mirror of
https://github.com/TomHarte/CLK.git
synced 2025-01-27 06:35:04 +00:00
Made an attempt further to rationalise timing.
This commit is contained in:
Thomas Harte
parent
91d3453cc1
commit
8b342f77a9
@ -24,11 +24,35 @@ Machine::Machine() :
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_piaDataValue{0xff, 0xff},
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_tiaInputValue{0xff, 0xff},
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_upcomingEventsPointer(0),
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_objectCounterPointer(0)
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_objectCounterPointer(0),
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_stateByTime(_stateByExtendTime[0])
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{
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memset(_collisions, 0xff, sizeof(_collisions));
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set_reset_line(true);
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setup_reported_collisions();
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for(int vbextend = 0; vbextend < 2; vbextend++)
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{
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for(int c = 0; c < 57; c++)
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{
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OutputState state;
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// determine which output state will be active in four cycles from now
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switch(c)
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{
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case 0: case 1: case 2: case 3: state = OutputState::Blank; break;
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case 4: case 5: case 6: case 7: state = OutputState::Sync; break;
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case 8: case 9: case 10: case 11: state = OutputState::ColourBurst; break;
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case 12: case 13: case 14:
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case 15: case 16: state = OutputState::Blank; break;
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case 17: case 18: state = vbextend ? OutputState::Blank : OutputState::Pixel; break;
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default: state = OutputState::Pixel; break;
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}
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_stateByExtendTime[vbextend][c] = state;
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}
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}
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}
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void Machine::setup_output(float aspect_ratio)
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@ -85,9 +109,11 @@ void Machine::update_timers(int mask)
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_objectCounterPointer = (_objectCounterPointer + 1)%number_of_recorded_counters;
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ObjectCounter *oneClockAgo = _objectCounter[(_objectCounterPointer - 1 + number_of_recorded_counters)%number_of_recorded_counters];
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ObjectCounter *fourClocksAgo = _objectCounter[(_objectCounterPointer - 4 + number_of_recorded_counters)%number_of_recorded_counters];
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ObjectCounter *fiveClocksAgo = _objectCounter[(_objectCounterPointer - 5 + number_of_recorded_counters)%number_of_recorded_counters];
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ObjectCounter *sixClocksAgo = _objectCounter[(_objectCounterPointer - 6 + number_of_recorded_counters)%number_of_recorded_counters];
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ObjectCounter *twoClocksAgo = _objectCounter[(_objectCounterPointer - 2 + number_of_recorded_counters)%number_of_recorded_counters];
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// ObjectCounter *threeClocksAgo = _objectCounter[(_objectCounterPointer - 3 + number_of_recorded_counters)%number_of_recorded_counters];
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// ObjectCounter *fourClocksAgo = _objectCounter[(_objectCounterPointer - 4 + number_of_recorded_counters)%number_of_recorded_counters];
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// ObjectCounter *fiveClocksAgo = _objectCounter[(_objectCounterPointer - 5 + number_of_recorded_counters)%number_of_recorded_counters];
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// ObjectCounter *sixClocksAgo = _objectCounter[(_objectCounterPointer - 6 + number_of_recorded_counters)%number_of_recorded_counters];
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ObjectCounter *now = _objectCounter[_objectCounterPointer];
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// grab the background now, for application in four clocks
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@ -105,7 +131,7 @@ void Machine::update_timers(int mask)
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// clock delay on that triggering the start signal
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now[4].count = (oneClockAgo[4].count + 1)%160;
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now[4].pixel = oneClockAgo[4].pixel + 1;
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if(!fourClocksAgo[4].count) now[4].pixel = 0;
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if(!now[4].count) now[4].pixel = 0;
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}
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else
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{
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@ -136,8 +162,8 @@ void Machine::update_timers(int mask)
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}
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// check for a rollover six clocks ago or equality five clocks ago
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rollover = sixClocksAgo;
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equality = fiveClocksAgo;
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rollover = twoClocksAgo;
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equality = oneClockAgo;
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}
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else
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{
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@ -145,8 +171,8 @@ void Machine::update_timers(int mask)
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now[c].pixel = oneClockAgo[c].pixel + 1;
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// check for a rollover five clocks ago or equality four clocks ago
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rollover = fiveClocksAgo;
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equality = fourClocksAgo;
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rollover = oneClockAgo;
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equality = now;
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}
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if(
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@ -256,40 +282,10 @@ void Machine::output_pixels(unsigned int count)
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{
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while(count--)
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{
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OutputState state;
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// determine which output state will be active in four cycles from now
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switch(_horizontalTimer >> 2)
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{
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case 56: case 0: case 1: case 2: state = OutputState::Blank; break;
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case 3: case 4: case 5: case 6: state = OutputState::Sync; break;
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case 7: case 8: case 9: case 10: state = OutputState::ColourBurst; break;
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case 11: case 12: case 13:
