Removes clock for NCR 5380.

It doesn't have one in real life, and now can live off the time counting that occurs on the SCSI bus.

Components/5380/ncr5380.cpp

@@ -18,6 +18,7 @@ NCR5380::NCR5380(SCSI::Bus &bus, int clock_rate) :
 	bus_(bus),
 	clock_rate_(clock_rate) {
 	device_id_ = bus_.add_device();
+	bus_.add_observer(this);
 }
 
 void NCR5380::write(int address, uint8_t value, bool dma_acknowledge) {
@@ -73,13 +74,14 @@ void NCR5380::write(int address, uint8_t value, bool dma_acknowledge) {
 
 				case 0x1:
 					arbitration_in_progress_ = true;
-					set_execution_state(ExecutionState::WatchingBusy);
+					set_execution_state(ExecutionState::WaitingForBusy);
 					lost_arbitration_ = false;
 				break;
 
 				default:
-					assert_data_bus_ = false; // TODO: proper logic for this.
+					assert_data_bus_ = false;
 					set_execution_state(ExecutionState::PerformingDMA);
+					bus_.update_observers();
 				break;
 			}
 			update_control_output();
@@ -229,11 +231,7 @@ void NCR5380::update_control_output() {
 	}
 }
 
-void NCR5380::run_for(Cycles cycles) {
-	if(state_ == ExecutionState::None) return;
-
-	const auto bus_state = bus_.get_state();
-	++time_in_state_;
+void NCR5380::scsi_bus_did_change(SCSI::Bus *, SCSI::BusState new_state, double time_since_change) {
 	switch(state_) {
 		default: break;
 
@@ -258,23 +256,20 @@ void NCR5380::run_for(Cycles cycles) {
 					(iii) check that BSY and SEL are inactive.
 		*/
 
+		case ExecutionState::WaitingForBusy:
+			if(!(new_state & SCSI::Line::Busy) || time_since_change < SCSI::DeskewDelay) return;
+			state_ = ExecutionState::WatchingBusy;
+
 		case ExecutionState::WatchingBusy:
-			if(bus_state & SCSI::Line::Busy) {
-				// Arbitration is lost only if a non-busy state had previously been observed.
-				if(time_in_state_ > 1) {
+			if(!(new_state & SCSI::Line::Busy)) {
 				lost_arbitration_ = true;
 				set_execution_state(ExecutionState::None);
-				} else {
-					time_in_state_ = 0;
 			}
-			} /* else {
-				arbitration_in_progress_ = true;
-			}*/
 
 			// Check for having hit 400ns (more or less) since BSY was inactive.
-			if(!lost_arbitration_ && time_in_state_ == int(int64_t(400) * int64_t(clock_rate_) / int64_t(1000000000))) {
+			if(time_since_change >= SCSI::BusSettleDelay) {
 //				arbitration_in_progress_ = false;
-				if(bus_.get_state() & SCSI::Line::SelectTarget) {
+				if(new_state & SCSI::Line::SelectTarget) {
 					lost_arbitration_ = true;
 					set_execution_state(ExecutionState::None);
 				} else {
@@ -287,9 +282,11 @@ void NCR5380::run_for(Cycles cycles) {
 		break;
 
 		case ExecutionState::PerformingDMA:
+			if(time_since_change < SCSI::DeskewDelay) return;
+
 			// Signal a DMA request if the request line is active, i.e. meaningful data is
 			// on the bus, and this device hasn't yet acknowledged it.
-			switch(bus_state & (SCSI::Line::Request | SCSI::Line::Acknowledge)) {
+			switch(new_state & (SCSI::Line::Request | SCSI::Line::Acknowledge)) {
 				case 0:
 					dma_request_ = false;
 				break;
@@ -311,15 +308,6 @@ void NCR5380::run_for(Cycles cycles) {
 }
 
 void NCR5380::set_execution_state(ExecutionState state) {
-	time_in_state_ = 0;
 	state_ = state;
 	if(state != ExecutionState::PerformingDMA) dma_operation_ = DMAOperation::Ready;
-	update_clocking_observer();
-}
-
-ClockingHint::Preference NCR5380::preferred_clocking() {
-	// Request real-time clocking if any sort of timed bus watching is ongoing,
-	// given that there's no knowledge in here as to what clocking other devices
-	// on the SCSI bus might be enjoying.
-	return (state_ < ExecutionState::WatchingBusy) ? ClockingHint::Preference::None : ClockingHint::Preference::RealTime;
 }

Components/5380/ncr5380.hpp

@@ -12,8 +12,6 @@
 #include <cstdint>
 
 #include "../../Storage/MassStorage/SCSI/SCSI.hpp"
-#include "../../ClockReceiver/ClockReceiver.hpp"
-#include "../../ClockReceiver/ClockingHintSource.hpp"
 
 
 namespace NCR {
@@ -22,7 +20,7 @@ namespace NCR5380 {
 /*!
 	Models the NCR 5380, a SCSI interface chip.
 */
-class NCR5380 final: public ClockingHint::Source {
+class NCR5380 final: public SCSI::Bus::Observer {
 	public:
 		NCR5380(SCSI::Bus &bus, int clock_rate);
 
