Maxwell3D: read small-index draw and primitive topology override registers

This allows Galaxy and Sunshine to render for the first time.

src/video_core/engines/maxwell_3d.cpp

@@ -208,6 +208,10 @@ void Maxwell3D::ProcessMethodCall(u32 method, u32 argument, u32 nonshadow_argume
         return ProcessCBBind(4);
     case MAXWELL3D_REG_INDEX(draw.vertex_end_gl):
         return DrawArrays();
+    case MAXWELL3D_REG_INDEX(small_index):
+        regs.index_array.count = regs.small_index.count;
+        regs.index_array.first = regs.small_index.first;
+        return DrawArrays();
     case MAXWELL3D_REG_INDEX(clear_buffers):
         return ProcessClearBuffers();
     case MAXWELL3D_REG_INDEX(query.query_get):
@@ -360,6 +364,12 @@ void Maxwell3D::CallMethodFromMME(u32 method, u32 method_argument) {
     }
 }
 
+void Maxwell3D::ProcessTopologyOverride() {
+    if (regs.draw.topology != regs.topology_override) {
+        regs.draw.topology.Assign(regs.topology_override);
+    }
+}
+
 void Maxwell3D::FlushMMEInlineDraw() {
     LOG_TRACE(HW_GPU, "called, topology={}, count={}", regs.draw.topology.Value(),
               regs.vertex_buffer.count);
@@ -370,6 +380,8 @@ void Maxwell3D::FlushMMEInlineDraw() {
     ASSERT_MSG(!regs.draw.instance_next || !regs.draw.instance_cont,
                "Illegal combination of instancing parameters");
 
+    ProcessTopologyOverride();
+
     const bool is_indexed = mme_draw.current_mode == MMEDrawMode::Indexed;
     if (ShouldExecute()) {
         rasterizer->Draw(is_indexed, true);
@@ -529,6 +541,8 @@ void Maxwell3D::DrawArrays() {
     ASSERT_MSG(!regs.draw.instance_next || !regs.draw.instance_cont,
                "Illegal combination of instancing parameters");
 
+    ProcessTopologyOverride();
+
     if (regs.draw.instance_next) {
         // Increment the current instance *before* drawing.
         state.current_instance += 1;

src/video_core/engines/maxwell_3d.h

@@ -1200,7 +1200,12 @@ public:
                     }
                 } index_array;
 
-                INSERT_PADDING_WORDS_NOINIT(0x7);
+                union {
+                    BitField<0, 16, u32> first;
+                    BitField<16, 16, u32> count;
+                } small_index;
+
+                INSERT_PADDING_WORDS_NOINIT(0x6);
 
                 INSERT_PADDING_WORDS_NOINIT(0x1F);
 
@@ -1244,7 +1249,11 @@ public:
                     BitField<11, 1, u32> depth_clamp_disabled;
                 } view_volume_clip_control;
 
-                INSERT_PADDING_WORDS_NOINIT(0x1F);
+                INSERT_PADDING_WORDS_NOINIT(0xC);
+
+                PrimitiveTopology topology_override;
+
+                INSERT_PADDING_WORDS_NOINIT(0x12);
 
                 u32 depth_bounds_enable;
 
@@ -1531,6 +1540,9 @@ private:
     /// Handles a write to the VERTEX_END_GL register, triggering a draw.
     void DrawArrays();
 
+    /// Handles use of topology overrides (e.g., to avoid using a topology assigned from a macro)
+    void ProcessTopologyOverride();
+
     // Handles a instance drawcall from MME
     void StepInstance(MMEDrawMode expected_mode, u32 count);
 
@@ -1685,6 +1697,7 @@ ASSERT_REG_POSITION(draw, 0x585);
 ASSERT_REG_POSITION(primitive_restart, 0x591);
 ASSERT_REG_POSITION(provoking_vertex_last, 0x5A1);
 ASSERT_REG_POSITION(index_array, 0x5F2);
+ASSERT_REG_POSITION(small_index, 0x5F9);
 ASSERT_REG_POSITION(polygon_offset_clamp, 0x61F);
 ASSERT_REG_POSITION(instanced_arrays, 0x620);
 ASSERT_REG_POSITION(vp_point_size, 0x644);
@@ -1694,6 +1707,7 @@ ASSERT_REG_POSITION(cull_face, 0x648);
 ASSERT_REG_POSITION(pixel_center_integer, 0x649);
 ASSERT_REG_POSITION(viewport_transform_enabled, 0x64B);
 ASSERT_REG_POSITION(view_volume_clip_control, 0x64F);
+ASSERT_REG_POSITION(topology_override, 0x65C);
 ASSERT_REG_POSITION(depth_bounds_enable, 0x66F);
 ASSERT_REG_POSITION(logic_op, 0x671);
 ASSERT_REG_POSITION(clear_buffers, 0x674);