Ignore callgrind files.

.gitignore

@@ -1,2 +1,3 @@
 /target
 /indivisible.1.gz
+callgrind.out.*

benchmark.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+BIN="./target/release/indivisible"
+TRIALS=20
+
+if ! [ -f "$BIN" ]
+then
+	>&2 echo "Release build not available. Please run 'cargo build -r'."
+	exit 1
+fi
+
+if ! command -v calc &>/dev/null
+then
+	>&2 echo "Missing 'calc' program. Please install it for this script."
+	exit 1
+fi
+
+echo "Calculating primes up to 100,000,000"
+TOTAL="0"
+for _ in $(seq "$TRIALS")
+do
+	TIME=$(command time -f "%e" "$BIN" 100000000 2>&1 >/dev/null)
+	TOTAL=$(calc "$TOTAL + $TIME")
+done
+
+AVG=$(calc "$TOTAL / $TRIALS")
+
+echo "Average time: ${AVG}s"

src/candidate.rs

@@ -1,82 +0,0 @@
-/*
- * Copyright (C) 2025  Nicolás Ortega Froysa <nicolas@ortegas.org>
- * Author: Nicolás Ortega Froysa <nicolas@ortegas.org>
- *
- * 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, 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 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/>.
- */
-
-pub struct CandidateGenerator {
-	base:u64,
-	// first use of the base
-	first_use:bool,
-}
-
-impl CandidateGenerator {
-	pub fn new() -> Self {
-		CandidateGenerator {
-			base: 0,
-			first_use: true,
-		}
-	}
-
-	pub fn calc_base(&mut self, last_prime:u64) {
-		if last_prime == 2 {
-			self.base = 0;
-			self.first_use = false;
-		} else if last_prime == 3 {
-			self.base = 6;
-			self.first_use = true;
-		} else {
-			let modulo = last_prime % 6;
-			if modulo == 1 {
-				self.base = last_prime + 5;
-				self.first_use = true;
-			} else if modulo == 5 {
-				self.base = last_prime + 1;
-				self.first_use = false;
-			} else {
-				panic!("Invalid last prime {}" , last_prime);
-			}
-		}
-	}
-
-	pub fn next(&mut self) -> u64 {
-		/*
-		 * All primes, except 2 and 3, will be equal to (n * 6 ± 1). This avoids
-		 * multiples of three, optimizing our counting.
-		 */
-		let val;
-
-		if self.base != 0 {
-			if self.first_use {
-				val = self.base - 1;
-			} else {
-				val = self.base + 1;
-			}
-		} else {
-			if self.first_use {
-				val = 2;
-			} else {
-				val = 3;
-			}
-		}
-
-		if !self.first_use {
-			self.base += 6;
-		}
-		self.first_use = !self.first_use;
-
-		val
-	}
-}

src/main.rs

@@ -16,15 +16,12 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-use std::collections::VecDeque;
-use std::fs::File;
-use std::io::{BufRead, BufReader};
-use std::path::PathBuf;
+//use std::fs::File;
+//use std::io::{BufRead, BufReader};
+//use std::path::PathBuf;
 use std::process;
 use structopt::StructOpt;
 
-mod candidate;
-use candidate::CandidateGenerator;
 mod worker;
 
 #[derive(StructOpt)]
@@ -32,85 +29,53 @@ mod worker;
 struct Opt {
 	#[structopt(short, long, help = "Print all found primes")]
 	verbose:bool,
-	#[structopt(short, long, name = "FILE", help = "Import prime numbers from FILE")]
-	import:Option<PathBuf>,
+	//#[structopt(short, long, name = "FILE", help = "Import prime numbers from FILE")]
+	//import:Option<PathBuf>,
 	#[structopt(short, long, help = "Test if num is prime instead of generation")]
 	test:bool,
-	#[structopt(help = "Ordinal of the prime to generate or number to test for primality")]
-	num:u64,
-	#[structopt(short, long, name = "n", default_value = "1", help = "Number of threads to spawn")]
-	jobs:u64,
+	#[structopt(help = "Max of the prime to generate or number to test for primality")]
+	num:usize,
+	//#[structopt(short, long, name = "n", default_value = "1", help = "Number of threads to spawn")]
+	//jobs:u64,
 }
 
 fn main() {
 	let opts = Opt::from_args();
 
-	let mut prime_list = VecDeque::<u64>::new();
-
-	if opts.import.is_some() {
+	/*if opts.import.is_some() {
 		let in_file = File::open(opts.import.unwrap()).unwrap();
 		let reader = BufReader::new(in_file);
 		for p in reader.lines().into_iter() {
-			prime_list.push_back(p.unwrap().parse().unwrap());
+			prime_list.push(p.unwrap().parse().unwrap());
 		}
-	}
+	}*/
 