@@ -32,25 +30,6 @@ class NCR5380 final: public ClockingHint::Source {
 		/*! Reads from @c address. */
 		uint8_t read(int address, bool dma_acknowledge = false);
 
-		/*!
-			As per its design manual:
-
-				"The NCR 5380 is a clockless device. Delays such as bus
-				free delay, bus set delay and bus settle delay are
-				implemented using gate delays."
-
-			Therefore this fictitious implementation of an NCR5380 needs
-			a way to track time even though the real one doesn't take in
-			a clock. This is provided by `run_for`.
-
-			Nevertheless, the clocking doesn't need to be very precise.
-			Please provide a clock that is close to 200,000 Hz.
-		*/
-		void run_for(Cycles);
-
-		/// As per ClockingHint::Source.
-		ClockingHint::Preference preferred_clocking() final;
-
 	private:
 		SCSI::Bus &bus_;
 
@@ -70,7 +49,7 @@ class NCR5380 final: public ClockingHint::Source {
 
 		enum class ExecutionState {
 			None,
-
+			WaitingForBusy,
 			WatchingBusy,
 			PerformingDMA,
 		} state_ = ExecutionState::None;
@@ -80,13 +59,14 @@ class NCR5380 final: public ClockingHint::Source {
 			TargetReceive,
 			InitiatorReceive
 		} dma_operation_ = DMAOperation::Ready;
-		int time_in_state_ = 0;
 		bool lost_arbitration_ = false, arbitration_in_progress_ = false;
 
 		void set_execution_state(ExecutionState state);
 
 		SCSI::BusState target_output();
 		void update_control_output();
+
+		void scsi_bus_did_change(SCSI::Bus *, SCSI::BusState new_state, double time_since_change) final;
 };
 
 }

Machines/Apple/Macintosh/Macintosh.cpp

@@ -140,7 +140,6 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 
 			// Also watch for changes in clocking requirement from the SCSI chip.
 			if(model == Analyser::Static::Macintosh::Target::Model::MacPlus) {
-				scsi_.set_clocking_hint_observer(this);
 				scsi_bus_.set_clocking_hint_observer(this);
 			}
 
@@ -505,7 +504,6 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 
 	private:
 		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) override {
-			scsi_is_clocked_ = scsi_.preferred_clocking() != ClockingHint::Preference::None;
 			scsi_bus_is_clocked_ = scsi_bus_.preferred_clocking() != ClockingHint::Preference::None;
 		}
 
@@ -599,7 +597,6 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 
 			// Update the SCSI if currently active.
 			if(model == Analyser::Static::Macintosh::Target::Model::MacPlus) {
-				if(scsi_is_clocked_) scsi_.run_for(Cycles(duration.as_int()));
 				if(scsi_bus_is_clocked_) scsi_bus_.run_for(duration);
 			}
 		}
@@ -744,7 +741,6 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 		SCSI::Bus scsi_bus_;
  		NCR::NCR5380::NCR5380 scsi_;
 		SCSI::Target::Target<SCSI::DirectAccessDevice> hard_drive_;
- 		bool scsi_is_clocked_ = false;
  		bool scsi_bus_is_clocked_ = false;
 
  		HalfCycles via_clock_;

Storage/MassStorage/SCSI/SCSI.cpp

@@ -76,6 +76,13 @@ ClockingHint::Preference Bus::preferred_clocking() {
 	return (dispatch_index_ < dispatch_times_.size()) ? ClockingHint::Preference::RealTime : ClockingHint::Preference::None;
 }
 
+void Bus::update_observers() {
+	const auto time_elapsed = double(time_in_state_.as_int()) * cycles_to_time_;
+	for(auto &observer: observers_) {
+		observer->scsi_bus_did_change(this, state_, time_elapsed);
+	}
+}
+
 void Bus::run_for(HalfCycles time) {
 	if(dispatch_index_ < dispatch_times_.size()) {
 		time_in_state_ += time;
@@ -87,9 +94,7 @@ void Bus::run_for(HalfCycles time) {
 		}
 
 		if(dispatch_index_ != old_index) {
-			for(auto &observer: observers_) {
-				observer->scsi_bus_did_change(this, state_, double(time_as_int) * cycles_to_time_);
-			}
+			update_observers();
 		}
 
 		if(preferred_clocking() == ClockingHint::Preference::None) {

Storage/MassStorage/SCSI/SCSI.hpp

@@ -132,6 +132,11 @@ class Bus: public ClockingHint::Source {
 		*/
 		void run_for(HalfCycles);
 
+		/*!
+			Forces a `scsi_bus_did_change` propagation now.
+		*/
+		void update_observers();
+
 		/// As per ClockingHint::Source.
 		ClockingHint::Preference preferred_clocking() final;