Introduce the possibility of operation type as a template parameter.

It's already proven possible to provide this for instruction fetch, so I think it'll immediately be a win. But more importantly it opens a path forwards for further improvement.
2024-11-21 21:33:54 +00:00 · 2023-11-27 11:48:34 -05:00 · 2023-11-27 11:48:34 -05:00 · 5c7f94d2ef
commit 5c7f94d2ef
parent ed31cfd80a
6 changed files with 117 additions and 87 deletions
--- a/Machines/Amiga/Amiga.cpp
+++ b/Machines/Amiga/Amiga.cpp
@ -80,11 +80,13 @@ class ConcreteMachine:
 		}

 		// MARK: - MC68000::BusHandler.
-		template <typename Microcycle> HalfCycles perform_bus_operation(const Microcycle &cycle, int) {
+		using Microcycle = CPU::MC68000::Microcycle;
+		template <Microcycle::OperationT op> HalfCycles perform_bus_operation(const Microcycle &cycle, int) {
+			const auto operation = (op != Microcycle::DecodeDynamically) ? op : cycle.operation;

 			// Do a quick advance check for Chip RAM access; add a suitable delay if required.
 			HalfCycles total_length;
-			if(cycle.operation & Microcycle::NewAddress && *cycle.address < 0x20'0000) {
+			if(operation & Microcycle::NewAddress && *cycle.address < 0x20'0000) {
 				total_length = chipset_.run_until_after_cpu_slot().duration;
 				assert(total_length >= cycle.length);
 			} else {
@ -94,19 +96,19 @@ class ConcreteMachine:
 			mc68000_.set_interrupt_level(chipset_.get_interrupt_level());

 			// Check for assertion of reset.
-			if(cycle.operation & Microcycle::Reset) {
+			if(operation & Microcycle::Reset) {
 				memory_.reset();
 				LOG("Reset; PC is around " << PADHEX(8) << mc68000_.get_state().registers.program_counter);
 			}

 			// Autovector interrupts.
-			if(cycle.operation & Microcycle::InterruptAcknowledge) {
+			if(operation & Microcycle::InterruptAcknowledge) {
 				mc68000_.set_is_peripheral_address(true);
 				return total_length - cycle.length;
 			}

 			// Do nothing if no address is exposed.
-			if(!(cycle.operation & (Microcycle::NewAddress | Microcycle::SameAddress))) return total_length - cycle.length;
+			if(!(operation & (Microcycle::NewAddress | Microcycle::SameAddress))) return total_length - cycle.length;

 			// Grab the target address to pick a memory source.
 			const uint32_t address = cycle.host_endian_byte_address();
@ -115,7 +117,7 @@ class ConcreteMachine:
 			mc68000_.set_is_peripheral_address((address & 0xe0'0000) == 0xa0'0000);

 			if(!memory_.regions[address >> 18].read_write_mask) {
-				if((cycle.operation & (Microcycle::SelectByte | Microcycle::SelectWord))) {
+				if((operation & (Microcycle::SelectByte | Microcycle::SelectWord))) {
 					// Check for various potential chip accesses.

 					// Per the manual:
@ -133,7 +135,7 @@ class ConcreteMachine:
 						const bool select_a = !(address & 0x1000);
 						const bool select_b = !(address & 0x2000);

-						if(cycle.operation & Microcycle::Read) {
+						if(operation & Microcycle::Read) {
 							uint16_t result = 0xffff;
 							if(select_a) result &= 0xff00 | (chipset_.cia_a.read(reg) << 0);
 							if(select_b) result &= 0x00ff | (chipset_.cia_b.read(reg) << 8);
@ -143,7 +145,7 @@ class ConcreteMachine:
 							if(select_b) chipset_.cia_b.write(reg, cycle.value8_high());
 						}

