From b094815ecb16bec069fe637c9f0a54acf824b4e1 Mon Sep 17 00:00:00 2001
From: Tony Wasserka <neobrain@users.noreply.github.com>
Date: Sat, 9 Mar 2024 20:02:29 +0100
Subject: [PATCH] Make DSP emulation opt-in

---
 externals/teakra              |  2 +-
 source/framework/settings.hpp |  7 ++++++-
 source/gui-sdl/main.cpp       |  3 +++
 source/os.cpp                 | 21 ++++++++++++++++-----
 source/settings.cpp           |  3 +++
 5 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/externals/teakra b/externals/teakra
index ad99cb9..019d18c 160000
--- a/externals/teakra
+++ b/externals/teakra
@@ -1 +1 @@
-Subproject commit ad99cb93dec7a042e3736d506783fb2dc1117851
+Subproject commit 019d18c7ee137899030b378feca038cd7789a1b7
diff --git a/source/framework/settings.hpp b/source/framework/settings.hpp
index 64cea6c..e4f6e18 100644
--- a/source/framework/settings.hpp
+++ b/source/framework/settings.hpp
@@ -89,6 +89,10 @@ struct ShaderEngineTag : Config::OptionDefault<ShaderEngine> {
     static constexpr const char* name = "ShaderEngine";
 };
 
+struct EnableAudioEmulation : Config::BooleanOption<EnableAudioEmulation> {
+    static constexpr const char* name = "EnableAudioEmulation";
+};
+
 
 struct Settings : Config::Options<CPUEngineTag,
                                   InitialApplicationTag,
@@ -100,6 +104,7 @@ struct Settings : Config::Options<CPUEngineTag,
                                   AttachToProcessOnStartup,
                                   AppMemType,
                                   RendererTag,
-                                  ShaderEngineTag> { };
+                                  ShaderEngineTag,
+                                  EnableAudioEmulation> { };
 
 } // namespace Settings
diff --git a/source/gui-sdl/main.cpp b/source/gui-sdl/main.cpp
index 7c49c65..8022810 100644
--- a/source/gui-sdl/main.cpp
+++ b/source/gui-sdl/main.cpp
@@ -196,6 +196,7 @@ int main(int argc, char* argv[]) {
             ("shader_engine", bpo::value<Settings::ShaderEngine>()->default_value(Settings::ShaderEngineTag::default_value()), "Select which Shader engine to use (interpreter, bytecode, or glsl)")
             ("enable_logging", bpo::bool_switch(&enable_logging), "Enable logging (slow!)")
             ("bootstrap_nand", bpo::bool_switch(&bootstrap_nand), "Bootstrap NAND from game update partition")
+            ("enable_audio", bpo::bool_switch(), "Enable audio emulation (slow!)")
             ;
 
         boost::program_options::positional_options_description p;
@@ -252,6 +253,8 @@ int main(int argc, char* argv[]) {
             std::exit(1);
         }
 
+        settings.set<Settings::EnableAudioEmulation>(vm["enable_audio"].as<bool>());
+
         if (vm.count("input")) {
             Settings::InitialApplicationTag::HostFile file{vm["input"].as<std::string>()};
             settings.set<Settings::InitialApplicationTag>({file});
diff --git a/source/os.cpp b/source/os.cpp
index 99ead04..0c570ab 100644
--- a/source/os.cpp
+++ b/source/os.cpp
@@ -5432,6 +5432,17 @@ uint64_t OS::GetTimeInNanoSeconds() const {
 static ticks dsp_tick;
 OS* g_os = nullptr;
 
+static ticks GetDspTick(OS& os) {
+    if (os.settings.get<Settings::EnableAudioEmulation>()) {
+        // DSP clock rate is half the CPU clock rate
+        return os.system_tick / 2;
+    } else {
+        // Disabling DSP emulation entirely would break games.
+        // However we can safely underclock the DSP to save work.
+        return os.system_tick / 64;
+    }
+}
+
 void SetupOSDSPCallbacks(OS& os) {
     static auto dsp_interrupt_handlera = [&os]() {
         fprintf(stderr, "DSP INTERRUPT0\n");
@@ -5457,7 +5468,7 @@ void SetupOSDSPCallbacks(OS& os) {
         g_teakra->SetRecvDataHandler(2, dsp_interrupt_handlerc);
         g_teakra->SetSemaphoreHandler(dsp_interrupt_handler2);
     }
-    dsp_tick = os.system_tick / 2;
+    dsp_tick = GetDspTick(os);
 }
 
 void OS::EnterExecutionLoop() {
@@ -5479,7 +5490,7 @@ void OS::EnterExecutionLoop() {
 //        NotifyInterrupt(0x4a);
 //    };
 
-    /*auto */dsp_tick = system_tick / 2;
+    /*auto */dsp_tick = GetDspTick(*this);
 
     while (!stop_requested) {
         // TODO: Gather these from the "caller" (i.e. the coroutine)
@@ -5492,20 +5503,20 @@ void OS::EnterExecutionLoop() {
 //                g_teakra->SetRecvDataHandler(1, dsp_interrupt_handlerb);
 //                g_teakra->SetRecvDataHandler(2, dsp_interrupt_handlerc);
 //                g_teakra->SetSemaphoreHandler(dsp_interrupt_handler2);
-//                dsp_tick = system_tick / 2;
+//                dsp_tick = GetDspTick(*this);
 //            }
 
             // Run DSP time slices of at least 100 ticks.
             // This number was carefully chosen, since too large minimum bounds
             // trigger hangs.
-            auto dsp_tick_diff = system_tick / 2 - dsp_tick;
+            auto dsp_tick_diff = GetDspTick(*this) - dsp_tick;
             if (dsp_tick_diff.count() > 100) {
                 // For profiling, present DSP emulation as one logical fiber
                 TracyFiberEnter("DSP");
                 TracyCZoneN(DSPSliceZone, "DSPSlice", true);
 //                fprintf(stderr, "Running %d teakra cycles\n", (int)dsp_tick_diff.count());
                 g_teakra->Run(dsp_tick_diff.count());
-                dsp_tick = system_tick / 2;
+                dsp_tick = GetDspTick(*this);
                 TracyCZoneEnd(DSPSliceZone);
                 TracyFiberLeave;
             }
diff --git a/source/settings.cpp b/source/settings.cpp
index 2a0b42f..218ee73 100644
--- a/source/settings.cpp
+++ b/source/settings.cpp
@@ -35,4 +35,7 @@ Settings::Renderer OptionDefault<Settings::Renderer>::default_val = Settings::Re
 template<>
 Settings::ShaderEngine OptionDefault<Settings::ShaderEngine>::default_val = Settings::ShaderEngine::Bytecode;
 
+template<>
+bool BooleanOption<Settings::EnableAudioEmulation>::default_val = false;
+
 } // namespace Config