From e5efc4b348448964c4baf7906093e9ba1c71060c Mon Sep 17 00:00:00 2001
From: Jesse Talavera-Greenberg <jesse@jesse.tg>
Date: Tue, 24 Oct 2023 14:51:45 -0400
Subject: [PATCH] First crack at ensuring the render thread doesn't touch GPU
 state while it's being serialized

---
 src/GPU3D.cpp      | 10 ++++++++++
 src/GPU3D_Soft.cpp | 13 +++++++++++--
 src/GPU3D_Soft.h   |  2 ++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/GPU3D.cpp b/src/GPU3D.cpp
index 8cc380ad..181e4104 100644
--- a/src/GPU3D.cpp
+++ b/src/GPU3D.cpp
@@ -393,6 +393,12 @@ void DoSavestate(Savestate* file)
 {
     file->Section("GP3D");
 
+    SoftRenderer* softRenderer = dynamic_cast<SoftRenderer*>(CurrentRenderer.get());
+    if (softRenderer && softRenderer->IsThreaded())
+    {
+        softRenderer->SetupRenderThread();
+    }
+
     CmdFIFO.DoSavestate(file);
     CmdPIPE.DoSavestate(file);
 
@@ -630,6 +636,10 @@ void DoSavestate(Savestate* file)
     file->VarArray(ShininessTable, 128*sizeof(u8));
 
     file->Bool32(&AbortFrame);
+    if (softRenderer && softRenderer->IsThreaded())
+    {
+        softRenderer->EnableRenderThread();
+    }
 }
 
 
diff --git a/src/GPU3D_Soft.cpp b/src/GPU3D_Soft.cpp
index 8848a541..b9eefc48 100644
--- a/src/GPU3D_Soft.cpp
+++ b/src/GPU3D_Soft.cpp
@@ -62,8 +62,7 @@ void SoftRenderer::SetupRenderThread()
         Platform::Semaphore_Reset(Sema_RenderDone);
         Platform::Semaphore_Reset(Sema_RenderStart);
         Platform::Semaphore_Reset(Sema_ScanlineCount);
-
-        Platform::Semaphore_Post(Sema_RenderStart);
+        Platform::Semaphore_Wait(Sema_RenderStart);
     }
     else
     {
@@ -71,6 +70,13 @@ void SoftRenderer::SetupRenderThread()
     }
 }
 
+void SoftRenderer::EnableRenderThread()
+{
+    if (Threaded && Sema_RenderStart)
+    {
+        Platform::Semaphore_Post(Sema_RenderStart);
+    }
+}
 
 SoftRenderer::SoftRenderer() noexcept
     : Renderer3D(false)
@@ -103,12 +109,14 @@ void SoftRenderer::Reset()
     PrevIsShadowMask = false;
 
     SetupRenderThread();
+    EnableRenderThread();
 }
 
 void SoftRenderer::SetRenderSettings(GPU::RenderSettings& settings)
 {
     Threaded = settings.Soft_Threaded;
     SetupRenderThread();
+    EnableRenderThread();
 }
 
 void SoftRenderer::TextureLookup(u32 texparam, u32 texpal, s16 s, s16 t, u16* color, u8* alpha)
@@ -1726,6 +1734,7 @@ void SoftRenderer::RenderFrame()
 void SoftRenderer::RestartFrame()
 {
     SetupRenderThread();
+    EnableRenderThread();
 }
 
 void SoftRenderer::RenderThreadFunc()
diff --git a/src/GPU3D_Soft.h b/src/GPU3D_Soft.h
index 948832f4..0e4bb66e 100644
--- a/src/GPU3D_Soft.h
+++ b/src/GPU3D_Soft.h
@@ -40,7 +40,9 @@ public:
     virtual u32* GetLine(int line) override;
 
     void SetupRenderThread();
+    void EnableRenderThread();
     void StopRenderThread();
+    bool IsThreaded() const noexcept { return Threaded; }
 private:
     // Notes on the interpolator:
     //