                        ret.b() = Color::Convert4To8(static_cast<u8>(separate.b2));
-                    }
-                }
-
-                // Add modifier
-                unsigned table_index =
-                    static_cast<int>((x < 2) ? table_index_1.Value() : table_index_2.Value());
-
-                static const std::array<std::array<u8, 2>, 8> etc1_modifier_table = {{
-                    {{2, 8}},
-                    {{5, 17}},
-                    {{9, 29}},
-                    {{13, 42}},
-                    {{18, 60}},
-                    {{24, 80}},
-                    {{33, 106}},
-                    {{47, 183}},
-                }};
-
-                int modifier = etc1_modifier_table.at(table_index).at(GetTableSubIndex(texel));
-                if (GetNegationFlag(texel))
-                    modifier *= -1;
-
-                ret.r() = MathUtil::Clamp(ret.r() + modifier, 0, 255);
-                ret.g() = MathUtil::Clamp(ret.g() + modifier, 0, 255);
-                ret.b() = MathUtil::Clamp(ret.b() + modifier, 0, 255);
-
-                return ret.Cast<u8>();
-            }
-        } const* etc1_tile = reinterpret_cast<const ETC1Tile*>(source_ptr);
-
-        alpha >>= 4 * ((x & 3) * 4 + (y & 3));
-        return Math::MakeVec(etc1_tile->GetRGB(x & 3, y & 3),
-                             disable_alpha ? (u8)255 : Color::Convert4To8(alpha & 0xF));
+        u64_le subtile_data;
+        memcpy(&subtile_data, subtile_ptr, sizeof(u64));
+
+        return Math::MakeVec(SampleETC1Subtile(subtile_data, x, y),
+                             disable_alpha ? (u8)255 : alpha);
     }
 
     default: