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https://github.com/TomHarte/CLK.git
synced 2024-11-29 12:50:28 +00:00
The actual work begins: starts implementing 65816 micro-ops.
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@ -29,6 +29,7 @@ class ProcessorBase: protected ProcessorStorage {
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inline void set_power_on(bool);
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inline void set_irq_line(bool);
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inline void set_nmi_line(bool);
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inline void set_reset_line(bool);
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void set_value_of_register(Register r, uint16_t value);
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inline bool is_jammed() const;
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@ -12,25 +12,25 @@ using namespace CPU::WDC65816;
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uint16_t ProcessorBase::get_value_of_register(Register r) const {
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switch (r) {
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// case Register::ProgramCounter: return pc_.full;
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// case Register::LastOperationAddress: return last_operation_pc_.full;
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// case Register::StackPointer: return s_;
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case Register::ProgramCounter: return pc_;
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case Register::LastOperationAddress: return last_operation_pc_;
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case Register::StackPointer: return s_;
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// case Register::Flags: return get_flags();
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// case Register::A: return a_;
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// case Register::X: return x_;
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// case Register::Y: return y_;
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case Register::A: return a_.full;
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case Register::X: return x_.full;
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case Register::Y: return y_.full;
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default: return 0;
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}
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}
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void ProcessorBase::set_value_of_register(Register r, uint16_t value) {
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switch (r) {
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// case Register::ProgramCounter: pc_.full = value; break;
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// case Register::StackPointer: s_ = uint8_t(value); break;
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case Register::ProgramCounter: pc_ = value; break;
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case Register::StackPointer: s_ = value; break;
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// case Register::Flags: set_flags(uint8_t(value)); break;
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// case Register::A: a_ = uint8_t(value); break;
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// case Register::X: x_ = uint8_t(value); break;
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// case Register::Y: y_ = uint8_t(value); break;
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case Register::A: a_ = value; break;
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case Register::X: x_ = value; break;
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case Register::Y: y_ = value; break;
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default: break;
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}
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}
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@ -7,28 +7,130 @@
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//
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template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles cycles) {
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auto int_cycles = cycles.as_integral();
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while(int_cycles--) {
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// Temporary storage for the next bus cycle.
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uint32_t bus_address = 0;
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uint8_t *bus_value = nullptr;
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uint8_t throwaway = 0;
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BusOperation bus_operation = BusOperation::None;
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Cycles number_of_cycles = cycles + cycles_left_to_run_;
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while(number_of_cycles > Cycles(0)) {
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const MicroOp operation = *next_op_;
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++next_op_;
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switch(operation) {
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//
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// Scheduling.
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//
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case OperationMoveToNextProgram:
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// The exception program will determine the appropriate way to respond
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// based on the pending exception if one exists; otherwise just do a
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// standard fetch-decode-execute.
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next_op_ = µ_ops_[instructions[pending_exceptions_ ? size_t(OperationSlot::Exception) : size_t(OperationSlot::FetchDecodeExecute)].program_offset];
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// TODO: reset instruction buffer.
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instruction_buffer_.clear();
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data_buffer_.clear();
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last_operation_pc_ = pc_;
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continue;
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case OperationDecode:
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// A VERY TEMPORARY piece of logging.
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printf("%02x\n", instruction_buffer_.value);
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active_instruction_ = &instructions[instruction_buffer_.value];
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next_op_ = µ_ops_[active_instruction_->program_offset];
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instruction_buffer_.clear();
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continue;
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//
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// PC fetches.
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//
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case CycleFetchIncrementPC:
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bus_address = pc_ | program_bank_;
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bus_value = instruction_buffer_.next();
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bus_operation = MOS6502Esque::Read; // TODO: indicate ReadOpcode when appropriate.
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++pc_;
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break;
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case CycleFetchPC:
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bus_address = pc_ | program_bank_;
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bus_value = &throwaway;
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bus_operation = MOS6502Esque::Read;
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break;
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//
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// Data movement.
