2 files changed, 418 insertions, 109 deletions

diff --git a/src/video_core/debug_utils/debug_utils.cpp b/src/video_core/debug_utils/debug_utils.cpp
index 275b06b7c..5921185a6 100644
--- a/src/video_core/debug_utils/debug_utils.cpp
+++ b/src/video_core/debug_utils/debug_utils.cpp
@@ -3,6 +3,8 @@
 // Refer to the license.txt file included.
 
 #include <algorithm>
+#include <condition_variable>
+#include <list>
 #include <map>
 #include <fstream>
 #include <mutex>
@@ -12,14 +14,62 @@
 #include <png.h>
 #endif
 
+#include <nihstro/shader_binary.h>
+
+#include "common/log.h"
 #include "common/file_util.h"
 
+#include "video_core/math.h"
 #include "video_core/pica.h"
 
 #include "debug_utils.h"
 
+using nihstro::DVLBHeader;
+using nihstro::DVLEHeader;
+using nihstro::DVLPHeader;
+
 namespace Pica {
 
+void DebugContext::OnEvent(Event event, void* data) {
+    if (!breakpoints[event].enabled)
+        return;
+
+    {
+        std::unique_lock<std::mutex> lock(breakpoint_mutex);
+
+        // TODO: Should stop the CPU thread here once we multithread emulation.
+
+        active_breakpoint = event;
+        at_breakpoint = true;
+
+        // Tell all observers that we hit a breakpoint
+        for (auto& breakpoint_observer : breakpoint_observers) {
+            breakpoint_observer->OnPicaBreakPointHit(event, data);
+        }
+
+        // Wait until another thread tells us to Resume()
+        resume_from_breakpoint.wait(lock, [&]{ return !at_breakpoint; });
+    }
+}
+
+void DebugContext::Resume() {
+    {
+        std::unique_lock<std::mutex> lock(breakpoint_mutex);
+
+        // Tell all observers that we are about to resume
+        for (auto& breakpoint_observer : breakpoint_observers) {
+            breakpoint_observer->OnPicaResume();
+        }
+
+        // Resume the waiting thread (i.e. OnEvent())
+        at_breakpoint = false;
+    }
+
+    resume_from_breakpoint.notify_one();
+}
+
+std::shared_ptr<DebugContext> g_debug_context; // TODO: Get rid of this global
+
 namespace DebugUtils {
 
 void GeometryDumper::AddTriangle(Vertex& v0, Vertex& v1, Vertex& v2) {
@@ -54,65 +104,6 @@ void GeometryDumper::Dump() {
     }
 }
 
-#pragma pack(1)
-struct DVLBHeader {
-    enum : u32 {
-        MAGIC_WORD = 0x424C5644, // "DVLB"
-    };
-
-    u32 magic_word;
-    u32 num_programs;
-//    u32 dvle_offset_table[];
-};
-static_assert(sizeof(DVLBHeader) == 0x8, "Incorrect structure size");
-
-struct DVLPHeader {
-    enum : u32 {
-        MAGIC_WORD = 0x504C5644, // "DVLP"
-    };
-
-    u32 magic_word;
-    u32 version;
-    u32 binary_offset;  // relative to DVLP start
-    u32 binary_size_words;
-    u32 swizzle_patterns_offset;
-    u32 swizzle_patterns_num_entries;
-    u32 unk2;
-};
-static_assert(sizeof(DVLPHeader) == 0x1C, "Incorrect structure size");
-
-struct DVLEHeader {
-    enum : u32 {
-        MAGIC_WORD = 0x454c5644, // "DVLE"
-    };
-
-    enum class ShaderType : u8 {
-        VERTEX = 0,
-        GEOMETRY = 1,
-    };
-
-    u32 magic_word;
-    u16 pad1;
-    ShaderType type;
-    u8 pad2;
-    u32 main_offset_words; // offset within binary blob
-    u32 endmain_offset_words;
-    u32 pad3;
-    u32 pad4;
-    u32 constant_table_offset;
-    u32 constant_table_size; // number of entries
-    u32 label_table_offset;
-    u32 label_table_size;
-    u32 output_register_table_offset;
-    u32 output_register_table_size;
-    u32 uniform_table_offset;
-    u32 uniform_table_size;
-    u32 symbol_table_offset;
-    u32 symbol_table_size;
-
-};
-static_assert(sizeof(DVLEHeader) == 0x40, "Incorrect structure size");
-#pragma pack()
 
 void DumpShader(const u32* binary_data, u32 binary_size, const u32* swizzle_data, u32 swizzle_size,
                 u32 main_offset, const Regs::VSOutputAttributes* output_attributes)
@@ -155,7 +146,7 @@ void DumpShader(const u32* binary_data, u32 binary_size, const u32* swizzle_data
 
     // This is put into a try-catch block to make sure we notice unknown configurations.
     std::vector<OutputRegisterInfo> output_info_table;
-        for (int i = 0; i < 7; ++i) {
+        for (unsigned i = 0; i < 7; ++i) {
             using OutputAttributes = Pica::Regs::VSOutputAttributes;
 
             // TODO: It's still unclear how the attribute components map to the register!
@@ -204,8 +195,8 @@ void DumpShader(const u32* binary_data, u32 binary_size, const u32* swizzle_data
                         it->component_mask = it->component_mask | component_mask;
                     }
                 } catch (const std::out_of_range& ) {
-                    _dbg_assert_msg_(GPU, 0, "Unknown output attribute mapping");
-                    ERROR_LOG(GPU, "Unknown output attribute mapping: %03x, %03x, %03x, %03x",
+                    _dbg_assert_msg_(HW_GPU, 0, "Unknown output attribute mapping");
+                    LOG_ERROR(HW_GPU, "Unknown output attribute mapping: %03x, %03x, %03x, %03x",
                               (int)output_attributes[i].map_x.Value(),
                               (int)output_attributes[i].map_y.Value(),
                               (int)output_attributes[i].map_z.Value(),
@@ -232,8 +223,8 @@ void DumpShader(const u32* binary_data, u32 binary_size, const u32* swizzle_data
     dvlp.binary_size_words = binary_size;
     QueueForWriting((u8*)binary_data, binary_size * sizeof(u32));
 
-    dvlp.swizzle_patterns_offset = write_offset - dvlp_offset;
-    dvlp.swizzle_patterns_num_entries = swizzle_size;
+    dvlp.swizzle_info_offset = write_offset - dvlp_offset;
+    dvlp.swizzle_info_num_entries = swizzle_size;
     u32 dummy = 0;
     for (unsigned int i = 0; i < swizzle_size; ++i) {
         QueueForWriting((u8*)&swizzle_data[i], sizeof(swizzle_data[i]));
@@ -265,7 +256,7 @@ static int is_pica_tracing = false;
 void StartPicaTracing()
 {
     if (is_pica_tracing) {
-        ERROR_LOG(GPU, "StartPicaTracing called even though tracing already running!");
+        LOG_WARNING(HW_GPU, "StartPicaTracing called even though tracing already running!");
         return;
     }
 
@@ -298,7 +289,7 @@ void OnPicaRegWrite(u32 id, u32 value)
 std::unique_ptr<PicaTrace> FinishPicaTracing()
 {
     if (!is_pica_tracing) {
-        ERROR_LOG(GPU, "FinishPicaTracing called even though tracing already running!");
+        LOG_WARNING(HW_GPU, "FinishPicaTracing called even though tracing isn't running!");
         return {};
     }
 
@@ -312,6 +303,173 @@ std::unique_ptr<PicaTrace> FinishPicaTracing()
     return std::move(ret);
 }
 
+const Math::Vec4<u8> LookupTexture(const u8* source, int x, int y, const TextureInfo& info, bool disable_alpha) {
+    // Images are split into 8x8 tiles. Each tile is composed of four 4x4 subtiles each
+    // of which is composed of four 2x2 subtiles each of which is composed of four texels.
+    // Each structure is embedded into the next-bigger one in a diagonal pattern, e.g.
+    // texels are laid out in a 2x2 subtile like this:
+    // 2 3
+    // 0 1
+    //
+    // The full 8x8 tile has the texels arranged like this:
+    //
+    // 42 43 46 47 58 59 62 63
+    // 40 41 44 45 56 57 60 61
+    // 34 35 38 39 50 51 54 55
+    // 32 33 36 37 48 49 52 53
+    // 10 11 14 15 26 27 30 31
+    // 08 09 12 13 24 25 28 29
+    // 02 03 06 07 18 19 22 23
+    // 00 01 04 05 16 17 20 21
+
+    const unsigned int block_width = 8;
+    const unsigned int block_height = 8;
+
+    const unsigned int coarse_x = x & ~7;
+    const unsigned int coarse_y = y & ~7;
+
+    // Interleave the lower 3 bits of each coordinate to get the intra-block offsets, which are
+    // arranged in a Z-order curve. More details on the bit manipulation at:
+    // https://fgiesen.wordpress.com/2009/12/13/decoding-morton-codes/
+    unsigned int i = (x | (y << 8)) & 0x0707; // ---- -210
+    i = (i ^ (i << 2)) & 0x1313;              // ---2 --10
+    i = (i ^ (i << 1)) & 0x1515;              // ---2 -1-0
+    i = (i | (i >> 7)) & 0x3F;
+
+    source += coarse_y * info.stride;
+    const unsigned int offset = coarse_x * block_height + i;
+
+    switch (info.format) {
+    case Regs::TextureFormat::RGBA8:
+    {
+        const u8* source_ptr = source + offset * 4;
+        return { source_ptr[3], source_ptr[2], source_ptr[1], disable_alpha ? (u8)255 : source_ptr[0] };
+    }
+
+    case Regs::TextureFormat::RGB8:
+    {
+        const u8* source_ptr = source + offset * 3;
+        return { source_ptr[2], source_ptr[1], source_ptr[0], 255 };
+    }
+
+    case Regs::TextureFormat::RGBA5551:
+    {
+        const u16 source_ptr = *(const u16*)(source + offset * 2);
+        u8 r = (source_ptr >> 11) & 0x1F;
+        u8 g = ((source_ptr) >> 6) & 0x1F;
+        u8 b = (source_ptr >> 1) & 0x1F;
+        u8 a = source_ptr & 1;
+        return Math::MakeVec<u8>((r << 3) | (r >> 2), (g << 3) | (g >> 2), (b << 3) | (b >> 2), disable_alpha ? 255 : (a * 255));
+    }
+
+    case Regs::TextureFormat::RGB565:
+    {
+        const u16 source_ptr = *(const u16*)(source + offset * 2);
+        u8 r = (source_ptr >> 11) & 0x1F;
+        u8 g = ((source_ptr) >> 5) & 0x3F;
+        u8 b = (source_ptr) & 0x1F;
+        return Math::MakeVec<u8>((r << 3) | (r >> 2), (g << 2) | (g >> 4), (b << 3) | (b >> 2), 255);
+    }
+
+    case Regs::TextureFormat::RGBA4:
+    {
+        const u8* source_ptr = source + offset * 2;
+        u8 r = source_ptr[1] >> 4;
+        u8 g = source_ptr[1] & 0xFF;
+        u8 b = source_ptr[0] >> 4;
+        u8 a = source_ptr[0] & 0xFF;
+        r = (r << 4) | r;
+        g = (g << 4) | g;
+        b = (b << 4) | b;
+        a = (a << 4) | a;
+        return { r, g, b, disable_alpha ? (u8)255 : a };
+    }
+
+    case Regs::TextureFormat::IA8:
+    {
+        const u8* source_ptr = source + offset * 2;
+
+        // TODO: component order not verified
+
+        if (disable_alpha) {
+            // Show intensity as red, alpha as green
+            return { source_ptr[0], source_ptr[1], 0, 255 };
+        } else {
+            return { source_ptr[0], source_ptr[0], source_ptr[0], source_ptr[1]};
+        }
+    }
+
+    case Regs::TextureFormat::I8:
+    {
+        const u8* source_ptr = source + offset;
+        return { *source_ptr, *source_ptr, *source_ptr, 255 };
+    }
+
+    case Regs::TextureFormat::A8:
+    {
+        const u8* source_ptr = source + offset;
+
+        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 + offset / 2;
+
+        // TODO: component order not verified
+
+        u8 i = (*source_ptr) & 0xF;
+        u8 a = ((*source_ptr) & 0xF0) >> 4;
+        a |= a << 4;
+        i |= i << 4;
+
+        if (disable_alpha) {
+            // Show intensity as red, alpha as green
+            return { i, a, 0, 255 };
+        } else {
+            return { i, i, i, a };
+        }
+    }
+
+    case Regs::TextureFormat::A4:
+    {
+        const u8* source_ptr = source + offset / 2;
+
+        // TODO: component order not verified
+
+        u8 a = (coarse_x % 2) ? ((*source_ptr)&0xF) : (((*source_ptr) & 0xF0) >> 4);
+        a |= a << 4;
+
+        if (disable_alpha) {
+            return { *source_ptr, *source_ptr, *source_ptr, 255 };
+        } else {
+            return { 0, 0, 0, *source_ptr };
+        }
+    }
+
+    default:
+        LOG_ERROR(HW_GPU, "Unknown texture format: %x", (u32)info.format);
+        _dbg_assert_(HW_GPU, 0);
+        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;
+}
+
 void DumpTexture(const Pica::Regs::TextureConfig& texture_config, u8* data) {
     // NOTE: Permanently enabling this just trashes hard disks for no reason.
     //       Hence, this is currently disabled.
@@ -341,7 +499,7 @@ void DumpTexture(const Pica::Regs::TextureConfig& texture_config, u8* data) {
     // Initialize write structure
     png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
     if (png_ptr == nullptr) {
-        ERROR_LOG(GPU, "Could not allocate write struct\n");
+        LOG_ERROR(Debug_GPU, "Could not allocate write struct\n");
         goto finalise;
 
