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CLK/Processors/68000/Implementation/68000Implementation.hpp
Thomas Harte 9009645cea Add 'reset' functions.
2022-06-07 16:55:39 -04:00

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//
// 68000Implementation.hpp
// Clock Signal
//
// Created by Thomas Harte on 10/03/2019.
// Copyright © 2019 Thomas Harte. All rights reserved.
//
#define ccr() \
( \
(carry_flag_ ? 0x0001 : 0x0000) | \
(overflow_flag_ ? 0x0002 : 0x0000) | \
(zero_result_ ? 0x0000 : 0x0004) | \
(negative_flag_ ? 0x0008 : 0x0000) | \
(extend_flag_ ? 0x0010 : 0x0000) \
)
#define status() \
uint16_t( \
ccr() | \
(interrupt_level_ << 8) | \
(trace_flag_ ? 0x8000 : 0x0000) | \
(is_supervisor_ << 13) \
)
#define apply_ccr(x) \
carry_flag_ = (x) & 0x0001; \
overflow_flag_ = (x) & 0x0002; \
zero_result_ = ((x) & 0x0004) ^ 0x0004; \
negative_flag_ = (x) & 0x0008; \
extend_flag_ = (x) & 0x0010;
#define apply_status(x) \
apply_ccr(x) \
interrupt_level_ = ((x) >> 8) & 7; \
trace_flag_ = (x) & 0x8000; \
set_is_supervisor(!!(((x) >> 13) & 1));
#define get_bus_code() \
uint16_t( \
((active_step_->microcycle.operation & Microcycle::IsProgram) ? 0x02 : 0x01) | \
(is_supervisor_ << 2) | \
(active_program_ ? 0x08 : 0) | \
((active_step_->microcycle.operation & Microcycle::Read) ? 0x10 : 0) | \
(decoded_instruction_.full & 0xffe0) \
)
#define u_extend16(x) uint32_t(int16_t(x))
#define u_extend8(x) uint32_t(int8_t(x))
#define s_extend16(x) int32_t(int16_t(x))
#define s_extend8(x) int32_t(int8_t(x))
#define convert_to_bit_count_16(x) \
x = ((x & 0xaaaa) >> 1) + (x & 0x5555); \
x = ((x & 0xcccc) >> 2) + (x & 0x3333); \
x = ((x & 0xf0f0) >> 4) + (x & 0x0f0f); \
x = ((x & 0xff00) >> 8) + (x & 0x00ff);
// Sets the length of the next microcycle; if this is a debug build, also confirms
// that the microcycle being adjusted is the one that it's permissible to adjust.
#ifdef NDEBUG
#define set_next_microcycle_length(x) \
bus_program->microcycle.length = x
#else
#define set_next_microcycle_length(x) \
assert(bus_program->microcycle.is_resizeable); \
bus_program->microcycle.length = x
#endif
template <class T, bool dtack_is_implicit, bool signal_will_perform> void Processor<T, dtack_is_implicit, signal_will_perform>::run_for(HalfCycles duration) {
const HalfCycles remaining_duration = duration + half_cycles_left_to_run_;
// This loop counts upwards rather than downwards because it simplifies calculation of
// E as and when required.
HalfCycles cycles_run_for;
while(cycles_run_for < remaining_duration) {
/*
PERFORM THE CURRENT BUS STEP'S MICROCYCLE.
*/
switch(execution_state_) {
default:
case ExecutionState::Executing:
// Check for entry into the halted state.
if(halt_ && active_step_[0].microcycle.operation & Microcycle::NewAddress) {
execution_state_ = ExecutionState::Halted;
continue;
}
if(active_step_->microcycle.data_select_active()) {
// Check whether the processor needs to await DTack.
if(!dtack_is_implicit && !dtack_ && !bus_error_) {
execution_state_ = ExecutionState::WaitingForDTack;
dtack_cycle_ = active_step_->microcycle;
dtack_cycle_.length = HalfCycles(2);
dtack_cycle_.operation &= ~(Microcycle::SelectByte | Microcycle::SelectWord);
continue;
}
// Check for bus error.
if(bus_error_ && !is_starting_interrupt_) {
const auto offending_address = *active_step_->microcycle.address;
active_program_ = nullptr;
active_micro_op_ = long_exception_micro_ops_;
populate_bus_error_steps(2, status(), get_bus_code(), offending_address);
program_counter_.full -= 4;
active_step_ = &all_bus_steps_[active_micro_op_->bus_program];
}
}
// Check for an address error. Which I have assumed happens before the microcycle that
// would nominate the new address.
if(
(active_step_[0].microcycle.operation & Microcycle::NewAddress) &&
(active_step_[1].microcycle.operation & Microcycle::SelectWord) &&
*active_step_->microcycle.address & 1) {
const auto offending_address = *active_step_->microcycle.address;
active_program_ = nullptr;
active_micro_op_ = long_exception_micro_ops_;
populate_bus_error_steps(3, status(), get_bus_code(), offending_address);
program_counter_.full -= 4;
active_step_ = &all_bus_steps_[active_micro_op_->bus_program];
// TODO: the above is only correct prior to the final microcycle of an
// instruction. If an exception occurs in the final microcycle then
// the next instruction will already have moved into the current instruction
// slot (decoded_instruction_ in my terms).
// TODO: it's also not correct for a bus error that occurs during another exception.
}
// Perform the microcycle if it is of non-zero length. If this is an operation that
// would normally strobe one of the data selects and VPA is active, it will also need
// stretching.
if(active_step_->microcycle.length != HalfCycles(0)) {
if(is_peripheral_address_ && active_step_->microcycle.data_select_active()) {
auto cycle_copy = active_step_->microcycle;
cycle_copy.operation |= Microcycle::IsPeripheral;
// Length will be: (i) distance to next E cycle, plus (ii) difference between
// current length and a whole E cycle.
const auto phase_now = (e_clock_phase_ + cycles_run_for) % 20;
const auto time_to_boundary = (HalfCycles(20) - phase_now) % HalfCycles(20);
cycle_copy.length = HalfCycles(20) + time_to_boundary;
cycles_run_for +=
cycle_copy.length +
bus_handler_.perform_bus_operation(cycle_copy, is_supervisor_);
} else {
cycles_run_for +=
active_step_->microcycle.length +
bus_handler_.perform_bus_operation(active_step_->microcycle, is_supervisor_);
}
}
#ifdef LOG_TRACE
if(should_log && !(active_step_->microcycle.operation & Microcycle::IsProgram)) {
switch(active_step_->microcycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
default: break;
case Microcycle::SelectWord | Microcycle::Read:
printf("[%08x -> %04x] ", *active_step_->microcycle.address, active_step_->microcycle.value->full);
break;
case Microcycle::SelectByte | Microcycle::Read:
printf("[%08x -> %02x] ", *active_step_->microcycle.address, active_step_->microcycle.value->halves.low);
break;
case Microcycle::SelectWord:
printf("{%04x -> %08x} ", active_step_->microcycle.value->full, *active_step_->microcycle.address);
break;
case Microcycle::SelectByte:
printf("{%02x -> %08x} ", active_step_->microcycle.value->halves.low, *active_step_->microcycle.address);
break;
}
}
#endif
/*
PERFORM THE BUS STEP'S ACTION.
*/
switch(active_step_->action) {
default:
std::cerr << "Unimplemented 68000 bus step action: " << int(active_step_->action) << std::endl;
return;
break;
case BusStep::Action::None: break;
case BusStep::Action::IncrementEffectiveAddress0: effective_address_[0].full += 2; break;
case BusStep::Action::IncrementEffectiveAddress1: effective_address_[1].full += 2; break;
case BusStep::Action::DecrementEffectiveAddress0: effective_address_[0].full -= 2; break;
case BusStep::Action::DecrementEffectiveAddress1: effective_address_[1].full -= 2; break;
case BusStep::Action::IncrementProgramCounter: program_counter_.full += 2; break;
case BusStep::Action::IncrementEffectiveAddress0AlignStackPointer:
effective_address_[0].full += 2;
address_[7].full &= 0xffff'fffe;
break;
case BusStep::Action::AdvancePrefetch:
prefetch_queue_.halves.high = prefetch_queue_.halves.low;
// During prefetch advance seems to be the only time the interrupt inputs are sampled;
// TODO: determine whether this really happens on *every* advance.
if(bus_interrupt_level_ > interrupt_level_) {
pending_interrupt_level_ = bus_interrupt_level_;
}
break;
}
// Move to the next bus step.
++ active_step_;
break;
case ExecutionState::Stopped:
// If an interrupt (TODO: or reset) has finally arrived that will be serviced,
// exit the STOP.
if(bus_interrupt_level_ > interrupt_level_) {
pending_interrupt_level_ = bus_interrupt_level_;
program_counter_.full += 4; // Don't return to this stop.
execution_state_ = ExecutionState::WillBeginInterrupt;
continue;
}
// Otherwise continue being stopped.
cycles_run_for +=
stop_cycle_.length +
bus_handler_.perform_bus_operation(stop_cycle_, is_supervisor_);
continue;
case ExecutionState::WaitingForDTack:
// If DTack or bus error has been signalled, stop waiting.
if(dtack_ || bus_error_) {
execution_state_ = ExecutionState::Executing;
continue;
}
// Otherwise, signal another cycle of wait.
cycles_run_for +=
dtack_cycle_.length +
bus_handler_.perform_bus_operation(dtack_cycle_, is_supervisor_);
continue;
case ExecutionState::Halted:
if(!halt_) {
execution_state_ = ExecutionState::Executing;
continue;
}
cycles_run_for +=
stop_cycle_.length +
bus_handler_.perform_bus_operation(stop_cycle_, is_supervisor_);
continue;
case ExecutionState::WillBeginInterrupt:
#ifdef LOG_TRACE
// should_log = true;
#endif
active_program_ = nullptr;
active_micro_op_ = interrupt_micro_ops_;
execution_state_ = ExecutionState::Executing;
active_step_ = &all_bus_steps_[active_micro_op_->bus_program];
is_starting_interrupt_ = true;
break;
}
/*
FIND THE NEXT MICRO-OP IF UNKNOWN.