-//						LOG("CIA " << (((address >> 12) & 3)^3) << " " << (cycle.operation & Microcycle::Read ? "read " : "write ") << std::dec << (reg & 0xf) << " of " << PADHEX(4) << +cycle.value16());
+//						LOG("CIA " << (((address >> 12) & 3)^3) << " " << (operation & Microcycle::Read ? "read " : "write ") << std::dec << (reg & 0xf) << " of " << PADHEX(4) << +cycle.value16());
 					} else if(address >= 0xdf'f000 && address <= 0xdf'f1be) {
 						chipset_.perform(cycle);
 					} else if(address >= 0xe8'0000 && address < 0xe9'0000) {
@ -155,13 +157,13 @@ class ConcreteMachine:
 						memory_.perform(cycle);
 					} else {
 						// This'll do for open bus, for now.
-						if(cycle.operation & Microcycle::Read) {
+						if(operation & Microcycle::Read) {
 							cycle.set_value16(0xffff);
 						}

 						// Don't log for the region that is definitely just ROM this machine doesn't have.
 						if(address < 0xf0'0000) {
-							LOG("Unmapped " << (cycle.operation & Microcycle::Read ? "read from " : "write to ") << PADHEX(6) << ((*cycle.address)&0xffffff) << " of " << cycle.value16());
+							LOG("Unmapped " << (operation & Microcycle::Read ? "read from " : "write to ") << PADHEX(6) << ((*cycle.address)&0xffffff) << " of " << cycle.value16());
 						}
 					}
 				}
--- a/Machines/Apple/Macintosh/Macintosh.cpp
+++ b/Machines/Apple/Macintosh/Macintosh.cpp
@ -192,13 +192,14 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 		}

 		using Microcycle = CPU::MC68000::Microcycle;
+		template <Microcycle::OperationT op> HalfCycles perform_bus_operation(const Microcycle &cycle, int) {
+			const auto operation = (op != Microcycle::DecodeDynamically) ? op : cycle.operation;

-		HalfCycles perform_bus_operation(const Microcycle &cycle, int) {
 			// Advance time.
 			advance_time(cycle.length);

 			// A null cycle leaves nothing else to do.
-			if(!(cycle.operation & (Microcycle::NewAddress | Microcycle::SameAddress))) return HalfCycles(0);
+			if(!(operation & (Microcycle::NewAddress | Microcycle::SameAddress))) return HalfCycles(0);

 			// Grab the address.
 			auto address = cycle.host_endian_byte_address();
@ -218,7 +219,7 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 			// having set VPA above deals with those given that the generated address
 			// for interrupt acknowledge cycles always has all bits set except the
 			// lowest explicit address lines.
-			if(!cycle.data_select_active() || (cycle.operation & Microcycle::InterruptAcknowledge)) return HalfCycles(0);
+			if(!cycle.data_select_active() || (operation & Microcycle::InterruptAcknowledge)) return HalfCycles(0);

 			// Grab the word-precision address being accessed.
 			uint8_t *memory_base = nullptr;
@ -227,18 +228,18 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 				default: assert(false);

 				case BusDevice::Unassigned:
-					fill_unmapped(cycle);
+					fill_unmapped<op>(cycle);
 				return delay;

 				case BusDevice::VIA: {
 					if(*cycle.address & 1) {
-						fill_unmapped(cycle);
+						fill_unmapped<op>(cycle);
 					} else {
 						const int register_address = address >> 9;

 						// VIA accesses are via address 0xefe1fe + register*512,
 						// which at word precision is 0x77f0ff + register*256.
-						if(cycle.operation & Microcycle::Read) {
+						if(operation & Microcycle::Read) {
 							cycle.set_value8_high(via_.read(register_address));
 						} else {
 							via_.write(register_address, cycle.value8_high());
@ -247,7 +248,7 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 				} return delay;

 				case BusDevice::PhaseRead: {
-					if(cycle.operation & Microcycle::Read) {
+					if(operation & Microcycle::Read) {
 						cycle.set_value8_low(phase_ & 7);
 					}
 				} return delay;
@ -257,13 +258,13 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 						const int register_address = address >> 9;

 						// The IWM; this is a purely polled device, so can be run on demand.
-						if(cycle.operation & Microcycle::Read) {
+						if(operation & Microcycle::Read) {
 							cycle.set_value8_low(iwm_->read(register_address));
 						} else {
 							iwm_->write(register_address, cycle.value8_low());
 						}
 					} else {
-						fill_unmapped(cycle);
+						fill_unmapped<op>(cycle);
 					}
 				} return delay;

@ -274,14 +275,14 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 					// Even accesses = read; odd = write.
 					if(*cycle.address & 1) {
 						// Odd access => this is a write. Data will be in the upper byte.
-						if(cycle.operation & Microcycle::Read) {
+						if(operation & Microcycle::Read) {
 							scsi_.write(register_address, 0xff, dma_acknowledge);
 						} else {
 							scsi_.write(register_address, cycle.value8_high());
 						}
 					} else {
 						// Even access => this is a read.
-						if(cycle.operation & Microcycle::Read) {
+						if(operation & Microcycle::Read) {
 							cycle.set_value8_high(scsi_.read(register_address, dma_acknowledge));
 						}
 					}
@ -289,19 +290,19 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin

 				case BusDevice::SCCReadResetPhase: {
 					// Any word access here adjusts phase.
-					if(cycle.operation & Microcycle::SelectWord) {
+					if(operation & Microcycle::SelectWord) {
 						adjust_phase();
 					} else {
 						// A0 = 1 => reset; A0 = 0 => read.
 						if(*cycle.address & 1) {
 							scc_.reset();

-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								cycle.set_value16(0xffff);
 							}
 						} else {
 							const auto read = scc_.read(int(address >> 1));
-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								cycle.set_value8_high(read);
 							}
 						}
@ -310,20 +311,20 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin

 				case BusDevice::SCCWrite: {
 					// Any word access here adjusts phase.
-					if(cycle.operation & Microcycle::SelectWord) {
+					if(operation & Microcycle::SelectWord) {
 						adjust_phase();
 					} else {
 						// This is definitely a byte access; either it's to an odd address, in which
 						// case it will reach the SCC, or it isn't, in which case it won't.
 						if(*cycle.address & 1) {
-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								scc_.write(int(address >> 1), 0xff);
 								cycle.value->b = 0xff;
 							} else {
 								scc_.write(int(address >> 1), cycle.value->b);
 							}
 						} else {
-							fill_unmapped(cycle);
+							fill_unmapped<op>(cycle);
 						}
 					}
 				} return delay;
@ -351,7 +352,7 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 				} break;

 				case BusDevice::ROM: {
-					if(!(cycle.operation & Microcycle::Read)) return delay;
+					if(!(operation & Microcycle::Read)) return delay;
 					memory_base = rom_;
 					address &= rom_mask_;
 				} break;
@ -543,8 +544,10 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 			++phase_;
 		}

+		template <Microcycle::OperationT op>
 		forceinline void fill_unmapped(const Microcycle &cycle) {
-			if(!(cycle.operation & Microcycle::Read)) return;
+			const auto operation = (op != Microcycle::DecodeDynamically) ? op : cycle.operation;
+			if(!(operation & Microcycle::Read)) return;
 			cycle.set_value16(0xffff);
 		}

--- a/Machines/Atari/ST/AtariST.cpp
+++ b/Machines/Atari/ST/AtariST.cpp
@ -174,7 +174,10 @@ class ConcreteMachine:
 		}

 		// MARK: MC68000::BusHandler
-		template <typename Microcycle> HalfCycles perform_bus_operation(const Microcycle &cycle, int is_supervisor) {
+		using Microcycle = CPU::MC68000::Microcycle;
+		template <Microcycle::OperationT op> HalfCycles perform_bus_operation(const Microcycle &cycle, int is_supervisor) {
+			const auto operation = (op != Microcycle::DecodeDynamically) ? op : cycle.operation;
+
 			// Just in case the last cycle was an interrupt acknowledge or bus error. TODO: find a better solution?
 			mc68000_.set_is_peripheral_address(false);
 			mc68000_.set_bus_error(false);
@ -183,15 +186,15 @@ class ConcreteMachine:
 			advance_time(cycle.length);

 			// Check for assertion of reset.
-			if(cycle.operation & Microcycle::Reset) {
+			if(operation & Microcycle::Reset) {
 				LOG("Unhandled Reset");
 			}

 			// A null cycle leaves nothing else to do.
-			if(!(cycle.operation & (Microcycle::NewAddress | Microcycle::SameAddress))) return HalfCycles(0);
+			if(!(operation & (Microcycle::NewAddress | Microcycle::SameAddress))) return HalfCycles(0);

 			// An interrupt acknowledge, perhaps?
-			if(cycle.operation & Microcycle::InterruptAcknowledge) {
+			if(operation & Microcycle::InterruptAcknowledge) {
 				// Current implementation: everything other than 6 (i.e. the MFP) is autovectored.
 				const int interrupt_level = cycle.word_address()&7;
 				if(interrupt_level != 6) {
@ -200,7 +203,7 @@ class ConcreteMachine:
 					mc68000_.set_is_peripheral_address(true);
 					return HalfCycles(0);
 				} else {
-					if(cycle.operation & Microcycle::SelectByte) {
+					if(operation & Microcycle::SelectByte) {
 						const int interrupt = mfp_->acknowledge_interrupt();
 						if(interrupt != Motorola::MFP68901::MFP68901::NoAcknowledgement) {
 							cycle.value->b = uint8_t(interrupt);
@ -217,7 +220,7 @@ class ConcreteMachine:

 			// If this is a new strobing of the address signal, test for bus error and pre-DTack delay.
 			HalfCycles delay(0);
-			if(cycle.operation & Microcycle::NewAddress) {
+			if(operation & Microcycle::NewAddress) {
 				// Bus error test.
 				if(
 					// Anything unassigned should generate a bus error.
@ -269,7 +272,7 @@ class ConcreteMachine:
 						TOS 1.0 appears to attempt to read from the catridge before it has setup
 						the bus error vector. Therefore I assume no bus error flows.
 					*/
-					switch(cycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
+					switch(operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
 						default: break;
 						case Microcycle::SelectWord | Microcycle::Read:
 							cycle.value->w = 0xffff;
@ -313,7 +316,7 @@ class ConcreteMachine:
 						case 0x8260:	case 0x8262:
 							if(!cycle.data_select_active()) return delay;

-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								cycle.set_value16(video_->read(int(address >> 1)));
 							} else {
 								video_->write(int(address >> 1), cycle.value16());
@ -324,7 +327,7 @@ class ConcreteMachine:
 						case 0x8604:	case 0x8606:	case 0x8608:	case 0x860a:	case 0x860c:
 							if(!cycle.data_select_active()) return delay;

-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								cycle.set_value16(dma_->read(int(address >> 1)));
 							} else {
 								dma_->write(int(address >> 1), cycle.value16());
@ -360,7 +363,7 @@ class ConcreteMachine:
 							advance_time(HalfCycles(2));
 							update_audio();

-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								cycle.set_value8_high(GI::AY38910::Utility::read(ay_));
 							} else {
 								// Net effect here: addresses with bit 1 set write to a register,
@ -380,7 +383,7 @@ class ConcreteMachine:
 						case 0xfa38:	case 0xfa3a:	case 0xfa3c:	case 0xfa3e:
 							if(!cycle.data_select_active()) return delay;

-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								cycle.set_value8_low(mfp_->read(int(address >> 1)));
 							} else {
 								mfp_->write(int(address >> 1), cycle.value8_low());
@ -394,7 +397,7 @@ class ConcreteMachine:
 							if(!cycle.data_select_active()) return delay;

 							const auto acia_ = (address & 4) ? &midi_acia_ : &keyboard_acia_;
-							if(cycle.operation & Microcycle::Read) {
+							if(operation & Microcycle::Read) {
 								cycle.set_value8_high((*acia_)->read(int(address >> 1)));
 							} else {
 								(*acia_)->write(int(address >> 1), cycle.value8_high());
@ -405,7 +408,7 @@ class ConcreteMachine:
 			}

