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CLK/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp

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//
// 68000Mk2Implementation.hpp
// Clock Signal
//
// Created by Thomas Harte on 16/05/2022.
// Copyright © 2022 Thomas Harte. All rights reserved.
//
#ifndef _8000Mk2Implementation_h
#define _8000Mk2Implementation_h
#include <cassert>
#include <cstdio>
#include "../../../InstructionSets/M68k/ExceptionVectors.hpp"
namespace CPU {
namespace MC68000Mk2 {
/// States for the state machine which are named by
/// me for their purpose rather than automatically by file position.
/// These are negative to avoid ambiguity with the other group.
enum ExecutionState: int {
Reset = std::numeric_limits<int>::min(),
Decode,
WaitForDTACK,
/// Perform the proper sequence to fetch a byte or word operand.
FetchOperand_bw,
/// Perform the proper sequence to fetch a long-word operand.
FetchOperand_l,
StoreOperand,
StoreOperand_bw,
StoreOperand_l,
StandardException,
BusOrAddressErrorException,
// Specific addressing mode fetches.
FetchAddressRegisterIndirect_bw,
FetchAddressRegisterIndirectWithPostincrement_bw,
FetchAddressRegisterIndirectWithPredecrement_bw,
FetchAddressRegisterIndirectWithDisplacement_bw,
FetchAddressRegisterIndirectWithIndex8bitDisplacement_bw,
FetchProgramCounterIndirectWithDisplacement_bw,
FetchProgramCounterIndirectWithIndex8bitDisplacement_bw,
FetchAbsoluteShort_bw,
FetchAbsoluteLong_bw,
FetchImmediateData_bw,
FetchAddressRegisterIndirect_l,
FetchAddressRegisterIndirectWithPostincrement_l,
FetchAddressRegisterIndirectWithPredecrement_l,
FetchAddressRegisterIndirectWithDisplacement_l,
FetchAddressRegisterIndirectWithIndex8bitDisplacement_l,
FetchProgramCounterIndirectWithDisplacement_l,
FetchProgramCounterIndirectWithIndex8bitDisplacement_l,
FetchAbsoluteShort_l,
FetchAbsoluteLong_l,
FetchImmediateData_l,
// Various forms of perform; each of these will
// perform the current instruction, then do the
// indicated bus cycle.
Perform_np,
Perform_np_n,
Perform_np_nn,
// MOVE has unique bus usage, so has specialised states.
MOVEw,
MOVEwRegisterDirect,
MOVEwAddressRegisterIndirectWithPostincrement,
SABCD_PreDec,
CHK,
CHK_no_trap,
CHK_was_over,
CHK_was_under,
};
// MARK: - The state machine.
template <class BusHandler, bool dtack_is_implicit, bool permit_overrun, bool signal_will_perform>
void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perform>::run_for(HalfCycles duration) {
// Accumulate the newly paid-in cycles. If this instance remains in deficit, exit.
time_remaining_ += duration;
if(time_remaining_ <= HalfCycles(0)) return;
// Check whether all remaining time has been expended; if so then exit, having set this line up as
// the next resumption point.
#define ConsiderExit() if(time_remaining_ <= HalfCycles(0)) { state_ = __COUNTER__+1; return; } [[fallthrough]]; case __COUNTER__:
// Subtracts `n` half-cycles from `time_remaining_`; if permit_overrun is false, also ConsiderExit()
#define Spend(n) time_remaining_ -= (n); if constexpr (!permit_overrun) ConsiderExit()
// Performs ConsiderExit() only if permit_overrun is true.
#define CheckOverrun() if constexpr (permit_overrun) ConsiderExit()
// Sets `x` as the next state, and exits now if all remaining time has been extended and permit_overrun is true.
// Jumps directly to the state otherwise.
#define MoveToState(x) { state_ = ExecutionState::x; goto x; }
// Sets the start position for state x.
#define BeginState(x) case ExecutionState::x: [[maybe_unused]] x
//
// So basic structure is, in general:
//
// BeginState(Action):
// do_something();
// Spend(20);
// do_something_else();
// Spend(10);
// do_a_third_thing();
// Spend(30);
// MoveToState(next_action);
//
// Additional notes:
//
// Action and all equivalents should be negative values, since the
// switch-for-computed-goto-for-a-coroutine structure uses __COUNTER__* for
// its invented entry- and exit-points, meaning that negative numbers are
// the easiest group that is safely definitely never going to collide.