     }
@@ -349,13 +507,13 @@ void DumpTexture(const Pica::Regs::TextureConfig& texture_config, u8* data) {
     // Initialize info structure
     info_ptr = png_create_info_struct(png_ptr);
     if (info_ptr == nullptr) {
-        ERROR_LOG(GPU, "Could not allocate info struct\n");
+        LOG_ERROR(Debug_GPU, "Could not allocate info struct\n");
         goto finalise;
     }
 
     // Setup Exception handling
     if (setjmp(png_jmpbuf(png_ptr))) {
-        ERROR_LOG(GPU, "Error during png creation\n");
+        LOG_ERROR(Debug_GPU, "Error during png creation\n");
         goto finalise;
     }
 
@@ -375,34 +533,22 @@ void DumpTexture(const Pica::Regs::TextureConfig& texture_config, u8* data) {
     png_write_info(png_ptr, info_ptr);
 
     buf = new u8[row_stride * texture_config.height];
-    for (int y = 0; y < texture_config.height; ++y) {
-        for (int x = 0; x < texture_config.width; ++x) {
-            // Cf. rasterizer code for an explanation of this algorithm.
-            int texel_index_within_tile = 0;
-            for (int block_size_index = 0; block_size_index < 3; ++block_size_index) {
-                int sub_tile_width = 1 << block_size_index;
-                int sub_tile_height = 1 << block_size_index;
-
-                int sub_tile_index = (x & sub_tile_width) << block_size_index;
-                sub_tile_index += 2 * ((y & sub_tile_height) << block_size_index);
-                texel_index_within_tile += sub_tile_index;
-            }
-
-            const int block_width = 8;
-            const int block_height = 8;
-
-            int coarse_x = (x / block_width) * block_width;
-            int coarse_y = (y / block_height) * block_height;
-
-            u8* source_ptr = (u8*)data + coarse_x * block_height * 3 + coarse_y * row_stride + texel_index_within_tile * 3;
-            buf[3 * x + y * row_stride    ] = source_ptr[2];
-            buf[3 * x + y * row_stride + 1] = source_ptr[1];
-            buf[3 * x + y * row_stride + 2] = source_ptr[0];
+    for (unsigned y = 0; y < texture_config.height; ++y) {
+        for (unsigned x = 0; x < texture_config.width; ++x) {
+            TextureInfo info;
+            info.width = texture_config.width;
+            info.height = texture_config.height;
+            info.stride = row_stride;
+            info.format = registers.texture0_format;
+            Math::Vec4<u8> texture_color = LookupTexture(data, x, y, info);
+            buf[3 * x + y * row_stride    ] = texture_color.r();
+            buf[3 * x + y * row_stride + 1] = texture_color.g();
+            buf[3 * x + y * row_stride + 2] = texture_color.b();
         }
     }
 
