From e78aca34b9454328b2de445806a28076ca21023b Mon Sep 17 00:00:00 2001
From: byuu <2107894+byuu@users.noreply.github.com>
Date: Mon, 7 Oct 2019 13:32:21 +0900
Subject: [PATCH] v111.3

Save state improvements: rewind should be fully stable now.
Before, Star Ocean and Tales of Phantasia would rarely hang with rewind.
---
 bsnes/emulator/emulator.hpp                   |  2 +-
 bsnes/sfc/coprocessor/armdsp/armdsp.cpp       |  8 ++-
 bsnes/sfc/coprocessor/epsonrtc/epsonrtc.cpp   |  8 ++-
 bsnes/sfc/coprocessor/event/event.cpp         |  8 ++-
 .../sfc/coprocessor/hitachidsp/hitachidsp.cpp |  8 ++-
 bsnes/sfc/coprocessor/icd/icd.cpp             |  5 +-
 bsnes/sfc/coprocessor/msu1/msu1.cpp           |  8 ++-
 bsnes/sfc/coprocessor/necdsp/necdsp.cpp       |  8 ++-
 bsnes/sfc/coprocessor/sa1/sa1.cpp             |  8 ++-
 bsnes/sfc/coprocessor/sa1/sa1.hpp             |  2 +-
 bsnes/sfc/coprocessor/sharprtc/sharprtc.cpp   |  8 ++-
 bsnes/sfc/coprocessor/spc7110/spc7110.cpp     |  8 ++-
 bsnes/sfc/coprocessor/superfx/superfx.cpp     |  8 ++-
 bsnes/sfc/coprocessor/superfx/superfx.hpp     |  2 +-
 bsnes/sfc/cpu/cpu.cpp                         |  8 ++-
 bsnes/sfc/ppu-fast/ppu.cpp                    | 11 +++-
 bsnes/sfc/ppu/main.cpp                        |  2 +-
 bsnes/sfc/ppu/ppu.cpp                         |  5 +-
 bsnes/sfc/sfc.hpp                             | 14 +++-
 bsnes/sfc/slot/bsmemory/bsmemory.cpp          |  8 ++-
 bsnes/sfc/smp/smp.cpp                         |  5 +-
 bsnes/sfc/smp/smp.hpp                         |  2 +-
 bsnes/sfc/system/serialization.cpp            |  1 +
 bsnes/sfc/system/system.cpp                   | 66 ++++++++++++-------
 bsnes/sfc/system/system.hpp                   |  3 +
 .../presentation/presentation.cpp             |  2 +-
 26 files changed, 155 insertions(+), 63 deletions(-)

diff --git a/bsnes/emulator/emulator.hpp b/bsnes/emulator/emulator.hpp
index 1a0a0a38..aa60c8b8 100644
--- a/bsnes/emulator/emulator.hpp
+++ b/bsnes/emulator/emulator.hpp
@@ -29,7 +29,7 @@ using namespace nall;
 
 namespace Emulator {
   static const string Name    = "bsnes";
-  static const string Version = "111.2";
+  static const string Version = "111.3";
   static const string Author  = "byuu";
   static const string License = "GPLv3";
   static const string Website = "https://byuu.org";
diff --git a/bsnes/sfc/coprocessor/armdsp/armdsp.cpp b/bsnes/sfc/coprocessor/armdsp/armdsp.cpp
index 2a2111e7..29095b11 100644
--- a/bsnes/sfc/coprocessor/armdsp/armdsp.cpp
+++ b/bsnes/sfc/coprocessor/armdsp/armdsp.cpp
@@ -7,12 +7,16 @@ namespace SuperFamicom {
 ArmDSP armdsp;
 
 auto ArmDSP::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto ArmDSP::Enter() -> void {
   armdsp.boot();
-  while(true) scheduler.synchronize(), armdsp.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    armdsp.main();
+  }
 }
 
 auto ArmDSP::boot() -> void {
diff --git a/bsnes/sfc/coprocessor/epsonrtc/epsonrtc.cpp b/bsnes/sfc/coprocessor/epsonrtc/epsonrtc.cpp
index 4ddc20c9..de700ce9 100644
--- a/bsnes/sfc/coprocessor/epsonrtc/epsonrtc.cpp
+++ b/bsnes/sfc/coprocessor/epsonrtc/epsonrtc.cpp
@@ -8,11 +8,15 @@ namespace SuperFamicom {
 EpsonRTC epsonrtc;
 
 auto EpsonRTC::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto EpsonRTC::Enter() -> void {
-  while(true) scheduler.synchronize(), epsonrtc.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    epsonrtc.main();
+  }
 }
 
 auto EpsonRTC::main() -> void {
diff --git a/bsnes/sfc/coprocessor/event/event.cpp b/bsnes/sfc/coprocessor/event/event.cpp
index 4727be58..2316c3e2 100644
--- a/bsnes/sfc/coprocessor/event/event.cpp
+++ b/bsnes/sfc/coprocessor/event/event.cpp
@@ -6,11 +6,15 @@ namespace SuperFamicom {
 Event event;
 
 auto Event::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto Event::Enter() -> void {
-  while(true) scheduler.synchronize(), event.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    event.main();
+  }
 }
 
 auto Event::main() -> void {
diff --git a/bsnes/sfc/coprocessor/hitachidsp/hitachidsp.cpp b/bsnes/sfc/coprocessor/hitachidsp/hitachidsp.cpp
index 56a0852a..5b07b634 100644
--- a/bsnes/sfc/coprocessor/hitachidsp/hitachidsp.cpp
+++ b/bsnes/sfc/coprocessor/hitachidsp/hitachidsp.cpp
@@ -9,11 +9,15 @@ namespace SuperFamicom {
 HitachiDSP hitachidsp;
 
 auto HitachiDSP::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto HitachiDSP::Enter() -> void {
-  while(true) scheduler.synchronize(), hitachidsp.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    hitachidsp.main();
+  }
 }
 
 auto HitachiDSP::step(uint clocks) -> void {
diff --git a/bsnes/sfc/coprocessor/icd/icd.cpp b/bsnes/sfc/coprocessor/icd/icd.cpp
index 480bdce8..788cd8a5 100644
--- a/bsnes/sfc/coprocessor/icd/icd.cpp
+++ b/bsnes/sfc/coprocessor/icd/icd.cpp
@@ -48,12 +48,13 @@ namespace SameBoy {
 }
 
 auto ICD::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto ICD::Enter() -> void {
   while(true) {
-    scheduler.synchronize();
+    scheduler.synchronizeAll();
     icd.main();
   }
 }
diff --git a/bsnes/sfc/coprocessor/msu1/msu1.cpp b/bsnes/sfc/coprocessor/msu1/msu1.cpp
index c95a8098..b0b891bb 100644
--- a/bsnes/sfc/coprocessor/msu1/msu1.cpp
+++ b/bsnes/sfc/coprocessor/msu1/msu1.cpp
@@ -7,12 +7,16 @@ MSU1 msu1;
 #include "serialization.cpp"
 
 auto MSU1::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 
 auto MSU1::Enter() -> void {
-  while(true) scheduler.synchronize(), msu1.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    msu1.main();
+  }
 }
 
 auto MSU1::main() -> void {
diff --git a/bsnes/sfc/coprocessor/necdsp/necdsp.cpp b/bsnes/sfc/coprocessor/necdsp/necdsp.cpp
index 522dc87a..fbbdb3d6 100644
--- a/bsnes/sfc/coprocessor/necdsp/necdsp.cpp
+++ b/bsnes/sfc/coprocessor/necdsp/necdsp.cpp
@@ -7,11 +7,15 @@ namespace SuperFamicom {
 NECDSP necdsp;
 
 auto NECDSP::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto NECDSP::Enter() -> void {
-  while(true) scheduler.synchronize(), necdsp.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    necdsp.main();
+  }
 }
 
 auto NECDSP::main() -> void {
diff --git a/bsnes/sfc/coprocessor/sa1/sa1.cpp b/bsnes/sfc/coprocessor/sa1/sa1.cpp
index 535b7708..0a87173c 100644
--- a/bsnes/sfc/coprocessor/sa1/sa1.cpp
+++ b/bsnes/sfc/coprocessor/sa1/sa1.cpp
@@ -12,11 +12,15 @@ namespace SuperFamicom {
 SA1 sa1;
 
 auto SA1::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto SA1::Enter() -> void {
-  while(true) scheduler.synchronize(), sa1.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    sa1.main();
+  }
 }
 
 auto SA1::main() -> void {
diff --git a/bsnes/sfc/coprocessor/sa1/sa1.hpp b/bsnes/sfc/coprocessor/sa1/sa1.hpp
index c493ce6b..21c46656 100644
--- a/bsnes/sfc/coprocessor/sa1/sa1.hpp
+++ b/bsnes/sfc/coprocessor/sa1/sa1.hpp
@@ -1,7 +1,7 @@
 //Super Accelerator (SA-1)
 
 struct SA1 : Processor::WDC65816, Thread {
-  inline auto synchronizing() const -> bool override { return scheduler.mode == Scheduler::Mode::SynchronizeAll; }
+  inline auto synchronizing() const -> bool override { return scheduler.synchronizingAll(); }
 
   //sa1.cpp
   auto synchronizeCPU() -> void;
diff --git a/bsnes/sfc/coprocessor/sharprtc/sharprtc.cpp b/bsnes/sfc/coprocessor/sharprtc/sharprtc.cpp
index ee8e0326..372ffd56 100644
--- a/bsnes/sfc/coprocessor/sharprtc/sharprtc.cpp
+++ b/bsnes/sfc/coprocessor/sharprtc/sharprtc.cpp
@@ -8,11 +8,15 @@ namespace SuperFamicom {
 SharpRTC sharprtc;
 
 auto SharpRTC::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto SharpRTC::Enter() -> void {
-  while(true) scheduler.synchronize(), sharprtc.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    sharprtc.main();
+  }
 }
 
 auto SharpRTC::main() -> void {
diff --git a/bsnes/sfc/coprocessor/spc7110/spc7110.cpp b/bsnes/sfc/coprocessor/spc7110/spc7110.cpp
index fb253efb..85c7354c 100644
--- a/bsnes/sfc/coprocessor/spc7110/spc7110.cpp
+++ b/bsnes/sfc/coprocessor/spc7110/spc7110.cpp
@@ -17,11 +17,15 @@ SPC7110::~SPC7110() {
 }
 
 auto SPC7110::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto SPC7110::Enter() -> void {
-  while(true) scheduler.synchronize(), spc7110.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    spc7110.main();
+  }
 }
 
 auto SPC7110::main() -> void {
diff --git a/bsnes/sfc/coprocessor/superfx/superfx.cpp b/bsnes/sfc/coprocessor/superfx/superfx.cpp
index 9b3dc9f9..b9ddf09d 100644
--- a/bsnes/sfc/coprocessor/superfx/superfx.cpp
+++ b/bsnes/sfc/coprocessor/superfx/superfx.cpp
@@ -12,11 +12,15 @@ namespace SuperFamicom {
 SuperFX superfx;
 
 auto SuperFX::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto SuperFX::Enter() -> void {
-  while(true) scheduler.synchronize(), superfx.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    superfx.main();
+  }
 }
 
 auto SuperFX::main() -> void {
diff --git a/bsnes/sfc/coprocessor/superfx/superfx.hpp b/bsnes/sfc/coprocessor/superfx/superfx.hpp
index 0ef80292..680e9b1e 100644
--- a/bsnes/sfc/coprocessor/superfx/superfx.hpp
+++ b/bsnes/sfc/coprocessor/superfx/superfx.hpp
@@ -2,7 +2,7 @@ struct SuperFX : Processor::GSU, Thread {
   ReadableMemory rom;
   WritableMemory ram;
 
-  inline auto synchronizing() const -> bool { return scheduler.mode == Scheduler::Mode::SynchronizeAll; }
+  inline auto synchronizing() const -> bool { return scheduler.synchronizingAll(); }
 