//
// (* an extension supported by at least GCC, Clang and MSVC)
// Spare containers:
HalfCycles delay; // To receive any additional time added on by calls to perform_bus_operation.
// Helper macros for common bus transactions:
// 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_); \
Spend(x.length + delay)
// Performs no bus activity for the specified number of microcycles.
#define IdleBus(n) \
idle.length = HalfCycles(n * 4); \
PerformBusOperation(idle)
// Spin until DTACK, VPA or BERR is asserted (unless DTACK is implicit),
// holding the bus cycle provided.
#define WaitForDTACK(x) \
if constexpr (!dtack_is_implicit && !dtack_ && !vpa_ && !berr_) { \
awaiting_dtack = x; \
awaiting_dtack.length = HalfCycles(2); \
post_dtack_state_ = __COUNTER__+1; \
state_ = ExecutionState::WaitForDTACK; \
break; \
} \
[[fallthrough]]; case __COUNTER__:
// Performs the bus operation provided, which will be one with a
// SelectWord or SelectByte operation, stretching it to match the E
// bus if VPA is currently asserted.
//
// TODO: If BERR is asserted, stop here and perform a bus error exception.
//
// TODO: If VPA is asserted, stretch this cycle.
#define CompleteAccess(x) \
PerformBusOperation(x)
// 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); \
} \
PerformBusOperation(announce); \
WaitForDTACK(announce); \
CompleteAccess(perform);
// Sets up the next data access size and read flags.
#define SetupDataAccess(read_flag, select_flag) \
access_announce.operation = Microcycle::NewAddress | Microcycle::IsData | (read_flag); \
access.operation = access_announce.operation | (select_flag);
// Sets the address source for the next data access.
#define SetDataAddress(addr) \
access.address = access_announce.address = &addr;
// Performs the access established by SetupDataAccess into val.
#define Access(val) \
AccessPair(val, access_announce, access)
// Reads the program (i.e. non-data) word from addr into val.
#define ReadProgramWord(val) \
AccessPair(val, read_program_announce, read_program); \
program_counter_.l += 2;
// Reads one futher word from the program counter and inserts it into
// the prefetch queue.
#define Prefetch() \
prefetch_.high = prefetch_.low; \
ReadProgramWord(prefetch_.low)
using Mode = InstructionSet::M68k::AddressingMode;
// Otherwise continue for all time, until back in debt.
// Formatting is slightly obtuse here to make this look more like a coroutine.
while(true) { switch(state_) {
// Spin in place, one cycle at a time, until one of DTACK,
// BERR or VPA is asserted.
BeginState(WaitForDTACK):
PerformBusOperation(awaiting_dtack);
if(dtack_ || berr_ || vpa_) {
state_ = post_dtack_state_;
continue;
}
MoveToState(WaitForDTACK);
// Perform the RESET exception, which seeds the stack pointer and program
// counter, populates the prefetch queue, and then moves to instruction dispatch.
BeginState(Reset):
IdleBus(7); // (n-)*5 nn
// Establish general reset state.
status_.is_supervisor = true;
status_.interrupt_level = 7;
status_.trace_flag = 0;
did_update_status();
SetupDataAccess(Microcycle::Read, Microcycle::SelectWord);
SetDataAddress(temporary_address_);
temporary_address_ = 0;
Access(registers_[15].high); // nF
temporary_address_ += 2;
Access(registers_[15].low); // nf
temporary_address_ += 2;
Access(program_counter_.high); // nV
temporary_address_ += 2;
Access(program_counter_.low); // nv
Prefetch(); // np
IdleBus(1); // n
Prefetch(); // np
MoveToState(Decode);
// Perform a 'standard' exception, i.e. a Group 1 or 2.
BeginState(StandardException):
captured_status_.w = status_.status();
// Switch to supervisor mode.
status_.is_supervisor = true;
status_.trace_flag = 0;
did_update_status();
SetupDataAccess(0, Microcycle::SelectWord);
SetDataAddress(registers_[15].l);
// Push status and current program counter.
