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Allow repetition for MVN and MVP only.

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This commit is contained in:
Thomas Harte 2022-06-24 10:34:43 -04:00
parent 6c638712f3
commit a442077eac
1 changed files with 7 additions and 1 deletions
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8
OSBindings/Mac/Clock SignalTests/65816ComparativeTests.mm
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@ -35,7 +35,7 @@ struct BusHandler: public CPU::MOS6502Esque::BusHandler<uint32_t> {
auto ram_value = ram.find(address);
switch(operation) {
case BusOperation::ReadOpcode:
if(initial_pc && *initial_pc != address) {
if(initial_pc && (*initial_pc != address || !allow_pc_repetition)) {
cycles.pop_back();
pc_overshoot = -1;
throw StopException();
@ -79,6 +79,11 @@ struct BusHandler: public CPU::MOS6502Esque::BusHandler<uint32_t> {
pc_overshoot = 0;
initial_pc = std::nullopt;
// For MVP or MVN, keep tracking fetches via the same location.
// For other instructions, don't. That's to avoid endless loops
// for flow control that happens to jump back to where it began.
allow_pc_repetition = opcode == 0x54 || opcode == 0x44;
using Register = CPU::MOS6502Esque::Register;
const uint32_t pc =
processor.get_value_of_register(Register::ProgramCounter) |
@ -88,6 +93,7 @@ struct BusHandler: public CPU::MOS6502Esque::BusHandler<uint32_t> {
int pc_overshoot = 0;
std::optional<uint32_t> initial_pc;
bool allow_pc_repetition = false;
struct Cycle {
CPU::MOS6502Esque::BusOperation operation;