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https://github.com/TomHarte/CLK.git
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Explicitly separated vertical and horizontal sync event tracking, so as explicitly to be able to handle a coincidental simultaneous occurrence of both. Also for clarity.
This commit is contained in:
Thomas Harte
parent
529f61caa1
commit
33c06baffa
160
Outputs/CRT.cpp
160
Outputs/CRT.cpp
@ -75,17 +75,8 @@ CRT::~CRT()
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#pragma mark - Sync loop
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CRT::SyncEvent CRT::advance_to_next_sync_event(bool hsync_is_requested, bool vsync_is_charging, int cycles_to_run_for, int *cycles_advanced)
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CRT::SyncEvent CRT::next_vertical_sync_event(bool vsync_is_charging, int cycles_to_run_for, int *cycles_advanced)
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{
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// do we recognise this hsync, thereby adjusting time expectations?
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if ((_horizontal_counter < _hsync_error_window || _horizontal_counter >= _expected_next_hsync - _hsync_error_window) && hsync_is_requested) {
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_did_detect_hsync = true;
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int time_now = (_horizontal_counter < _hsync_error_window) ? _expected_next_hsync + _horizontal_counter : _horizontal_counter;
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_expected_next_hsync = (_expected_next_hsync + time_now) >> 1;
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// printf("to %d for %d\n", _expected_next_hsync, time_now);
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}
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SyncEvent proposedEvent = SyncEvent::None;
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int proposedSyncTime = cycles_to_run_for;
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@ -99,18 +90,6 @@ CRT::SyncEvent CRT::advance_to_next_sync_event(bool hsync_is_requested, bool vsy
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}
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}
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// will we end an ongoing hsync?
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if (_horizontal_counter < _horizontal_retrace_time && _horizontal_counter+proposedSyncTime >= _horizontal_retrace_time) {
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proposedSyncTime = _horizontal_retrace_time - _horizontal_counter;
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proposedEvent = SyncEvent::EndHSync;
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}
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// will we start an hsync?
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if (_horizontal_counter + proposedSyncTime >= _expected_next_hsync) {
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proposedSyncTime = _expected_next_hsync - _horizontal_counter;
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proposedEvent = SyncEvent::StartHSync;
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}
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// will an acceptable vertical sync be triggered?
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if (vsync_is_charging && !_vretrace_counter) {
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if (_sync_capacitor_charge_level < _sync_capacitor_charge_threshold && _sync_capacitor_charge_level + proposedSyncTime >= _sync_capacitor_charge_threshold) {
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@ -131,6 +110,35 @@ CRT::SyncEvent CRT::advance_to_next_sync_event(bool hsync_is_requested, bool vsy
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return proposedEvent;
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}
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CRT::SyncEvent CRT::next_horizontal_sync_event(bool hsync_is_requested, int cycles_to_run_for, int *cycles_advanced)
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{
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// do we recognise this hsync, thereby adjusting future time expectations?
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if ((_horizontal_counter < _hsync_error_window || _horizontal_counter >= _expected_next_hsync - _hsync_error_window) && hsync_is_requested) {
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_did_detect_hsync = true;
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int time_now = (_horizontal_counter < _hsync_error_window) ? _expected_next_hsync + _horizontal_counter : _horizontal_counter;
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_expected_next_hsync = (_expected_next_hsync + time_now) >> 1;
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}
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SyncEvent proposedEvent = SyncEvent::None;
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int proposedSyncTime = cycles_to_run_for;
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// will we end an ongoing hsync?
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if (_horizontal_counter < _horizontal_retrace_time && _horizontal_counter+proposedSyncTime >= _horizontal_retrace_time) {
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proposedSyncTime = _horizontal_retrace_time - _horizontal_counter;
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proposedEvent = SyncEvent::EndHSync;
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}
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// will we start an hsync?
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if (_horizontal_counter + proposedSyncTime >= _expected_next_hsync) {
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proposedSyncTime = _expected_next_hsync - _horizontal_counter;
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proposedEvent = SyncEvent::StartHSync;
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}
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*cycles_advanced = proposedSyncTime;
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return proposedEvent;
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}
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void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool vsync_charging, const CRTRun::Type type, const char *data_type)
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{
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// this is safe to keep locally because it accumulates over this run of cycles only
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@ -138,16 +146,19 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
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while(number_of_cycles) {
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// get the next sync event and its timing; hsync request is instantaneous (being edge triggered) so
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// set it to false for the next run through this loop (if any)
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int next_run_length;
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SyncEvent next_event = advance_to_next_sync_event(hsync_requested, vsync_charging, number_of_cycles, &next_run_length);
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int time_until_vertical_sync_event, time_until_horizontal_sync_event;
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SyncEvent next_vertical_sync_event = this->next_vertical_sync_event(vsync_charging, number_of_cycles, &time_until_vertical_sync_event);
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SyncEvent next_horizontal_sync_event = this->next_horizontal_sync_event(hsync_requested, time_until_vertical_sync_event, &time_until_horizontal_sync_event);
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hsync_requested = false;
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if(_current_frame)
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{
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CRTRun *nextRun = _current_frame->get_next_run();
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// get the next sync event and its timing; hsync request is instantaneous (being edge triggered) so
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// set it to false for the next run through this loop (if any)
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int next_run_length = std::min(time_until_vertical_sync_event, time_until_horizontal_sync_event);
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CRTRun *nextRun = (_current_frame && next_run_length) ? _current_frame->get_next_run() : nullptr;
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if(nextRun)
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{
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// set the type, initial raster position and type of this run
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nextRun->type = type;
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nextRun->start_point.dst_x = _rasterPosition.x;
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@ -205,52 +216,63 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
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_vretrace_counter = std::max(_vretrace_counter - next_run_length, 0);
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// react to the incoming event...
