From 00d82ca6edeb70334e40f12fdd8018e64d04ac11 Mon Sep 17 00:00:00 2001
From: wheremyfoodat <gponiris2004@gmail.com>
Date: Thu, 22 Sep 2022 04:03:55 +0300
Subject: [PATCH] [PICA] Implement drawArrays, get our first triangle data

---
 include/PICA/gpu.hpp   | 2 ++
 include/PICA/regs.hpp  | 6 ++++++
 src/core/PICA/gpu.cpp  | 8 ++++++++
 src/core/PICA/regs.cpp | 5 +++++
 4 files changed, 21 insertions(+)

diff --git a/include/PICA/gpu.hpp b/include/PICA/gpu.hpp
index 2b99880d..9b2129f1 100644
--- a/include/PICA/gpu.hpp
+++ b/include/PICA/gpu.hpp
@@ -10,6 +10,8 @@ class GPU {
 	ShaderUnit shaderUnit;
 	std::array<u32, regNum> regs; // GPU internal registers
 
+	void drawArrays();
+
 public:
 	GPU(Memory& mem) : mem(mem) {}
 	void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control);
diff --git a/include/PICA/regs.hpp b/include/PICA/regs.hpp
index 61d2f33c..afcaa5e5 100644
--- a/include/PICA/regs.hpp
+++ b/include/PICA/regs.hpp
@@ -2,6 +2,12 @@
 
 namespace PICAInternalRegs {
 	enum : u32 {
+		// Draw command regs
+		VertexCountReg = 0x228,
+		VertexOffsetReg = 0x22A,
+		SignalDrawArrays = 0x22E,
+
+		// Vertex shader registers
 		VertexShaderTransferEnd = 0x2BF,
 		VertexShaderTransferIndex = 0x2CB,
 		VertexShaderData0 = 0x2CC,
diff --git a/src/core/PICA/gpu.cpp b/src/core/PICA/gpu.cpp
index a9e74b2e..1abbf5a5 100644
--- a/src/core/PICA/gpu.cpp
+++ b/src/core/PICA/gpu.cpp
@@ -1,4 +1,5 @@
 #include "PICA/gpu.hpp"
+#include "PICA/regs.hpp"
 #include <cstdio>
 
 void GPU::reset() {
@@ -9,4 +10,11 @@ void GPU::reset() {
 
 void GPU::clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) {
 	printf("GPU: Clear buffer\nStart: %08X End: %08X\nValue: %08X Control: %08X\n", startAddress, endAddress, value, control);
+}
+
+void GPU::drawArrays() {
+	const u32 vertexCount = regs[PICAInternalRegs::VertexCountReg];
+	const u32 vertexOffset = regs[PICAInternalRegs::VertexOffsetReg];
+
+	printf("PICA::DrawArrays(vertex count = %d, vertexOffset = %d)\n", vertexCount, vertexOffset);
 }
\ No newline at end of file
diff --git a/src/core/PICA/regs.cpp b/src/core/PICA/regs.cpp
index 9d37df4d..649e2584 100644
--- a/src/core/PICA/regs.cpp
+++ b/src/core/PICA/regs.cpp
@@ -34,10 +34,15 @@ void GPU::writeInternalReg(u32 index, u32 value, u32 mask) {
 
 	u32 currentValue = regs[index];
 	u32 newValue = (currentValue & ~mask) | (value & mask); // Only overwrite the bits specified by "mask"
+	regs[index] = newValue;
 
 	// TODO: Figure out if things like the shader index use the unmasked value or the masked one
 	// We currently use the unmasked value like Citra does
 	switch (index) {
+		case SignalDrawArrays:
+			if (value != 0) drawArrays();
+			break;
+
 		case VertexShaderTransferEnd:
 			if (value != 0) shaderUnit.vs.finalize();
 			break;