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Forces the outward-communicated composite angles to have the same precision as the cycle counts.

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While also making a minor improvement to output range. Which is neither here nor there.
This commit is contained in:
Thomas Harte 2019-02-24 14:29:43 -05:00
parent 2f491b5be1
commit 2f9e825728
1 changed files with 9 additions and 1 deletions
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10
Outputs/CRT/CRT.cpp
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@ -169,8 +169,12 @@ Outputs::Display::ScanTarget::Scan::EndPoint CRT::end_point(uint16_t data_offset
end_point.x = uint16_t(horizontal_flywheel_->get_current_output_position());
end_point.y = uint16_t(vertical_flywheel_->get_current_output_position() / vertical_flywheel_output_divider_);
end_point.composite_angle = int16_t((phase_numerator_ << 6) / phase_denominator_) * (is_alernate_line_ ? -1 : 1);
end_point.data_offset = data_offset;
// TODO: this is a workaround for the limited precision that can be posted onwards;
// it'd be better to make time_multiplier_ an explicit modal and just not divide by it.
const auto lost_precision = cycles_since_horizontal_sync_ % time_multiplier_;
end_point.composite_angle = int16_t(((phase_numerator_ - lost_precision * colour_cycle_numerator_) << 6) / phase_denominator_) * (is_alernate_line_ ? -1 : 1);
end_point.cycles_since_end_of_horizontal_retrace = uint16_t(cycles_since_horizontal_sync_ / time_multiplier_);
return end_point;
@ -227,6 +231,10 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, bool vsync_
// Reset the cycles-since-sync counter if this is the end of retrace.
if(next_horizontal_sync_event == Flywheel::SyncEvent::EndRetrace) {
cycles_since_horizontal_sync_ = 0;
// This is unnecessary, strictly speaking, but seeks to help ScanTargets fit as
// much as possible into a fixed range.
phase_numerator_ %= phase_denominator_;
}
// Announce event.