 			// If control has fallen through to here, the access is either a read from ROM, or a read or write to RAM.
-			switch(cycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
+			switch(operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
 				default:
 				break;

--- a/Processors/68000/68000.hpp
+++ b/Processors/68000/68000.hpp
@ -85,6 +85,11 @@ struct Microcycle {
 	/// Provides the 68000's bus grant line — indicating whether a bus request has been acknowledged.
 	static constexpr OperationT BusGrant				= 1 << 12;

+	/// An otherwise invalid combination; used as the operaiton template parameter to @c perform_bus_operation if
+	/// the operation wasn't knowable in advance and the receiver should decode dynamically using the microcycle's
+	/// .operation field.
+	static constexpr OperationT DecodeDynamically		= NewAddress | SameAddress;
+
 	/// Contains a valid combination of the various static constexpr int flags, describing the operation
 	/// performed by this Microcycle.
 	OperationT operation = 0;
--- a/Processors/68000/Implementation/68000Implementation.hpp
+++ b/Processors/68000/Implementation/68000Implementation.hpp
@ -282,14 +282,17 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor

 	// Performs the bus operation and then applies a `Spend` of its length
 	// plus any additional length returned by the bus handler.
-#define PerformBusOperation(x)										\
-	delay = bus_handler_.perform_bus_operation(x, is_supervisor_);	\
+#define PerformBusOperation(x, op)												\
+	delay = bus_handler_.template perform_bus_operation<op>(x, is_supervisor_);	\
 	Spend(x.length + delay)

+// TODO: the templated operation type to perform_bus_operation is intended to allow a much
+// cheaper through cost where the operation is knowable in advance. So use that pathway.
+
 	// Performs no bus activity for the specified number of microcycles.
 #define IdleBus(n)						\
 	idle.length = HalfCycles((n) << 2);	\
-	PerformBusOperation(idle)
+	PerformBusOperation(idle, 0)

 	// Spin until DTACK, VPA or BERR is asserted (unless DTACK is implicit),
 	// holding the bus cycle provided.
@ -312,7 +315,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 	//
 	//	(1) wait until end of current 10-cycle window;
 	//	(2) run for the next 10-cycle window.
-#define CompleteAccess(x)												\
+#define CompleteAccess(x, op)											\
 	if(berr_) {															\
 		RaiseBusOrAddressError(AccessFault, x);							\
 	}																	\
@ -321,21 +324,21 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 	} else {															\
 		x.length = HalfCycles(4);										\
 	}																	\
-	PerformBusOperation(x)
+	PerformBusOperation(x, op)

 	// Performs the memory access implied by the announce, perform pair,
 	// honouring DTACK, BERR and VPA as necessary.
-#define AccessPair(val, announce, perform)					\
-	perform.value = &val;									\
-	if constexpr (!dtack_is_implicit) {						\
-		announce.length = HalfCycles(4);					\
-	}														\
-	if(*perform.address & (perform.operation >> 1) & 1) {	\
-		RaiseBusOrAddressError(AddressError, perform);		\
-	}														\
-	PerformBusOperation(announce);							\
-	WaitForDTACK(announce);									\
-	CompleteAccess(perform);
+#define AccessPair(val, announce, announce_op, perform, perform_op)		\
+	perform.value = &val;												\
+	if constexpr (!dtack_is_implicit) {									\
+		announce.length = HalfCycles(4);								\
+	}																	\
+	if(*perform.address & (perform.operation >> 1) & 1) {				\
+		RaiseBusOrAddressError(AddressError, perform);					\
+	}																	\
+	PerformBusOperation(announce, announce_op);							\
+	WaitForDTACK(announce);												\
+	CompleteAccess(perform, perform_op);

 	// Sets up the next data access size and read flags.
 #define SetupDataAccess(read_flag, select_flag)												\
@ -348,11 +351,11 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor

 	// Performs the access established by SetupDataAccess into val.
 #define Access(val)										\
-	AccessPair(val, access_announce, access)
+	AccessPair(val, access_announce, Microcycle::DecodeDynamically, access, Microcycle::DecodeDynamically)

 	// Reads the program (i.e. non-data) word from addr into val.
 #define ReadProgramWord(val)								\
-	AccessPair(val, read_program_announce, read_program);	\
+	AccessPair(val, read_program_announce, ReadProgramAnnounceOperation, read_program, ReadProgramOperation);	\
 	program_counter_.l += 2;

 	// Reads one futher word from the program counter and inserts it into
@ -377,7 +380,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 		// Spin in place, one cycle at a time, until one of DTACK,
 		// BERR or VPA is asserted.
 		BeginState(WaitForDTACK):
-			PerformBusOperation(awaiting_dtack);
+			PerformBusOperation(awaiting_dtack, 0);

 			if(dtack_ || berr_ || vpa_) {
 				MoveToStateDynamic(post_dtack_state_);
@ -601,8 +604,8 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 			temporary_address_.l = 0xffff'fff1 | uint32_t(captured_interrupt_level_ << 1);
 			interrupt_cycles[0].address = interrupt_cycles[1].address = &temporary_address_.l;
 			interrupt_cycles[0].value = interrupt_cycles[1].value = &temporary_value_.low;
-			PerformBusOperation(interrupt_cycles[0]);
-			CompleteAccess(interrupt_cycles[1]);		// ni
+			PerformBusOperation(interrupt_cycles[0], InterruptCycleOperations[0]);
+			CompleteAccess(interrupt_cycles[1], InterruptCycleOperations[1]);		// ni

 			// If VPA is set, autovector.
 			if(vpa_) {
@ -2627,11 +2630,11 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 			tas_cycles[3].value = tas_cycles[4].value = &operand_[0].low;

 			// First two parts: the read.
-			PerformBusOperation(tas_cycles[0]);
-			CompleteAccess(tas_cycles[1]);
+			PerformBusOperation(tas_cycles[0], TASOperations[0]);
+			CompleteAccess(tas_cycles[1], TASOperations[1]);

 			// Third part: processing time.
-			PerformBusOperation(tas_cycles[2]);
+			PerformBusOperation(tas_cycles[2], TASOperations[2]);

 			// Do the actual TAS operation.
 			status_.overflow_flag = status_.carry_flag = 0;
@ -2640,8 +2643,8 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor

 			// Final parts: write back.
 			operand_[0].b |= 0x80;
-			PerformBusOperation(tas_cycles[3]);
-			CompleteAccess(tas_cycles[4]);
+			PerformBusOperation(tas_cycles[3], TASOperations[3]);
+			CompleteAccess(tas_cycles[4], TASOperations[4]);

 			Prefetch();
 		MoveToStateSpecific(Decode);
@ -2755,7 +2758,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 		//
 		BeginState(RESET):
 			IdleBus(2);
-			PerformBusOperation(reset_cycle);
+			PerformBusOperation(reset_cycle, ResetOperation);
 			Prefetch();
 		MoveToStateSpecific(Decode);

@ -3081,13 +3084,13 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 	captured_interrupt_level_ = bus_interrupt_level_;

 	read_program.value = &prefetch_.high;
-	bus_handler_.perform_bus_operation(read_program_announce, is_supervisor_);
-	bus_handler_.perform_bus_operation(read_program, is_supervisor_);
+	bus_handler_.perform_bus_operation<ReadProgramAnnounceOperation>(read_program_announce, is_supervisor_);
+	bus_handler_.perform_bus_operation<ReadProgramOperation>(read_program, is_supervisor_);
 	program_counter_.l += 2;

 	read_program.value = &prefetch_.low;
-	bus_handler_.perform_bus_operation(read_program_announce, is_supervisor_);
-	bus_handler_.perform_bus_operation(read_program, is_supervisor_);
+	bus_handler_.perform_bus_operation<ReadProgramAnnounceOperation>(read_program_announce, is_supervisor_);
+	bus_handler_.perform_bus_operation<ReadProgramOperation>(read_program, is_supervisor_);
 	program_counter_.l += 2;
 }

