3 files changed, 123 insertions, 0 deletions

diff --git a/src/video_core/shader/const_buffer_locker.cpp b/src/video_core/shader/const_buffer_locker.cpp
new file mode 100644
index 000000000..6a9e0ed5e
--- /dev/null
+++ b/src/video_core/shader/const_buffer_locker.cpp
@@ -0,0 +1,72 @@
+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/assert.h"
+#include "common/common_types.h"
+#include "video_core/engines/maxwell_3d.h"
+#include "video_core/shader/const_buffer_locker.h"
+
+namespace VideoCommon::Shader {
+
+ConstBufferLocker::ConstBufferLocker(Tegra::Engines::ShaderType shader_stage)
+    : engine{nullptr}, shader_stage{shader_stage} {}
+
+ConstBufferLocker::ConstBufferLocker(Tegra::Engines::ShaderType shader_stage,
+                                     Tegra::Engines::ConstBufferEngineInterface* engine)
+    : engine{engine}, shader_stage{shader_stage} {}
+
+bool ConstBufferLocker::IsEngineSet() const {
+    return engine != nullptr;
+}
+
+void ConstBufferLocker::SetEngine(Tegra::Engines::ConstBufferEngineInterface* engine_) {
+    engine = engine_;
+}
+
+std::optional<u32> ConstBufferLocker::ObtainKey(u32 buffer, u32 offset) {
+    const std::pair<u32, u32> key = {buffer, offset};
+    const auto iter = keys.find(key);
+    if (iter != keys.end()) {
+        return {iter->second};
+    }
+    if (!IsEngineSet()) {
+        return {};
+    }
+    const u32 value = engine->AccessConstBuffer32(shader_stage, buffer, offset);
+    keys.emplace(key, value);
+    return {value};
+}
+
+void ConstBufferLocker::InsertKey(u32 buffer, u32 offset, u32 value) {
+    const std::pair<u32, u32> key = {buffer, offset};
+    keys[key] = value;
+}
+
+u32 ConstBufferLocker::NumKeys() const {
+    return keys.size();
+}
+
+const std::unordered_map<std::pair<u32, u32>, u32, Common::PairHash>&
+ConstBufferLocker::AccessKeys() const {
+    return keys;
+}
+
+bool ConstBufferLocker::AreKeysConsistant() const {
+    if (!IsEngineSet()) {
+        return false;
+    }
+    for (const auto& key_val : keys) {
+        const std::pair<u32, u32> key = key_val.first;
+        const u32 value = key_val.second;
+        const u32 other_value = engine->AccessConstBuffer32(shader_stage, key.first, key.second);
+        if (other_value != value) {
+            return false;
+        }
+    }
+    return true;
+}
+
+} // namespace VideoCommon::Shader
diff --git a/src/video_core/shader/const_buffer_locker.h b/src/video_core/shader/const_buffer_locker.h
new file mode 100644
index 000000000..39e62584d
--- /dev/null
+++ b/src/video_core/shader/const_buffer_locker.h
@@ -0,0 +1,50 @@
+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <unordered_map>
+#include "common/common_types.h"
+#include "common/hash.h"
+#include "video_core/engines/const_buffer_engine_interface.h"
+
+namespace VideoCommon::Shader {
+
+class ConstBufferLocker {
+public:
+    explicit ConstBufferLocker(Tegra::Engines::ShaderType shader_stage);
+
+    explicit ConstBufferLocker(Tegra::Engines::ShaderType shader_stage,
+                               Tegra::Engines::ConstBufferEngineInterface* engine);
+
+    // Checks if an engine is setup, it may be possible that during disk shader
+    // cache run, the engines have not been created yet.
+    bool IsEngineSet() const;
+
+    // Use this to set/change the engine used for this shader.
+    void SetEngine(Tegra::Engines::ConstBufferEngineInterface* engine);
+
+    // Retrieves a key from the locker, if it's registered, it will give the
+    // registered value, if not it will obtain it from maxwell3d and register it.
+    std::optional<u32> ObtainKey(u32 buffer, u32 offset);
+
+    // Manually inserts a key.
+    void InsertKey(u32 buffer, u32 offset, u32 value);
+
+    // Retrieves the number of keys registered.
+    u32 NumKeys() const;
+
+    // Gives an accessor to the key's database.
+    const std::unordered_map<std::pair<u32, u32>, u32, Common::PairHash>& AccessKeys() const;
+
+    // Checks keys against maxwell3d's current const buffers. Returns true if they
+    // are the same value, false otherwise;
+    bool AreKeysConsistant() const;
+
+private:
+    Tegra::Engines::ConstBufferEngineInterface* engine;
+    Tegra::Engines::ShaderType shader_stage;
+    std::unordered_map<std::pair<u32, u32>, u32, Common::PairHash> keys{};
+};
+} // namespace VideoCommon::Shader
diff --git a/src/video_core/shader/shader_ir.h b/src/video_core/shader/shader_ir.h
index 91cd0a534..68818643c 100644
--- a/src/video_core/shader/shader_ir.h
+++ b/src/video_core/shader/shader_ir.h
@@ -17,6 +17,7 @@
 #include "video_core/engines/shader_header.h"
 #include "video_core/shader/ast.h"
 #include "video_core/shader/compiler_settings.h"
+#include "video_core/shader/const_buffer_locker.h"
 #include "video_core/shader/node.h"
 
 namespace VideoCommon::Shader {