2 files changed, 310 insertions, 0 deletions

diff --git a/src/video_core/texture/texture_decode.cpp b/src/video_core/texture/texture_decode.cpp
new file mode 100644
index 000000000..a3b05fe81
--- /dev/null
+++ b/src/video_core/texture/texture_decode.cpp
@@ -0,0 +1,270 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/assert.h"
+#include "common/color.h"
+#include "common/logging/log.h"
+#include "common/math_util.h"
+#include "common/vector_math.h"
+#include "video_core/texture/texture_decode.h"
+#include "video_core/utils.h"
+
+namespace Pica {
+namespace Texture {
+
+Math::Vec4<u8> LookupTexture(const u8* source, int x, int y, const TextureInfo& info,
+                             bool disable_alpha) {
+    const unsigned int coarse_x = x & ~7;
+    const unsigned int coarse_y = y & ~7;
+
+    if (info.format != Regs::TextureFormat::ETC1 && info.format != Regs::TextureFormat::ETC1A4) {
+        // TODO(neobrain): Fix code design to unify vertical block offsets!
+        source += coarse_y * info.stride;
+    }
+
+    // TODO: Assert that width/height are multiples of block dimensions
+
+    switch (info.format) {
+    case Regs::TextureFormat::RGBA8: {
+        auto res = Color::DecodeRGBA8(source + VideoCore::GetMortonOffset(x, y, 4));
+        return {res.r(), res.g(), res.b(), static_cast<u8>(disable_alpha ? 255 : res.a())};
+    }
+
+    case Regs::TextureFormat::RGB8: {
+        auto res = Color::DecodeRGB8(source + VideoCore::GetMortonOffset(x, y, 3));
+        return {res.r(), res.g(), res.b(), 255};
+    }
+
+    case Regs::TextureFormat::RGB5A1: {
+        auto res = Color::DecodeRGB5A1(source + VideoCore::GetMortonOffset(x, y, 2));
+        return {res.r(), res.g(), res.b(), static_cast<u8>(disable_alpha ? 255 : res.a())};
+    }
+
+    case Regs::TextureFormat::RGB565: {
+        auto res = Color::DecodeRGB565(source + VideoCore::GetMortonOffset(x, y, 2));
+        return {res.r(), res.g(), res.b(), 255};
+    }
+
+    case Regs::TextureFormat::RGBA4: {
+        auto res = Color::DecodeRGBA4(source + VideoCore::GetMortonOffset(x, y, 2));
+        return {res.r(), res.g(), res.b(), static_cast<u8>(disable_alpha ? 255 : res.a())};
+    }
+
+    case Regs::TextureFormat::IA8: {
+        const u8* source_ptr = source + VideoCore::GetMortonOffset(x, y, 2);
+
+        if (disable_alpha) {
+            // Show intensity as red, alpha as green
+            return {source_ptr[1], source_ptr[0], 0, 255};
+        } else {
+            return {source_ptr[1], source_ptr[1], source_ptr[1], source_ptr[0]};
+        }
+    }
+
+    case Regs::TextureFormat::RG8: {
+        auto res = Color::DecodeRG8(source + VideoCore::GetMortonOffset(x, y, 2));
+        return {res.r(), res.g(), 0, 255};
+    }
+
+    case Regs::TextureFormat::I8: {
+        const u8* source_ptr = source + VideoCore::GetMortonOffset(x, y, 1);
+        return {*source_ptr, *source_ptr, *source_ptr, 255};
+    }
+
+    case Regs::TextureFormat::A8: {
+        const u8* source_ptr = source + VideoCore::GetMortonOffset(x, y, 1);
+
+        if (disable_alpha) {
+            return {*source_ptr, *source_ptr, *source_ptr, 255};
+        } else {
+            return {0, 0, 0, *source_ptr};
+        }
+    }
+
+    case Regs::TextureFormat::IA4: {
+        const u8* source_ptr = source + VideoCore::GetMortonOffset(x, y, 1);
+
+        u8 i = Color::Convert4To8(((*source_ptr) & 0xF0) >> 4);
+        u8 a = Color::Convert4To8((*source_ptr) & 0xF);
+
+        if (disable_alpha) {
+            // Show intensity as red, alpha as green
+            return {i, a, 0, 255};
+        } else {
+            return {i, i, i, a};
+        }
+    }
+
+    case Regs::TextureFormat::I4: {
+        u32 morton_offset = VideoCore::GetMortonOffset(x, y, 1);