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case 14: case 15: state = OutputState::Blank; break;
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case 16: case 17: state = _vBlankExtend ? OutputState::Blank : OutputState::Pixel; break;
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default: state = OutputState::Pixel; break;
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}
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// update pixel timers
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if(state == OutputState::Pixel)
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{
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update_timers(~0);
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}
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// if vsync is enabled, output the opposite of the automatic hsync output
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if(_vSyncEnabled) {
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state = (state = OutputState::Sync) ? OutputState::Blank : OutputState::Sync;
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}
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// write that state as the one that will become effective in four clocks
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_upcomingEvents[(_upcomingEventsPointer+4)%number_of_upcoming_events].state = state;
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// apply any queued changes and flush the record
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if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveSetup)
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{
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_upcomingEvents[_upcomingEventsPointer].updates |= Event::Action::HMoveCompare;
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_vBlankExtend = true;
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_stateByTime = _stateByExtendTime[1];
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// clear any ongoing moves
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if(_hMoveFlags)
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@ -303,6 +299,9 @@ void Machine::output_pixels(unsigned int count)
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// schedule new moves
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_hMoveFlags = 0x1f;
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_hMoveCounter = 15;
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// follow-through into a compare immediately
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_upcomingEvents[_upcomingEventsPointer].updates |= Event::Action::HMoveCompare;
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}
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if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveCompare)
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@ -326,25 +325,36 @@ void Machine::output_pixels(unsigned int count)
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{
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update_timers(_hMoveFlags);
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}
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_upcomingEvents[_upcomingEventsPointer].updates = 0;
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_upcomingEventsPointer = (_upcomingEventsPointer + 1)%number_of_upcoming_events;
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// reload the playfield pixel if appropriate
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if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::Playfield)
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// determine which output state is currently active
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OutputState primary_state = _stateByTime[_horizontalTimer >> 2];
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OutputState effective_state = primary_state;
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// update pixel timers
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if(primary_state == OutputState::Pixel) update_timers(~0);
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// update the background chain
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if(_horizontalTimer >= 64 && _horizontalTimer <= 160+64 && !(_horizontalTimer&3))
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{
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_playfieldOutput = _upcomingEvents[_upcomingEventsPointer].playfieldPixel;
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_playfieldOutput = _nextPlayfieldOutput;
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_nextPlayfieldOutput = _playfield[(_horizontalTimer - 64) >> 2];
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}
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// read that state
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state = _upcomingEvents[_upcomingEventsPointer].state;
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OutputState actingState = state;
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// if vsync is enabled, output the opposite of the automatic hsync output
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if(_vSyncEnabled) {
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effective_state = (effective_state = OutputState::Sync) ? OutputState::Blank : OutputState::Sync;
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}
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// honour the vertical blank flag
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if(_vBlankEnabled && state == OutputState::Pixel) {
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actingState = OutputState::Blank;
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if(_vBlankEnabled && effective_state == OutputState::Pixel) {
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effective_state = OutputState::Blank;
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}
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// decide what that means needs to be communicated to the CRT
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_lastOutputStateDuration++;
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if(actingState != _lastOutputState) {
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if(effective_state != _lastOutputState) {
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switch(_lastOutputState) {
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case OutputState::Blank: _crt->output_blank(_lastOutputStateDuration); break;
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case OutputState::Sync: _crt->output_sync(_lastOutputStateDuration); break;
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@ -352,9 +362,9 @@ void Machine::output_pixels(unsigned int count)
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case OutputState::Pixel: _crt->output_data(_lastOutputStateDuration, 1); break;
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}
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_lastOutputStateDuration = 0;
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_lastOutputState = actingState;
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_lastOutputState = effective_state;
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if(actingState == OutputState::Pixel) {
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if(effective_state == OutputState::Pixel) {
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_outputBuffer = _crt->allocate_write_area(160);
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} else {
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_outputBuffer = nullptr;
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@ -362,7 +372,7 @@ void Machine::output_pixels(unsigned int count)
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}
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// decide on a pixel colour if that's what's happening
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if(state == OutputState::Pixel)
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if(effective_state == OutputState::Pixel)
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{
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uint8_t colour = get_output_pixel();
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if(_outputBuffer)