   //superfx.cpp
   auto synchronizeCPU() -> void;
diff --git a/bsnes/sfc/cpu/cpu.cpp b/bsnes/sfc/cpu/cpu.cpp
index 782c1d57..2505dc92 100644
--- a/bsnes/sfc/cpu/cpu.cpp
+++ b/bsnes/sfc/cpu/cpu.cpp
@@ -11,14 +11,17 @@ CPU cpu;
 #include "serialization.cpp"
 
 auto CPU::synchronizeSMP() -> void {
+  if(scheduler.synchronizingAll()) return;
   if(smp.clock < 0) co_switch(smp.thread);
 }
 
 auto CPU::synchronizePPU() -> void {
+  if(scheduler.synchronizingAll()) return;
   if(ppu.clock < 0) co_switch(ppu.thread);
 }
 
 auto CPU::synchronizeCoprocessors() -> void {
+  if(scheduler.synchronizingAll()) return;
   for(auto coprocessor : coprocessors) {
     if(coprocessor->clock < 0) co_switch(coprocessor->thread);
   }
@@ -26,9 +29,8 @@ auto CPU::synchronizeCoprocessors() -> void {
 
 auto CPU::Enter() -> void {
   while(true) {
-    if(scheduler.mode == Scheduler::Mode::SynchronizeCPU) {
-      scheduler.leave(Scheduler::Event::Synchronize);
-    }
+    scheduler.synchronizeCPU();
+    scheduler.synchronizeAll();
     cpu.main();
   }
 }
diff --git a/bsnes/sfc/ppu-fast/ppu.cpp b/bsnes/sfc/ppu-fast/ppu.cpp
index 861669b5..6dd09b6c 100644
--- a/bsnes/sfc/ppu-fast/ppu.cpp
+++ b/bsnes/sfc/ppu-fast/ppu.cpp
@@ -69,12 +69,13 @@ PPU::~PPU() {
 }
 
 auto PPU::synchronizeCPU() -> void {
-  if(ppubase.clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(ppubase.clock >= 0) co_switch(cpu.thread);
 }
 
 auto PPU::Enter() -> void {
   while(true) {
-    scheduler.synchronize();
+    scheduler.synchronizeAll();
     ppu.main();
   }
 }
@@ -122,10 +123,14 @@ auto PPU::scanline() -> void {
     if(!io.displayDisable) oamAddressReset();
   }
 
-  if(vcounter() == 240) {
+  if(vcounter() == vdisp()) {  //240
     Line::flush();
     scheduler.leave(Scheduler::Event::Frame);
   }
+
+  if(vcounter() == 240) {
+    Line::flush();
+  }
 }
 
 auto PPU::refresh() -> void {
diff --git a/bsnes/sfc/ppu/main.cpp b/bsnes/sfc/ppu/main.cpp
index 8c9fe468..598ac2ba 100644
--- a/bsnes/sfc/ppu/main.cpp
+++ b/bsnes/sfc/ppu/main.cpp
@@ -21,7 +21,7 @@ auto PPU::main() -> void {
     if(auto device = controllerPort2.device) device->latch();  //light guns
   }
 
-  if(vcounter() == 240) {
+  if(vcounter() == vdisp()) {  //240
     scheduler.leave(Scheduler::Event::Frame);
   }
 
diff --git a/bsnes/sfc/ppu/ppu.cpp b/bsnes/sfc/ppu/ppu.cpp
index 6e08641f..a3de2dca 100644
--- a/bsnes/sfc/ppu/ppu.cpp
+++ b/bsnes/sfc/ppu/ppu.cpp
@@ -39,7 +39,8 @@ PPU::~PPU() {
 }
 
 auto PPU::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto PPU::step() -> void {
@@ -59,7 +60,7 @@ auto PPU::step(uint clocks) -> void {
 
 auto PPU::Enter() -> void {
   while(true) {
-    scheduler.synchronize();
+    scheduler.synchronizeAll();
     ppu.main();
   }
 }
diff --git a/bsnes/sfc/sfc.hpp b/bsnes/sfc/sfc.hpp
index 8412ebae..0f209dcf 100644
--- a/bsnes/sfc/sfc.hpp
+++ b/bsnes/sfc/sfc.hpp
@@ -45,7 +45,19 @@ namespace SuperFamicom {
       co_switch(host);
     }
 