// Write order is wacky here, but I think it's correct.
registers_[15].l -= 6;
Access(captured_status_); // ns
registers_[15].l += 4;
Access(instruction_address_.low); // ns
registers_[15].l -= 2;
Access(instruction_address_.high); // nS
registers_[15].l -= 2;
// Grab new program counter.
SetupDataAccess(Microcycle::Read, Microcycle::SelectWord);
SetDataAddress(temporary_address_);
temporary_address_ = exception_vector_ << 2;
Access(program_counter_.high); // nV
temporary_address_ += 2;
Access(program_counter_.low); // nv
// Populate the prefetch queue.
Prefetch(); // np
IdleBus(1); // n
Prefetch(); // np
MoveToState(Decode);
// Inspect the prefetch queue in order to decode the next instruction,
// and segue into the fetching of operands.
BeginState(Decode):
CheckOverrun();
opcode_ = prefetch_.high.w;
instruction_ = decoder_.decode(opcode_);
instruction_address_.l = program_counter_.l - 4;
// Signal the bus handler if requested.
if constexpr (signal_will_perform) {
bus_handler_.will_perform(instruction_address_.l, opcode_);
}
// Check for a privilege violation.
if(instruction_.requires_supervisor() && !status_.is_supervisor) {
exception_vector_ = InstructionSet::M68k::Exception::PrivilegeViolation;
MoveToState(StandardException);
}
// Check for an unrecognised opcode.
if(instruction_.operation == InstructionSet::M68k::Operation::Undefined) {
switch(opcode_ & 0xf000) {
default:
exception_vector_ = InstructionSet::M68k::Exception::IllegalInstruction;
continue;
case 0xa000:
exception_vector_ = InstructionSet::M68k::Exception::Line1010;
continue;
case 0xf000:
exception_vector_ = InstructionSet::M68k::Exception::Line1111;
continue;
}
MoveToState(StandardException);
}
// Ensure the first parameter is next fetched.
next_operand_ = 0;
// Obtain operand flags and pick a perform pattern.
#define CASE(x) \
case InstructionSet::M68k::Operation::x: \
operand_flags_ = InstructionSet::M68k::operand_flags<InstructionSet::M68k::Model::M68000, InstructionSet::M68k::Operation::x>();
#define StdCASE(x, y) \
CASE(x) \
y; \
\
if constexpr (InstructionSet::M68k::operand_size<InstructionSet::M68k::Operation::x>() == InstructionSet::M68k::DataSize::LongWord) { \
SetupDataAccess(Microcycle::Read, Microcycle::SelectWord); \
MoveToState(FetchOperand_l); \
} else { \
if constexpr (InstructionSet::M68k::operand_size<InstructionSet::M68k::Operation::x>() == InstructionSet::M68k::DataSize::Byte) { \
SetupDataAccess(Microcycle::Read, Microcycle::SelectByte); \
} else { \
SetupDataAccess(Microcycle::Read, Microcycle::SelectWord); \
} \
MoveToState(FetchOperand_bw); \
}
#define Duplicate(x, y) \
case InstructionSet::M68k::Operation::x: \
static_assert( \
InstructionSet::M68k::operand_flags<InstructionSet::M68k::Model::M68000, InstructionSet::M68k::Operation::x>() == \
InstructionSet::M68k::operand_flags<InstructionSet::M68k::Model::M68000, InstructionSet::M68k::Operation::y>() && \