*/
if(active_step_->is_terminal()) {
while(true) {
// If there are any more micro-operations available, just move onwards.
if(active_micro_op_ && !active_micro_op_->is_terminal()) {
++active_micro_op_;
} else {
// Either the micro-operations for this instruction have been exhausted, or
// no instruction was ongoing. Either way, do a standard instruction operation.
if(pending_interrupt_level_) {
execution_state_ = ExecutionState::WillBeginInterrupt;
break;
}
if(trace_flag_ && last_trace_flag_) {
// The user has set the trace bit in the status register.
active_program_ = nullptr;
active_micro_op_ = short_exception_micro_ops_;
populate_trap_steps(9, status());
program_counter_.full -= 4;
} else {
#ifdef LOG_TRACE
if(should_log) {
std::cout << std::setfill('0');
std::cout << (extend_flag_ ? 'x' : '-') << (negative_flag_ ? 'n' : '-') << (zero_result_ ? '-' : 'z');
std::cout << (overflow_flag_ ? 'v' : '-') << (carry_flag_ ? 'c' : '-') << '\t';
std::cout << (is_supervisor_ ? 's' : 'u') << '\t';
for(int c = 0; c < 8; ++ c) std::cout << "d" << c << ":" << std::setw(8) << data_[c].full << " ";
for(int c = 0; c < 8; ++ c) std::cout << "a" << c << ":" << std::setw(8) << address_[c].full << " ";
if(is_supervisor_) {
std::cout << "usp:" << std::setw(8) << std::setfill('0') << stack_pointers_[0].full << " ";
} else {
std::cout << "ssp:" << std::setw(8) << std::setfill('0') << stack_pointers_[1].full << " ";
}
std::cout << '\n';
}
#endif
decoded_instruction_.full = prefetch_queue_.halves.high.full;
#ifndef NDEBUG
/* Debugging feature: reset the effective addresses and data latches, so that it's
more obvious if some of the instructions aren't properly feeding them. */
effective_address_[0].full = effective_address_[1].full = source_bus_data_.full = destination_bus_data_.full = 0x12344321;
#endif
#ifdef LOG_TRACE
if(should_log) {
std::cout << std::hex << (program_counter_.full - 4) << ": " << std::setw(4) << decoded_instruction_.full << '\t';
}
#endif
if constexpr (signal_will_perform) {
bus_handler_.will_perform(program_counter_.full - 4, decoded_instruction_.full);
}
#ifdef LOG_TRACE
// const uint32_t fetched_pc = (program_counter_.full - 4)&0xffffff;
// should_log |= fetched_pc == 0x6d9c;
// should_log = (fetched_pc >= 0x41806A && fetched_pc <= 0x418618);
// should_log |= fetched_pc == 0x4012A2;
// should_log &= fetched_pc != 0x4012AE;
// should_log = (fetched_pc >= 0x408D66) && (fetched_pc <= 0x408D84);
#endif
if(instructions[decoded_instruction_.full].micro_operations != Program::NoSuchProgram) {
if((instructions[decoded_instruction_.full].requires_supervisor) && !is_supervisor_) {
// A privilege violation has been detected.
active_program_ = nullptr;
active_micro_op_ = short_exception_micro_ops_;
populate_trap_steps(8, status());
// The location of the failed instruction is what should end up on the stack.
program_counter_.full -= 4;
} else {
// Standard instruction dispatch.
active_program_ = &instructions[decoded_instruction_.full];
active_micro_op_ = &all_micro_ops_[active_program_->micro_operations];
}
} else {
// The opcode fetched isn't valid.
active_program_ = nullptr;
active_micro_op_ = short_exception_micro_ops_;
// The location of the failed instruction is what should end up on the stack.
program_counter_.full -= 4;
#ifdef LOG_TRACE
// should_log = true;
#endif
// The vector used depends on whether this is a vanilla unrecognised instruction,
// or one on the A or F lines.
switch(decoded_instruction_.full >> 12) {
default:
populate_trap_steps(4, status());
break;
case 0xa:
populate_trap_steps(10, status());
break;
case 0xf:
populate_trap_steps(11, status());
break;
}
}
}
last_trace_flag_ = trace_flag_;
}
auto bus_program = &all_bus_steps_[active_micro_op_->bus_program];
using int_type = decltype(active_micro_op_->action);
switch(active_micro_op_->action) {
default:
std::cerr << "Unhandled 68000 micro op action " << std::hex << active_micro_op_->action << " within instruction " << decoded_instruction_.full << std::endl;
break;
case int_type(MicroOp::Action::None): break;
#define offset_pointer(x) reinterpret_cast<RegisterPair32 *>(&reinterpret_cast<uint8_t *>(static_cast<ProcessorStorage *>(this))[x])
#define source() offset_pointer(active_program_->source_offset)
#define source_address() address_[active_program_->source]
#define destination() offset_pointer(active_program_->destination_offset)
#define destination_address() address_[active_program_->dest]
case int_type(MicroOp::Action::PerformOperation):
#define sub_overflow() ((result ^ destination) & (destination ^ source))
#define add_overflow() ((result ^ destination) & ~(destination ^ source))
switch(active_program_->operation) {
/*
ABCD adds the lowest bytes form the source and destination using BCD arithmetic,
obeying the extend flag.
*/
case Operation::ABCD: {
// Pull out the two halves, for simplicity.
const uint8_t source = source()->halves.low.halves.low;
const uint8_t destination = destination()->halves.low.halves.low;
// Perform the BCD add by evaluating the two nibbles separately.
const int unadjusted_result = destination + source + (extend_flag_ ? 1 : 0);
int result = (destination & 0xf) + (source & 0xf) + (extend_flag_ ? 1 : 0);
if(result > 0x09) result += 0x06;
result += (destination & 0xf0) + (source & 0xf0);
if(result > 0x99) result += 0x60;
// Set all flags essentially as if this were normal addition.
zero_result_ |= result & 0xff;
extend_flag_ = carry_flag_ = uint_fast32_t(result & ~0xff);
negative_flag_ = result & 0x80;
overflow_flag_ = ~unadjusted_result & result & 0x80;
// Store the result.
destination()->halves.low.halves.low = uint8_t(result);
} break;
// ADD and ADDA add two quantities, the latter sign extending and without setting any flags;
// ADDQ and SUBQ act as ADD and SUB, but taking the second argument from the instruction code.
#define addop(a, b, x) a + b + (x ? 1 : 0)
#define subop(a, b, x) a - b - (x ? 1 : 0)
#define z_set(a, b) a = b
#define z_or(a, b) a |= b
#define addsubb(a, b, dest, op, overflow, x, zero_op) \
const int source = a; \
const int destination = b; \
const auto result = op(destination, source, x); \
\
dest = uint8_t(result); \
zero_op(zero_result_, dest); \
extend_flag_ = carry_flag_ = uint_fast32_t(result & ~0xff); \
negative_flag_ = result & 0x80; \
overflow_flag_ = overflow() & 0x80;
#define addsubw(a, b, dest, op, overflow, x, zero_op) \
const int source = a; \
const int destination = b; \
const auto result = op(destination, source, x); \
\
dest = uint16_t(result); \
zero_op(zero_result_, dest); \
extend_flag_ = carry_flag_ = uint_fast32_t(result & ~0xffff); \
negative_flag_ = result & 0x8000; \
overflow_flag_ = overflow() & 0x8000;
#define addsubl(a, b, dest, op, overflow, x, zero_op) \
const uint64_t source = a; \
const uint64_t destination = b; \
const auto result = op(destination, source, x); \
\
dest = uint32_t(result); \
zero_op(zero_result_, dest); \
extend_flag_ = carry_flag_ = uint_fast32_t(result >> 32); \
negative_flag_ = result & 0x80000000; \
overflow_flag_ = overflow() & 0x80000000;
#define addb(a, b, dest, x, z) addsubb(a, b, dest, addop, add_overflow, x, z)
#define subb(a, b, dest, x, z) addsubb(a, b, dest, subop, sub_overflow, x, z)
#define addw(a, b, dest, x, z) addsubw(a, b, dest, addop, add_overflow, x, z)
#define subw(a, b, dest, x, z) addsubw(a, b, dest, subop, sub_overflow, x, z)
#define addl(a, b, dest, x, z) addsubl(a, b, dest, addop, add_overflow, x, z)
#define subl(a, b, dest, x, z) addsubl(a, b, dest, subop, sub_overflow, x, z)
#define no_extend(op, a, b, c) op(a, b, c, 0, z_set)
#define extend(op, a, b, c) op(a, b, c, extend_flag_, z_or)
#define q() (((decoded_instruction_.full >> 9)&7) ? ((decoded_instruction_.full >> 9)&7) : 8)
case Operation::ADDb: {
no_extend( addb,
source()->halves.low.halves.low,
destination()->halves.low.halves.low,
destination()->halves.low.halves.low);
} break;
case Operation::ADDXb: {
extend( addb,
source()->halves.low.halves.low,
destination()->halves.low.halves.low,
destination()->halves.low.halves.low);
} break;
case Operation::ADDQb: {
no_extend( addb,
q(),
destination()->halves.low.halves.low,
destination()->halves.low.halves.low);
} break;
case Operation::ADDw: {
no_extend( addw,
source()->halves.low.full,
destination()->halves.low.full,
destination()->halves.low.full);
} break;
case Operation::ADDXw: {
extend( addw,
source()->halves.low.full,
destination()->halves.low.full,
destination()->halves.low.full);
} break;
case Operation::ADDQw: {
no_extend( addw,
q(),
destination()->halves.low.full,
destination()->halves.low.full);
} break;
case Operation::ADDl: {
no_extend( addl,
source()->full,
destination()->full,
destination()->full);
} break;
case Operation::ADDXl: {
extend( addl,
source()->full,
destination()->full,
destination()->full);
} break;
case Operation::ADDQl: {
no_extend( addl,
q(),
destination()->full,
destination()->full);
} break;
case Operation::SUBb: {
no_extend( subb,
source()->halves.low.halves.low,
destination()->halves.low.halves.low,
destination()->halves.low.halves.low);
} break;
case Operation::SUBXb: {
extend( subb,
source()->halves.low.halves.low,
destination()->halves.low.halves.low,
destination()->halves.low.halves.low);
} break;
case Operation::SUBQb: {
no_extend( subb,
q(),
destination()->halves.low.halves.low,
destination()->halves.low.halves.low);
} break;
case Operation::SUBw: {
no_extend( subw,
source()->halves.low.full,
destination()->halves.low.full,
destination()->halves.low.full);
} break;
case Operation::SUBXw: {
extend( subw,
source()->halves.low.full,
destination()->halves.low.full,
destination()->halves.low.full);
} break;
case Operation::SUBQw: {
no_extend( subw,
q(),
destination()->halves.low.full,
destination()->halves.low.full);
} break;
case Operation::SUBl: {
no_extend( subl,
source()->full,
destination()->full,
destination()->full);
} break;
case Operation::SUBXl: {
extend( subl,
source()->full,
destination()->full,
destination()->full);
} break;
case Operation::SUBQl: {
no_extend( subl,
q(),
destination()->full,
destination()->full);
} break;
case Operation::ADDQAl:
destination()->full += q();
break;
case Operation::SUBQAl:
destination()->full -= q();
break;
#undef addl
#undef addw
#undef addb
#undef subl
#undef subw
#undef subb
#undef addsubl
#undef addsubw
#undef addsubb
#undef q
#undef z_set
#undef z_or
#undef no_extend
#undef extend
#undef addop
#undef subop
case Operation::ADDAw:
destination()->full += u_extend16(source()->halves.low.full);
break;
case Operation::ADDAl:
destination()->full += source()->full;
break;
case Operation::SUBAw:
destination()->full -= u_extend16(source()->halves.low.full);
break;
case Operation::SUBAl:
destination()->full -= source()->full;
break;
// BRA: alters the program counter, exclusively via the prefetch queue.