-    auto synchronize() -> void {
+    inline auto synchronizingCPU() const -> bool {
+      return mode == Mode::SynchronizeCPU;
+    }
+
+    inline auto synchronizingAll() const -> bool {
+      return mode == Mode::SynchronizeAll;
+    }
+
+    inline auto synchronizeCPU() -> void {
+      if(mode == Mode::SynchronizeCPU) leave(Event::Synchronize);
+    }
+
+    inline auto synchronizeAll() -> void {
       if(mode == Mode::SynchronizeAll) leave(Event::Synchronize);
     }
   };
diff --git a/bsnes/sfc/slot/bsmemory/bsmemory.cpp b/bsnes/sfc/slot/bsmemory/bsmemory.cpp
index 86d76673..17f51a48 100644
--- a/bsnes/sfc/slot/bsmemory/bsmemory.cpp
+++ b/bsnes/sfc/slot/bsmemory/bsmemory.cpp
@@ -13,11 +13,15 @@ BSMemory::BSMemory() {
 }
 
 auto BSMemory::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto BSMemory::Enter() -> void {
-  while(true) scheduler.synchronize(), bsmemory.main();
+  while(true) {
+    scheduler.synchronizeAll();
+    bsmemory.main();
+  }
 }
 
 auto BSMemory::main() -> void {
diff --git a/bsnes/sfc/smp/smp.cpp b/bsnes/sfc/smp/smp.cpp
index abea3a58..7d9ae842 100644
--- a/bsnes/sfc/smp/smp.cpp
+++ b/bsnes/sfc/smp/smp.cpp
@@ -9,7 +9,8 @@ SMP smp;
 #include "serialization.cpp"
 
 auto SMP::synchronizeCPU() -> void {
-  if(clock >= 0 && scheduler.mode != Scheduler::Mode::SynchronizeAll) co_switch(cpu.thread);
+  if(scheduler.synchronizingAll()) return;
+  if(clock >= 0) co_switch(cpu.thread);
 }
 
 auto SMP::synchronizeDSP() -> void {
@@ -18,7 +19,7 @@ auto SMP::synchronizeDSP() -> void {
 
 auto SMP::Enter() -> void {
   while(true) {
-    scheduler.synchronize();
+    scheduler.synchronizeAll();
     smp.main();
   }
 }
diff --git a/bsnes/sfc/smp/smp.hpp b/bsnes/sfc/smp/smp.hpp
index ee2aaecf..c973c079 100644
--- a/bsnes/sfc/smp/smp.hpp
+++ b/bsnes/sfc/smp/smp.hpp
@@ -1,7 +1,7 @@
 //Sony CXP1100Q-1
 
 struct SMP : Processor::SPC700, Thread {
-  inline auto synchronizing() const -> bool override { return scheduler.mode == Scheduler::Mode::SynchronizeAll; }
+  inline auto synchronizing() const -> bool override { return scheduler.synchronizingAll(); }
 
   //io.cpp
   auto portRead(uint2 port) const -> uint8;
diff --git a/bsnes/sfc/system/serialization.cpp b/bsnes/sfc/system/serialization.cpp
index 63764487..5dcf89a2 100644
--- a/bsnes/sfc/system/serialization.cpp
+++ b/bsnes/sfc/system/serialization.cpp
@@ -33,6 +33,7 @@ auto System::unserialize(serializer& s) -> bool {
   power(/* reset = */ false);
   serializeAll(s);
   serializeInit();  //hacks.fastPPU setting changes serializeSize
+
   return true;
 }
 
diff --git a/bsnes/sfc/system/system.cpp b/bsnes/sfc/system/system.cpp
index 4e682d7a..d83689cd 100644
--- a/bsnes/sfc/system/system.cpp
+++ b/bsnes/sfc/system/system.cpp
@@ -11,39 +11,61 @@ Cheat cheat;
 auto System::run() -> void {
   scheduler.mode = Scheduler::Mode::Run;
   scheduler.enter();
-  if(scheduler.event == Scheduler::Event::Frame) {
-    ppu.refresh();
-
-    //refresh all cheat codes once per frame
-    Memory::GlobalWriteEnable = true;
-    for(auto& code : cheat.codes) {
-      if(code.enable) {
-        bus.write(code.address, code.data);
-      }
-    }
-    Memory::GlobalWriteEnable = false;
-  }
+  if(scheduler.event == Scheduler::Event::Frame) frameEvent();
 }
 
 auto System::runToSave() -> void {
+  //run the CPU thread normally, exiting once we reach the next synchronization point.
+  //the CPU thread may run in the pathological case for up to 10 frames for a long 8-channel x 64KB DMA transfer.
+  //in practice, this will typically be at most one DMA transfer.
   scheduler.mode = Scheduler::Mode::SynchronizeCPU;
-  while(true) { scheduler.enter(); if(scheduler.event == Scheduler::Event::Synchronize) break; }
+  runToSynchronize();
 