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//
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case OperationCopyPCToData:
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data_buffer_.size = 2;
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data_buffer_.value = pc_;
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break;
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case OperationCopyInstructionToData:
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data_buffer_ = instruction_buffer_;
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break;
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//
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// Performance.
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//
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case OperationPerform:
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switch(active_instruction_->operation) {
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case CLD:
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// TODO.
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break;
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case LDX:
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// TODO.
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break;
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default:
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assert(false);
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}
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break;
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default:
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assert(false);
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}
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number_of_cycles -= bus_handler_.perform_bus_operation(bus_operation, bus_address, bus_value);
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}
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cycles_left_to_run_ = number_of_cycles;
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}
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void ProcessorBase::set_power_on(bool active) {
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if(active) {
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pending_exceptions_ |= PowerOn;
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} else {
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pending_exceptions_ &= ~PowerOn;
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}
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}
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void ProcessorBase::set_power_on(bool) {}
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void ProcessorBase::set_irq_line(bool) {}
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void ProcessorBase::set_nmi_line(bool) {}
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void ProcessorBase::set_irq_line(bool active) {
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if(active) {
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pending_exceptions_ |= IRQ;
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} else {
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pending_exceptions_ &= ~IRQ;
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}
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}
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void ProcessorBase::set_reset_line(bool active) {
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if(active) {
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pending_exceptions_ |= Reset;
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} else {
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pending_exceptions_ &= ~Reset;
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}
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}
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void ProcessorBase::set_nmi_line(bool active) {
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// This is edge triggered.
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if(active) {
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pending_exceptions_ |= NMI;
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}
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}
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// The 65816 can't jam.
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bool ProcessorBase::is_jammed() const { return false; }
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@ -988,6 +988,10 @@ ProcessorStorage::ProcessorStorage() {
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constructor.set_exception_generator(&ProcessorStorageConstructor::stack_exception);
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constructor.install_fetch_decode_execute();
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// Find any OperationMoveToNextProgram.
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next_op_ = micro_ops_.data();
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while(*next_op_ != OperationMoveToNextProgram) ++next_op_;
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#ifndef NDEBUG
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assert(micro_ops_.size() < 65536);
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printf("Generated %zd micro-ops in total; covered %d opcodes\n", micro_ops_.size(), constructor.opcode);
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@ -185,34 +185,29 @@ struct ProcessorStorage {
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FetchDecodeExecute
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};
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void set_power_on(bool power_on) {
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if(power_on) {
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// Set next_op_ to start the exception program.
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next_op_ = µ_ops_[instructions[size_t(OperationSlot::Exception)].program_offset];
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pending_exceptions_ = PowerOn;
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} else {
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pending_exceptions_ &= ~PowerOn;
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}
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}
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// Registers.
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RegisterPair16 a_;
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RegisterPair16 x_, y_;
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uint16_t pc_, s_;
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// A helper for testing.
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uint16_t last_operation_pc_;
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Instruction *active_instruction_;
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Cycles cycles_left_to_run_;
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// I.e. the offset for direct addressing (outside of emulation mode).
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uint16_t direct_;
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uint16_t direct_ = 0;
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// Banking registers are all stored with the relevant byte
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// shifted up bits 16–23.
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uint32_t data_bank_; // i.e. DBR.
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uint32_t program_bank_; // i.e. PBR.
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uint32_t data_bank_ = 0; // i.e. DBR.
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uint32_t program_bank_ = 0; // i.e. PBR.
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static constexpr int PowerOn = 1 << 0;
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static constexpr int Reset = 1 << 1;
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static constexpr int IRQ = 1 << 2;
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static constexpr int NMI = 1 << 3;
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int pending_exceptions_ = 0;
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int pending_exceptions_ = PowerOn; // By default.
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/// Defines a four-byte buffer which can be cleared or filled in single-byte increments from least significant byte
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/// to most significant.
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