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switch(next_event) {
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if(next_run_length == time_until_horizontal_sync_event)
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{
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switch(next_horizontal_sync_event)
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{
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// start of hsync: zero the scanline counter, note that we're now in
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// horizontal sync, increment the lines-in-this-frame counter
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case SyncEvent::StartHSync:
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_horizontal_counter = 0;
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_is_in_hsync = true;
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break;
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// start of hsync: zero the scanline counter, note that we're now in
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// horizontal sync, increment the lines-in-this-frame counter
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case SyncEvent::StartHSync:
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_horizontal_counter = 0;
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_is_in_hsync = true;
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break;
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// end of horizontal sync: update the flywheel's velocity, note that we're no longer
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// in horizontal sync
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case SyncEvent::EndHSync:
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if (!_did_detect_hsync) {
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_expected_next_hsync = (_expected_next_hsync + (_hsync_error_window >> 1) + _cycles_per_line) >> 1;
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}
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_did_detect_hsync = false;
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_is_in_hsync = false;
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break;
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// end of horizontal sync: update the flywheel's velocity, note that we're no longer
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// in horizontal sync
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case SyncEvent::EndHSync:
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if (!_did_detect_hsync) {
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_expected_next_hsync = (_expected_next_hsync + (_hsync_error_window >> 1) + _cycles_per_line) >> 1;
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}
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_did_detect_hsync = false;
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_is_in_hsync = false;
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break;
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default: break;
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}
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}
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// start of vertical sync: reset the lines-in-this-frame counter,
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// load the retrace counter with the amount of time it'll take to retrace
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case SyncEvent::StartVSync:
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_vretrace_counter = _vertical_retrace_time;
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break;
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if(next_run_length == time_until_vertical_sync_event)
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{
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switch(next_vertical_sync_event)
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{
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// start of vertical sync: reset the lines-in-this-frame counter,
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// load the retrace counter with the amount of time it'll take to retrace
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case SyncEvent::StartVSync:
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_vretrace_counter = _vertical_retrace_time;
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break;
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// end of vertical sync: tell the delegate that we finished vertical sync,
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// releasing all runs back into the common pool
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case SyncEvent::EndVSync:
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if(_delegate && _current_frame)
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{
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_current_frame->complete();
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_frames_with_delegate++;
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_delegate->crt_did_end_frame(this, _current_frame);
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}
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// end of vertical sync: tell the delegate that we finished vertical sync,
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// releasing all runs back into the common pool
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case SyncEvent::EndVSync:
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if(_delegate && _current_frame)
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{
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_current_frame->complete();
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_frames_with_delegate++;
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_delegate->crt_did_end_frame(this, _current_frame);
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}
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if(_frames_with_delegate < kCRTNumberOfFrames)
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{
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_frame_read_pointer = (_frame_read_pointer + 1)%kCRTNumberOfFrames;
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_current_frame = _frames[_frame_read_pointer];
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_current_frame->reset();
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}
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else
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_current_frame = nullptr;
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break;
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if(_frames_with_delegate < kCRTNumberOfFrames)
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{
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_frame_read_pointer = (_frame_read_pointer + 1)%kCRTNumberOfFrames;
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_current_frame = _frames[_frame_read_pointer];
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_current_frame->reset();
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}
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else
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_current_frame = nullptr;
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break;
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default: break;
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default: break;
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}
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}
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}
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}
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@ -132,7 +132,8 @@ class CRT {
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StartHSync, EndHSync,
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StartVSync, EndVSync
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};
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SyncEvent advance_to_next_sync_event(bool hsync_is_requested, bool vsync_is_charging, int cycles_to_run_for, int *cycles_advanced);
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SyncEvent next_vertical_sync_event(bool vsync_is_charging, int cycles_to_run_for, int *cycles_advanced);
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SyncEvent next_horizontal_sync_event(bool hsync_is_requested, int cycles_to_run_for, int *cycles_advanced);
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};
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}
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