1 files changed, 40 insertions, 0 deletions
diff --git a/src/utility.rs b/src/utility.rs
new file mode 100644
index 0000000..3f7850b
--- /dev/null
+++ b/src/utility.rs
@@ -0,0 +1,40 @@
+// This file is part of Guitar <https://github.com/Fuwn/guitar>.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// Copyright (C) 2022-2022 Fuwn <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-only
+
+// https://pages.mtu.edu/~suits/notefreqs.html
+pub const SPEED_OF_SOUND_METRES_PER_SECOND: f64 = 345.0;
+pub const SPEED_OF_SOUND_FEET_PER_SECOND: f64 = 1130.33;
+pub const SPEED_OF_SOUND_MILES_PER_HOUR: f64 = 770.0;
+
+/// Capitalize the first letter of a string.
+///
+/// This is used internally to make sure that pitch names are capitalized.
+pub fn capitalize_first_letter(string: &str) -> String {
+  let mut characters = string.chars();
+
+  characters.next().map_or_else(String::new, |f| {
+    f.to_uppercase().collect::<String>() + characters.as_str()
+  })
+}
+
+#[must_use]
+pub fn centimeters_to_inches(centimeters: f64) -> f64 { centimeters / 2.54 }
+
+#[must_use]
+pub fn frequency_to_wavelength_cm(frequency: f64) -> f64 {
+  SPEED_OF_SOUND_METRES_PER_SECOND / frequency * 100.0
+}