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@ -372,16 +382,13 @@ void Machine::output_pixels(unsigned int count)
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}
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}
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// advance
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_upcomingEvents[_upcomingEventsPointer].updates = 0;
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_upcomingEventsPointer = (_upcomingEventsPointer + 1)%number_of_upcoming_events;
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// advance horizontal timer, perform reset actions if requested
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// advance horizontal timer, perform reset actions if desired
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_horizontalTimer = (_horizontalTimer + 1) % horizontalTimerPeriod;
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if(!_horizontalTimer)
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{
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_vBlankExtend = false;
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_stateByTime = _stateByExtendTime[0];
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set_ready_line(false);
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// printf("\n");
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}
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}
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}
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@ -391,8 +398,7 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
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set_reset_line(false);
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uint8_t returnValue = 0xff;
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unsigned int cycles_run_for = 1;
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unsigned int additional_pixels = 0;
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unsigned int cycles_run_for = 3;
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// this occurs as a feedback loop — the 2600 requests ready, then performs the cycles_run_for
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// leap to the end of ready only once ready is signalled — because on a 6502 ready doesn't take
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@ -400,11 +406,10 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
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// skips to the end of the line.
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if(operation == CPU6502::BusOperation::Ready) {
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unsigned int distance_to_end_of_ready = horizontalTimerPeriod - _horizontalTimer;
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cycles_run_for = distance_to_end_of_ready / 3;
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additional_pixels = distance_to_end_of_ready % 3;
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cycles_run_for = distance_to_end_of_ready;
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}
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output_pixels(additional_pixels + cycles_run_for * 3);
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output_pixels(2);
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if(operation != CPU6502::BusOperation::Ready) {
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@ -482,7 +487,8 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
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case 0x02:
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// printf("%d\n", _horizontalTimer);
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// printf("W");
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if(_horizontalTimer) set_ready_line(true);
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// if(_horizontalTimer)
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set_ready_line(true);
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break;
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case 0x03:
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// Reset is delayed by four cycles.
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@ -691,17 +697,17 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
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}
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}
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if(_piaTimerValue >= cycles_run_for) {
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_piaTimerValue -= cycles_run_for;
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if(_piaTimerValue >= cycles_run_for / 3) {
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_piaTimerValue -= cycles_run_for / 3;
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} else {
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_piaTimerValue += 0xff - cycles_run_for;
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_piaTimerValue += 0xff - cycles_run_for / 3;
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_piaTimerShift = 0;
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_piaTimerStatus |= 0xc0;
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}
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// output_pixels(additional_pixels + cycles_run_for * 3);
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output_pixels(cycles_run_for - 2);
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return cycles_run_for;
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return cycles_run_for / 3;
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}
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void Machine::set_digital_input(Atari2600DigitalInput input, bool state)
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@ -49,7 +49,7 @@ class Machine: public CPU6502::Processor<Machine> {
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uint8_t _playfieldControl;
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uint8_t _playfieldColour;
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uint8_t _backgroundColour;
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uint8_t _playfield[40];
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uint8_t _playfield[41];
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// ... and derivatives
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int _ballSize, _missileSize[2];
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@ -90,7 +90,7 @@ class Machine: public CPU6502::Processor<Machine> {
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unsigned int _objectCounterPointer;
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// the latched playfield output
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uint8_t _playfieldOutput;
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uint8_t _playfieldOutput, _nextPlayfieldOutput;
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// player registers
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uint8_t _playerColour[2];
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@ -119,7 +119,6 @@ class Machine: public CPU6502::Processor<Machine> {
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// graphics output
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unsigned int _horizontalTimer;
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bool _vSyncEnabled, _vBlankEnabled;
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bool _vBlankExtend;
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// horizontal motion control
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uint8_t _hMoveCounter;
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@ -140,6 +139,8 @@ class Machine: public CPU6502::Processor<Machine> {
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// latched output state
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unsigned int _lastOutputStateDuration;
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OutputState _stateByExtendTime[2][57];
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OutputState *_stateByTime;
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OutputState _lastOutputState;
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uint8_t *_outputBuffer;
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