From d77ddaf4fa2e3118708f8620b4435587153e5cb4 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 4 Apr 2021 17:33:49 -0400
Subject: [PATCH] Switches the Electron to JustInTimeActor video.

Also reorders template parameters; I think that specifying a different time base is likely to be more common than using a divider.
---
 ClockReceiver/JustInTime.hpp                |  8 +--
 Machines/Apple/AppleIIgs/AppleIIgs.cpp      |  6 +--
 Machines/Atari/ST/AtariST.cpp               |  6 +--
 Machines/ColecoVision/ColecoVision.cpp      |  2 +-
 Machines/Electron/Electron.cpp              | 59 ++++++++-------------
 Machines/Electron/Video.cpp                 | 46 +++++++++-------
 Machines/Electron/Video.hpp                 | 18 +++----
 Machines/Sinclair/ZXSpectrum/ZXSpectrum.cpp |  2 +-
 8 files changed, 69 insertions(+), 78 deletions(-)

diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
index 0391515ad..35edfae7f 100644
--- a/ClockReceiver/JustInTime.hpp
+++ b/ClockReceiver/JustInTime.hpp
@@ -32,7 +32,7 @@
 
 	TODO: incorporate and codify AsyncJustInTimeActor.
 */
-template <class T, int multiplier = 1, int divider = 1, class LocalTimeScale = HalfCycles> class JustInTimeActor:
+template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int divider = 1> class JustInTimeActor:
 	public ClockingHint::Observer {
 	private:
 		/*!
@@ -47,7 +47,7 @@ template <class T, int multiplier = 1, int divider = 1, class LocalTimeScale = H
 		*/
 		class SequencePointAwareDeleter {
 			public:
-				explicit SequencePointAwareDeleter(JustInTimeActor<T, multiplier, divider, LocalTimeScale> *actor) noexcept
+				explicit SequencePointAwareDeleter(JustInTimeActor<T, LocalTimeScale, multiplier, divider> *actor) noexcept
 					: actor_(actor) {}
 
 				forceinline void operator ()(const T *const) const {
@@ -57,7 +57,7 @@ template <class T, int multiplier = 1, int divider = 1, class LocalTimeScale = H
 				}
 
 			private:
-				JustInTimeActor<T, multiplier, divider, LocalTimeScale> *const actor_;
+				JustInTimeActor<T, LocalTimeScale, multiplier, divider> *const actor_;
 		};
 
 		// This block of SFINAE determines whether objects of type T accepts Cycles or HalfCycles.
@@ -126,7 +126,7 @@ template <class T, int multiplier = 1, int divider = 1, class LocalTimeScale = H
 		///
 		/// Despite being const, this will flush the object and, if relevant, update the next sequence point.
 		[[nodiscard]] forceinline auto operator -> () const {
-			auto non_const_this = const_cast<JustInTimeActor<T, multiplier, divider, LocalTimeScale> *>(this);
+			auto non_const_this = const_cast<JustInTimeActor<T, LocalTimeScale, multiplier, divider> *>(this);
 			non_const_this->flush();
 			return std::unique_ptr<const T, SequencePointAwareDeleter>(&object_, SequencePointAwareDeleter(non_const_this));
 		}
diff --git a/Machines/Apple/AppleIIgs/AppleIIgs.cpp b/Machines/Apple/AppleIIgs/AppleIIgs.cpp
index 7c0d8ccc5..218da7d9e 100644
--- a/Machines/Apple/AppleIIgs/AppleIIgs.cpp
+++ b/Machines/Apple/AppleIIgs/AppleIIgs.cpp
@@ -1093,10 +1093,10 @@ class ConcreteMachine:
 		// MARK: - Other components.
 
 		Apple::Clock::ParallelClock clock_;
-		JustInTimeActor<Apple::IIgs::Video::Video, 1, 2, Cycles> video_;	// i.e. run video at 7Mhz.
-		JustInTimeActor<Apple::IIgs::ADB::GLU, 1, 4, Cycles> adb_glu_;		// i.e. 3,579,545Mhz.
+		JustInTimeActor<Apple::IIgs::Video::Video, Cycles, 1, 2> video_;	// i.e. run video at 7Mhz.
+		JustInTimeActor<Apple::IIgs::ADB::GLU, Cycles, 1, 4> adb_glu_;		// i.e. 3,579,545Mhz.
  		Zilog::SCC::z8530 scc_;
- 		JustInTimeActor<Apple::IWM, 1, 2, Cycles> iwm_;
+ 		JustInTimeActor<Apple::IWM, Cycles, 1, 2> iwm_;
  		Cycles cycles_since_clock_tick_;
 		Apple::Macintosh::DoubleDensityDrive drives35_[2];
 		Apple::Disk::DiskIIDrive drives525_[2];
diff --git a/Machines/Atari/ST/AtariST.cpp b/Machines/Atari/ST/AtariST.cpp
index 17800a525..1c3f496e0 100644
--- a/Machines/Atari/ST/AtariST.cpp
+++ b/Machines/Atari/ST/AtariST.cpp
@@ -479,9 +479,9 @@ class ConcreteMachine:
 		JustInTimeActor<Video> video_;
 
 		// The MFP runs at 819200/2673749ths of the CPU clock rate.
-		JustInTimeActor<Motorola::MFP68901::MFP68901, 819200, 2673749> mfp_;
-		JustInTimeActor<Motorola::ACIA::ACIA, 16> keyboard_acia_;
-		JustInTimeActor<Motorola::ACIA::ACIA, 16> midi_acia_;
+		JustInTimeActor<Motorola::MFP68901::MFP68901, HalfCycles, 819200, 2673749> mfp_;
+		JustInTimeActor<Motorola::ACIA::ACIA, HalfCycles, 16> keyboard_acia_;
+		JustInTimeActor<Motorola::ACIA::ACIA, HalfCycles, 16> midi_acia_;
 
 		Concurrency::DeferringAsyncTaskQueue audio_queue_;
 		GI::AY38910::AY38910<false> ay_;
diff --git a/Machines/ColecoVision/ColecoVision.cpp b/Machines/ColecoVision/ColecoVision.cpp
index 7f048d1ba..1f483fbb2 100644
--- a/Machines/ColecoVision/ColecoVision.cpp
+++ b/Machines/ColecoVision/ColecoVision.cpp
@@ -384,7 +384,7 @@ class ConcreteMachine:
 		}
 
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
-		JustInTimeActor<TI::TMS::TMS9918, 1, 1, HalfCycles> vdp_;
+		JustInTimeActor<TI::TMS::TMS9918> vdp_;
 
 		Concurrency::DeferringAsyncTaskQueue audio_queue_;
 		TI::SN76489 sn76489_;
diff --git a/Machines/Electron/Electron.cpp b/Machines/Electron/Electron.cpp
index 076547ff1..8b8c96db9 100644
--- a/Machines/Electron/Electron.cpp
+++ b/Machines/Electron/Electron.cpp
@@ -25,6 +25,8 @@
 #include "../Utility/Typer.hpp"
 #include "../../Analyser/Static/Acorn/Target.hpp"
 
+#include "../../ClockReceiver/JustInTime.hpp"
+
 #include "Interrupts.hpp"
 #include "Keyboard.hpp"
 #include "Plus3.hpp"
@@ -54,7 +56,7 @@ template <bool has_scsi_bus> class ConcreteMachine:
 				scsi_bus_(4'000'000),
 				hard_drive_(scsi_bus_, 0),
 				scsi_device_(scsi_bus_.add_device()),
-				video_output_(ram_),
+				video_(ram_),
 				sound_generator_(audio_queue_),
 				speaker_(sound_generator_) {
 			memset(key_states_, 0, sizeof(key_states_));
@@ -230,13 +232,15 @@ template <bool has_scsi_bus> class ConcreteMachine:
 				if(isReadOperation(operation)) {
 					*value = ram_[address];
 				} else {
-					if(address >= video_access_range_.low_address && address <= video_access_range_.high_address) update_display();
+					if(address >= video_access_range_.low_address && address <= video_access_range_.high_address) {
+						video_.flush();
+					}
 					ram_[address] = *value;
 				}
 
-				// for the entire frame, RAM is accessible only on odd cycles; in modes below 4
-				// it's also accessible only outside of the pixel regions
-				cycles += video_output_.get_cycles_until_next_ram_availability(int(cycles_since_display_update_.as_integral()) + 1);
+				// For the entire frame, RAM is accessible only on odd cycles; in modes below 4
+				// it's also accessible only outside of the pixel regions.
+				cycles += video_.last_valid()->get_cycles_until_next_ram_availability(video_.time_since_flush().template as<int>() + 1);
 			} else {
 				switch(address & 0xff0f) {
 					case 0xfe00:
@@ -274,10 +278,8 @@ template <bool has_scsi_bus> class ConcreteMachine:
 					case 0xfe08: case 0xfe09: case 0xfe0a: case 0xfe0b:
 					case 0xfe0c: case 0xfe0d: case 0xfe0e: case 0xfe0f:
 						if(!isReadOperation(operation)) {
-							update_display();
-							video_output_.write(address, *value);
-							video_access_range_ = video_output_.get_memory_access_range();
-							queue_next_display_interrupt();
+							video_->write(address, *value);
+							video_access_range_ = video_.last_valid()->get_memory_access_range();
 						}
 					break;
 					case 0xfe04:
@@ -483,18 +485,14 @@ template <bool has_scsi_bus> class ConcreteMachine:
 				}
 			}
 
-			cycles_since_display_update_ += Cycles(int(cycles));
+			if(video_ += Cycles(int(cycles))) {
+				signal_interrupt(video_.last_valid()->get_interrupts());
+			}
+
 			cycles_since_audio_update_ += Cycles(int(cycles));
 			if(cycles_since_audio_update_ > Cycles(16384)) update_audio();
 			tape_.run_for(Cycles(int(cycles)));
 
-			cycles_until_display_interrupt_ -= cycles;
-			if(cycles_until_display_interrupt_ < 0) {
-				signal_interrupt(next_display_interrupt_);
-				update_display();
-				queue_next_display_interrupt();
-			}
-
 			if(typer_) typer_->run_for(Cycles(int(cycles)));
 			if(plus3_) plus3_->run_for(Cycles(4*int(cycles)));
 			if(shift_restart_counter_) {
@@ -517,25 +515,25 @@ template <bool has_scsi_bus> class ConcreteMachine:
 		}
 
 		forceinline void flush() {
-			update_display();
+			video_.flush();
 			update_audio();
 			audio_queue_.perform();
 		}
 
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target) final {
-			video_output_.set_scan_target(scan_target);
+			video_->set_scan_target(scan_target);
 		}
 
 		Outputs::Display::ScanStatus get_scaled_scan_status() const final {
-			return video_output_.get_scaled_scan_status();
+			return video_->get_scaled_scan_status();
 		}
 
 		void set_display_type(Outputs::Display::DisplayType display_type) final {
-			video_output_.set_display_type(display_type);
+			video_->set_display_type(display_type);
 		}
 
 		Outputs::Display::DisplayType get_display_type() const final {
-			return video_output_.get_display_type();
+			return video_->get_display_type();
 		}
 
 		Outputs::Speaker::Speaker *get_speaker() final {
@@ -693,18 +691,6 @@ template <bool has_scsi_bus> class ConcreteMachine:
 		}
 
 		// MARK: - Work deferral updates.
-		inline void update_display() {
-			if(cycles_since_display_update_ > 0) {
-				video_output_.run_for(cycles_since_display_update_.flush<Cycles>());
-			}
-		}
-
-		inline void queue_next_display_interrupt() {
-			VideoOutput::Interrupt next_interrupt = video_output_.get_next_interrupt();
-			cycles_until_display_interrupt_ = next_interrupt.cycles;
-			next_display_interrupt_ = next_interrupt.interrupt;
-		}
-
 		inline void update_audio() {
 			speaker_.run_for(audio_queue_, cycles_since_audio_update_.divide(Cycles(SoundGenerator::clock_rate_divider)));
 		}
@@ -754,10 +740,7 @@ template <bool has_scsi_bus> class ConcreteMachine:
 		Electron::KeyboardMapper keyboard_mapper_;
 
 		// Counters related to simultaneous subsystems
-		Cycles cycles_since_display_update_ = 0;
 		Cycles cycles_since_audio_update_ = 0;
-		int cycles_until_display_interrupt_ = 0;
-		Interrupt next_display_interrupt_ = Interrupt::RealTimeClock;
 		VideoOutput::Range video_access_range_ = {0, 0xffff};
 
 		// Tape
@@ -794,7 +777,7 @@ template <bool has_scsi_bus> class ConcreteMachine:
 		}
 
 		// Outputs
-		VideoOutput video_output_;
+		JustInTimeActor<VideoOutput, Cycles> video_;
 
 		Concurrency::DeferringAsyncTaskQueue audio_queue_;
 		SoundGenerator sound_generator_;
diff --git a/Machines/Electron/Video.cpp b/Machines/Electron/Video.cpp
index 461057ebf..31f69fad6 100644
--- a/Machines/Electron/Video.cpp
+++ b/Machines/Electron/Video.cpp
@@ -234,7 +234,23 @@ void VideoOutput::output_pixels(int number_of_cycles) {
 
 void VideoOutput::run_for(const Cycles cycles) {
 	int number_of_cycles = int(cycles.as_integral());
+	const auto start_position = output_position_;
 	output_position_ = (output_position_ + number_of_cycles) % cycles_per_frame;
+
+	if(
+		(start_position < real_time_clock_interrupt_1 && output_position_ >= real_time_clock_interrupt_1) ||
+		(start_position < real_time_clock_interrupt_2 && output_position_ >= real_time_clock_interrupt_2)
+	) {
+		interrupts_ = Electron::Interrupt(interrupts_ | Electron::Interrupt::RealTimeClock);
+	}
+
+	if(
+		(start_position < display_end_interrupt_1 && output_position_ >= display_end_interrupt_1) ||
+		(start_position < display_end_interrupt_2 && output_position_ >= display_end_interrupt_2)
+	) {
+		interrupts_ = Electron::Interrupt(interrupts_ | Electron::Interrupt::DisplayEnd);
+	}
+
 	while(number_of_cycles) {
 		int draw_action_length = screen_map_[screen_map_pointer_].length;
 		int time_left_in_action = std::min(number_of_cycles, draw_action_length - cycles_into_draw_action_);
@@ -354,36 +370,30 @@ void VideoOutput::setup_base_address() {
 
 // MARK: - Interrupts
 
-VideoOutput::Interrupt VideoOutput::get_next_interrupt() {
-	VideoOutput::Interrupt interrupt;
-
+Cycles VideoOutput::get_next_sequence_point() {
 	if(output_position_ < real_time_clock_interrupt_1) {
-		interrupt.cycles = real_time_clock_interrupt_1 - output_position_;
-		interrupt.interrupt = RealTimeClock;
-		return interrupt;
+		return real_time_clock_interrupt_1 - output_position_;
 	}
 
 	if(output_position_ < display_end_interrupt_1) {
-		interrupt.cycles = display_end_interrupt_1 - output_position_;
-		interrupt.interrupt = DisplayEnd;
-		return interrupt;
+		return display_end_interrupt_1 - output_position_;
 	}
 
 	if(output_position_ < real_time_clock_interrupt_2) {
-		interrupt.cycles = real_time_clock_interrupt_2 - output_position_;
-		interrupt.interrupt = RealTimeClock;
-		return interrupt;
+		return real_time_clock_interrupt_2 - output_position_;
 	}
 
 	if(output_position_ < display_end_interrupt_2) {
-		interrupt.cycles = display_end_interrupt_2 - output_position_;
-		interrupt.interrupt = DisplayEnd;
-		return interrupt;
+		return display_end_interrupt_2 - output_position_;
 	}
 
-	interrupt.cycles = real_time_clock_interrupt_1 + cycles_per_frame - output_position_;
-	interrupt.interrupt = RealTimeClock;
-	return interrupt;
+	return real_time_clock_interrupt_1 + cycles_per_frame - output_position_;
+}
+
+Electron::Interrupt VideoOutput::get_interrupts() {
+	const auto interrupts = interrupts_;
+	interrupts_ = Electron::Interrupt(0);
+	return interrupts;
 }
 
 // MARK: - RAM timing and access information
diff --git a/Machines/Electron/Video.hpp b/Machines/Electron/Video.hpp
index 38507a6c2..db6a4e617 100644
--- a/Machines/Electron/Video.hpp
+++ b/Machines/Electron/Video.hpp
@@ -54,15 +54,6 @@ class VideoOutput {
 		*/
 		void write(int address, uint8_t value);
 
-		/*!
-			Describes an interrupt the video hardware will generate by its identity and scheduling time.
-		*/
-		struct Interrupt {
-			/// The interrupt that will be signalled.
-			Electron::Interrupt interrupt;
-			/// The number of cycles until it is signalled.
-			int cycles;
-		};
 		/*!
 			@returns the next interrupt that should be generated as a result of the video hardware.
 			The time until signalling returned is the number of cycles after the final one triggered
@@ -70,7 +61,12 @@ class VideoOutput {
 
 			This result may be mutated by calls to @c write.
 		*/
-		Interrupt get_next_interrupt();
+		Cycles get_next_sequence_point();
+
+		/*!
+			@returns a bit mask of all interrupts that have been triggered since the last call to get_interrupt().
+		*/
+		Electron::Interrupt get_interrupts();
 
 		/*!
 			@returns the number of cycles after (final cycle of last run_for batch + @c from_time)
@@ -136,6 +132,8 @@ class VideoOutput {
 		void emplace_pixel_line();
 		std::size_t screen_map_pointer_ = 0;
 		int cycles_into_draw_action_ = 0;
+
+		Electron::Interrupt interrupts_ = Electron::Interrupt(0);
 };
 
 }
diff --git a/Machines/Sinclair/ZXSpectrum/ZXSpectrum.cpp b/Machines/Sinclair/ZXSpectrum/ZXSpectrum.cpp
index 11e03c647..d6f9a2c3b 100644
--- a/Machines/Sinclair/ZXSpectrum/ZXSpectrum.cpp
+++ b/Machines/Sinclair/ZXSpectrum/ZXSpectrum.cpp
@@ -664,7 +664,7 @@ template<Model model> class ConcreteMachine:
 		}
 
 		// MARK: - Disc.
-		JustInTimeActor<Amstrad::FDC, 1, 1, Cycles> fdc_;
+		JustInTimeActor<Amstrad::FDC, Cycles> fdc_;
 
 		// MARK: - Automatic startup.
 		Cycles duration_to_press_enter_;