1 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! The ISAAC random number generator.
15 use core::iter::{range_step, repeat};
17 use {Rng, SeedableRng, Rand};
19 const RAND_SIZE_LEN: u32 = 8;
20 const RAND_SIZE: u32 = 1 << (RAND_SIZE_LEN as uint);
21 const RAND_SIZE_UINT: uint = 1 << (RAND_SIZE_LEN as uint);
23 /// A random number generator that uses the ISAAC algorithm[1].
25 /// The ISAAC algorithm is generally accepted as suitable for
26 /// cryptographic purposes, but this implementation has not be
27 /// verified as such. Prefer a generator like `OsRng` that defers to
28 /// the operating system for cases that need high security.
30 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
31 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
35 rsl: [u32; RAND_SIZE_UINT],
36 mem: [u32; RAND_SIZE_UINT],
42 static EMPTY: IsaacRng = IsaacRng {
44 rsl: [0; RAND_SIZE_UINT],
45 mem: [0; RAND_SIZE_UINT],
51 /// Create an ISAAC random number generator using the default
53 pub fn new_unseeded() -> IsaacRng {
59 /// Initialises `self`. If `use_rsl` is true, then use the current value
60 /// of `rsl` as a seed, otherwise construct one algorithmically (not
62 fn init(&mut self, use_rsl: bool) {
63 let mut a = 0x9e3779b9;
85 for _ in range(0u, 4) {
90 macro_rules! memloop {
92 for i in range_step(0, RAND_SIZE as uint, 8) {
93 a+=$arr[i ]; b+=$arr[i+1];
94 c+=$arr[i+2]; d+=$arr[i+3];
95 e+=$arr[i+4]; f+=$arr[i+5];
96 g+=$arr[i+6]; h+=$arr[i+7];
98 self.mem[i ]=a; self.mem[i+1]=b;
99 self.mem[i+2]=c; self.mem[i+3]=d;
100 self.mem[i+4]=e; self.mem[i+5]=f;
101 self.mem[i+6]=g; self.mem[i+7]=h;
109 for i in range_step(0, RAND_SIZE as uint, 8) {
111 self.mem[i ]=a; self.mem[i+1]=b;
112 self.mem[i+2]=c; self.mem[i+3]=d;
113 self.mem[i+4]=e; self.mem[i+5]=f;
114 self.mem[i+6]=g; self.mem[i+7]=h;
121 /// Refills the output buffer (`self.rsl`)
123 #[allow(unsigned_negation)]
124 fn isaac(&mut self) {
128 let mut b = self.b + self.c;
130 static MIDPOINT: uint = (RAND_SIZE / 2) as uint;
133 ($x:expr) => ( self.mem[(($x >> 2) as uint & ((RAND_SIZE - 1) as uint))] )
136 let r = [(0, MIDPOINT), (MIDPOINT, 0)];
137 for &(mr_offset, m2_offset) in r.iter() {
139 macro_rules! rngstepp {
140 ($j:expr, $shift:expr) => {{
142 let mix = a << $shift as uint;
144 let x = self.mem[base + mr_offset];
145 a = (a ^ mix) + self.mem[base + m2_offset];
146 let y = ind!(x) + a + b;
147 self.mem[base + mr_offset] = y;
149 b = ind!(y >> RAND_SIZE_LEN as uint) + x;
150 self.rsl[base + mr_offset] = b;
154 macro_rules! rngstepn {
155 ($j:expr, $shift:expr) => {{
157 let mix = a >> $shift as uint;
159 let x = self.mem[base + mr_offset];
160 a = (a ^ mix) + self.mem[base + m2_offset];
161 let y = ind!(x) + a + b;
162 self.mem[base + mr_offset] = y;
164 b = ind!(y >> RAND_SIZE_LEN as uint) + x;
165 self.rsl[base + mr_offset] = b;
169 for i in range_step(0u, MIDPOINT, 4) {
170 rngstepp!(i + 0, 13);
173 rngstepn!(i + 3, 16);
179 self.cnt = RAND_SIZE;
183 // Cannot be derived because [u32; 256] does not implement Clone
184 impl Clone for IsaacRng {
185 fn clone(&self) -> IsaacRng {
190 impl Rng for IsaacRng {
192 fn next_u32(&mut self) -> u32 {
194 // make some more numbers
199 // self.cnt is at most RAND_SIZE, but that is before the
200 // subtraction above. We want to index without bounds
201 // checking, but this could lead to incorrect code if someone
202 // misrefactors, so we check, sometimes.
204 // (Changes here should be reflected in Isaac64Rng.next_u64.)
205 debug_assert!(self.cnt < RAND_SIZE);
207 // (the % is cheaply telling the optimiser that we're always
208 // in bounds, without unsafe. NB. this is a power of two, so
209 // it optimises to a bitwise mask).
210 self.rsl[(self.cnt % RAND_SIZE) as uint]
214 impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
215 fn reseed(&mut self, seed: &'a [u32]) {
216 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
217 // - 1], 0, 0, ...], to fill rng.rsl.
218 let seed_iter = seed.iter().map(|&x| x).chain(repeat(0u32));
220 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
221 *rsl_elem = seed_elem;
231 /// Create an ISAAC random number generator with a seed. This can
232 /// be any length, although the maximum number of elements used is
233 /// 256 and any more will be silently ignored. A generator
234 /// constructed with a given seed will generate the same sequence
235 /// of values as all other generators constructed with that seed.
236 fn from_seed(seed: &'a [u32]) -> IsaacRng {
243 impl Rand for IsaacRng {
244 fn rand<R: Rng>(other: &mut R) -> IsaacRng {
247 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
249 let slice = slice::from_raw_mut_buf(&ptr, (RAND_SIZE * 4) as uint);
250 other.fill_bytes(slice);
262 const RAND_SIZE_64_LEN: uint = 8;
263 const RAND_SIZE_64: uint = 1 << RAND_SIZE_64_LEN;
265 /// A random number generator that uses ISAAC-64[1], the 64-bit
266 /// variant of the ISAAC algorithm.
268 /// The ISAAC algorithm is generally accepted as suitable for
269 /// cryptographic purposes, but this implementation has not be
270 /// verified as such. Prefer a generator like `OsRng` that defers to
271 /// the operating system for cases that need high security.
273 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
274 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
276 pub struct Isaac64Rng {
278 rsl: [u64; RAND_SIZE_64],
279 mem: [u64; RAND_SIZE_64],
285 static EMPTY_64: Isaac64Rng = Isaac64Rng {
287 rsl: [0; RAND_SIZE_64],
288 mem: [0; RAND_SIZE_64],
293 /// Create a 64-bit ISAAC random number generator using the
294 /// default fixed seed.
295 pub fn new_unseeded() -> Isaac64Rng {
296 let mut rng = EMPTY_64;
301 /// Initialises `self`. If `use_rsl` is true, then use the current value
302 /// of `rsl` as a seed, otherwise construct one algorithmically (not
304 fn init(&mut self, use_rsl: bool) {
307 let mut $var = 0x9e3779b97f4a7c13;
310 init!(a); init!(b); init!(c); init!(d);
311 init!(e); init!(f); init!(g); init!(h);
317 c-=g; h^=b>>23; b+=c;
318 d-=h; a^=c<<15; c+=d;
319 e-=a; b^=d>>14; d+=e;
320 f-=b; c^=e<<20; e+=f;
321 g-=c; d^=f>>17; f+=g;
322 h-=d; e^=g<<14; g+=h;
326 for _ in range(0u, 4) {
331 macro_rules! memloop {
333 for i in range(0, RAND_SIZE_64 / 8).map(|i| i * 8) {
334 a+=$arr[i ]; b+=$arr[i+1];
335 c+=$arr[i+2]; d+=$arr[i+3];
336 e+=$arr[i+4]; f+=$arr[i+5];
337 g+=$arr[i+6]; h+=$arr[i+7];
