From 60049cc9e5e685488f398a1216e5e693948813a6 Mon Sep 17 00:00:00 2001
From: Jaby Blubb <fenir50@web.de>
Date: Sun, 30 Apr 2023 14:18:11 +0200
Subject: [PATCH] Add BootImage to second DisplayBuffer during boot

---
 include/PSX/GPU/gpu_types.hpp                     | 15 +++++++++++++++
 include/PSX/System/IOPorts/gpu_io.hpp             |  4 ++++
 src/Library/internal-include/GPU/gpu_internal.hpp | 13 ++++++++++---
 src/Library/src/BootLoader/gpu_boot.cpp           |  5 ++++-
 4 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/include/PSX/GPU/gpu_types.hpp b/include/PSX/GPU/gpu_types.hpp
index 48bfc0ca..187b9f9f 100644
--- a/include/PSX/GPU/gpu_types.hpp
+++ b/include/PSX/GPU/gpu_types.hpp
@@ -92,11 +92,26 @@ namespace JabyEngine {
             }
         };
 
+        template<typename T>
+        struct Area {
+            Position<T> position;
+            Size<T>     size;
+
+            constexpr Area() = default;
+            constexpr Area(Position<T> position, Size<T> size) : position(position), size(size) {
+            }
+            constexpr Area(T position_x, T position_y, T size_width, T size_height) : position{position_x, position_y}, size{size_width, size_height} {
+            }
+        };
+
         typedef Position<int16_t>  PositionI16;
         typedef Position<uint16_t> PositionU16;
 
         typedef Size<int16_t>  SizeI16;
         typedef Size<uint16_t> SizeU16;
+
+        typedef Area<int16_t>  AreaI16;
+        typedef Area<uint16_t> AreaU16;
     }
 }
 #endif //!__JABYENGINE_GPU_TYPES_HPP__
\ No newline at end of file
diff --git a/include/PSX/System/IOPorts/gpu_io.hpp b/include/PSX/System/IOPorts/gpu_io.hpp
index 37307d49..b26059c3 100644
--- a/include/PSX/System/IOPorts/gpu_io.hpp
+++ b/include/PSX/System/IOPorts/gpu_io.hpp
@@ -106,6 +106,10 @@ namespace JabyEngine {
                 return {(0x02 << 24) | color.raw()};
             }
 
+            static constexpr GP0_t VRAM2VRAM_Blitting() {
+                return {(0b100u << 29)};
+            }
+
             static constexpr GP0_t CPU2VRAM_Blitting() {
                 return {(0b101u << 29)};
             }
diff --git a/src/Library/internal-include/GPU/gpu_internal.hpp b/src/Library/internal-include/GPU/gpu_internal.hpp
index 68c1d03d..74b57864 100644
--- a/src/Library/internal-include/GPU/gpu_internal.hpp
+++ b/src/Library/internal-include/GPU/gpu_internal.hpp
@@ -31,10 +31,17 @@ namespace JabyEngine {
                 GPU_IO::GP0 = GPU_IO::Command::DrawAreaBottomRight((x + Display::Width), (y + Display::Height));
             }
 
-            static void quick_fill_fast(const Color24& color, const PositionU16& pos, const SizeU16& size) {
+            static void copy_vram_to_vram(const AreaU16& dst, const PositionU16& src) {
+                GPU_IO::GP0 = GPU_IO::Command::VRAM2VRAM_Blitting();
+                GPU_IO::GP0 = GPU_IO::Command::TopLeftPosition(src.x, src.y);
+                GPU_IO::GP0 = GPU_IO::Command::TopLeftPosition(dst.position.x, dst.position.y);
+                GPU_IO::GP0 = GPU_IO::Command::WidthHeight(dst.size.width, dst.size.height);
+            }
+
+            static void quick_fill_fast(const Color24& color, const AreaU16& area) {
                 GPU_IO::GP0 = GPU_IO::Command::QuickFill(color);
-                GPU_IO::GP0 = GPU_IO::Command::TopLeftPosition(pos.x, pos.y);
-                GPU_IO::GP0 = GPU_IO::Command::WidthHeight(size.width, size.height);
+                GPU_IO::GP0 = GPU_IO::Command::TopLeftPosition(area.position.x, area.position.y);
+                GPU_IO::GP0 = GPU_IO::Command::WidthHeight(area.size.width, area.size.height);
             }
 
             static void reset_cmd_buffer() {
diff --git a/src/Library/src/BootLoader/gpu_boot.cpp b/src/Library/src/BootLoader/gpu_boot.cpp
index 22390d12..3c1f3fde 100644
--- a/src/Library/src/BootLoader/gpu_boot.cpp
+++ b/src/Library/src/BootLoader/gpu_boot.cpp
@@ -58,6 +58,9 @@ namespace JabyEngine {
                 auto state = FileProcessor::create(&__boot_loader_end, SimpleTIM(32, 0, 0, 0));
                 state.process(bytes_ready);
 
+                // Duplicate DisplayBuffer content
+                internal::copy_vram_to_vram({PositionU16(0, Display::Height), SizeU16(Display::Width, Display::Height)}, PositionU16(0, 0));
+
                 Display::enable();
             }
 
@@ -67,7 +70,7 @@ namespace JabyEngine {
                 internal::Display::exchange_buffer_and_display();
                 
                 GPU::internal::wait_ready_for_CMD();
-                GPU::internal::quick_fill_fast(Color24::Black(), PositionU16(32, 0), SizeU16(Display::Width, Display::Height));
+                GPU::internal::quick_fill_fast(Color24::Black(), {PositionU16(32, 0), SizeU16(Display::Width, Display::Height)});
 
                 __syscall_EnterCriticalSection();
                     __syscall_SysEnqIntRP(VblankIrq, &::JabyEngine::GPU::internal::callback);