From b03d91d5dd470386f5aba15eefb1d020bdf20ab2 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 8 Jul 2022 15:38:29 -0400
Subject: [PATCH] Permit granular specification of what to flush.

---
 Machines/Amiga/Amiga.cpp                         |  2 +-
 Machines/MasterSystem/MasterSystem.cpp           | 12 ++++++++----
 Machines/TimedMachine.hpp                        |  9 +++++++--
 OSBindings/Mac/Clock Signal/Machine/CSMachine.mm |  4 ++--
 4 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/Machines/Amiga/Amiga.cpp b/Machines/Amiga/Amiga.cpp
index 5a345359b..30afa9f43 100644
--- a/Machines/Amiga/Amiga.cpp
+++ b/Machines/Amiga/Amiga.cpp
@@ -219,7 +219,7 @@ class ConcreteMachine:
 			mc68000_.run_for(cycles);
 		}
 
-		void flush_output() final {
+		void flush_output(Output) final {
 			flush();
 		}
 
diff --git a/Machines/MasterSystem/MasterSystem.cpp b/Machines/MasterSystem/MasterSystem.cpp
index 507b318df..6c5b9dc49 100644
--- a/Machines/MasterSystem/MasterSystem.cpp
+++ b/Machines/MasterSystem/MasterSystem.cpp
@@ -210,10 +210,14 @@ class ConcreteMachine:
 			z80_.run_for(cycles);
 		}
 
-		void flush_output() final {
-			vdp_.flush();
-			update_audio();
-			audio_queue_.perform();
+		void flush_output(Output output) final {
+			if(int(output) & int(Output::Video)) {
+				vdp_.flush();
+			}
+			if(int(output) & int(Output::Audio)) {
+				update_audio();
+				audio_queue_.perform();
+			}
 		}
 
 		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
diff --git a/Machines/TimedMachine.hpp b/Machines/TimedMachine.hpp
index df17baece..c741d9016 100644
--- a/Machines/TimedMachine.hpp
+++ b/Machines/TimedMachine.hpp
@@ -61,8 +61,13 @@ class TimedMachine {
 		virtual float get_confidence() { return 0.5f; }
 		virtual std::string debug_type() { return ""; }
 
-		/// Ensures all locally-buffered output is posted onward.
-		virtual void flush_output() {}
+		enum class Output {
+			Video = 1 << 0,
+			Audio = 1 << 1
+		};
+		/// Ensures all locally-buffered output is posted onward for the types of output indicated
+		/// by the bitfield argument.
+		virtual void flush_output(Output) {}
 
 	protected:
 		/// Runs the machine for @c cycles.
diff --git a/OSBindings/Mac/Clock Signal/Machine/CSMachine.mm b/OSBindings/Mac/Clock Signal/Machine/CSMachine.mm
index bb66f3461..579a66451 100644
--- a/OSBindings/Mac/Clock Signal/Machine/CSMachine.mm	
+++ b/OSBindings/Mac/Clock Signal/Machine/CSMachine.mm	
@@ -678,13 +678,13 @@ struct ActivityObserver: public Activity::Observer {
 
 - (void)audioQueueIsRunningDry:(nonnull CSAudioQueue *)audioQueue {
 	updater.update([self] {
-		updater.performer.machine->flush_output();
+		updater.performer.machine->flush_output(MachineTypes::TimedMachine::Output::Audio);
 	});
 }
 
 - (void)scanTargetViewDisplayLinkDidFire:(CSScanTargetView *)view now:(const CVTimeStamp *)now outputTime:(const CVTimeStamp *)outputTime {
 	updater.update([self] {
-		updater.performer.machine->flush_output();
+		updater.performer.machine->flush_output(MachineTypes::TimedMachine::Output::Video);
 		dispatch_async(dispatch_get_main_queue(), ^{
 			[self.view updateBacking];
 			[self.view draw];