339 self.mem[i ]=a; self.mem[i+1]=b;
340 self.mem[i+2]=c; self.mem[i+3]=d;
341 self.mem[i+4]=e; self.mem[i+5]=f;
342 self.mem[i+6]=g; self.mem[i+7]=h;
350 for i in range(0, RAND_SIZE_64 / 8).map(|i| i * 8) {
352 self.mem[i ]=a; self.mem[i+1]=b;
353 self.mem[i+2]=c; self.mem[i+3]=d;
354 self.mem[i+4]=e; self.mem[i+5]=f;
355 self.mem[i+6]=g; self.mem[i+7]=h;
362 /// Refills the output buffer (`self.rsl`)
363 fn isaac64(&mut self) {
367 let mut b = self.b + self.c;
368 const MIDPOINT: uint = RAND_SIZE_64 / 2;
369 const MP_VEC: [(uint, uint); 2] = [(0,MIDPOINT), (MIDPOINT, 0)];
372 *self.mem.get_unchecked(($x as uint >> 3) & (RAND_SIZE_64 - 1))
376 for &(mr_offset, m2_offset) in MP_VEC.iter() {
377 for base in range(0, MIDPOINT / 4).map(|i| i * 4) {
379 macro_rules! rngstepp {
380 ($j:expr, $shift:expr) => {{
381 let base = base + $j;
382 let mix = a ^ (a << $shift as uint);
383 let mix = if $j == 0 {!mix} else {mix};
386 let x = *self.mem.get_unchecked(base + mr_offset);
387 a = mix + *self.mem.get_unchecked(base + m2_offset);
388 let y = ind!(x) + a + b;
389 *self.mem.get_unchecked_mut(base + mr_offset) = y;
391 b = ind!(y >> RAND_SIZE_64_LEN) + x;
392 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
397 macro_rules! rngstepn {
398 ($j:expr, $shift:expr) => {{
399 let base = base + $j;
400 let mix = a ^ (a >> $shift as uint);
401 let mix = if $j == 0 {!mix} else {mix};
404 let x = *self.mem.get_unchecked(base + mr_offset);
405 a = mix + *self.mem.get_unchecked(base + m2_offset);
406 let y = ind!(x) + a + b;
407 *self.mem.get_unchecked_mut(base + mr_offset) = y;
409 b = ind!(y >> RAND_SIZE_64_LEN) + x;
410 *self.rsl.get_unchecked_mut(base + mr_offset) = b;
424 self.cnt = RAND_SIZE_64;
428 // Cannot be derived because [u32; 256] does not implement Clone
429 impl Clone for Isaac64Rng {
430 fn clone(&self) -> Isaac64Rng {
435 impl Rng for Isaac64Rng {
436 // FIXME #7771: having next_u32 like this should be unnecessary
438 fn next_u32(&mut self) -> u32 {
439 self.next_u64() as u32
443 fn next_u64(&mut self) -> u64 {
445 // make some more numbers
450 // See corresponding location in IsaacRng.next_u32 for
452 debug_assert!(self.cnt < RAND_SIZE_64);
453 self.rsl[(self.cnt % RAND_SIZE_64) as uint]
457 impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
458 fn reseed(&mut self, seed: &'a [u64]) {
459 // make the seed into [seed[0], seed[1], ..., seed[seed.len()
460 // - 1], 0, 0, ...], to fill rng.rsl.
461 let seed_iter = seed.iter().map(|&x| x).chain(repeat(0u64));
463 for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
464 *rsl_elem = seed_elem;
474 /// Create an ISAAC random number generator with a seed. This can
475 /// be any length, although the maximum number of elements used is
476 /// 256 and any more will be silently ignored. A generator
477 /// constructed with a given seed will generate the same sequence
478 /// of values as all other generators constructed with that seed.
479 fn from_seed(seed: &'a [u64]) -> Isaac64Rng {
480 let mut rng = EMPTY_64;
486 impl Rand for Isaac64Rng {
487 fn rand<R: Rng>(other: &mut R) -> Isaac64Rng {
488 let mut ret = EMPTY_64;
490 let ptr = ret.rsl.as_mut_ptr() as *mut u8;
492 let slice = slice::from_raw_mut_buf(&ptr, (RAND_SIZE_64 * 8) as uint);
493 other.fill_bytes(slice);
508 use std::prelude::v1::*;
510 use core::iter::order;
511 use {Rng, SeedableRng};
512 use super::{IsaacRng, Isaac64Rng};
515 fn test_rng_32_rand_seeded() {
516 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
517 let mut ra: IsaacRng = SeedableRng::from_seed(s.as_slice());
518 let mut rb: IsaacRng = SeedableRng::from_seed(s.as_slice());
519 assert!(order::equals(ra.gen_ascii_chars().take(100),
520 rb.gen_ascii_chars().take(100)));
523 fn test_rng_64_rand_seeded() {
524 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
525 let mut ra: Isaac64Rng = SeedableRng::from_seed(s.as_slice());
526 let mut rb: Isaac64Rng = SeedableRng::from_seed(s.as_slice());
527 assert!(order::equals(ra.gen_ascii_chars().take(100),
528 rb.gen_ascii_chars().take(100)));
532 fn test_rng_32_seeded() {
533 let seed: &[_] = &[1, 23, 456, 7890, 12345];
534 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
535 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
536 assert!(order::equals(ra.gen_ascii_chars().take(100),
537 rb.gen_ascii_chars().take(100)));
540 fn test_rng_64_seeded() {
541 let seed: &[_] = &[1, 23, 456, 7890, 12345];
542 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
543 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
544 assert!(order::equals(ra.gen_ascii_chars().take(100),
545 rb.gen_ascii_chars().take(100)));
549 fn test_rng_32_reseed() {
550 let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
551 let mut r: IsaacRng = SeedableRng::from_seed(s.as_slice());
552 let string1: String = r.gen_ascii_chars().take(100).collect();
554 r.reseed(s.as_slice());
556 let string2: String = r.gen_ascii_chars().take(100).collect();
557 assert_eq!(string1, string2);
560 fn test_rng_64_reseed() {
561 let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
562 let mut r: Isaac64Rng = SeedableRng::from_seed(s.as_slice());
563 let string1: String = r.gen_ascii_chars().take(100).collect();
565 r.reseed(s.as_slice());
567 let string2: String = r.gen_ascii_chars().take(100).collect();
568 assert_eq!(string1, string2);
572 fn test_rng_32_true_values() {
573 let seed: &[_] = &[1, 23, 456, 7890, 12345];
574 let mut ra: IsaacRng = SeedableRng::from_seed(seed);
575 // Regression test that isaac is actually using the above vector
576 let v = range(0, 10).map(|_| ra.next_u32()).collect::<Vec<_>>();
578 vec!(2558573138, 873787463, 263499565, 2103644246, 3595684709,
579 4203127393, 264982119, 2765226902, 2737944514, 3900253796));
581 let seed: &[_] = &[12345, 67890, 54321, 9876];
582 let mut rb: IsaacRng = SeedableRng::from_seed(seed);
583 // skip forward to the 10000th number
584 for _ in range(0u, 10000) { rb.next_u32(); }
586 let v = range(0, 10).map(|_| rb.next_u32()).collect::<Vec<_>>();
588 vec!(3676831399, 3183332890, 2834741178, 3854698763, 2717568474,
589 1576568959, 3507990155, 179069555, 141456972, 2478885421));
592 fn test_rng_64_true_values() {
593 let seed: &[_] = &[1, 23, 456, 7890, 12345];
594 let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
595 // Regression test that isaac is actually using the above vector
596 let v = range(0, 10).map(|_| ra.next_u64()).collect::<Vec<_>>();
598 vec!(547121783600835980, 14377643087320773276, 17351601304698403469,
599 1238879483818134882, 11952566807690396487, 13970131091560099343,
600 4469761996653280935, 15552757044682284409, 6860251611068737823,
601 13722198873481261842));
603 let seed: &[_] = &[12345, 67890, 54321, 9876];
604 let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
605 // skip forward to the 10000th number
606 for _ in range(0u, 10000) { rb.next_u64(); }
608 let v = range(0, 10).map(|_| rb.next_u64()).collect::<Vec<_>>();
610 vec!(18143823860592706164, 8491801882678285927, 2699425367717515619,
611 17196852593171130876, 2606123525235546165, 15790932315217671084,
612 596345674630742204, 9947027391921273664, 11788097613744130851,
613 10391409374914919106));
617 fn test_rng_clone() {
618 let seed: &[_] = &[1, 23, 456, 7890, 12345];
619 let mut rng: Isaac64Rng = SeedableRng::from_seed(seed);
620 let mut clone = rng.clone();
621 for _ in range(0u, 16) {
622 assert_eq!(rng.next_u64(), clone.next_u64());