Merge branch 'hru' (closes #33)

src/hru.rs

@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * 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 Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::{
+	cmp::Ordering,
+	env::args,
+	io::{ stdin, stdout, Write },
+	process::{ ExitCode, exit },
+};
+
+extern crate sysexits;
+
+use sysexits::{ EX_DATAERR, EX_IOERR, EX_SOFTWARE };
+
+const LIST: [(u32, &str); 10] = [
+	(3, "k"),
+	(6, "M"),
+	(9, "G"),
+	(12, "T"),
+	(15, "P"),
+	(18, "E"),
+	(21, "Z"),
+	(24, "Y"),
+	(27, "R"),
+	(30, "Q")
+];
+
+fn convert(input: u128) -> Result<(f64, (u32, &'static str)), String> {
+
+	let mut out = (input as f64, (0_u32, ""));
+	if input < 1000 { return Ok(out); }
+
+	for (n, p) in LIST {
+		let c = match 10_u128.checked_pow(n) {
+			Some(c) => c,
+			None => {
+				return Err(format!("10^{}: Integer overflow.", n.to_string()));
+			},
+		};
+
+		match c.cmp(&input) {
+			Ordering::Less => {
+				out = (input as f64 / c as f64, (n, p));
+			},
+			Ordering::Equal => {
+				return Ok((input as f64 / c as f64, (n, p)));
+			},
+			Ordering::Greater => {},
+		};
+	}
+
+	Ok(out)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+	let mut buf = String::new();
+	while let Ok(_) = stdin().read_line(&mut buf) {
+		if buf.is_empty() { return ExitCode::SUCCESS; }
+
+		let n: u128 = match buf.trim().parse() {
+			Ok(f) => {
+				buf.clear();
+				f
+			},
+			Err(err) => {
+				eprintln!("{}: {}.", argv[0], err);
+				return ExitCode::from(EX_DATAERR as u8);
+			},
+		};
+
+		let (number, prefix) = match convert(n) {
+			Ok(x) => x,
+			Err(err) => {
+				eprintln!("{}: {}.", argv[0], err);
+				return ExitCode::from(EX_SOFTWARE as u8);
+			},
+		};
+
+		let si_prefix = format!("{}B", prefix.1);
+
+		let out = ((number * 10.0).round() / 10.0).to_string();
+
+		stdout().write_all(format!("{} {}\n", out, si_prefix).as_bytes())
+			.unwrap_or_else(|e| {
+				eprintln!("{}: {}.", argv[0], e);
+				exit(EX_IOERR);
+			});
+	}
+
+	ExitCode::SUCCESS
+}