Added FemtoDuration for high-accuracy time measurements.

.vscode/settings.json

@@ -1,3 +1,13 @@
 {
-  "cSpell.words": ["byteorder", "ftmemsim", "hemem", "itertools"]
+  "cSpell.words": [
+    "byteorder",
+    "femto",
+    "FEMTOS",
+    "ftmemsim",
+    "hemem",
+    "itertools",
+    "optane",
+    "pico",
+    "PICOS"
+  ]
 }

src/util.rs

@@ -1,5 +1,11 @@
 //! Utilities
 
+// Modules
+mod duration;
+
+// Exports
+pub use duration::FemtoDuration;
+
 // Imports
 use std::io;
 

src/util/duration.rs

@@ -0,0 +1,64 @@
+//! Duration
+
+// Imports
+use std::{fmt, writeln};
+
+/// Duration with femto-second precision
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+pub struct FemtoDuration {
+	/// Whole seconds
+	secs: u64,
+
+	/// femto seconds (0..FEMTOS_PER_SEC)
+	femto_secs: u64,
+}
+
+impl FemtoDuration {
+	/// Number of femto-seconds per nano-second
+	pub const FEMTOS_PER_NANO: u64 = 1_000_000;
+	/// Number of nano-seconds per second
+	pub const NANOS_PER_SEC: u64 = 1_000_000_000;
+	/// Number of femto-seconds per second
+	pub const _FEMTOS_PER_SEC: u64 = 1_000_000_000_000_000;
+
+	/// Creates a new duration from floating-point nanoseconds
+	// TODO: Deal with rounding better?
+	pub fn from_nanos_f64(nanos: f64) -> Self {
+		let secs = (nanos / Self::NANOS_PER_SEC as f64) as u64;
+		let femto_secs = ((nanos % Self::NANOS_PER_SEC as f64) * Self::FEMTOS_PER_NANO as f64) as u64;
+
+		Self { secs, femto_secs }
+	}
+}
+
+
+impl fmt::Display for FemtoDuration {
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		let secs = self.secs % 60;
+		let mins = self.secs / 60 % 60;
+		let hours = self.secs / 60 / 60;
+
+		let femtos = self.femto_secs % 1000;
+		let picos = self.femto_secs / 1000 % 1000;
+		let nanos = self.femto_secs / 1000 / 1000 % 1000;
+		let micros = self.femto_secs / 1000 / 1000 / 1000 % 1000;
+		let millis = self.femto_secs / 1000 / 1000 / 1000 / 1000 % 1000;
+
+		match (hours, mins, secs, millis, micros, nanos, picos, femtos) {
+			// If we have no hours, mins or secs, format in the smallest unit
+			(0, 0, 0, 0, 0, 0, 0, 0) => (),
+			(0, 0, 0, 0, 0, 0, 0, _) => writeln!(f, "{femtos}fs")?,
+			(0, 0, 0, 0, 0, 0, ..) => writeln!(f, "{picos}.{femtos}ps")?,
+			(0, 0, 0, 0, 0, ..) => writeln!(f, "{nanos}.{picos}{femtos}ns")?,
+			(0, 0, 0, 0, ..) => writeln!(f, "{micros}.{nanos}{picos}{femtos}µs")?,
+			(0, 0, 0, ..) => writeln!(f, "{millis}.{micros}{nanos}{picos}{femtos}ms")?,
+
+			// Else format it as the decimal part
+			(0, 0, ..) => writeln!(f, "{secs}.{millis}{micros}{nanos}{picos}{femtos}s")?,
+			(0, ..) => writeln!(f, "{mins}m{secs}.{millis}{micros}{nanos}{picos}{femtos}s")?,
+			(..) => writeln!(f, "{hours}h{mins}m{secs}.{millis}{micros}{nanos}{picos}{femtos}s")?,
+		}
+
+		Ok(())
+	}
+}