     // Write image data
-    for (auto y = 0; y < texture_config.height; ++y)
+    for (unsigned y = 0; y < texture_config.height; ++y)
     {
         u8* row_ptr = (u8*)buf + y * row_stride;
         u8* ptr = row_ptr;
@@ -431,26 +577,32 @@ void DumpTevStageConfig(const std::array<Pica::Regs::TevStageConfig,6>& stages)
     for (size_t index = 0; index < stages.size(); ++index) {
         const auto& tev_stage = stages[index];
 
-        const std::map<Source, std::string> source_map = {
+        static const std::map<Source, std::string> source_map = {
             { Source::PrimaryColor, "PrimaryColor" },
             { Source::Texture0, "Texture0" },
+            { Source::Texture1, "Texture1" },
+            { Source::Texture2, "Texture2" },
             { Source::Constant, "Constant" },
             { Source::Previous, "Previous" },
         };
 
-        const std::map<ColorModifier, std::string> color_modifier_map = {
-            { ColorModifier::SourceColor, { "%source.rgb" } }
+        static const std::map<ColorModifier, std::string> color_modifier_map = {
+            { ColorModifier::SourceColor, { "%source.rgb" } },
+            { ColorModifier::SourceAlpha, { "%source.aaa" } },
         };
-        const std::map<AlphaModifier, std::string> alpha_modifier_map = {
-            { AlphaModifier::SourceAlpha, "%source.a" }
+        static const std::map<AlphaModifier, std::string> alpha_modifier_map = {
+            { AlphaModifier::SourceAlpha, "%source.a" },
+            { AlphaModifier::OneMinusSourceAlpha, "(255 - %source.a)" },
         };
 
-        std::map<Operation, std::string> combiner_map = {
+        static const std::map<Operation, std::string> combiner_map = {
             { Operation::Replace, "%source1" },
             { Operation::Modulate, "(%source1 * %source2) / 255" },
+            { Operation::Add, "(%source1 + %source2)" },
+            { Operation::Lerp, "lerp(%source1, %source2, %source3)" },
         };
 
-        auto ReplacePattern =
+        static auto ReplacePattern =
                 [](const std::string& input, const std::string& pattern, const std::string& replacement) -> std::string {
                     size_t start = input.find(pattern);
                     if (start == std::string::npos)
@@ -460,8 +612,8 @@ void DumpTevStageConfig(const std::array<Pica::Regs::TevStageConfig,6>& stages)
                     ret.replace(start, pattern.length(), replacement);
                     return ret;
                 };
-        auto GetColorSourceStr =
-                [&source_map,&color_modifier_map,&ReplacePattern](const Source& src, const ColorModifier& modifier) {
+        static auto GetColorSourceStr =
+                [](const Source& src, const ColorModifier& modifier) {
                     auto src_it = source_map.find(src);
                     std::string src_str = "Unknown";
                     if (src_it != source_map.end())
@@ -474,8 +626,8 @@ void DumpTevStageConfig(const std::array<Pica::Regs::TevStageConfig,6>& stages)
 
                     return ReplacePattern(modifier_str, "%source", src_str);
                 };
-        auto GetColorCombinerStr =
-                [&](const Regs::TevStageConfig& tev_stage) {
+        static auto GetColorCombinerStr =
+                [](const Regs::TevStageConfig& tev_stage) {
                     auto op_it = combiner_map.find(tev_stage.color_op);
                     std::string op_str = "Unknown op (%source1, %source2, %source3)";
                     if (op_it != combiner_map.end())
@@ -485,8 +637,8 @@ void DumpTevStageConfig(const std::array<Pica::Regs::TevStageConfig,6>& stages)
                     op_str = ReplacePattern(op_str, "%source2", GetColorSourceStr(tev_stage.color_source2, tev_stage.color_modifier2));
                     return   ReplacePattern(op_str, "%source3", GetColorSourceStr(tev_stage.color_source3, tev_stage.color_modifier3));
                 };
-        auto GetAlphaSourceStr =
-                [&source_map,&alpha_modifier_map,&ReplacePattern](const Source& src, const AlphaModifier& modifier) {
+        static auto GetAlphaSourceStr =
+                [](const Source& src, const AlphaModifier& modifier) {
                     auto src_it = source_map.find(src);
                     std::string src_str = "Unknown";
                     if (src_it != source_map.end())
@@ -499,8 +651,8 @@ void DumpTevStageConfig(const std::array<Pica::Regs::TevStageConfig,6>& stages)
 
                     return ReplacePattern(modifier_str, "%source", src_str);
                 };
-        auto GetAlphaCombinerStr =
-                [&](const Regs::TevStageConfig& tev_stage) {
+        static auto GetAlphaCombinerStr =
+                [](const Regs::TevStageConfig& tev_stage) {
                     auto op_it = combiner_map.find(tev_stage.alpha_op);
                     std::string op_str = "Unknown op (%source1, %source2, %source3)";
                     if (op_it != combiner_map.end())
@@ -514,7 +666,7 @@ void DumpTevStageConfig(const std::array<Pica::Regs::TevStageConfig,6>& stages)
         stage_info += "Stage " + std::to_string(index) + ": " + GetColorCombinerStr(tev_stage) + "   " + GetAlphaCombinerStr(tev_stage) + "\n";
     }
 
-    DEBUG_LOG(GPU, "%s", stage_info.c_str());
+    LOG_TRACE(HW_GPU, "%s", stage_info.c_str());
 }
 
 } // namespace
diff --git a/src/video_core/debug_utils/debug_utils.h b/src/video_core/debug_utils/debug_utils.h
index b1558cfae..f361a5385 100644
--- a/src/video_core/debug_utils/debug_utils.h
+++ b/src/video_core/debug_utils/debug_utils.h
@@ -5,13 +5,148 @@
 #pragma once
 
 #include <array>
+#include <condition_variable>
+#include <list>
+#include <map>
 #include <memory>
+#include <mutex>
 #include <vector>
 
+#include "video_core/math.h"
 #include "video_core/pica.h"
 
