2 files changed, 44 insertions, 3 deletions

diff --git a/src/video_core/engines/maxwell_3d.cpp b/src/video_core/engines/maxwell_3d.cpp
index 9784ee069..4b15ed2f2 100644
--- a/src/video_core/engines/maxwell_3d.cpp
+++ b/src/video_core/engines/maxwell_3d.cpp
@@ -84,7 +84,7 @@ void Maxwell3D::SetShader(const std::vector<u32>& parameters) {
     /**
      * Parameters description:
      * [0] = Shader Program.
-     * [1] = Unknown.
+     * [1] = Unknown, presumably the shader id.
      * [2] = Offset to the start of the shader, after the 0x30 bytes header.
      * [3] = Shader Type.
      * [4] = Const Buffer Address >> 8.
@@ -100,6 +100,24 @@ void Maxwell3D::SetShader(const std::vector<u32>& parameters) {
     shader.type = shader_type;
     shader.address = address;
     shader.cb_address = cb_address;
+
+    // Perform the same operations as the real macro code.
+    // TODO(Subv): Early exit if register 0xD1C + shader_program contains the same as params[1].
+    auto& shader_regs = regs.shader_config[static_cast<size_t>(shader_program)];
+    shader_regs.start_id = address;
+    // TODO(Subv): Write params[1] to register 0xD1C + shader_program.
+    // TODO(Subv): Write params[2] to register 0xD22 + shader_program.
+
+    // Note: This value is hardcoded in the macro's code.
+    static constexpr u32 DefaultCBSize = 0x10000;
+    regs.const_buffer.cb_size = DefaultCBSize;
+    regs.const_buffer.cb_address_high = cb_address >> 32;
+    regs.const_buffer.cb_address_low = cb_address & 0xFFFFFFFF;
+
+    // Write a hardcoded 0x11 to CB_BIND, this binds the current const buffer to buffer c1[] in the
+    // shader. It's likely that these are the constants for the shader.
+    regs.cb_bind[static_cast<size_t>(shader_type)].valid.Assign(1);
+    regs.cb_bind[static_cast<size_t>(shader_type)].index.Assign(1);
 }
 
 } // namespace Engines
diff --git a/src/video_core/engines/maxwell_3d.h b/src/video_core/engines/maxwell_3d.h
index 47df43c97..6eb98080d 100644
--- a/src/video_core/engines/maxwell_3d.h
+++ b/src/video_core/engines/maxwell_3d.h
@@ -35,8 +35,10 @@ public:
     struct Regs {
         static constexpr size_t NUM_REGS = 0xE36;
 
+        static constexpr size_t NumCBData = 16;
         static constexpr size_t NumVertexArrays = 32;
         static constexpr size_t MaxShaderProgram = 6;
+        static constexpr size_t MaxShaderType = 5;
 
         enum class QueryMode : u32 {
             Write = 0,
@@ -136,7 +138,27 @@ public:
                     INSERT_PADDING_WORDS(9);
                 } shader_config[MaxShaderProgram];
 
-                INSERT_PADDING_WORDS(0x5D0);
+                INSERT_PADDING_WORDS(0x8C);
+
+                struct {
+                    u32 cb_size;
+                    u32 cb_address_high;
+                    u32 cb_address_low;
+                    u32 cb_pos;
+                    u32 cb_data[NumCBData];
+                } const_buffer;
+
+                INSERT_PADDING_WORDS(0x74);
+
+                struct {
+                    union {
+                        BitField<0, 1, u32> valid;
+                        BitField<4, 5, u32> index;
+                    };
+                    INSERT_PADDING_WORDS(7);
+                } cb_bind[MaxShaderType];
+
+                INSERT_PADDING_WORDS(0x494);
 
                 struct {
                     u32 set_shader_call;
@@ -161,7 +183,7 @@ public:
         std::array<ShaderInfo, Regs::MaxShaderProgram> shaders;
     };
 
-    State state;
+    State state{};
 
 private:
     MemoryManager& memory_manager;
@@ -194,6 +216,7 @@ ASSERT_REG_POSITION(query, 0x6C0);
 ASSERT_REG_POSITION(vertex_array[0], 0x700);
 ASSERT_REG_POSITION(vertex_array_limit[0], 0x7C0);
 ASSERT_REG_POSITION(shader_config[0], 0x800);
+ASSERT_REG_POSITION(const_buffer, 0x8E0);
 ASSERT_REG_POSITION(set_shader, 0xE24);
 
 #undef ASSERT_REG_POSITION