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#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy, Hash)]
pub struct Prime {
n: u64,
}
impl std::fmt::Debug for Prime {
fn fmt(&self, w: &mut std::fmt::Formatter) -> std::fmt::Result {
write!(w, "{}", self.n)
}
}
impl std::fmt::Display for Prime {
fn fmt(&self, w: &mut std::fmt::Formatter) -> std::fmt::Result {
write!(w, "{}", self.n)
}
}
impl Prime {
pub fn new(n: u64) -> Option<Prime> {
if is_u64_prime(n) {
Some(Prime { n })
} else {
None
}
}
pub unsafe fn new_unsafe(n: u64) -> Prime {
Prime { n }
}
pub fn get(&self) -> u64 {
self.n
}
}
impl std::ops::Deref for Prime {
type Target = u64;
fn deref(&self) -> &Self::Target {
&self.n
}
}
pub fn is_u64_prime(n: u64) -> bool
{
if n == 2 || n == 3 {
true
} else if n & 1 == 0 || n < 5 {
false
} else if n < 2_047 {
sprp_u64(n, 2)
} else if n < 1_373_653 {
sprp_u64(n, 2) && sprp_u64(n, 3)
} else if n < 4_759_123_141 {
if n <= std::u32::MAX as u64 {
sprp_u64(n, 2) && sprp_u64(n, 7) && sprp_u64(n, 61)
} else {
let n = n as u128;
sprp_u128(n, 2) && sprp_u128(n, 7) && sprp_u128(n, 61)
}
} else {
let n = n as u128;
const P_LIST: [u8; 12] = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37];
for p in P_LIST.iter() {
if !sprp_u128(n, *p) {
return false;
}
}
true
}
}
pub const MAX_U64_PRIME: u64 = 18_446_744_073_709_551_557;
fn sprp_u64(n: u64, a: u8) -> bool {
let a = a as u64;
let d = n - 1;
let r = d.trailing_zeros();
let d = d >> r;
assert_eq!((1 << r) * d + 1, n);
let mut x = pow_mod_u64(a, d, n);
if x == 1 || x + 1 == n {
return true;
}
for _ in 1..r {
x = (x*x) % n;
if x + 1 == n {
return true;
}
}
false
}
fn pow_mod_u64(mut x: u64, mut p: u64, m: u64) -> u64 {
let mut res = 1;
loop {
if p & 1 == 1 {
res = (res * x) % m;
p -= 1;
}
if p > 0 {
x = (x * x) % m;
p /= 2;
} else {
break;
}
}
res
}
fn pow_mod_u128(mut x: u128, mut p: u128, m: u128) -> u128 {
let mut res = 1;
loop {
if p & 1 == 1 {
res = (res * x) % m;
p -= 1;
}
if p > 0 {
x = (x * x) % m;
p /= 2;
} else {
break;
}
}
res
}
fn sprp_u128(n: u128, a: u8) -> bool {
let a = a as u128;
let d = n - 1;
let r = d.trailing_zeros();
let d = d >> r;
assert_eq!((1 << r) * d + 1, n);
let mut x = pow_mod_u128(a, d, n);
if x == 1 || x + 1 == n {
return true;
}
for _ in 1..r {
x = (x*x) % n;
if x + 1 == n {
return true;
}
}
false
}
#[test]
fn dump_end() {
for p in (std::u64::MAX - 1000)..=std::u64::MAX {
if is_u64_prime(p) {
println!("{} (2^64 - {}) is prime", p, std::u64::MAX - p + 1);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use primal::Sieve;
fn test_prime_consistency(sieve: &Sieve, n: u64) {
assert_eq!(is_u64_prime(n), sieve.is_prime(n as usize), "Primality test inconsistent for n={}", n);
}
const LIMIT: u64 = 1_000_000;
#[test]
fn small_numbers() {
let sieve = Sieve::new(LIMIT as usize);
for i in 0..LIMIT {
test_prime_consistency(&sieve, i);
}
}
fn excessive_sprp_test(n: u64) -> bool {
assert!(n > LIMIT);
let n = n as u128;
for i in 0..100 {
let k = 3 + i*2;
if !sprp_u128(n, k as u8) {
return false;
}
}
true
}
fn test_prime_excessive(n: u64) {
if n < LIMIT {
return;
}
let x_sprp_res = excessive_sprp_test(n);
let is_prime_res = is_u64_prime(n);
assert_eq!(x_sprp_res, is_prime_res, "excessive test failed for n={}", n);
{
use gmp::mpz::{ Mpz, ProbabPrimeResult };
let n_gmp = Mpz::from(n);
let gmp_pp_res = n_gmp.probab_prime(100);
let gmp_pp_res: bool = match gmp_pp_res {
ProbabPrimeResult::NotPrime => false,
_ => true,
};
assert_eq!(gmp_pp_res, is_prime_res, "excessive gmp test failed for n={}", n);
}
}
#[test]
fn big_numbers() {
use std::num::Wrapping;
let inc = Wrapping(1_234_567_123_456_892);
let mut x = Wrapping(1);
let count = 10_000;
for _ in 0..count {
x += inc;
test_prime_excessive(x.0);
}
}
#[test]
fn compare_all_magnitudes() {
let radius = 1000;
for mag in 15..=63 {
let mid = 1 << mag;
let start = mid - radius;
let end = mid + radius;
for n in start..=end {
test_prime_excessive(n);
}
}
for n in (std::u64::MAX - radius)..=std::u64::MAX {
test_prime_excessive(n);
}
}
}