From 9417c75ca7234b4ba434606f6087fade38420a77 Mon Sep 17 00:00:00 2001
From: GPUCode <geoster3d@gmail.com>
Date: Wed, 9 Aug 2023 11:49:19 +0300
Subject: [PATCH] gsp: Fix setbufferswap framebuffer selection

---
 include/PICA/regs.hpp                | 3 +--
 src/core/renderer_gl/renderer_gl.cpp | 8 ++++++--
 src/core/services/gsp_gpu.cpp        | 8 ++++----
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/include/PICA/regs.hpp b/include/PICA/regs.hpp
index d67c2025..55b3e20b 100644
--- a/include/PICA/regs.hpp
+++ b/include/PICA/regs.hpp
@@ -191,8 +191,7 @@ namespace PICA {
 			VramBankControl = 0xB,
 			GPUBusy = 0xC,
 			BacklightControl = 0xBC,
-			// TODO: Framebuffer regs
-			Framebuffer0Size = 0x2F,
+			Framebuffer0Size = 0x118,
 			Framebuffer0AFirstAddr = 0x119,
 			Framebuffer0ASecondAddr = 0x11A,
 			Framebuffer0Config = 0x11B,
diff --git a/src/core/renderer_gl/renderer_gl.cpp b/src/core/renderer_gl/renderer_gl.cpp
index cd4a988f..e99e3196 100644
--- a/src/core/renderer_gl/renderer_gl.cpp
+++ b/src/core/renderer_gl/renderer_gl.cpp
@@ -462,13 +462,17 @@ void RendererGL::display() {
 	gl.disableClipPlane(1);
 
 	using namespace PICA::ExternalRegs;
-	const u32 topScreenAddr = externalRegs[Framebuffer0AFirstAddr];
-	const u32 bottomScreenAddr = externalRegs[Framebuffer1AFirstAddr];
+	const u32 topActiveFb = externalRegs[Framebuffer0Select] & 1;
+	const u32 topScreenAddr = externalRegs[topActiveFb == 0 ? Framebuffer0AFirstAddr : Framebuffer0ASecondAddr];
+	const u32 bottomActiveFb = externalRegs[Framebuffer1Select] & 1;
+	const u32 bottomScreenAddr = externalRegs[bottomActiveFb == 0 ? Framebuffer1AFirstAddr : Framebuffer1ASecondAddr];
 
 	auto topScreen = colourBufferCache.findFromAddress(topScreenAddr);
 	auto bottomScreen = colourBufferCache.findFromAddress(bottomScreenAddr);
 	screenFramebuffer.bind(OpenGL::DrawFramebuffer);
 
+	OpenGL::clearColor();
+
 	if (topScreen) {
 		topScreen->get().texture.bind();
 		OpenGL::setViewport(0, 240, 400, 240); // Top screen viewport
diff --git a/src/core/services/gsp_gpu.cpp b/src/core/services/gsp_gpu.cpp
index 25628e4b..bfecfbf8 100644
--- a/src/core/services/gsp_gpu.cpp
+++ b/src/core/services/gsp_gpu.cpp
@@ -398,16 +398,16 @@ void GPUService::setBufferSwapImpl(u32 screenId, const FramebufferInfo& info) {
 
 	constexpr static std::array<u32, 8> fb_addresses = {
 		Framebuffer0AFirstAddr,
-		Framebuffer0ASecondAddr,
 		Framebuffer0BFirstAddr,
-		Framebuffer0BSecondAddr,
 		Framebuffer1AFirstAddr,
-		Framebuffer1ASecondAddr,
 		Framebuffer1BFirstAddr,
+		Framebuffer0ASecondAddr,
+		Framebuffer0BSecondAddr,
+		Framebuffer1ASecondAddr,
 		Framebuffer1BSecondAddr,
 	};
 
-	const u32 fb_index = screenId * 4 + info.activeFb * 2;
+	const u32 fb_index = info.activeFb * 4 + screenId * 2;
 	gpu.writeExternalReg(fb_addresses[fb_index], VaddrToPaddr(info.leftFramebufferVaddr));
 	gpu.writeExternalReg(fb_addresses[fb_index + 1], VaddrToPaddr(info.rightFramebufferVaddr));