case Operation::BRA: {
const int8_t byte_offset = int8_t(prefetch_queue_.halves.high.halves.low);
// A non-zero offset byte branches by just that amount; otherwise use the word
// after as an offset. In both cases, treat as signed.
if(byte_offset) {
program_counter_.full += uint32_t(byte_offset);
} else {
program_counter_.full += u_extend16(prefetch_queue_.halves.low.full);
}
program_counter_.full -= 2;
} break;
// Two BTSTs: set the zero flag according to the value of the destination masked by
// the bit named in the source modulo the operation size.
case Operation::BTSTb:
zero_result_ = destination()->full & (1 << (source()->full & 7));
break;
case Operation::BTSTl:
zero_result_ = destination()->full & (1 << (source()->full & 31));
break;
case Operation::BCLRb:
zero_result_ = destination()->full & (1 << (source()->full & 7));
destination()->full &= ~(1 << (source()->full & 7));
break;
case Operation::BCLRl:
zero_result_ = destination()->full & (1 << (source()->full & 31));
destination()->full &= ~(1 << (source()->full & 31));
// Clearing in the top word requires an extra four cycles.
set_next_microcycle_length(HalfCycles(8 + ((source()->full & 31) / 16) * 4));
break;
case Operation::BCHGl:
zero_result_ = destination()->full & (1 << (source()->full & 31));
destination()->full ^= 1 << (source()->full & 31);
set_next_microcycle_length(HalfCycles(4 + (((source()->full & 31) / 16) * 4)));
break;
case Operation::BCHGb:
zero_result_ = destination()->halves.low.halves.low & (1 << (source()->full & 7));
destination()->halves.low.halves.low ^= 1 << (source()->full & 7);
break;
case Operation::BSETl:
zero_result_ = destination()->full & (1 << (source()->full & 31));
destination()->full |= 1 << (source()->full & 31);
set_next_microcycle_length(HalfCycles(4 + (((source()->full & 31) / 16) * 4)));
break;
case Operation::BSETb:
zero_result_ = destination()->halves.low.halves.low & (1 << (source()->full & 7));
destination()->halves.low.halves.low |= 1 << (source()->full & 7);
break;
// Bcc: ordinarily evaluates the relevant condition and displacement size and then:
// if condition is false, schedules bus operations to get past this instruction;
// otherwise applies the offset and schedules bus operations to refill the prefetch queue.
//
// Special case: the condition code is 1, which is ordinarily false. In that case this
// is the trailing step of a BSR.
case Operation::Bcc: {
// Grab the 8-bit offset.
const int8_t byte_offset = int8_t(prefetch_queue_.halves.high.halves.low);
// Check whether this is secretly BSR.
const bool is_bsr = ((decoded_instruction_.full >> 8) & 0xf) == 1;
// Test the conditional, treating 'false' as true.
const bool should_branch = is_bsr || evaluate_condition(decoded_instruction_.full >> 8);
// Schedule something appropriate, by rewriting the program for this instruction temporarily.
if(should_branch) {
if(byte_offset) {
program_counter_.full += decltype(program_counter_.full)(byte_offset);
} else {
program_counter_.full += u_extend16(prefetch_queue_.halves.low.full);
}
program_counter_.full -= 2;
bus_program = is_bsr ? bsr_bus_steps_ : branch_taken_bus_steps_;
} else {
if(byte_offset) {
bus_program = branch_byte_not_taken_bus_steps_;
} else {
bus_program = branch_word_not_taken_bus_steps_;
}
}
} break;
case Operation::DBcc: {
// Decide what sort of DBcc this is.
if(!evaluate_condition(decoded_instruction_.full >> 8)) {
-- source()->halves.low.full;
const auto target_program_counter = program_counter_.full + u_extend16(prefetch_queue_.halves.low.full) - 2;
if(source()->halves.low.full == 0xffff) {
// This DBcc will be ignored as the counter has underflowed.
// Schedule n np np np and continue. Assumed: the first np
// is from where the branch would have been if taken?
bus_program = dbcc_condition_false_no_branch_steps_;
dbcc_false_address_ = target_program_counter;
} else {
// Take the branch. Change PC and schedule n np np.
bus_program = dbcc_condition_false_branch_steps_;
program_counter_.full = target_program_counter;
}
} else {
// This DBcc will be ignored as the condition is true;
// perform nn np np and continue.
bus_program = dbcc_condition_true_steps_;
}
} break;
case Operation::Scc: {
destination()->halves.low.halves.low =
evaluate_condition(decoded_instruction_.full >> 8) ? 0xff : 0x00;
} break;
/*
CLRs: store 0 to the destination, set the zero flag, and clear
negative, overflow and carry.
*/
case Operation::CLRb:
destination()->halves.low.halves.low = 0;
negative_flag_ = overflow_flag_ = carry_flag_ = zero_result_ = 0;
break;
case Operation::CLRw:
destination()->halves.low.full = 0;
negative_flag_ = overflow_flag_ = carry_flag_ = zero_result_ = 0;
break;
case Operation::CLRl:
destination()->full = 0;
negative_flag_ = overflow_flag_ = carry_flag_ = zero_result_ = 0;
break;
/*
CMP.b, CMP.l and CMP.w: sets the condition flags (other than extend) based on a subtraction
of the source from the destination; the result of the subtraction is not stored.
*/
case Operation::CMPb: {
const uint8_t source = source()->halves.low.halves.low;
const uint8_t destination = destination()->halves.low.halves.low;
const int result = destination - source;
zero_result_ = result & 0xff;
carry_flag_ = decltype(carry_flag_)(result & ~0xff);
negative_flag_ = result & 0x80;
overflow_flag_ = sub_overflow() & 0x80;
} break;
case Operation::CMPw: {
const uint16_t source = source()->halves.low.full;
const uint16_t destination = destination()->halves.low.full;
const int result = destination - source;
zero_result_ = result & 0xffff;
carry_flag_ = decltype(carry_flag_)(result & ~0xffff);
negative_flag_ = result & 0x8000;
overflow_flag_ = sub_overflow() & 0x8000;
} break;
case Operation::CMPAw: {
const auto source = uint64_t(u_extend16(source()->halves.low.full));
const uint64_t destination = destination()->full;
const auto result = destination - source;
zero_result_ = uint32_t(result);
carry_flag_ = result >> 32;
negative_flag_ = result & 0x80000000;
overflow_flag_ = sub_overflow() & 0x80000000;
} break;
case Operation::CMPl: {
const auto source = uint64_t(source()->full);
const auto destination = uint64_t(destination()->full);
const auto result = destination - source;
zero_result_ = uint32_t(result);
carry_flag_ = result >> 32;
negative_flag_ = result & 0x80000000;
overflow_flag_ = sub_overflow() & 0x80000000;
} break;
// JMP: copies EA(0) to the program counter.
case Operation::JMP:
program_counter_ = effective_address_[0];
break;
// JMP: copies the source bus data to the program counter.
case Operation::RTS:
program_counter_ = source_bus_data_;
break;
/*
MOVE.b, MOVE.l and MOVE.w: move the least significant byte or word, or the entire long word,
and set negative, zero, overflow and carry as appropriate.
*/
case Operation::MOVEb:
zero_result_ = destination()->halves.low.halves.low = source()->halves.low.halves.low;
negative_flag_ = zero_result_ & 0x80;
overflow_flag_ = carry_flag_ = 0;
break;
case Operation::MOVEw:
zero_result_ = destination()->halves.low.full = source()->halves.low.full;
negative_flag_ = zero_result_ & 0x8000;
overflow_flag_ = carry_flag_ = 0;
break;
case Operation::MOVEl:
zero_result_ = destination()->full = source()->full;
negative_flag_ = zero_result_ & 0x80000000;
overflow_flag_ = carry_flag_ = 0;
break;
/*
MOVE.q: a single byte is moved from the current instruction, and sign extended.
*/
case Operation::MOVEq:
zero_result_ = destination()->full = prefetch_queue_.halves.high.halves.low;
negative_flag_ = zero_result_ & 0x80;
overflow_flag_ = carry_flag_ = 0;
destination()->full |= negative_flag_ ? 0xffffff00 : 0;
break;
/*
MOVEA.l: move the entire long word;
MOVEA.w: move the least significant word and sign extend it.
Neither sets any flags.
*/
case Operation::MOVEAw:
destination()->halves.low.full = source()->halves.low.full;
destination()->halves.high.full = (destination()->halves.low.full & 0x8000) ? 0xffff : 0;
break;
case Operation::MOVEAl:
destination()->full = source()->full;
break;
case Operation::PEA:
destination_bus_data_ = effective_address_[0];
break;
/*
Status word moves and manipulations.
*/
case Operation::MOVEtoSR:
apply_status(source()->full);
break;
case Operation::MOVEfromSR:
destination()->halves.low.full = status();
break;
case Operation::MOVEtoCCR:
apply_ccr(source()->full);
break;
case Operation::EXTbtow:
destination()->halves.low.halves.high =
(destination()->halves.low.halves.low & 0x80) ? 0xff : 0x00;
overflow_flag_ = carry_flag_ = 0;
zero_result_ = destination()->halves.low.full;
negative_flag_ = zero_result_ & 0x8000;
break;
case Operation::EXTwtol:
destination()->halves.high.full =
(destination()->halves.low.full & 0x8000) ? 0xffff : 0x0000;
overflow_flag_ = carry_flag_ = 0;
zero_result_ = destination()->full;
negative_flag_ = zero_result_ & 0x80000000;
break;
#define and_op(a, b) a &= b
#define or_op(a, b) a |= b
#define eor_op(a, b) a ^= b
#define apply(op, func) {\
auto status = status(); \
op(status, prefetch_queue_.halves.high.full); \
func(status); \
program_counter_.full -= 2; \
}
#define apply_op_sr(op) apply(op, apply_status)
#define apply_op_ccr(op) apply(op, apply_ccr)
case Operation::ANDItoSR: apply_op_sr(and_op); break;
case Operation::EORItoSR: apply_op_sr(eor_op); break;
case Operation::ORItoSR: apply_op_sr(or_op); break;
case Operation::ANDItoCCR: apply_op_ccr(and_op); break;
case Operation::EORItoCCR: apply_op_ccr(eor_op); break;
case Operation::ORItoCCR: apply_op_ccr(or_op); break;
#undef apply_op_ccr
#undef apply_op_sr
#undef apply
#undef eor_op
#undef or_op
#undef and_op
/*
Multiplications.
*/
case Operation::MULU: {
destination()->full = destination()->halves.low.full * source()->halves.low.full;
carry_flag_ = overflow_flag_ = 0;
zero_result_ = destination()->full;
negative_flag_ = zero_result_ & 0x80000000;
int number_of_ones = source()->halves.low.full;
convert_to_bit_count_16(number_of_ones);
// Time taken = 38 cycles + 2 cycles per 1 in the source.
set_next_microcycle_length(HalfCycles(4 * number_of_ones + 34*2));
} break;
case Operation::MULS: {
destination()->full =
u_extend16(destination()->halves.low.full) * u_extend16(source()->halves.low.full);
carry_flag_ = overflow_flag_ = 0;
zero_result_ = destination()->full;
negative_flag_ = zero_result_ & 0x80000000;
// Find the number of 01 or 10 pairs in the 17-bit number
// formed by the source value with a 0 suffix.
int number_of_pairs = source()->halves.low.full;
number_of_pairs = (number_of_pairs ^ (number_of_pairs << 1)) & 0xffff;
convert_to_bit_count_16(number_of_pairs);
// Time taken = 38 cycles + 2 cycles per 1 in the source.
set_next_microcycle_length(HalfCycles(4 * number_of_pairs + 34*2));
} break;
/*
Divisions.
*/
#define announce_divide_by_zero() \
negative_flag_ = overflow_flag_ = 0; \
zero_result_ = 1; \
active_program_ = nullptr; \
active_micro_op_ = short_exception_micro_ops_; \
bus_program = &all_bus_steps_[active_micro_op_->bus_program]; \
\
populate_trap_steps(5, status()); \
bus_program->microcycle.length = HalfCycles(20); \
\
program_counter_.full -= 6;
case Operation::DIVU: {
carry_flag_ = 0;
// An attempt to divide by zero schedules an exception.
if(!source()->halves.low.full) {
// Schedule a divide-by-zero exception.
announce_divide_by_zero();
break;
}
uint32_t dividend = destination()->full;
uint32_t divisor = source()->halves.low.full;
const auto quotient = dividend / divisor;
// If overflow would occur, appropriate flags are set and the result is not written back.
if(quotient > 65535) {
overflow_flag_ = zero_result_ = negative_flag_ = 1;
set_next_microcycle_length(HalfCycles(3*2*2));
break;
}
const uint16_t remainder = uint16_t(dividend % divisor);
destination()->halves.high.full = remainder;
destination()->halves.low.full = uint16_t(quotient);
overflow_flag_ = 0;
zero_result_ = quotient;
negative_flag_ = zero_result_ & 0x8000;
// Calculate cost; this is based on the flowchart in yacht.txt.
// I could actually calculate the division result here, since this is
// a classic divide algorithm, but would rather that errors produce
// incorrect timing only, not incorrect timing plus incorrect results.
int cycles_expended = 12; // Covers the nn n to get into the loop.
divisor <<= 16;
for(int c = 0; c < 15; ++c) {
if(dividend & 0x80000000) {
dividend = (dividend << 1) - divisor;
cycles_expended += 4; // Easy; just the fixed nn iteration cost.
} else {
dividend <<= 1;
// Yacht.txt, and indeed a real microprogram, would just subtract here
// and test the sign of the result, but this is easier to follow:
if (dividend >= divisor) {
dividend -= divisor;
cycles_expended += 6; // i.e. the original nn plus one further n before going down the MSB=0 route.
} else {
cycles_expended += 8; // The costliest path (since in real life it's a subtraction and then a step
// back from there) — all costs accrue. So the fixed nn loop plus another n,
// plus another one.
}
}
}
set_next_microcycle_length(HalfCycles(cycles_expended * 2));
} break;
case Operation::DIVS: {
carry_flag_ = 0;
// An attempt to divide by zero schedules an exception.
if(!source()->halves.low.full) {
// Schedule a divide-by-zero exception.
announce_divide_by_zero()
break;
}
const int32_t signed_dividend = int32_t(destination()->full);
const int32_t signed_divisor = s_extend16(source()->halves.low.full);
const auto result_sign =
( (0 <= signed_dividend) - (signed_dividend < 0) ) *
( (0 <= signed_divisor) - (signed_divisor < 0) );
const uint32_t dividend = uint32_t(abs(signed_dividend));
const uint32_t divisor = uint32_t(abs(signed_divisor));
int cycles_expended = 12; // Covers the nn nnn n to get beyond the sign test.
if(signed_dividend < 0) {
cycles_expended += 2; // An additional microycle applies if the dividend is negative.
}
// Check for overflow. If it exists, work here is already done.
const auto quotient = dividend / divisor;
if(quotient > 32767) {
overflow_flag_ = 1;
set_next_microcycle_length(HalfCycles(6*2*2));
break;
}
const uint16_t remainder = uint16_t(signed_dividend % signed_divisor);
const int signed_quotient = result_sign*int(quotient);
destination()->halves.high.full = remainder;
destination()->halves.low.full = uint16_t(signed_quotient);
zero_result_ = decltype(zero_result_)(signed_quotient);
negative_flag_ = zero_result_ & 0x8000;
overflow_flag_ = 0;
// Algorithm here: there is a fixed cost per unset bit
// in the first 15 bits of the unsigned quotient.
auto positive_quotient_bits = ~quotient & 0xfffe;
convert_to_bit_count_16(positive_quotient_bits);
cycles_expended += 2 * positive_quotient_bits;
// There's then no way to terminate the loop that isn't at least ten cycles long;
// there's also a fixed overhead per bit. The two together add up to the 104 below.
cycles_expended += 104;
// This picks up at 'No more bits' in yacht.txt's diagram.
if(signed_divisor < 0) {
cycles_expended += 2;
} else if(signed_dividend < 0) {
cycles_expended += 4;
}
set_next_microcycle_length(HalfCycles(cycles_expended * 2));
} break;
#undef announce_divide_by_zero
/*
MOVEP: move words and long-words a byte at a time.
*/
case Operation::MOVEPtoMw:
// Write pattern is nW+ nw, which should write the low word of the source in big-endian form.
destination_bus_data_.halves.high.full = source()->halves.low.halves.high;
destination_bus_data_.halves.low.full = source()->halves.low.halves.low;
break;
case Operation::MOVEPtoMl:
// Write pattern is nW+ nWr+ nw+ nwr, which should write the source in big-endian form.
destination_bus_data_.halves.high.full = source()->halves.high.halves.high;
source_bus_data_.halves.high.full = source()->halves.high.halves.low;
destination_bus_data_.halves.low.full = source()->halves.low.halves.high;
source_bus_data_.halves.low.full = source()->halves.low.halves.low;
break;
case Operation::MOVEPtoRw:
// Read pattern is nRd+ nrd.
source()->halves.low.halves.high = destination_bus_data_.halves.high.halves.low;
source()->halves.low.halves.low = destination_bus_data_.halves.low.halves.low;
break;
case Operation::MOVEPtoRl:
// Read pattern is nRd+ nR+ nrd+ nr.
source()->halves.high.halves.high = destination_bus_data_.halves.high.halves.low;
source()->halves.high.halves.low = source_bus_data_.halves.high.halves.low;
source()->halves.low.halves.high = destination_bus_data_.halves.low.halves.low;
source()->halves.low.halves.low = source_bus_data_.halves.low.halves.low;
break;
/*
MOVEM: multi-word moves.
*/
#define setup_movem(words_per_reg, base) \
/* Count the number of long words to move. */ \
size_t total_to_move = 0; \
auto mask = next_word_; \
while(mask) { \
total_to_move += mask&1; \
mask >>= 1; \
} \
\
/* Twice that many words plus one will need to be moved */ \
bus_program = base + (64 - total_to_move*words_per_reg)*2; \
\
/* Fill in the proper addresses and targets. */ \
const auto mode = (decoded_instruction_.full >> 3) & 7; \
uint32_t start_address; \
if(mode <= 4) { \
start_address = destination_address().full; \
} else { \
start_address = effective_address_[1].full; \
} \
\
auto step = bus_program; \
uint32_t *address_storage = precomputed_addresses_; \
mask = next_word_; \
int offset = 0;
#define inc_action(x, v) x += v
#define dec_action(x, v) x -= v
#define write_address_sequence_long(action, l) \
while(mask) { \
if(mask&1) { \
address_storage[0] = start_address; \
action(start_address, 2); \
address_storage[1] = start_address; \
action(start_address, 2); \
\
step[0].microcycle.address = step[1].microcycle.address = address_storage; \
step[2].microcycle.address = step[3].microcycle.address = address_storage + 1; \
\
const auto target = (offset > 7) ? &address_[offset&7] : &data_[offset]; \
step[l].microcycle.value = step[l+1].microcycle.value = &target->halves.high; \
step[(l^2)].microcycle.value = step[(l^2)+1].microcycle.value = &target->halves.low; \
\
address_storage += 2; \
step += 4; \
} \
mask >>= 1; \
action(offset, 1); \
}
#define write_address_sequence_word(action) \
while(mask) { \
if(mask&1) { \
address_storage[0] = start_address; \
action(start_address, 2); \
\
step[0].microcycle.address = step[1].microcycle.address = address_storage; \
\
const auto target = (offset > 7) ? &address_[offset&7] : &data_[offset]; \
step[0].microcycle.value = step[1].microcycle.value = &target->halves.low; \
\
++ address_storage; \
step += 2; \
} \
mask >>= 1; \
action(offset, 1); \
}
case Operation::MOVEMtoRl: {
setup_movem(2, movem_read_steps_);
// Everything for move to registers is based on an incrementing
// address; per M68000PRM:
//
// "[If using the postincrement addressing mode then] the incremented address
// register contains the address of the last operand loaded plus the operand length.
// If the addressing register is also loaded from memory, the memory value is ignored
// and the register is written with the postincremented effective address."
//
// The latter part is dealt with by MicroOp::Action::MOVEMtoRComplete, which also
// does any necessary sign extension.
write_address_sequence_long(inc_action, 0);
// MOVEM to R always reads one word too many.
address_storage[0] = start_address;
step[0].microcycle.address = step[1].microcycle.address = address_storage;
step[0].microcycle.value = step[1].microcycle.value = &throwaway_value_;
movem_final_address_ = start_address;
} break;
case Operation::MOVEMtoRw: {
setup_movem(1, movem_read_steps_);
write_address_sequence_word(inc_action);
// MOVEM to R always reads one word too many.
address_storage[0] = start_address;
step[0].microcycle.address = step[1].microcycle.address = address_storage;
step[0].microcycle.value = step[1].microcycle.value = &throwaway_value_;
movem_final_address_ = start_address;
} break;
case Operation::MOVEMtoMl: {
setup_movem(2, movem_write_steps_);
// MOVEM to M counts downwards and enumerates the registers in reverse order
// if subject to the predecrementing mode; otherwise it counts upwards and
// operates exactly as does MOVEM to R.
//
// Note also: "The MC68000 and MC68010 write the initial register value
// (not decremented) [when writing a register that is providing
// pre-decrementing addressing]."
//
// Hence the decrementing register (if any) is updated
// by MicroOp::Action::MOVEMtoMComplete.
if(mode == 4) {
offset = 15;
start_address -= 2;
write_address_sequence_long(dec_action, 2);
movem_final_address_ = start_address + 2;
} else {
write_address_sequence_long(inc_action, 0);
}
} break;
case Operation::MOVEMtoMw: {
setup_movem(1, movem_write_steps_);
if(mode == 4) {
offset = 15;
start_address -= 2;
write_address_sequence_word(dec_action);
movem_final_address_ = start_address + 2;
} else {
write_address_sequence_word(inc_action);
}
} break;
#undef setup_movem
#undef write_address_sequence_long
#undef write_address_sequence_word
#undef inc_action
#undef dec_action
// TRAP, which is a nicer form of ILLEGAL.
case Operation::TRAP: {
// Select the trap steps as next; the initial microcycle should be 4 cycles long.
bus_program = trap_steps_;
populate_trap_steps((decoded_instruction_.full & 15) + 32, status());
set_next_microcycle_length(HalfCycles(12));
// The program counter to push is actually one slot ago.
program_counter_.full -= 2;
} break;
case Operation::TRAPV: {
if(overflow_flag_) {
// Select the trap steps as next; the initial microcycle should be skipped.
bus_program = trap_steps_;
populate_trap_steps(7, status());
set_next_microcycle_length(HalfCycles(4));
// Push the address after the TRAPV.
program_counter_.full -= 4;
}
} break;
case Operation::CHK: {
const bool is_under = s_extend16(destination()->halves.low.full) < 0;
const bool is_over = s_extend16(destination()->halves.low.full) > s_extend16(source()->halves.low.full);
overflow_flag_ = carry_flag_ = 0;
zero_result_ = destination()->halves.low.full;
// Test applied for N:
//
// if Dn < 0, set negative flag;
// otherwise, if Dn > <ea>, reset negative flag.
if(is_over) negative_flag_ = 0;
if(is_under) negative_flag_ = 1;
// No exception is the default course of action; deviate only if an
// exception is necessary.
if(is_under || is_over) {
bus_program = trap_steps_;
populate_trap_steps(6, status());
if(is_over) {
set_next_microcycle_length(HalfCycles(20));
} else {
set_next_microcycle_length(HalfCycles(24));
}
// The program counter to push is two slots ago as whatever was the correct prefetch
// to continue without an exception has already happened, just in case.
program_counter_.full -= 4;
}
} break;
/*
NEGs: negatives the destination, setting the zero,
negative, overflow and carry flags appropriate, and extend.
NB: since the same logic as SUB is used to calculate overflow,
and SUB calculates `destination - source`, the NEGs deliberately
label 'source' and 'destination' differently from Motorola.
*/
case Operation::NEGb: {
const int destination = 0;
const int source = destination()->halves.low.halves.low;
const auto result = destination - source;
destination()->halves.low.halves.low = uint8_t(result);
zero_result_ = result & 0xff;
extend_flag_ = carry_flag_ = decltype(carry_flag_)(result & ~0xff);
negative_flag_ = result & 0x80;
overflow_flag_ = sub_overflow() & 0x80;
} break;
case Operation::NEGw: {
const int destination = 0;
const int source = destination()->halves.low.full;
const auto result = destination - source;
destination()->halves.low.full = uint16_t(result);
zero_result_ = result & 0xffff;
extend_flag_ = carry_flag_ = decltype(carry_flag_)(result & ~0xffff);
negative_flag_ = result & 0x8000;
overflow_flag_ = sub_overflow() & 0x8000;
} break;
case Operation::NEGl: {
const uint64_t destination = 0;
const uint64_t source = destination()->full;
const auto result = destination - source;
destination()->full = uint32_t(result);
zero_result_ = uint_fast32_t(result);
extend_flag_ = carry_flag_ = result >> 32;
negative_flag_ = result & 0x80000000;
overflow_flag_ = sub_overflow() & 0x80000000;
} break;
/*
NEGXs: NEG, with extend.
*/
case Operation::NEGXb: {
const int source = destination()->halves.low.halves.low;
const int destination = 0;
const auto result = destination - source - (extend_flag_ ? 1 : 0);
destination()->halves.low.halves.low = uint8_t(result);
zero_result_ |= result & 0xff;
extend_flag_ = carry_flag_ = decltype(carry_flag_)(result & ~0xff);
negative_flag_ = result & 0x80;
overflow_flag_ = sub_overflow() & 0x80;
} break;
case Operation::NEGXw: {
const int source = destination()->halves.low.full;
const int destination = 0;
const auto result = destination - source - (extend_flag_ ? 1 : 0);
destination()->halves.low.full = uint16_t(result);
zero_result_ |= result & 0xffff;
extend_flag_ = carry_flag_ = decltype(carry_flag_)(result & ~0xffff);
negative_flag_ = result & 0x8000;
overflow_flag_ = sub_overflow() & 0x8000;
} break;
case Operation::NEGXl: {
const uint64_t source = destination()->full;
const uint64_t destination = 0;
const auto result = destination - source - (extend_flag_ ? 1 : 0);
destination()->full = uint32_t(result);
zero_result_ |= uint_fast32_t(result);
extend_flag_ = carry_flag_ = result >> 32;
negative_flag_ = result & 0x80000000;
overflow_flag_ = sub_overflow() & 0x80000000;
} break;
/*
The no-op.
*/
case Operation::None:
break;
/*
LINK and UNLINK help with stack frames, allowing a certain
amount of stack space to be allocated or deallocated.
*/
case Operation::LINK:
// Make space for the new long-word value, and set up
// the proper target address for the stack operations to follow.
address_[7].full -= 4;
effective_address_[1].full = address_[7].full;
// The current value of the address register will be pushed.
destination_bus_data_.full = source()->full;
// The address register will then contain the bottom of the stack,
// and the stack pointer will be offset.
source()->full = address_[7].full;
address_[7].full += u_extend16(prefetch_queue_.halves.low.full);
break;
case Operation::UNLINK:
address_[7].full = effective_address_[1].full + 2;
destination()->full = destination_bus_data_.full;
break;
/*
TAS: sets zero and negative depending on the current value of the destination,
and sets the high bit.
*/
case Operation::TAS:
overflow_flag_ = carry_flag_ = 0;
zero_result_ = destination()->halves.low.halves.low;
negative_flag_ = destination()->halves.low.halves.low & 0x80;
destination()->halves.low.halves.low |= 0x80;
break;
/*
Bitwise operators: AND, OR and EOR. All three clear the overflow and carry flags,
and set zero and negative appropriately.
*/
#define op_and(x, y) x &= y
#define op_or(x, y) x |= y
#define op_eor(x, y) x ^= y
#define bitwise(source, dest, sign_mask, operator) \
operator(dest, source); \
overflow_flag_ = carry_flag_ = 0; \
zero_result_ = dest; \
negative_flag_ = dest & sign_mask;
#define andx(source, dest, sign_mask) bitwise(source, dest, sign_mask, op_and)
#define eorx(source, dest, sign_mask) bitwise(source, dest, sign_mask, op_eor)
#define orx(source, dest, sign_mask) bitwise(source, dest, sign_mask, op_or)
#define op_bwl(name, op) \
case Operation::name##b: op(source()->halves.low.halves.low, destination()->halves.low.halves.low, 0x80); break; \
case Operation::name##w: op(source()->halves.low.full, destination()->halves.low.full, 0x8000); break; \
case Operation::name##l: op(source()->full, destination()->full, 0x80000000); break;
op_bwl(AND, andx);
op_bwl(EOR, eorx);
op_bwl(OR, orx);
#undef op_bwl
#undef orx
#undef eorx
#undef andx
#undef bitwise
#undef op_eor
#undef op_or
#undef op_and
// NOTs: take the logical inverse, affecting the negative and zero flags.
case Operation::NOTb:
destination()->halves.low.halves.low ^= 0xff;
zero_result_ = destination()->halves.low.halves.low;
negative_flag_ = zero_result_ & 0x80;
overflow_flag_ = carry_flag_ = 0;
break;
case Operation::NOTw:
destination()->halves.low.full ^= 0xffff;
zero_result_ = destination()->halves.low.full;
negative_flag_ = zero_result_ & 0x8000;
overflow_flag_ = carry_flag_ = 0;
break;
case Operation::NOTl:
destination()->full ^= 0xffffffff;
zero_result_ = destination()->full;
negative_flag_ = zero_result_ & 0x80000000;
overflow_flag_ = carry_flag_ = 0;
break;
#define sbcd() \
/* Perform the BCD arithmetic by evaluating the two nibbles separately. */ \
const int unadjusted_result = destination - source - (extend_flag_ ? 1 : 0); \
int result = (destination & 0xf) - (source & 0xf) - (extend_flag_ ? 1 : 0); \
if((result & 0x1f) > 0x09) result -= 0x06; \
result += (destination & 0xf0) - (source & 0xf0); \
extend_flag_ = carry_flag_ = decltype(carry_flag_)((result & 0x1ff) > 0x99); \
if(carry_flag_) result -= 0x60; \
\
/* Set all flags essentially as if this were normal subtraction. */ \
zero_result_ |= result & 0xff; \
negative_flag_ = result & 0x80; \
overflow_flag_ = unadjusted_result & ~result & 0x80; \
\
/* Store the result. */ \
destination()->halves.low.halves.low = uint8_t(result);
/*
SBCD subtracts the lowest byte of the source from that of the destination using
BCD arithmetic, obeying the extend flag.
*/
case Operation::SBCD: {
const uint8_t source = source()->halves.low.halves.low;
const uint8_t destination = destination()->halves.low.halves.low;
sbcd();
} break;
/*
NBCD is like SBCD except that the result is 0 - destination rather than
destination - source.
*/
case Operation::NBCD: {
const uint8_t source = destination()->halves.low.halves.low;
const uint8_t destination = 0;
sbcd();
} break;
// EXG and SWAP exchange/swap words or long words.
case Operation::EXG: {
const auto temporary = source()->full;
source()->full = destination()->full;
destination()->full = temporary;
} break;
case Operation::SWAP: {
const auto temporary = destination()->halves.low.full;
destination()->halves.low.full = destination()->halves.high.full;
destination()->halves.high.full = temporary;
zero_result_ = destination()->full;
negative_flag_ = temporary & 0x8000;
overflow_flag_ = carry_flag_ = 0;
} break;
#undef sbcd
/*
Shifts and rotates.
*/
#define set_neg_zero(v, m) \
zero_result_ = decltype(zero_result_)(v); \
negative_flag_ = zero_result_ & decltype(negative_flag_)(m);
#define set_neg_zero_overflow(v, m) \
set_neg_zero(v, m); \
overflow_flag_ = (decltype(zero_result_)(value) ^ zero_result_) & decltype(overflow_flag_)(m);
#define decode_shift_count() \
int shift_count = (decoded_instruction_.full & 32) ? data_[(decoded_instruction_.full >> 9) & 7].full&63 : ( ((decoded_instruction_.full >> 9)&7) ? ((decoded_instruction_.full >> 9)&7) : 8) ; \
set_next_microcycle_length(HalfCycles(4 * shift_count));
#define set_flags_b(t) set_flags(destination()->halves.low.halves.low, 0x80, t)
#define set_flags_w(t) set_flags(destination()->halves.low.full, 0x8000, t)
#define set_flags_l(t) set_flags(destination()->full, 0x80000000, t)
#define asl(destination, size) {\
decode_shift_count(); \
const auto value = destination; \
\
if(!shift_count) { \
carry_flag_ = overflow_flag_ = 0; \
} else { \
destination = (shift_count < size) ? decltype(destination)(value << shift_count) : 0; \
extend_flag_ = carry_flag_ = decltype(carry_flag_)(value) & decltype(carry_flag_)( (1u << (size - 1)) >> (shift_count - 1) ); \
\
if(shift_count >= size) overflow_flag_ = value && (value != decltype(value)(-1)); \
else { \
const auto mask = decltype(destination)(0xffffffff << (size - shift_count)); \
overflow_flag_ = mask & value && ((mask & value) != mask); \
} \
} \
\
set_neg_zero(destination, 1 << (size - 1)); \
}
case Operation::ASLm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = uint16_t(value << 1);
extend_flag_ = carry_flag_ = value & 0x8000;
set_neg_zero_overflow(destination()->halves.low.full, 0x8000);
} break;
case Operation::ASLb: asl(destination()->halves.low.halves.low, 8); break;
case Operation::ASLw: asl(destination()->halves.low.full, 16); break;
case Operation::ASLl: asl(destination()->full, 32); break;
#define asr(destination, size) {\
decode_shift_count(); \
const auto value = destination; \
\
if(!shift_count) { \
carry_flag_ = 0; \
} else { \
destination = (shift_count < size) ? \
decltype(destination)(\
(value >> shift_count) | \
((value & decltype(value)(1 << (size - 1)) ? 0xffffffff : 0x000000000) << (size - shift_count)) \
) : \
decltype(destination)( \
(value & decltype(value)(1 << (size - 1))) ? 0xffffffff : 0x000000000 \
); \
extend_flag_ = carry_flag_ = decltype(carry_flag_)(value) & decltype(carry_flag_)(1 << (shift_count - 1)); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ASRm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = (value&0x8000) | (value >> 1);
extend_flag_ = carry_flag_ = value & 1;
set_neg_zero_overflow(destination()->halves.low.full, 0x8000);
} break;
case Operation::ASRb: asr(destination()->halves.low.halves.low, 8); break;
case Operation::ASRw: asr(destination()->halves.low.full, 16); break;
case Operation::ASRl: asr(destination()->full, 32); break;
#undef set_neg_zero_overflow
#define set_neg_zero_overflow(v, m) \
set_neg_zero(v, m); \
overflow_flag_ = 0;
#undef set_flags
#define set_flags(v, m, t) \
zero_result_ = v; \
negative_flag_ = zero_result_ & (m); \
overflow_flag_ = 0; \
carry_flag_ = value & (t);
#define lsl(destination, size) {\
decode_shift_count(); \
const auto value = destination; \
\
if(!shift_count) { \
carry_flag_ = 0; \
} else { \
destination = (shift_count < size) ? decltype(destination)(value << shift_count) : 0; \
extend_flag_ = carry_flag_ = decltype(carry_flag_)(value) & decltype(carry_flag_)( (1u << (size - 1)) >> (shift_count - 1) ); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::LSLm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = uint16_t(value << 1);
extend_flag_ = carry_flag_ = value & 0x8000;
set_neg_zero_overflow(destination()->halves.low.full, 0x8000);
} break;
case Operation::LSLb: lsl(destination()->halves.low.halves.low, 8); break;
case Operation::LSLw: lsl(destination()->halves.low.full, 16); break;
case Operation::LSLl: lsl(destination()->full, 32); break;
#define lsr(destination, size) {\
decode_shift_count(); \
const auto value = destination; \
\
if(!shift_count) { \
carry_flag_ = 0; \
} else { \