-	if opts.num == 0 {
+	if opts.num < 2 {
 		eprintln!("Invalid value for num: {}", opts.num);
 		process::exit(1);
 	}
 
-	if opts.test && *prime_list.back().unwrap_or(&0) >= opts.num {
-		for i in prime_list.iter() {
-			if *i == opts.num {
-				process::exit(0)
+	let prime_list = worker::work_segment(0, opts.num);
+
+	if opts.test {
+		if *prime_list.last().unwrap() == (opts.num as u64) {
+			if opts.verbose {
+				println!("{} is prime", opts.num);
 			}
+			process::exit(0);
+		} else {
+			if opts.verbose {
+				println!("{} is composite", opts.num);
+			}
+			process::exit(1);
 		}
-		process::exit(1)
-	} else if !opts.test && prime_list.len() >= opts.num as usize {
-		let res = *prime_list.get(opts.num as usize).unwrap();
-		println!("{}", res);
 	} else {
-		let mut cand_gen = CandidateGenerator::new();
-		if !prime_list.is_empty() {
-			cand_gen.calc_base(*prime_list.back().unwrap());
-		}
-
-		loop {
-			let cand = cand_gen.next();
-			if opts.test && cand > opts.num {
-				break;
+		if !opts.verbose {
+			println!("{}", prime_list.last().unwrap());
+		} else {
+			for p in prime_list {
+				println!("{}", p);
 			}
-
-			let mut is_prime = true;
-			for p in prime_list.iter() {
-				if cand % *p == 0 {
-					is_prime = false;
-					break;
-				}
-			}
-
-			if is_prime {
-				prime_list.push_back(cand);
-				if opts.verbose {
-					println!("{}", cand);
-				}
-
-				if !opts.test && prime_list.len() == opts.num as usize {
-					break;
-				}
-			}
-		}
-
-		if opts.test {
-			if *prime_list.back().unwrap() == opts.num {
-				process::exit(0)
-			} else {
-				process::exit(1)
-			}
-		} else if !opts.verbose {
-			let last_prime = *prime_list.back().unwrap();
-			println!("{}", last_prime);
 		}
 	}
 }

src/worker.rs

@@ -16,21 +16,68 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-use std::cell::RefCell;
-use std::collections::VecDeque;
-use std::rc::Rc;
+/**
+ * @brief Work on a segment.
+ *
+ * @param start:usize Beginning of the segment (inclusive).
+ * @param end:usize End of the segment (inclusive).
+ *
+ * @return List of primes found in segment.
+ */
+pub fn work_segment(start:usize, end:usize) -> Vec<u64> {
+	let mut found_primes = Vec::<u64>::new();
+	let mut arr = vec![false; end - start + 1];
 
-pub struct Worker {
-	prime_list:Rc<RefCell<VecDeque<u64>>>,
-}
+	if start < 2 && end > 2 {
+		arr[2] = true;
+	}
+	if start < 3 && end > 3 {
+		arr[3] = true;
+	}
 
-impl Worker {
-	pub fn new(primes_list:Rc<RefCell<VecDeque<u64>>>) -> Worker {
-		Worker {
-			prime_list: primes_list,
+	let sqrt_of_num = f64::sqrt(end as f64) as usize;
+	for x in 1..=sqrt_of_num {
+		let xx4 = 4 * x * x;
+		let xx3 = 3 * x * x;
+		for y in 1..=sqrt_of_num {
+			let yy = y * y;
+
+			let n1 = xx4 + yy;
+			if n1 <= end && (n1 % 12 == 1 || n1 % 12 == 5) {
+				arr[n1] = !arr[n1];
+			}
+
+			let n2 = xx3 + yy;
+			if n2 <= end && n2 % 12 == 7 {
+				arr[n2] = !arr[n2];
+			}
+
+			if x > y {
+				let n3 = xx3 - yy;
+				if n3 <= end && n3 % 12 == 11 {
+					arr[n3] = !arr[n3];
+				}
+			}
 		}
 	}
 
-	pub fn run(&mut self) {
+	for i in 5..=sqrt_of_num {
+		if !arr[i] {
+			continue;
+		}
+
+		let mut j = i * i;
+		while j <= end {
+			arr[j] = false;
+			j += i * i;
+		}
 	}
+
+	for i in 2..=end {
+		if arr[i] {
+			found_primes.push(i as u64);
+		}
+	}
+
+	found_primes
 }