+  //now synchronize every other thread to their synchronization points.
+  //stop after each thread is very slightly ahead of the CPU thread.
   scheduler.mode = Scheduler::Mode::SynchronizeAll;
-  scheduler.active = smp.thread;
-  while(true) { scheduler.enter(); if(scheduler.event == Scheduler::Event::Synchronize) break; }
+  runToThread(smp);
+  runToThread(ppu);
+  for(auto coprocessor : cpu.coprocessors) runToThread(*coprocessor);
 
-  scheduler.mode = Scheduler::Mode::SynchronizeAll;
-  scheduler.active = ppu.thread;
-  while(true) { scheduler.enter(); if(scheduler.event == Scheduler::Event::Synchronize) break; }
+  //at this point, the CPU thread is the furthest behind in time.
+  //all threads are now at their synchronization points and can be serialized safely.
+  scheduler.mode = Scheduler::Mode::Run;
+  scheduler.active = cpu.thread;
+}
 
-  for(auto coprocessor : cpu.coprocessors) {
-    scheduler.mode = Scheduler::Mode::SynchronizeAll;
-    scheduler.active = coprocessor->thread;
-    while(true) { scheduler.enter(); if(scheduler.event == Scheduler::Event::Synchronize) break; }
+auto System::runToSynchronize() -> void {
+  while(true) {
+    scheduler.enter();
+    if(scheduler.event == Scheduler::Event::Frame) frameEvent();
+    if(scheduler.event == Scheduler::Event::Synchronize) break;
   }
 }
 
+auto System::runToThread(Thread& aux) -> void {
+  //first, ensure that the CPU is ahead of the thread we want to synchronize to.
+  //because if it isn't, and the other thread is ahead, it will run even more ahead to synchronize itself.
+  scheduler.active = cpu.thread;
+  while(aux.clock >= 0) runToSynchronize();
+
+  //now that it is, run the other thread until it's just barely surpassed the CPU thread.
+  scheduler.active = aux.thread;
+  do runToSynchronize(); while(aux.clock < 0);
+}
+
+auto System::frameEvent() -> void {
+  ppu.refresh();
+
+  //refresh all cheat codes once per frame
+  Memory::GlobalWriteEnable = true;
+  for(auto& code : cheat.codes) {
+    if(code.enable) {
+      bus.write(code.address, code.data);
+    }
+  }
+  Memory::GlobalWriteEnable = false;
+}
+
 auto System::load(Emulator::Interface* interface) -> bool {
   information = {};
 
diff --git a/bsnes/sfc/system/system.hpp b/bsnes/sfc/system/system.hpp
index 6a4e3c37..3e717dc7 100644
--- a/bsnes/sfc/system/system.hpp
+++ b/bsnes/sfc/system/system.hpp
@@ -10,6 +10,9 @@ struct System {
 
   auto run() -> void;
   auto runToSave() -> void;
+  auto runToSynchronize() -> void;
+  auto runToThread(Thread&) -> void;
+  auto frameEvent() -> void;
 
   auto load(Emulator::Interface*) -> bool;
   auto save() -> void;
diff --git a/bsnes/target-bsnes/presentation/presentation.cpp b/bsnes/target-bsnes/presentation/presentation.cpp
index 700454e4..1b496c19 100644
--- a/bsnes/target-bsnes/presentation/presentation.cpp
+++ b/bsnes/target-bsnes/presentation/presentation.cpp
@@ -48,7 +48,7 @@ auto Presentation::create() -> void {
     settings.video.overscan = showOverscanArea.checked();
     resizeWindow();
   });
-  blurEmulation.setText("Blur Emulation").setChecked(settings.video.blur).onToggle([&] {
+  blurEmulation.setText("Hires Blur Emulation").setChecked(settings.video.blur).onToggle([&] {
     settings.video.blur = blurEmulation.checked();
     emulator->configure("Video/BlurEmulation", settings.video.blur);
   }).doToggle();