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Ensure you can't trace into divide-by-zero, etc.

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This commit is contained in:
Thomas Harte 2022-05-13 14:02:56 -04:00
parent 002a8c061f
commit 77b56c50e6
2 changed files with 17 additions and 4 deletions
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3
InstructionSets/M68k/Executor.hpp
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@ -113,7 +113,10 @@ template <Model model, typename BusHandler> class Executor {
CPU::SlicedInt32 stack_pointers[2];
uint32_t instruction_address;
uint16_t instruction_opcode;
// Things that are ephemerally duplicative of Status.
int active_stack_pointer = 0;
Status::FlagT should_trace = 0;
// Bus state.
int interrupt_input = 0;

18
InstructionSets/M68k/Implementation/ExecutorImplementation.hpp
View File

@ -69,6 +69,9 @@ void Executor<model, BusHandler>::run_for_instructions(int count) {
state_.status.trace_flag = 0;
state_.did_update_status();
// Ensure no tracing occurs into the exception.
state_.should_trace = 0;
// Push status and the program counter at instruction start.
state_.template write<uint16_t>(sp.l - 14, code);
state_.template write<uint32_t>(sp.l - 12, faulting_address);
@ -322,6 +325,14 @@ void Executor<model, BusHandler>::State::run(int &count) {
status.interrupt_level = interrupt_input;
}
// Capture the trace bit, indicating whether to trace
// after this instruction.
//
// If an exception occurs, this value will be cleared, but
// it'll persist across mere status register changes for
// one instruction's duration.
should_trace = status.trace_flag;
// Read the next instruction.
instruction_address = program_counter.l;
instruction_opcode = read_pc<uint16_t>();
@ -345,10 +356,6 @@ void Executor<model, BusHandler>::State::run(int &count) {
}
}
// Capture the trace bit, indicating whether to trace
// after this instruction.
const auto should_trace = status.trace_flag;
// Temporary storage.
CPU::SlicedInt32 operand_[2];
EffectiveAddress effective_address_[2];
@ -415,6 +422,9 @@ void Executor<model, BusHandler>::State::raise_exception(int index) {
write<uint16_t>(sp.l - 6, previous_status);
sp.l -= 6;
// Ensure no tracing occurs into the exception.
should_trace = 0;
// Fetch the new program counter.
program_counter.l = read<uint32_t>(address);
}