+        const u8* source_ptr = source + morton_offset / 2;
+
+        u8 i = (morton_offset % 2) ? ((*source_ptr & 0xF0) >> 4) : (*source_ptr & 0xF);
+        i = Color::Convert4To8(i);
+
+        return {i, i, i, 255};
+    }
+
+    case Regs::TextureFormat::A4: {
+        u32 morton_offset = VideoCore::GetMortonOffset(x, y, 1);
+        const u8* source_ptr = source + morton_offset / 2;
+
+        u8 a = (morton_offset % 2) ? ((*source_ptr & 0xF0) >> 4) : (*source_ptr & 0xF);
+        a = Color::Convert4To8(a);
+
+        if (disable_alpha) {
+            return {a, a, a, 255};
+        } else {
+            return {0, 0, 0, a};
+        }
+    }
+
+    case Regs::TextureFormat::ETC1:
+    case Regs::TextureFormat::ETC1A4: {
+        bool has_alpha = (info.format == Regs::TextureFormat::ETC1A4);
+
+        // ETC1 further subdivides each 8x8 tile into four 4x4 subtiles
+        const int subtile_width = 4;
+        const int subtile_height = 4;
+
+        int subtile_index = ((x / subtile_width) & 1) + 2 * ((y / subtile_height) & 1);
+        unsigned subtile_bytes = has_alpha ? 2 : 1; // TODO: Name...
+
+        const u64* source_ptr = (const u64*)(source + coarse_x * subtile_bytes * 4 +
+                                             coarse_y * subtile_bytes * 4 * (info.width / 8) +
+                                             subtile_index * subtile_bytes * 8);
+        u64 alpha = 0xFFFFFFFFFFFFFFFF;
+        if (has_alpha) {
+            alpha = *source_ptr;
+            source_ptr++;
+        }
+
+        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));
+    }
+
+    default:
+        LOG_ERROR(HW_GPU, "Unknown texture format: %x", (u32)info.format);
+        DEBUG_ASSERT(false);
+        return {};
+    }
+}
+
+TextureInfo TextureInfo::FromPicaRegister(const Regs::TextureConfig& config,
+                                          const Regs::TextureFormat& format) {
+    TextureInfo info;
+    info.physical_address = config.GetPhysicalAddress();
+    info.width = config.width;
+    info.height = config.height;
+    info.format = format;
+    info.stride = Pica::Regs::NibblesPerPixel(info.format) * info.width / 2;
+    return info;
+}
+
+} // namespace Texture
+} // namespace Pica
diff --git a/src/video_core/texture/texture_decode.h b/src/video_core/texture/texture_decode.h
new file mode 100644
index 000000000..0c1438b0f
--- /dev/null
+++ b/src/video_core/texture/texture_decode.h
@@ -0,0 +1,40 @@
+// 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"
+#include "video_core/pica.h"
+
+namespace Pica {
+namespace Texture {
+
+struct TextureInfo {
+    PAddr physical_address;
+    int width;
+    int height;
+    int stride;
+    Pica::Regs::TextureFormat format;
+
+    static TextureInfo FromPicaRegister(const Pica::Regs::TextureConfig& config,
+                                        const Pica::Regs::TextureFormat& format);
+};
+
+/**
+ * Lookup texel located at the given coordinates and return an RGBA vector of its color.
+ * @param source Source pointer to read data from
+ * @param s,t Texture coordinates to read from
+ * @param info TextureInfo object describing the texture setup
+ * @param disable_alpha This is used for debug widgets which use this method to display textures
+ * without providing a good way to visualize alpha by themselves. If true, this will return 255 for
+ * the alpha component, and either drop the information entirely or store it in an "unused" color
+ * channel.
+ * @todo Eventually we should get rid of the disable_alpha parameter.
+ */
+Math::Vec4<u8> LookupTexture(const u8* source, int s, int t, const TextureInfo& info,
+                             bool disable_alpha = false);
+
+} // namespace Texture
+} // namespace Pica