InstructionSet::M68k::operand_size<InstructionSet::M68k::Operation::x>() == \
InstructionSet::M68k::operand_size<InstructionSet::M68k::Operation::y>() \
);
switch(instruction_.operation) {
StdCASE(NBCD, {
if(instruction_.mode(0) == Mode::DataRegisterDirect) {
perform_state_ = Perform_np_n;
} else {
perform_state_ = Perform_np;
}
})
Duplicate(CLRb, NEGXb) Duplicate(NEGb, NEGXb) Duplicate(NOTb, NEGXb)
StdCASE(NEGXb, perform_state_ = Perform_np);
Duplicate(CLRw, NEGXw) Duplicate(NEGw, NEGXw) Duplicate(NOTw, NEGXw)
StdCASE(NEGXw, perform_state_ = Perform_np);
Duplicate(CLRl, NEGXl) Duplicate(NEGl, NEGXl) Duplicate(NOTl, NEGXl)
StdCASE(NEGXl,
if(instruction_.mode(0) == Mode::DataRegisterDirect) {
perform_state_ = Perform_np_n;
} else {
perform_state_ = Perform_np;
}
);
StdCASE(SWAP, perform_state_ = Perform_np);
StdCASE(EXG, perform_state_ = Perform_np_n);
StdCASE(EXTbtow, perform_state_ = Perform_np);
StdCASE(EXTwtol, perform_state_ = Perform_np);
StdCASE(MOVEw, perform_state_ = MOVEw);
StdCASE(CMPb, perform_state_ = Perform_np);
StdCASE(CMPw, perform_state_ = Perform_np);
StdCASE(CMPl, perform_state_ = Perform_np_n);
StdCASE(CMPAw, perform_state_ = Perform_np_n);
StdCASE(CMPAl, perform_state_ = Perform_np_n);
Duplicate(ANDb, ORb) StdCASE(ORb, perform_state_ = Perform_np);
Duplicate(ANDw, ORw) StdCASE(ORw, perform_state_ = Perform_np);
Duplicate(ANDl, ORl) StdCASE(ORl, {
if(instruction_.mode(1) == Mode::DataRegisterDirect) {
switch(instruction_.mode(0)) {
default:
perform_state_ = Perform_np_n;
break;
case Mode::DataRegisterDirect:
case Mode::ImmediateData:
perform_state_ = Perform_np_nn;
break;
}
} else {
perform_state_ = Perform_np;
}
});
StdCASE(EORb, perform_state_ = Perform_np);
StdCASE(EORw, perform_state_ = Perform_np);
StdCASE(EORl, {
if(instruction_.mode(1) == Mode::DataRegisterDirect) {
perform_state_ = Perform_np_nn;
} else {
perform_state_ = Perform_np;
}
})
Duplicate(SBCD, ABCD)
CASE(ABCD)
if(instruction_.mode(0) == Mode::DataRegisterDirect) {
perform_state_ = Perform_np_n;
SetupDataAccess(Microcycle::Read, Microcycle::SelectByte);
MoveToState(FetchOperand_bw);
} else {
MoveToState(SABCD_PreDec);
}
StdCASE(CHK, perform_state_ = CHK);
default:
assert(false);
}
#undef Duplicate
#undef StdCASE
#undef CASE
// MARK: - Fetch, dispatch.
#define MoveToNextOperand(x) \
++next_operand_; \
if(next_operand_ == 2) { \
state_ = perform_state_; \
continue; \
} \
MoveToState(x)
// Check the operand flags to determine whether the byte or word
// operand at index next_operand_ needs to be fetched, and if so
// then calculate the EA and do so.
BeginState(FetchOperand_bw):
// Check that this operand is meant to be fetched; if not then either:
//
// (i) this operand isn't used; or
// (ii) its address calculation will end up conflated with performance,
// so there's no generic bus-accurate approach.
if(!(operand_flags_ & (1 << next_operand_))) {
state_ = perform_state_;
continue;
}
// Figure out how to fetch it.
switch(instruction_.mode(next_operand_)) {
case Mode::AddressRegisterDirect:
case Mode::DataRegisterDirect:
operand_[next_operand_] = registers_[instruction_.lreg(next_operand_)];
MoveToNextOperand(FetchOperand_bw);
case Mode::Quick:
operand_[next_operand_].l = InstructionSet::M68k::quick(opcode_, instruction_.operation);
MoveToNextOperand(FetchOperand_bw);
case Mode::AddressRegisterIndirect:
MoveToState(FetchAddressRegisterIndirect_bw);
case Mode::AddressRegisterIndirectWithPostincrement:
MoveToState(FetchAddressRegisterIndirectWithPostincrement_bw);
case Mode::AddressRegisterIndirectWithPredecrement:
MoveToState(FetchAddressRegisterIndirectWithPredecrement_bw);
case Mode::AddressRegisterIndirectWithDisplacement:
MoveToState(FetchAddressRegisterIndirectWithDisplacement_bw);
case Mode::AddressRegisterIndirectWithIndex8bitDisplacement:
MoveToState(FetchAddressRegisterIndirectWithIndex8bitDisplacement_bw);
case Mode::ProgramCounterIndirectWithDisplacement:
MoveToState(FetchProgramCounterIndirectWithDisplacement_bw);
case Mode::ProgramCounterIndirectWithIndex8bitDisplacement:
MoveToState(FetchProgramCounterIndirectWithIndex8bitDisplacement_bw);
case Mode::AbsoluteShort:
MoveToState(FetchAbsoluteShort_bw);
case Mode::AbsoluteLong:
MoveToState(FetchAbsoluteLong_bw);
case Mode::ImmediateData:
MoveToState(FetchImmediateData_bw);
// Should be impossible to reach.
default:
assert(false);
}
break;
// As above, but for .l.
BeginState(FetchOperand_l):
if(!(operand_flags_ & (1 << next_operand_))) {
state_ = perform_state_;
continue;
}
switch(instruction_.mode(next_operand_)) {
case Mode::AddressRegisterDirect:
case Mode::DataRegisterDirect:
operand_[next_operand_] = registers_[instruction_.lreg(next_operand_)];
MoveToNextOperand(FetchOperand_bw);
case Mode::Quick:
operand_[next_operand_].l = InstructionSet::M68k::quick(opcode_, instruction_.operation);
MoveToNextOperand(FetchOperand_bw);
case Mode::AddressRegisterIndirect:
MoveToState(FetchAddressRegisterIndirect_l);
case Mode::AddressRegisterIndirectWithPostincrement:
MoveToState(FetchAddressRegisterIndirectWithPostincrement_l);
case Mode::AddressRegisterIndirectWithPredecrement:
MoveToState(FetchAddressRegisterIndirectWithPredecrement_l);
case Mode::AddressRegisterIndirectWithDisplacement:
MoveToState(FetchAddressRegisterIndirectWithDisplacement_l);
case Mode::AddressRegisterIndirectWithIndex8bitDisplacement:
MoveToState(FetchAddressRegisterIndirectWithIndex8bitDisplacement_l);
case Mode::ProgramCounterIndirectWithDisplacement:
MoveToState(FetchProgramCounterIndirectWithDisplacement_l);
case Mode::ProgramCounterIndirectWithIndex8bitDisplacement:
MoveToState(FetchProgramCounterIndirectWithIndex8bitDisplacement_l);
case Mode::AbsoluteShort:
MoveToState(FetchAbsoluteShort_l);
case Mode::AbsoluteLong:
MoveToState(FetchAbsoluteLong_l);
case Mode::ImmediateData:
MoveToState(FetchImmediateData_l);
// Should be impossible to reach.
default:
assert(false);
}
break;
// MARK: - Fetch, addressing modes.
//
// AddressRegisterIndirect
//
BeginState(FetchAddressRegisterIndirect_bw):
effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l;
SetDataAddress(effective_address_[next_operand_]);
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchAddressRegisterIndirect_l):
effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l;
SetDataAddress(effective_address_[next_operand_]);
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
//
// AddressRegisterIndirectWithPostincrement
//
BeginState(FetchAddressRegisterIndirectWithPostincrement_bw):
effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l;
registers_[8 + instruction_.reg(next_operand_)].l +=
byte_word_increments[int(instruction_.operand_size())][instruction_.reg(next_operand_)];
SetDataAddress(effective_address_[next_operand_]);
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchAddressRegisterIndirectWithPostincrement_l):
effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l;
registers_[8 + instruction_.reg(next_operand_)].l += 4;
SetDataAddress(effective_address_[next_operand_]);
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
//
// AddressRegisterIndirectWithPredecrement
//
BeginState(FetchAddressRegisterIndirectWithPredecrement_bw):
registers_[8 + instruction_.reg(next_operand_)].l -=