destination = (shift_count < size) ? (value >> shift_count) : 0; \
extend_flag_ = carry_flag_ = value & decltype(carry_flag_)(1 << (shift_count - 1)); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::LSRm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = value >> 1;
extend_flag_ = carry_flag_ = value & 1;
set_neg_zero_overflow(destination()->halves.low.full, 0x8000);
} break;
case Operation::LSRb: lsr(destination()->halves.low.halves.low, 8); break;
case Operation::LSRw: lsr(destination()->halves.low.full, 16); break;
case Operation::LSRl: lsr(destination()->full, 32); break;
#define rol(destination, size) { \
decode_shift_count(); \
const auto value = destination; \
\
if(!shift_count) { \
carry_flag_ = 0; \
} else { \
shift_count &= (size - 1); \
destination = decltype(destination)( \
(value << shift_count) | \
(value >> (size - shift_count)) \
); \
carry_flag_ = decltype(carry_flag_)(destination & 1); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ROLm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = uint16_t((value << 1) | (value >> 15));
carry_flag_ = destination()->halves.low.full & 1;
set_neg_zero_overflow(destination()->halves.low.full, 0x8000);
} break;
case Operation::ROLb: rol(destination()->halves.low.halves.low, 8); break;
case Operation::ROLw: rol(destination()->halves.low.full, 16); break;
case Operation::ROLl: rol(destination()->full, 32); break;
#define ror(destination, size) { \
decode_shift_count(); \
const auto value = destination; \
\
if(!shift_count) { \
carry_flag_ = 0; \
} else { \
shift_count &= (size - 1); \
destination = decltype(destination)(\
(value >> shift_count) | \
(value << (size - shift_count)) \
);\
carry_flag_ = destination & decltype(carry_flag_)(1 << (size - 1)); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::RORm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = uint16_t((value >> 1) | (value << 15));
carry_flag_ = destination()->halves.low.full & 0x8000;
set_neg_zero_overflow(destination()->halves.low.full, 0x8000);
} break;
case Operation::RORb: ror(destination()->halves.low.halves.low, 8); break;
case Operation::RORw: ror(destination()->halves.low.full, 16); break;
case Operation::RORl: ror(destination()->full, 32); break;
#define roxl(destination, size) { \
decode_shift_count(); \
\
shift_count %= (size + 1); \
uint64_t compound = uint64_t(destination) | (extend_flag_ ? (1ull << size) : 0); \
compound = \
(compound << shift_count) | \
(compound >> (size + 1 - shift_count)); \
carry_flag_ = extend_flag_ = decltype(carry_flag_)((compound >> size) & 1); \
destination = decltype(destination)(compound); \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ROXLm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = uint16_t((value << 1) | (extend_flag_ ? 0x0001 : 0x0000));
extend_flag_ = value & 0x8000;
set_flags_w(0x8000);
} break;
case Operation::ROXLb: roxl(destination()->halves.low.halves.low, 8); break;
case Operation::ROXLw: roxl(destination()->halves.low.full, 16); break;
case Operation::ROXLl: roxl(destination()->full, 32); break;
#define roxr(destination, size) { \
decode_shift_count(); \
\
shift_count %= (size + 1); \
uint64_t compound = uint64_t(destination) | (extend_flag_ ? (1ull << size) : 0); \
compound = \
(compound >> shift_count) | \
(compound << (size + 1 - shift_count)); \
carry_flag_ = extend_flag_ = decltype(carry_flag_)((compound >> size) & 1); \
destination = decltype(destination)(compound); \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ROXRm: {
const auto value = destination()->halves.low.full;
destination()->halves.low.full = (value >> 1) | (extend_flag_ ? 0x8000 : 0x0000);
extend_flag_ = value & 0x0001;
set_flags_w(0x0001);
} break;
case Operation::ROXRb: roxr(destination()->halves.low.halves.low, 8); break;
case Operation::ROXRw: roxr(destination()->halves.low.full, 16); break;
case Operation::ROXRl: roxr(destination()->full, 32); break;
#undef roxr
#undef roxl
#undef ror
#undef rol
#undef asr
#undef lsr
#undef lsl
#undef asl
#undef set_flagsx
#undef decode_shift_count
#undef set_flags_b
#undef set_flags_w
#undef set_flags_l
#undef set_neg_zero_overflow
#undef set_neg_zero
/*
RTE and RTR share an implementation.
*/
case Operation::RTE_RTR:
// If this is RTR, patch out the supervisor half of the status register.
if(decoded_instruction_.full == 0x4e77) {
const auto current_status = status();
source_bus_data_.halves.low.halves.high =
uint8_t(current_status >> 8);
}
apply_status(source_bus_data_.full);
break;
/*
TSTs: compare to zero.
*/
case Operation::TSTb:
carry_flag_ = overflow_flag_ = 0;
zero_result_ = source()->halves.low.halves.low;
negative_flag_ = zero_result_ & 0x80;
break;
case Operation::TSTw:
carry_flag_ = overflow_flag_ = 0;
zero_result_ = source()->halves.low.full;
negative_flag_ = zero_result_ & 0x8000;
break;
case Operation::TSTl:
carry_flag_ = overflow_flag_ = 0;
zero_result_ = source()->full;
negative_flag_ = zero_result_ & 0x80000000;
break;
case Operation::STOP:
apply_status(prefetch_queue_.halves.low.full);
execution_state_ = ExecutionState::Stopped;
break;
/*
Development period debugging.
*/
default:
std::cerr << "Should do something with program operation " << int(active_program_->operation) << std::endl;
break;
}
#undef sub_overflow
#undef add_overflow
break;
case int_type(MicroOp::Action::MOVEMtoRComplete): {
// If this was a word-sized move, perform sign extension.
if(active_program_->operation == Operation::MOVEMtoRw) {
auto mask = next_word_;
int offset = 0;
while(mask) {
if(mask&1) {
const auto target = (offset > 7) ? &address_[offset&7] : &data_[offset];
target->halves.high.full = (target->halves.low.full & 0x8000) ? 0xffff : 0x0000;
}
mask >>= 1;
++offset;
}
}
// If the post-increment mode was used, overwrite the source register.
const auto mode = (decoded_instruction_.full >> 3) & 7;
if(mode == 3) {
const auto reg = decoded_instruction_.full & 7;
address_[reg] = movem_final_address_;
}
} break;
case int_type(MicroOp::Action::MOVEMtoMComplete): {
const auto mode = (decoded_instruction_.full >> 3) & 7;
if(mode == 4) {
const auto reg = decoded_instruction_.full & 7;
address_[reg] = movem_final_address_;
}
} break;
case int_type(MicroOp::Action::PrepareJSR): {
const auto mode = (decoded_instruction_.full >> 3) & 7;
// Determine the proper resumption address.
switch(mode) {
case 2: destination_bus_data_.full = program_counter_.full - 2; break; /* (An) */
default:
destination_bus_data_.full = program_counter_.full; /* Everything other than (An) */
break;
}
address_[7].full -= 4;
effective_address_[1].full = address_[7].full;
} break;
case int_type(MicroOp::Action::PrepareBSR):
destination_bus_data_.full = (decoded_instruction_.full & 0xff) ? program_counter_.full - 2 : program_counter_.full;
address_[7].full -= 4;
effective_address_[1].full = address_[7].full;
break;
case int_type(MicroOp::Action::PrepareRTS):
effective_address_[0].full = address_[7].full;
address_[7].full += 4;
break;
case int_type(MicroOp::Action::PrepareRTE_RTR):
precomputed_addresses_[0] = address_[7].full + 2;
precomputed_addresses_[1] = address_[7].full;
precomputed_addresses_[2] = address_[7].full + 4;
address_[7].full += 6;
break;
case int_type(MicroOp::Action::PrepareINT):
// The INT sequence uses the same storage as the TRAP steps, so this'll get
// the necessary stack work set up.
populate_trap_steps(0, status());
// Mutate neessary internal state — effective_address_[0] is exposed
// on the data bus as the accepted interrupt number during the interrupt
// acknowledge cycle, with all other bits set, including the low bit as
// a real 68000 uses the lower data strobe to collect the corresponding vector byte.
//
// Cf. M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL 5.1.4.
accepted_interrupt_level_ = interrupt_level_ = pending_interrupt_level_;
pending_interrupt_level_ = 0;
effective_address_[0].full = 0xfffffff1 | uint32_t(accepted_interrupt_level_ << 1);
// Recede the program counter to where it would have been were there no
// prefetch; that's where the reading stream should pick up upon RTE.
program_counter_.full -= 4;
break;
case int_type(MicroOp::Action::PrepareINTVector):
// Let bus error go back to causing exceptions.
is_starting_interrupt_ = false;
// Bus error => spurious interrupt.
if(bus_error_) {
effective_address_[0].full = 24 << 2;
break;
}
// Valid peripheral address => autovectored interrupt.
if(is_peripheral_address_) {
effective_address_[0].full = uint32_t(24 + accepted_interrupt_level_) << 2;
break;
}
// Otherwise, the vector is whatever we were just told it is.
effective_address_[0].full = uint32_t(source_bus_data_.halves.low.halves.low << 2);
// printf("Interrupt vector: %06x\n", effective_address_[0].full);
break;
case int_type(MicroOp::Action::CopyNextWord):
next_word_ = prefetch_queue_.halves.low.full;
break;
// Increments and decrements.
#define op_add(x, y) x += y
#define op_sub(x, y) x -= y
#define Adjust(op, quantity, effect) \
case int_type(op) | MicroOp::SourceMask: effect(source_address().full, quantity); break; \
case int_type(op) | MicroOp::DestinationMask: effect(destination_address().full, quantity); break; \
case int_type(op) | MicroOp::SourceMask | MicroOp::DestinationMask: \
effect(destination_address().full, quantity); \
effect(source_address().full, quantity); \
break;
Adjust(MicroOp::Action::Decrement1, 1, op_sub);
Adjust(MicroOp::Action::Decrement2, 2, op_sub);
Adjust(MicroOp::Action::Decrement4, 4, op_sub);
Adjust(MicroOp::Action::Increment1, 1, op_add);
Adjust(MicroOp::Action::Increment2, 2, op_add);
Adjust(MicroOp::Action::Increment4, 4, op_add);
#undef Adjust
#undef op_add
#undef op_sub
case int_type(MicroOp::Action::SignExtendWord):
if(active_micro_op_->action & MicroOp::SourceMask) {
source()->halves.high.full =
(source()->halves.low.full & 0x8000) ? 0xffff : 0x0000;
}
if(active_micro_op_->action & MicroOp::DestinationMask) {
destination()->halves.high.full =
(destination()->halves.low.full & 0x8000) ? 0xffff : 0x0000;
}
break;
case int_type(MicroOp::Action::SignExtendByte):
if(active_micro_op_->action & MicroOp::SourceMask) {
source()->full = (source()->full & 0xff) |
(source()->full & 0x80) ? 0xffffff : 0x000000;
}
if(active_micro_op_->action & MicroOp::DestinationMask) {
destination()->full = (destination()->full & 0xff) |
(destination()->full & 0x80) ? 0xffffff : 0x000000;
}
break;
// 16-bit offset addressing modes.
case int_type(MicroOp::Action::CalcD16PC) | MicroOp::SourceMask:
// The address the low part of the prefetch queue was read from was two bytes ago, hence
// the subtraction of 2.
effective_address_[0] = u_extend16(prefetch_queue_.halves.low.full) + program_counter_.full - 2;
break;
case int_type(MicroOp::Action::CalcD16PC) | MicroOp::DestinationMask:
effective_address_[1] = u_extend16(prefetch_queue_.halves.low.full) + program_counter_.full - 2;
break;
case int_type(MicroOp::Action::CalcD16PC) | MicroOp::SourceMask | MicroOp::DestinationMask:
// Similar logic applies here to above, but the high part of the prefetch queue was four bytes
// ago rather than merely two.
effective_address_[0] = u_extend16(prefetch_queue_.halves.high.full) + program_counter_.full - 4;
effective_address_[1] = u_extend16(prefetch_queue_.halves.low.full) + program_counter_.full - 2;
break;
case int_type(MicroOp::Action::CalcD16An) | MicroOp::SourceMask:
effective_address_[0] = u_extend16(prefetch_queue_.halves.low.full) + source_address().full;
break;
case int_type(MicroOp::Action::CalcD16An) | MicroOp::DestinationMask:
effective_address_[1] = u_extend16(prefetch_queue_.halves.low.full) + destination_address().full;
break;
case int_type(MicroOp::Action::CalcD16An) | MicroOp::SourceMask | MicroOp::DestinationMask:
effective_address_[0] = u_extend16(prefetch_queue_.halves.high.full) + source_address().full;
effective_address_[1] = u_extend16(prefetch_queue_.halves.low.full) + destination_address().full;
break;
#define CalculateD8AnXn(data, source, target) {\
const auto register_index = (data.full >> 12) & 7; \
const RegisterPair32 &displacement = (data.full & 0x8000) ? address_[register_index] : data_[register_index]; \
target.full = u_extend8(data.halves.low) + source; \
\
if(data.full & 0x800) { \
target.full += displacement.full; \
} else { \
target.full += u_extend16(displacement.halves.low.full); \
} \
}
case int_type(MicroOp::Action::CalcD8AnXn) | MicroOp::SourceMask: {
CalculateD8AnXn(prefetch_queue_.halves.low, source_address().full, effective_address_[0]);
} break;
case int_type(MicroOp::Action::CalcD8AnXn) | MicroOp::DestinationMask: {
CalculateD8AnXn(prefetch_queue_.halves.low, destination_address().full, effective_address_[1]);
} break;
case int_type(MicroOp::Action::CalcD8AnXn) | MicroOp::SourceMask | MicroOp::DestinationMask: {
CalculateD8AnXn(prefetch_queue_.halves.high, source_address().full, effective_address_[0]);
CalculateD8AnXn(prefetch_queue_.halves.low, destination_address().full, effective_address_[1]);
} break;
case int_type(MicroOp::Action::CalcD8PCXn) | MicroOp::SourceMask: {
CalculateD8AnXn(prefetch_queue_.halves.low, program_counter_.full - 2, effective_address_[0]);
} break;
case int_type(MicroOp::Action::CalcD8PCXn) | MicroOp::DestinationMask: {
CalculateD8AnXn(prefetch_queue_.halves.low, program_counter_.full - 2, effective_address_[1]);
} break;
case int_type(MicroOp::Action::CalcD8PCXn) | MicroOp::SourceMask | MicroOp::DestinationMask: {
CalculateD8AnXn(prefetch_queue_.halves.high, program_counter_.full - 4, effective_address_[0]);
CalculateD8AnXn(prefetch_queue_.halves.low, program_counter_.full - 2, effective_address_[1]);
} break;
#undef CalculateD8AnXn
case int_type(MicroOp::Action::AssembleWordAddressFromPrefetch) | MicroOp::SourceMask:
effective_address_[0] = u_extend16(prefetch_queue_.halves.low.full);
break;
case int_type(MicroOp::Action::AssembleWordAddressFromPrefetch) | MicroOp::DestinationMask:
effective_address_[1] = u_extend16(prefetch_queue_.halves.low.full);
break;
case int_type(MicroOp::Action::AssembleLongWordAddressFromPrefetch) | MicroOp::SourceMask:
effective_address_[0] = prefetch_queue_.full;
break;
case int_type(MicroOp::Action::AssembleLongWordAddressFromPrefetch) | MicroOp::DestinationMask:
effective_address_[1] = prefetch_queue_.full;
break;
case int_type(MicroOp::Action::AssembleWordDataFromPrefetch) | MicroOp::SourceMask:
source_bus_data_ = prefetch_queue_.halves.low.full;
break;
case int_type(MicroOp::Action::AssembleWordDataFromPrefetch) | MicroOp::DestinationMask:
destination_bus_data_ = prefetch_queue_.halves.low.full;
break;
case int_type(MicroOp::Action::AssembleLongWordDataFromPrefetch) | MicroOp::SourceMask:
source_bus_data_ = prefetch_queue_.full;
break;
case int_type(MicroOp::Action::AssembleLongWordDataFromPrefetch) | MicroOp::DestinationMask:
destination_bus_data_ = prefetch_queue_.full;
break;
case int_type(MicroOp::Action::CopyToEffectiveAddress) | MicroOp::SourceMask:
effective_address_[0] = source_address();
break;
case int_type(MicroOp::Action::CopyToEffectiveAddress) | MicroOp::DestinationMask:
effective_address_[1] = destination_address();
break;
case int_type(MicroOp::Action::CopyToEffectiveAddress) | MicroOp::SourceMask | MicroOp::DestinationMask:
effective_address_[0] = source_address();
effective_address_[1] = destination_address();
break;
}
// If we've got to a micro-op that includes bus steps, break out of this loop.
if(!active_micro_op_->is_terminal()) {
active_step_ = bus_program;
if(!active_step_->is_terminal())
break;
}
}
}
}
#undef source
#undef source_address
#undef destination
#undef destination_address
bus_handler_.flush();
e_clock_phase_ = (e_clock_phase_ + cycles_run_for) % 20;
half_cycles_left_to_run_ = remaining_duration - cycles_run_for;
}
template <class T, bool dtack_is_implicit, bool signal_will_perform> ProcessorState Processor<T, dtack_is_implicit, signal_will_perform>::get_state() {
write_back_stack_pointer();
State state;
memcpy(state.data, data_, sizeof(state.data));
memcpy(state.address, address_, sizeof(state.address));
state.user_stack_pointer = stack_pointers_[0].full;
state.supervisor_stack_pointer = stack_pointers_[1].full;
state.program_counter = program_counter_.full;
state.status = status();
return state;
}
template <class T, bool dtack_is_implicit, bool signal_will_perform> void Processor<T, dtack_is_implicit, signal_will_perform>::set_state(const ProcessorState &state) {
memcpy(data_, state.data, sizeof(state.data));
memcpy(address_, state.address, sizeof(state.address));
apply_status(state.status);
stack_pointers_[0].full = state.user_stack_pointer;
stack_pointers_[1].full = state.supervisor_stack_pointer;
address_[7] = stack_pointers_[is_supervisor_];
}
uint16_t ProcessorStorage::get_status() const {
return status();
}
void ProcessorStorage::set_status(uint16_t status) {
apply_status(status);
}
template <class T, bool dtack_is_implicit, bool signal_will_perform> void Processor<T, dtack_is_implicit, signal_will_perform>::reset() {
execution_state_ = ExecutionState::Executing;
active_step_ = reset_bus_steps_;
is_supervisor_ = 1;
interrupt_level_ = 7;
}
#undef status
#undef apply_status
#undef apply_ccr
#undef ccr
#undef u_extend16
#undef u_extend8
#undef s_extend16
#undef s_extend8
#undef set_next_microcycle_length
#undef convert_to_bit_count_16
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