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mirror of https://github.com/TomHarte/CLK.git synced 2024-12-27 01:31:42 +00:00

The actual work begins: starts implementing 65816 micro-ops.

This commit is contained in:
Thomas Harte 2020-09-29 18:42:07 -04:00
parent ef1a514785
commit 78b3ec4b10
5 changed files with 134 additions and 32 deletions

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@ -29,6 +29,7 @@ class ProcessorBase: protected ProcessorStorage {
inline void set_power_on(bool);
inline void set_irq_line(bool);
inline void set_nmi_line(bool);
inline void set_reset_line(bool);
void set_value_of_register(Register r, uint16_t value);
inline bool is_jammed() const;

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@ -12,25 +12,25 @@ using namespace CPU::WDC65816;
uint16_t ProcessorBase::get_value_of_register(Register r) const {
switch (r) {
// case Register::ProgramCounter: return pc_.full;
// case Register::LastOperationAddress: return last_operation_pc_.full;
// case Register::StackPointer: return s_;
case Register::ProgramCounter: return pc_;
case Register::LastOperationAddress: return last_operation_pc_;
case Register::StackPointer: return s_;
// case Register::Flags: return get_flags();
// case Register::A: return a_;
// case Register::X: return x_;
// case Register::Y: return y_;
case Register::A: return a_.full;
case Register::X: return x_.full;
case Register::Y: return y_.full;
default: return 0;
}
}
void ProcessorBase::set_value_of_register(Register r, uint16_t value) {
switch (r) {
// case Register::ProgramCounter: pc_.full = value; break;
// case Register::StackPointer: s_ = uint8_t(value); break;
case Register::ProgramCounter: pc_ = value; break;
case Register::StackPointer: s_ = value; break;
// case Register::Flags: set_flags(uint8_t(value)); break;
// case Register::A: a_ = uint8_t(value); break;
// case Register::X: x_ = uint8_t(value); break;
// case Register::Y: y_ = uint8_t(value); break;
case Register::A: a_ = value; break;
case Register::X: x_ = value; break;
case Register::Y: y_ = value; break;
default: break;
}
}

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@ -7,28 +7,130 @@
//
template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles cycles) {
auto int_cycles = cycles.as_integral();
while(int_cycles--) {
// Temporary storage for the next bus cycle.
uint32_t bus_address = 0;
uint8_t *bus_value = nullptr;
uint8_t throwaway = 0;
BusOperation bus_operation = BusOperation::None;
Cycles number_of_cycles = cycles + cycles_left_to_run_;
while(number_of_cycles > Cycles(0)) {
const MicroOp operation = *next_op_;
++next_op_;
switch(operation) {
//
// Scheduling.
//
case OperationMoveToNextProgram:
// The exception program will determine the appropriate way to respond
// based on the pending exception if one exists; otherwise just do a
// standard fetch-decode-execute.
next_op_ = &micro_ops_[instructions[pending_exceptions_ ? size_t(OperationSlot::Exception) : size_t(OperationSlot::FetchDecodeExecute)].program_offset];
// TODO: reset instruction buffer.
instruction_buffer_.clear();
data_buffer_.clear();
last_operation_pc_ = pc_;
continue;
case OperationDecode:
// A VERY TEMPORARY piece of logging.
printf("%02x\n", instruction_buffer_.value);
active_instruction_ = &instructions[instruction_buffer_.value];
next_op_ = &micro_ops_[active_instruction_->program_offset];
instruction_buffer_.clear();
continue;
//
// PC fetches.
//
case CycleFetchIncrementPC:
bus_address = pc_ | program_bank_;
bus_value = instruction_buffer_.next();
bus_operation = MOS6502Esque::Read; // TODO: indicate ReadOpcode when appropriate.
++pc_;
break;
case CycleFetchPC:
bus_address = pc_ | program_bank_;
bus_value = &throwaway;
bus_operation = MOS6502Esque::Read;
break;
//
// Data movement.
//
case OperationCopyPCToData:
data_buffer_.size = 2;
data_buffer_.value = pc_;
break;
case OperationCopyInstructionToData:
data_buffer_ = instruction_buffer_;
break;
//
// Performance.
//
case OperationPerform:
switch(active_instruction_->operation) {
case CLD:
// TODO.
break;
case LDX:
// TODO.
break;
default:
assert(false);
}
break;
default:
assert(false);
}
number_of_cycles -= bus_handler_.perform_bus_operation(bus_operation, bus_address, bus_value);
}
cycles_left_to_run_ = number_of_cycles;
}
void ProcessorBase::set_power_on(bool active) {
if(active) {
pending_exceptions_ |= PowerOn;
} else {
pending_exceptions_ &= ~PowerOn;
}
}
void ProcessorBase::set_power_on(bool) {}
void ProcessorBase::set_irq_line(bool) {}
void ProcessorBase::set_nmi_line(bool) {}
void ProcessorBase::set_irq_line(bool active) {
if(active) {
pending_exceptions_ |= IRQ;
} else {
pending_exceptions_ &= ~IRQ;
}
}
void ProcessorBase::set_reset_line(bool active) {
if(active) {
pending_exceptions_ |= Reset;
} else {
pending_exceptions_ &= ~Reset;
}
}
void ProcessorBase::set_nmi_line(bool active) {
// This is edge triggered.
if(active) {
pending_exceptions_ |= NMI;
}
}
// The 65816 can't jam.
bool ProcessorBase::is_jammed() const { return false; }

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@ -988,6 +988,10 @@ ProcessorStorage::ProcessorStorage() {
constructor.set_exception_generator(&ProcessorStorageConstructor::stack_exception);
constructor.install_fetch_decode_execute();
// Find any OperationMoveToNextProgram.
next_op_ = micro_ops_.data();
while(*next_op_ != OperationMoveToNextProgram) ++next_op_;
#ifndef NDEBUG
assert(micro_ops_.size() < 65536);
printf("Generated %zd micro-ops in total; covered %d opcodes\n", micro_ops_.size(), constructor.opcode);

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@ -185,34 +185,29 @@ struct ProcessorStorage {
FetchDecodeExecute
};
void set_power_on(bool power_on) {
if(power_on) {
// Set next_op_ to start the exception program.
next_op_ = &micro_ops_[instructions[size_t(OperationSlot::Exception)].program_offset];
pending_exceptions_ = PowerOn;
} else {
pending_exceptions_ &= ~PowerOn;
}
}
// Registers.
RegisterPair16 a_;
RegisterPair16 x_, y_;
uint16_t pc_, s_;
// A helper for testing.
uint16_t last_operation_pc_;
Instruction *active_instruction_;
Cycles cycles_left_to_run_;
// I.e. the offset for direct addressing (outside of emulation mode).
uint16_t direct_;
uint16_t direct_ = 0;
// Banking registers are all stored with the relevant byte
// shifted up bits 1623.
uint32_t data_bank_; // i.e. DBR.
uint32_t program_bank_; // i.e. PBR.
uint32_t data_bank_ = 0; // i.e. DBR.
uint32_t program_bank_ = 0; // i.e. PBR.
static constexpr int PowerOn = 1 << 0;
static constexpr int Reset = 1 << 1;
static constexpr int IRQ = 1 << 2;
static constexpr int NMI = 1 << 3;
int pending_exceptions_ = 0;
int pending_exceptions_ = PowerOn; // By default.
/// Defines a four-byte buffer which can be cleared or filled in single-byte increments from least significant byte
/// to most significant.