From 82e5def7c4d6ae2ebe9e6db29e274eef6ca1ca41 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 20 Jan 2020 21:58:34 -0500
Subject: [PATCH] Implements get_scan_status, but for scale being incorrect.

---
 Outputs/CRT/CRT.cpp                |  6 +++++-
 Outputs/CRT/Internals/Flywheel.hpp | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Outputs/CRT/CRT.cpp b/Outputs/CRT/CRT.cpp
index 8d45b645d..0e2e6a6b2 100644
--- a/Outputs/CRT/CRT.cpp
+++ b/Outputs/CRT/CRT.cpp
@@ -469,5 +469,9 @@ Outputs::Display::Rect CRT::get_rect_for_area(int first_line_after_sync, int num
 }
 
 Outputs::Display::ScanStatus CRT::get_scan_status() const {
-	return Outputs::Display::ScanStatus();
+	Outputs::Display::ScanStatus status;
+	status.field_duration = vertical_flywheel_->get_locked_period();
+	status.field_duration_gradient = vertical_flywheel_->get_last_period_adjustment();
+	status.current_position = float(vertical_flywheel_->get_current_output_position()) / float(vertical_flywheel_->get_locked_period());
+	return status;
 }
diff --git a/Outputs/CRT/Internals/Flywheel.hpp b/Outputs/CRT/Internals/Flywheel.hpp
index 465785fce..eecde8b40 100644
--- a/Outputs/CRT/Internals/Flywheel.hpp
+++ b/Outputs/CRT/Internals/Flywheel.hpp
@@ -63,6 +63,7 @@ struct Flywheel {
 	inline SyncEvent get_next_event_in_period(bool sync_is_requested, int cycles_to_run_for, int *cycles_advanced) {
 		// If sync is signalled _now_, consider adjusting expected_next_sync_.
 		if(sync_is_requested) {
+			const auto last_sync = expected_next_sync_;
 			if(counter_ < sync_error_window_ || counter_ > expected_next_sync_ - sync_error_window_) {
 				const int time_now = (counter_ < sync_error_window_) ? expected_next_sync_ + counter_ : counter_;
 				expected_next_sync_ = (3*expected_next_sync_ + time_now) >> 2;
@@ -75,6 +76,7 @@ struct Flywheel {
 					expected_next_sync_ = (3*expected_next_sync_ + standard_period_ - sync_error_window_) >> 2;
 				}
 			}
+			last_adjustment_ = expected_next_sync_ - last_sync;
 		}
 
 		SyncEvent proposed_event = SyncEvent::None;
@@ -165,6 +167,20 @@ struct Flywheel {
 		return standard_period_;
 	}
 
+	/*!
+		@returns the actual current period for a complete scan (including retrace).
+	*/
+	inline int get_locked_period() {
+		return expected_next_sync_;
+	}
+
+	/*!
+		@returns the amount by which the @c locked_period was adjusted, the last time that an adjustment was applied.
+	*/
+	inline int get_last_period_adjustment() {
+		return last_adjustment_;
+	}
+
 	/*!
 		@returns the number of synchronisation events that have seemed surprising since the last time this method was called;
 		a low number indicates good synchronisation.
@@ -195,6 +211,8 @@ struct Flywheel {
 
 		int number_of_surprises_ = 0;	// a count of the surprising syncs
 
+		int last_adjustment_ = 0;		// The amount by which
+
 		/*
 			Implementation notes: