Partial save support; fix build

1 files changed, 107 insertions, 0 deletions

diff --git a/src/gallop.rs b/src/gallop.rs
new file mode 100644
index 0000000..214a739
--- /dev/null
+++ b/src/gallop.rs
@@ -0,0 +1,107 @@
+use std::{
+	cmp::Ordering,
+	time::{Duration, Instant},
+};
+
+pub const GALLOP_SENSETIVITY: Duration = Duration::from_millis(25);
+pub const GALLOP_TOLERANCE: Duration = Duration::from_millis(250);
+
+#[derive(Clone, Debug, Default)]
+pub struct Gallop {
+	keys: [Option<Instant>; 4],
+}
+
+impl Gallop {
+	pub fn push(&mut self, idx: usize) {
+		if idx >= self.keys.len() {
+			panic!("gallop index out of bound");
+		}
+
+		self.keys[idx] = Some(Instant::now());
+	}
+
+	pub fn event(&mut self) -> Option<GallopEvent> {
+		let mut sorted: Vec<(usize, Option<Instant>)> = self.keys.into_iter().enumerate().collect();
+		sorted.sort_by(|(_, a_inst), (_, b_inst)| {
+			if a_inst.is_none() {
+				Ordering::Greater
+			} else if b_inst.is_none() {
+				Ordering::Less
+			} else {
+				a_inst.cmp(&b_inst)
+			}
+		});
+
+		let (early2_idx, Some(early2)) = sorted[0] else {
+			return None;
+		};
+
+		let (early_idx, Some(early)) = sorted[1] else {
+			return None;
+		};
+
+		tracing::info!(
+			"early = [{}] {}us // early2 = [{}] {}us",
+			early_idx,
+			early.elapsed().as_micros(),
+			early2_idx,
+			early2.elapsed().as_micros()
+		);
+
+		let high = self.keys.len() - 1;
+		if early_idx == 0 && early2_idx == high {
+			tracing::trace!("gallop (+) wrap special case");
+			self.keys[early2_idx] = None;
+			return Some(GallopEvent::Positive(early.duration_since(early2)));
+		} else if early_idx == high && early2_idx == 0 {
+			tracing::trace!("gallop (-) wrap special case");
+		}
+
+		if early_idx > early2_idx {
+			let delta = early_idx - early2_idx;
+			self.keys[early2_idx] = None;
+
+			if delta > 1 {
+				tracing::info!("gallop (+) delta>1");
+				None
+			} else {
+				Some(GallopEvent::Positive(early.duration_since(early2)))
+			}
+		} else if early_idx < early2_idx {
+			let delta = early2_idx - early_idx;
+			self.keys[early2_idx] = None;
+
+			if delta > 1 {
+				tracing::info!("gallop (-) delta>1");
+				None
+			} else {
+				Some(GallopEvent::Negative(early.duration_since(early2)))
+			}
+		} else {
+			None
+		}
+	}
+}
+
+#[derive(Clone, Debug)]
+pub enum GallopEvent {
+	Positive(Duration),
+	Negative(Duration),
+}
+
+impl GallopEvent {
+	pub fn value(&self) -> f32 {
+		match self {
+			Self::Positive(gdur) => {
+				let delta = GALLOP_TOLERANCE - *gdur;
+				let units = delta.as_millis() as f32 / GALLOP_SENSETIVITY.as_millis() as f32;
+				units
+			}
+			Self::Negative(gdur) => {
+				let delta = GALLOP_TOLERANCE - *gdur;
+				let units = delta.as_millis() as f32 / GALLOP_SENSETIVITY.as_millis() as f32;
+				-units
+			}
+		}
+	}
+}