--- a/Processors/68000/Implementation/68000Storage.hpp
+++ b/Processors/68000/Implementation/68000Storage.hpp
@ -184,12 +184,12 @@ struct ProcessorBase: public InstructionSet::M68k::NullFlowController {
 	Microcycle idle{0};

 	// Read a program word. All accesses via the program counter are word sized.
-	Microcycle read_program_announce {
-		Microcycle::Read | Microcycle::NewAddress | Microcycle::IsProgram
-	};
-	Microcycle read_program {
-		Microcycle::Read | Microcycle::SameAddress | Microcycle::SelectWord | Microcycle::IsProgram
-	};
+	static constexpr Microcycle::OperationT
+		ReadProgramAnnounceOperation = Microcycle::Read | Microcycle::NewAddress | Microcycle::IsProgram;
+	static constexpr Microcycle::OperationT
+		ReadProgramOperation = Microcycle::Read | Microcycle::SameAddress | Microcycle::SelectWord | Microcycle::IsProgram;
+	Microcycle read_program_announce { ReadProgramAnnounceOperation };
+	Microcycle read_program { ReadProgramOperation };

 	// Read a data word or byte.
 	Microcycle access_announce {
@ -200,21 +200,35 @@ struct ProcessorBase: public InstructionSet::M68k::NullFlowController {
 	};

 	// TAS.
+	static constexpr Microcycle::OperationT
+		TASOperations[5] = {
+			Microcycle::Read | Microcycle::NewAddress | Microcycle::IsData,
+			Microcycle::Read | Microcycle::SameAddress | Microcycle::IsData | Microcycle::SelectByte,
+			Microcycle::SameAddress,
+			Microcycle::SameAddress | Microcycle::IsData,
+			Microcycle::SameAddress | Microcycle::IsData | Microcycle::SelectByte,
+		};
 	Microcycle tas_cycles[5] = {
-		{ Microcycle::Read | Microcycle::NewAddress | Microcycle::IsData },
-		{ Microcycle::Read | Microcycle::SameAddress | Microcycle::IsData | Microcycle::SelectByte },
-		{ Microcycle::SameAddress },
-		{ Microcycle::SameAddress | Microcycle::IsData },
-		{ Microcycle::SameAddress | Microcycle::IsData | Microcycle::SelectByte },
+		{ TASOperations[0] },
+		{ TASOperations[1] },
+		{ TASOperations[2] },
+		{ TASOperations[3] },
+		{ TASOperations[4] },
 	};

 	// Reset.
-	Microcycle reset_cycle { Microcycle::Reset, HalfCycles(248) };
+	static constexpr Microcycle::OperationT ResetOperation = Microcycle::Reset;
+	Microcycle reset_cycle { ResetOperation, HalfCycles(248) };

 	// Interrupt acknowledge.
+	static constexpr Microcycle::OperationT
+		InterruptCycleOperations[2] = {
+			Microcycle::InterruptAcknowledge | Microcycle::Read | Microcycle::NewAddress,
+			Microcycle::InterruptAcknowledge | Microcycle::Read | Microcycle::SameAddress | Microcycle::SelectByte
+		};
 	Microcycle interrupt_cycles[2] = {
-		{ Microcycle::InterruptAcknowledge | Microcycle::Read | Microcycle::NewAddress },
-		{ Microcycle::InterruptAcknowledge | Microcycle::Read | Microcycle::SameAddress | Microcycle::SelectByte },
+		{ InterruptCycleOperations[0] },
+		{ InterruptCycleOperations[1] },
 	};

 	// Holding spot when awaiting DTACK/etc.