From 587aa20dcc55fb6dbe2d8f43d719d23eb9f5c9b7 Mon Sep 17 00:00:00 2001
From: png183 <97423514+png183@users.noreply.github.com>
Date: Mon, 10 Jun 2024 00:26:22 -0700
Subject: [PATCH] gba: improve video capture DMA (#1519)

Video capture DMAs should run only if the mode was enabled on scanline
162 of the previous frame, and should clear the DMA enable bit once
complete.
---
 ares/gba/ppu/ppu.cpp              | 6 +++++-
 ares/gba/ppu/ppu.hpp              | 2 ++
 ares/gba/ppu/serialization.cpp    | 2 ++
 ares/gba/system/serialization.cpp | 2 +-
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/ares/gba/ppu/ppu.cpp b/ares/gba/ppu/ppu.cpp
index 0079e48bf..0939d3673 100644
--- a/ares/gba/ppu/ppu.cpp
+++ b/ares/gba/ppu/ppu.cpp
@@ -141,7 +141,11 @@ auto PPU::main() -> void {
   step(226);
   io.hblank = 0;
   if(++io.vcounter == 228) io.vcounter = 0;
-  if(io.vcounter > 1 && io.vcounter < 162) cpu.dmaHDMA();
+  if(io.vcounter == 162) {
+    if(videoCapture) cpu.dma[3].enable = 0;
+    videoCapture = !videoCapture && cpu.dma[3].timingMode == 3 && cpu.dma[3].enable;
+  }
+  if(io.vcounter >= 2 && io.vcounter < 162 && videoCapture) cpu.dmaHDMA();
 }
 
 auto PPU::frame() -> void {
diff --git a/ares/gba/ppu/ppu.hpp b/ares/gba/ppu/ppu.hpp
index 3a3843f4c..cf5d61377 100644
--- a/ares/gba/ppu/ppu.hpp
+++ b/ares/gba/ppu/ppu.hpp
@@ -255,6 +255,8 @@ private:
     i16 pc;
     i16 pd;
   } objectParam[32];
+  
+  n1 videoCapture = 0;
 };
 
 extern PPU ppu;
diff --git a/ares/gba/ppu/serialization.cpp b/ares/gba/ppu/serialization.cpp
index 7d0f9e044..8f7b94d88 100644
--- a/ares/gba/ppu/serialization.cpp
+++ b/ares/gba/ppu/serialization.cpp
@@ -16,6 +16,8 @@ auto PPU::serialize(serializer& s) -> void {
   s(io.vcompare);
   s(io.vcounter);
 
+  s(videoCapture);
+
   s(Background::IO::mode);
   s(Background::IO::frame);
   s(Background::IO::mosaicWidth);
diff --git a/ares/gba/system/serialization.cpp b/ares/gba/system/serialization.cpp
index ce9dd53ea..e58e702b8 100644
--- a/ares/gba/system/serialization.cpp
+++ b/ares/gba/system/serialization.cpp
@@ -1,4 +1,4 @@
-static const string SerializerVersion = "v138";
+static const string SerializerVersion = "v138.1";
 
 auto System::serialize(bool synchronize) -> serializer {
   if(synchronize) scheduler.enter(Scheduler::Mode::Synchronize);