byte_word_increments[int(instruction_.operand_size())][instruction_.reg(next_operand_)];
effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l;
SetDataAddress(effective_address_[next_operand_]);
IdleBus(1); // n
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchAddressRegisterIndirectWithPredecrement_l):
registers_[8 + instruction_.reg(next_operand_)].l -= 4;
effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l;
SetDataAddress(effective_address_[next_operand_]);
IdleBus(1); // n
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
//
// AddressRegisterIndirectWithDisplacement
//
BeginState(FetchAddressRegisterIndirectWithDisplacement_bw):
effective_address_[next_operand_] =
registers_[8 + instruction_.reg(next_operand_)].l +
int16_t(prefetch_.w);
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchAddressRegisterIndirectWithDisplacement_l):
effective_address_[next_operand_] =
registers_[8 + instruction_.reg(next_operand_)].l +
int16_t(prefetch_.w);
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
//
// ProgramCounterIndirectWithDisplacement
//
BeginState(FetchProgramCounterIndirectWithDisplacement_bw):
effective_address_[next_operand_] =
instruction_address_.l + 2 +
int16_t(prefetch_.w);
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchProgramCounterIndirectWithDisplacement_l):
effective_address_[next_operand_] =
instruction_address_.l + 2 +
int16_t(prefetch_.w);
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
#define d8Xn(base) \
base + \
((prefetch_.w & 0x800) ? \
registers_[prefetch_.w >> 12].l : \
int16_t(registers_[prefetch_.w >> 12].w)) + \
int8_t(prefetch_.b);
//
// AddressRegisterIndirectWithIndex8bitDisplacement
//
BeginState(FetchAddressRegisterIndirectWithIndex8bitDisplacement_bw):
effective_address_[next_operand_] = d8Xn(registers_[8 + instruction_.reg(next_operand_)].l);
SetDataAddress(effective_address_[next_operand_]);
IdleBus(1); // n
Prefetch(); // np
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchAddressRegisterIndirectWithIndex8bitDisplacement_l):
effective_address_[next_operand_] = d8Xn(registers_[8 + instruction_.reg(next_operand_)].l);
SetDataAddress(effective_address_[next_operand_]);
IdleBus(1); // n
Prefetch(); // np
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
//
// ProgramCounterIndirectWithIndex8bitDisplacement
//
BeginState(FetchProgramCounterIndirectWithIndex8bitDisplacement_bw):
effective_address_[next_operand_] = d8Xn(instruction_address_.l + 2);
SetDataAddress(effective_address_[next_operand_]);
IdleBus(1); // n
Prefetch(); // np
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchProgramCounterIndirectWithIndex8bitDisplacement_l):
effective_address_[next_operand_] = d8Xn(instruction_address_.l + 2);;
SetDataAddress(effective_address_[next_operand_]);
IdleBus(1); // n
Prefetch(); // np
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
#undef d8Xn
//
// AbsoluteShort
//
BeginState(FetchAbsoluteShort_bw):
effective_address_[next_operand_] = int16_t(prefetch_.w);
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchAbsoluteShort_l):
effective_address_[next_operand_] = int16_t(prefetch_.w);
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
//
// AbsoluteLong
//
BeginState(FetchAbsoluteLong_bw):
Prefetch(); // np
effective_address_[next_operand_] = prefetch_.l;
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchAbsoluteLong_l):
Prefetch(); // np
effective_address_[next_operand_] = prefetch_.l;
SetDataAddress(effective_address_[next_operand_]);
Prefetch(); // np
Access(operand_[next_operand_].high); // nR
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l);
//
// ImmediateData
//
BeginState(FetchImmediateData_bw):
operand_[next_operand_].w = prefetch_.w;
Prefetch(); // np
MoveToNextOperand(FetchOperand_bw);
BeginState(FetchImmediateData_l):
Prefetch(); // np
operand_[next_operand_].l = prefetch_.l;
Prefetch(); // np
MoveToNextOperand(FetchOperand_l);
#undef MoveToNextOperand
// MARK: - Store.
#define MoveToNextOperand(x) \
++next_operand_; \
if(next_operand_ == 2) { \
MoveToState(Decode); \
} \
MoveToState(x)
// Store operand is a lot simpler: only one operand is ever stored, and its address
// is already known. So this can either skip straight back to ::Decode if the target
// is a register, otherwise a single write operation can occur.
BeginState(StoreOperand):
switch(instruction_.operand_size()) {
case InstructionSet::M68k::DataSize::LongWord:
SetupDataAccess(0, Microcycle::SelectWord);
MoveToState(StoreOperand_l);
case InstructionSet::M68k::DataSize::Word:
SetupDataAccess(0, Microcycle::SelectWord);
MoveToState(StoreOperand_bw);
case InstructionSet::M68k::DataSize::Byte:
SetupDataAccess(0, Microcycle::SelectByte);
MoveToState(StoreOperand_bw);
}
BeginState(StoreOperand_bw):
if(!(operand_flags_ & 0x4 << next_operand_)) {
MoveToNextOperand(StoreOperand_bw);
}
if(instruction_.mode(next_operand_) <= Mode::AddressRegisterDirect) {
registers_[instruction_.lreg(next_operand_)] = operand_[next_operand_];
MoveToNextOperand(StoreOperand_bw);
}
SetDataAddress(effective_address_[next_operand_]);
Access(operand_[next_operand_].low); // nw
MoveToNextOperand(StoreOperand_bw);
BeginState(StoreOperand_l):
if(!(operand_flags_ & 0x4 << next_operand_)) {
MoveToNextOperand(StoreOperand_l);
}
if(instruction_.mode(next_operand_) <= Mode::AddressRegisterDirect) {
registers_[instruction_.lreg(next_operand_)] = operand_[next_operand_];
MoveToNextOperand(StoreOperand_l);
}
SetupDataAccess(0, Microcycle::SelectWord);
SetDataAddress(effective_address_[next_operand_]);
Access(operand_[next_operand_].low); // nw
effective_address_[next_operand_] -= 2;
Access(operand_[next_operand_].high); // nW
MoveToNextOperand(StoreOperand_l);
//
// Various generic forms of perform.
//
#define MoveToWritePhase() \
next_operand_ = 0; \
if(operand_flags_ & 0x0c) MoveToState(StoreOperand) else MoveToState(Decode)
BeginState(Perform_np):
InstructionSet::M68k::perform<InstructionSet::M68k::Model::M68000>(
instruction_, operand_[0], operand_[1], status_, *static_cast<ProcessorBase *>(this));
Prefetch(); // np
MoveToWritePhase();
BeginState(Perform_np_n):
InstructionSet::M68k::perform<InstructionSet::M68k::Model::M68000>(
instruction_, operand_[0], operand_[1], status_, *static_cast<ProcessorBase *>(this));
Prefetch(); // np
IdleBus(1); // n
MoveToWritePhase();
BeginState(Perform_np_nn):
InstructionSet::M68k::perform<InstructionSet::M68k::Model::M68000>(
instruction_, operand_[0], operand_[1], status_, *static_cast<ProcessorBase *>(this));
Prefetch(); // np
IdleBus(2); // nn
MoveToWritePhase();
#undef MoveToWritePhase
//
// Specific forms of perform.
//
BeginState(MOVEw):
switch(instruction_.mode(1)) {
case Mode::DataRegisterDirect:
case Mode::AddressRegisterDirect:
MoveToState(MOVEwRegisterDirect);
case Mode::AddressRegisterIndirectWithPostincrement:
MoveToState(MOVEwAddressRegisterIndirectWithPostincrement);
default: assert(false);
}
BeginState(MOVEwRegisterDirect):
registers_[instruction_.lreg(1)].w = operand_[1].w;
Prefetch(); // np
MoveToState(Decode);
BeginState(MOVEwAddressRegisterIndirectWithPostincrement):
// TODO: nw
assert(false);
Prefetch() // np
MoveToState(Decode);
BeginState(SABCD_PreDec):
IdleBus(1); // n
SetupDataAccess(Microcycle::Read, Microcycle::SelectByte);
registers_[8 + instruction_.reg(0)].l -= byte_word_increments[0][instruction_.reg(0)];
SetDataAddress(registers_[8 + instruction_.reg(0)].l);
Access(operand_[0].low); // nr
registers_[8 + instruction_.reg(1)].l -= byte_word_increments[0][instruction_.reg(1)];
SetDataAddress(registers_[8 + instruction_.reg(1)].l);
Access(operand_[1].low); // nr
Prefetch(); // np
InstructionSet::M68k::perform<InstructionSet::M68k::Model::M68000>(
instruction_, operand_[0], operand_[1], status_, *static_cast<ProcessorBase *>(this));
SetupDataAccess(0, Microcycle::SelectByte);
Access(operand_[1].low); // nw
MoveToState(Decode);
BeginState(CHK):
Prefetch(); // np
InstructionSet::M68k::perform<
InstructionSet::M68k::Model::M68000,
ProcessorBase,
InstructionSet::M68k::Operation::CHK
>(
instruction_, operand_[0], operand_[1], status_, *static_cast<ProcessorBase *>(this));
// Proper next state will have been set by the flow controller
// call-in; just allow dispatch to whatever it was.
break;
BeginState(CHK_no_trap):
IdleBus(3); // nn n
MoveToState(Decode);
BeginState(CHK_was_over):
IdleBus(2); // nn
instruction_address_.l = program_counter_.l - 4;
exception_vector_ = InstructionSet::M68k::Exception::CHK;
MoveToState(StandardException);
BeginState(CHK_was_under):
IdleBus(3); // n nn
instruction_address_.l = program_counter_.l - 4;
exception_vector_ = InstructionSet::M68k::Exception::CHK;
MoveToState(StandardException);
// Various states TODO.
#define TODOState(x) \
BeginState(x): [[fallthrough]];
TODOState(BusOrAddressErrorException);
#undef TODOState
default:
printf("Unhandled state: %d; opcode is %04x\n", state_, opcode_);
assert(false);
}}
#undef Prefetch
#undef ReadProgramWord
#undef ReadDataWord
#undef AccessPair
#undef CompleteAccess
#undef WaitForDTACK
#undef IdleBus
#undef PerformBusOperation
#undef MoveToState
#undef CheckOverrun
#undef Spend
#undef ConsiderExit
}
// MARK: - Flow Controller.
void ProcessorBase::did_update_status() {
// Shuffle the stack pointers.
stack_pointers_[is_supervisor_] = registers_[15];
registers_[15] = stack_pointers_[int(status_.is_supervisor)];
is_supervisor_ = int(status_.is_supervisor);
}
void ProcessorBase::did_chk(bool was_under, bool was_over) {
if(was_over) {
state_ = CHK_was_over;
} else if(was_under) {
state_ = CHK_was_under;
} else {
state_ = CHK_no_trap;
}
}
// MARK: - External state.
template <class BusHandler, bool dtack_is_implicit, bool permit_overrun, bool signal_will_perform>
CPU::MC68000Mk2::State Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perform>::get_state() {
CPU::MC68000Mk2::State state;
// This isn't true, but will ensure that both stack_pointers_ have their proper values.
did_update_status();
for(int c = 0; c < 7; c++) {
state.registers.data[c] = registers_[c].l;
state.registers.address[c] = registers_[c + 8].l;
}
state.registers.data[7] = registers_[7].l;
state.registers.program_counter = program_counter_.l;
state.registers.status = status_.status();
state.registers.user_stack_pointer = stack_pointers_[0].l;
state.registers.supervisor_stack_pointer = stack_pointers_[1].l;
return state;
}
template <class BusHandler, bool dtack_is_implicit, bool permit_overrun, bool signal_will_perform>
void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perform>::set_state(const CPU::MC68000Mk2::State &state) {
// Copy registers and the program counter.
for(int c = 0; c < 7; c++) {
registers_[c].l = state.registers.data[c];
registers_[c + 8].l = state.registers.address[c];
}
registers_[7].l = state.registers.data[7];
program_counter_.l = state.registers.program_counter;
// Set status first in order to get the proper is-supervisor flag in place.
status_.set_status(state.registers.status);
// Update stack pointers, being careful to copy the right one.
stack_pointers_[0].l = state.registers.user_stack_pointer;
stack_pointers_[1].l = state.registers.supervisor_stack_pointer;
registers_[15] = stack_pointers_[is_supervisor_];
// Ensure the local is-supervisor flag is updated.
did_update_status();
}
}
}
#endif /* _8000Mk2Implementation_h */
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