 namespace Pica {
 
+class DebugContext {
+public:
+    enum class Event {
+        FirstEvent = 0,
+
+        CommandLoaded = FirstEvent,
+        CommandProcessed,
+        IncomingPrimitiveBatch,
+        FinishedPrimitiveBatch,
+        VertexLoaded,
+
+        NumEvents
+    };
+
+    /**
+     * Inherit from this class to be notified of events registered to some debug context.
+     * Most importantly this is used for our debugger GUI.
+     *
+     * To implement event handling, override the OnPicaBreakPointHit and OnPicaResume methods.
+     * @warning All BreakPointObservers need to be on the same thread to guarantee thread-safe state access
+     * @todo Evaluate an alternative interface, in which there is only one managing observer and multiple child observers running (by design) on the same thread.
+     */
+    class BreakPointObserver {
+    public:
+        /// Constructs the object such that it observes events of the given DebugContext.
+        BreakPointObserver(std::shared_ptr<DebugContext> debug_context) : context_weak(debug_context) {
+            std::unique_lock<std::mutex> lock(debug_context->breakpoint_mutex);
+            debug_context->breakpoint_observers.push_back(this);
+        }
+
+        virtual ~BreakPointObserver() {
+            auto context = context_weak.lock();
+            if (context) {
+                std::unique_lock<std::mutex> lock(context->breakpoint_mutex);
+                context->breakpoint_observers.remove(this);
+
+                // If we are the last observer to be destroyed, tell the debugger context that
+                // it is free to continue. In particular, this is required for a proper Citra
+                // shutdown, when the emulation thread is waiting at a breakpoint.
+                if (context->breakpoint_observers.empty())
+                    context->Resume();
+            }
+        }
+
+        /**
+         * Action to perform when a breakpoint was reached.
+         * @param event Type of event which triggered the breakpoint
+         * @param data Optional data pointer (if unused, this is a nullptr)
+         * @note This function will perform nothing unless it is overridden in the child class.
+         */
+        virtual void OnPicaBreakPointHit(Event, void*) {
+        }
+
+        /**
+         * Action to perform when emulation is resumed from a breakpoint.
+         * @note This function will perform nothing unless it is overridden in the child class.
+         */
+        virtual void OnPicaResume() {
+        }
+
+    protected:
+        /**
+         * Weak context pointer. This need not be valid, so when requesting a shared_ptr via
+         * context_weak.lock(), always compare the result against nullptr.
+         */
+        std::weak_ptr<DebugContext> context_weak;
+    };
+
+    /**
+     * Simple structure defining a breakpoint state
+     */
+    struct BreakPoint {
+        bool enabled = false;
+    };
+
+    /**
+     * Static constructor used to create a shared_ptr of a DebugContext.
+     */
+    static std::shared_ptr<DebugContext> Construct() {
+        return std::shared_ptr<DebugContext>(new DebugContext);
+    }
+
+    /**
+     * Used by the emulation core when a given event has happened. If a breakpoint has been set
+     * for this event, OnEvent calls the event handlers of the registered breakpoint observers.
+     * The current thread then is halted until Resume() is called from another thread (or until
+     * emulation is stopped).
+     * @param event Event which has happened
+     * @param data Optional data pointer (pass nullptr if unused). Needs to remain valid until Resume() is called.
+     */
+    void OnEvent(Event event, void* data);
+
+    /**
+     * Resume from the current breakpoint.
+     * @warning Calling this from the same thread that OnEvent was called in will cause a deadlock. Calling from any other thread is safe.
+     */
+    void Resume();
+
+    /**
+     * Delete all set breakpoints and resume emulation.
+     */
+    void ClearBreakpoints() {
+        breakpoints.clear();
+        Resume();
+    }
+
+    // TODO: Evaluate if access to these members should be hidden behind a public interface.
+    std::map<Event, BreakPoint> breakpoints;
+    Event active_breakpoint;
+    bool at_breakpoint = false;
+
+private:
+    /**
+     * Private default constructor to make sure people always construct this through Construct()
+     * instead.
+     */
+    DebugContext() = default;
+
+    /// Mutex protecting current breakpoint state and the observer list.
+    std::mutex breakpoint_mutex;
+
+    /// Used by OnEvent to wait for resumption.
+    std::condition_variable resume_from_breakpoint;
+
+    /// List of registered observers
+    std::list<BreakPointObserver*> breakpoint_observers;
+};
+
+extern std::shared_ptr<DebugContext> g_debug_context; // TODO: Get rid of this global
+
 namespace DebugUtils {
 
 // Simple utility class for dumping geometry data to an OBJ file
@@ -57,6 +192,28 @@ bool IsPicaTracing();
 void OnPicaRegWrite(u32 id, u32 value);
 std::unique_ptr<PicaTrace> FinishPicaTracing();
 
+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.
+ */
+const Math::Vec4<u8> LookupTexture(const u8* source, int s, int t, const TextureInfo& info,
+                                   bool disable_alpha = false);
+
 void DumpTexture(const Pica::Regs::TextureConfig& texture_config, u8* data);
 
 void DumpTevStageConfig(const std::array<Pica::Regs::TevStageConfig,6>& stages);