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Accounts for periods near an expected sync after a sync actually occurred.

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This commit is contained in:
Thomas Harte 2019-02-12 22:30:40 -05:00
parent 5d68a5bdd0
commit 77bebd4a65
1 changed files with 13 additions and 4 deletions
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17
Outputs/CRT/Internals/Flywheel.hpp
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@ -79,13 +79,13 @@ struct Flywheel {
SyncEvent proposed_event = SyncEvent::None;
int proposed_sync_time = cycles_to_run_for;
// will we end an ongoing retrace?
// End an ongoing retrace?
if(counter_ < retrace_time_ && counter_ + proposed_sync_time >= retrace_time_) {
proposed_sync_time = retrace_time_ - counter_;
proposed_event = SyncEvent::EndRetrace;
}
// will we start a retrace?
// Start a retrace?
if(counter_ + proposed_sync_time >= expected_next_sync_) {
proposed_sync_time = expected_next_sync_ - counter_;
proposed_event = SyncEvent::StartRetrace;
@ -104,7 +104,14 @@ struct Flywheel {
@param event The synchronisation event to apply after that period.
*/
inline void apply_event(int cycles_advanced, SyncEvent event) {
// In debug builds, perform a sanity check for counter overflow.
#ifndef NDEBUG
const int old_counter = counter_;
#endif
counter_ += cycles_advanced;
#ifndef NDEBUG
assert(old_counter <= counter_);
#endif
switch(event) {
default: return;
@ -170,10 +177,12 @@ struct Flywheel {
}
/*!
@returns `true` if a sync is expected soon or the time at which it was expected was recent.
@returns `true` if a sync is expected soon or if the time at which it was expected (or received) was recent.
*/
inline bool is_near_expected_sync() {
return abs(counter_ - expected_next_sync_) < standard_period_ / 50;
return
(counter_ < (standard_period_ / 100)) ||
(counter_ >= expected_next_sync_ - (standard_period_ / 100));
}
private: