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-rw-r--r--rand/src/prng/isaac64.rs340
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diff --git a/rand/src/prng/isaac64.rs b/rand/src/prng/isaac64.rs
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-// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! The ISAAC-64 random number generator.
-
-use core::slice;
-use core::iter::repeat;
-use core::num::Wrapping as w;
-use core::fmt;
-
-use {Rng, SeedableRng, Rand};
-
-#[allow(bad_style)]
-type w64 = w<u64>;
-
-const RAND_SIZE_64_LEN: usize = 8;
-const RAND_SIZE_64: usize = 1 << RAND_SIZE_64_LEN;
-
-/// A random number generator that uses ISAAC-64[1], the 64-bit
-/// variant of the ISAAC algorithm.
-///
-/// The ISAAC algorithm is generally accepted as suitable for
-/// cryptographic purposes, but this implementation has not be
-/// verified as such. Prefer a generator like `OsRng` that defers to
-/// the operating system for cases that need high security.
-///
-/// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
-/// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
-#[derive(Copy)]
-pub struct Isaac64Rng {
- cnt: usize,
- rsl: [w64; RAND_SIZE_64],
- mem: [w64; RAND_SIZE_64],
- a: w64,
- b: w64,
- c: w64,
-}
-
-static EMPTY_64: Isaac64Rng = Isaac64Rng {
- cnt: 0,
- rsl: [w(0); RAND_SIZE_64],
- mem: [w(0); RAND_SIZE_64],
- a: w(0), b: w(0), c: w(0),
-};
-
-impl Isaac64Rng {
- /// Create a 64-bit ISAAC random number generator using the
- /// default fixed seed.
- pub fn new_unseeded() -> Isaac64Rng {
- let mut rng = EMPTY_64;
- rng.init(false);
- rng
- }
-
- /// Initialises `self`. If `use_rsl` is true, then use the current value
- /// of `rsl` as a seed, otherwise construct one algorithmically (not
- /// randomly).
- fn init(&mut self, use_rsl: bool) {
- macro_rules! init {
- ($var:ident) => (
- let mut $var = w(0x9e3779b97f4a7c13);
- )
- }
- init!(a); init!(b); init!(c); init!(d);
- init!(e); init!(f); init!(g); init!(h);
-
- macro_rules! mix {
- () => {{
- a=a-e; f=f^(h>>9); h=h+a;
- b=b-f; g=g^(a<<9); a=a+b;
- c=c-g; h=h^(b>>23); b=b+c;
- d=d-h; a=a^(c<<15); c=c+d;
- e=e-a; b=b^(d>>14); d=d+e;
- f=f-b; c=c^(e<<20); e=e+f;
- g=g-c; d=d^(f>>17); f=f+g;
- h=h-d; e=e^(g<<14); g=g+h;
- }}
- }
-
- for _ in 0..4 {
- mix!();
- }
-
- if use_rsl {
- macro_rules! memloop {
- ($arr:expr) => {{
- for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
- a=a+$arr[i ]; b=b+$arr[i+1];
- c=c+$arr[i+2]; d=d+$arr[i+3];
- e=e+$arr[i+4]; f=f+$arr[i+5];
- g=g+$arr[i+6]; h=h+$arr[i+7];
- mix!();
- self.mem[i ]=a; self.mem[i+1]=b;
- self.mem[i+2]=c; self.mem[i+3]=d;
- self.mem[i+4]=e; self.mem[i+5]=f;
- self.mem[i+6]=g; self.mem[i+7]=h;
- }
- }}
- }
-
- memloop!(self.rsl);
- memloop!(self.mem);
- } else {
- for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) {
- mix!();
- self.mem[i ]=a; self.mem[i+1]=b;
- self.mem[i+2]=c; self.mem[i+3]=d;
- self.mem[i+4]=e; self.mem[i+5]=f;
- self.mem[i+6]=g; self.mem[i+7]=h;
- }
- }
-
- self.isaac64();
- }
-
- /// Refills the output buffer (`self.rsl`)
- fn isaac64(&mut self) {
- self.c = self.c + w(1);
- // abbreviations
- let mut a = self.a;
- let mut b = self.b + self.c;
- const MIDPOINT: usize = RAND_SIZE_64 / 2;
- const MP_VEC: [(usize, usize); 2] = [(0,MIDPOINT), (MIDPOINT, 0)];
- macro_rules! ind {
- ($x:expr) => {
- *self.mem.get_unchecked((($x >> 3usize).0 as usize) & (RAND_SIZE_64 - 1))
- }
- }
-
- for &(mr_offset, m2_offset) in MP_VEC.iter() {
- for base in (0..MIDPOINT / 4).map(|i| i * 4) {
-
- macro_rules! rngstepp {
- ($j:expr, $shift:expr) => {{
- let base = base + $j;
- let mix = a ^ (a << $shift);
- let mix = if $j == 0 {!mix} else {mix};
-
- unsafe {
- let x = *self.mem.get_unchecked(base + mr_offset);
- a = mix + *self.mem.get_unchecked(base + m2_offset);
- let y = ind!(x) + a + b;
- *self.mem.get_unchecked_mut(base + mr_offset) = y;
-
- b = ind!(y >> RAND_SIZE_64_LEN) + x;
- *self.rsl.get_unchecked_mut(base + mr_offset) = b;
- }
- }}
- }
-
- macro_rules! rngstepn {
- ($j:expr, $shift:expr) => {{
- let base = base + $j;
- let mix = a ^ (a >> $shift);
- let mix = if $j == 0 {!mix} else {mix};
-
- unsafe {
- let x = *self.mem.get_unchecked(base + mr_offset);
- a = mix + *self.mem.get_unchecked(base + m2_offset);
- let y = ind!(x) + a + b;
- *self.mem.get_unchecked_mut(base + mr_offset) = y;
-
- b = ind!(y >> RAND_SIZE_64_LEN) + x;
- *self.rsl.get_unchecked_mut(base + mr_offset) = b;
- }
- }}
- }
-
- rngstepp!(0, 21);
- rngstepn!(1, 5);
- rngstepp!(2, 12);
- rngstepn!(3, 33);
- }
- }
-
- self.a = a;
- self.b = b;
- self.cnt = RAND_SIZE_64;
- }
-}
-
-// Cannot be derived because [u32; 256] does not implement Clone
-impl Clone for Isaac64Rng {
- fn clone(&self) -> Isaac64Rng {
- *self
- }
-}
-
-impl Rng for Isaac64Rng {
- #[inline]
- fn next_u32(&mut self) -> u32 {
- self.next_u64() as u32
- }
-
- #[inline]
- fn next_u64(&mut self) -> u64 {
- if self.cnt == 0 {
- // make some more numbers
- self.isaac64();
- }
- self.cnt -= 1;
-
- // See corresponding location in IsaacRng.next_u32 for
- // explanation.
- debug_assert!(self.cnt < RAND_SIZE_64);
- self.rsl[(self.cnt % RAND_SIZE_64) as usize].0
- }
-}
-
-impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
- fn reseed(&mut self, seed: &'a [u64]) {
- // make the seed into [seed[0], seed[1], ..., seed[seed.len()
- // - 1], 0, 0, ...], to fill rng.rsl.
- let seed_iter = seed.iter().map(|&x| x).chain(repeat(0u64));
-
- for (rsl_elem, seed_elem) in self.rsl.iter_mut().zip(seed_iter) {
- *rsl_elem = w(seed_elem);
- }
- self.cnt = 0;
- self.a = w(0);
- self.b = w(0);
- self.c = w(0);
-
- self.init(true);
- }
-
- /// Create an ISAAC random number generator with a seed. This can
- /// be any length, although the maximum number of elements used is
- /// 256 and any more will be silently ignored. A generator
- /// constructed with a given seed will generate the same sequence
- /// of values as all other generators constructed with that seed.
- fn from_seed(seed: &'a [u64]) -> Isaac64Rng {
- let mut rng = EMPTY_64;
- rng.reseed(seed);
- rng
- }
-}
-
-impl Rand for Isaac64Rng {
- fn rand<R: Rng>(other: &mut R) -> Isaac64Rng {
- let mut ret = EMPTY_64;
- unsafe {
- let ptr = ret.rsl.as_mut_ptr() as *mut u8;
-
- let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_64 * 8);
- other.fill_bytes(slice);
- }
- ret.cnt = 0;
- ret.a = w(0);
- ret.b = w(0);
- ret.c = w(0);
-
- ret.init(true);
- return ret;
- }
-}
-
-impl fmt::Debug for Isaac64Rng {
- fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- write!(f, "Isaac64Rng {{}}")
- }
-}
-
-#[cfg(test)]
-mod test {
- use {Rng, SeedableRng};
- use super::Isaac64Rng;
-
- #[test]
- fn test_rng_64_rand_seeded() {
- let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
- let mut ra: Isaac64Rng = SeedableRng::from_seed(&s[..]);
- let mut rb: Isaac64Rng = SeedableRng::from_seed(&s[..]);
- assert!(::test::iter_eq(ra.gen_ascii_chars().take(100),
- rb.gen_ascii_chars().take(100)));
- }
-
- #[test]
- fn test_rng_64_seeded() {
- let seed: &[_] = &[1, 23, 456, 7890, 12345];
- let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
- let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
- assert!(::test::iter_eq(ra.gen_ascii_chars().take(100),
- rb.gen_ascii_chars().take(100)));
- }
-
- #[test]
- fn test_rng_64_reseed() {
- let s = ::test::rng().gen_iter::<u64>().take(256).collect::<Vec<u64>>();
- let mut r: Isaac64Rng = SeedableRng::from_seed(&s[..]);
- let string1: String = r.gen_ascii_chars().take(100).collect();
-
- r.reseed(&s[..]);
-
- let string2: String = r.gen_ascii_chars().take(100).collect();
- assert_eq!(string1, string2);
- }
-
- #[test]
- fn test_rng_64_true_values() {
- let seed: &[_] = &[1, 23, 456, 7890, 12345];
- let mut ra: Isaac64Rng = SeedableRng::from_seed(seed);
- // Regression test that isaac is actually using the above vector
- let v = (0..10).map(|_| ra.next_u64()).collect::<Vec<_>>();
- assert_eq!(v,
- vec!(547121783600835980, 14377643087320773276, 17351601304698403469,
- 1238879483818134882, 11952566807690396487, 13970131091560099343,
- 4469761996653280935, 15552757044682284409, 6860251611068737823,
- 13722198873481261842));
-
- let seed: &[_] = &[12345, 67890, 54321, 9876];
- let mut rb: Isaac64Rng = SeedableRng::from_seed(seed);
- // skip forward to the 10000th number
- for _ in 0..10000 { rb.next_u64(); }
-
- let v = (0..10).map(|_| rb.next_u64()).collect::<Vec<_>>();
- assert_eq!(v,
- vec!(18143823860592706164, 8491801882678285927, 2699425367717515619,
- 17196852593171130876, 2606123525235546165, 15790932315217671084,
- 596345674630742204, 9947027391921273664, 11788097613744130851,
- 10391409374914919106));
- }
-
- #[test]
- fn test_rng_clone() {
- let seed: &[_] = &[1, 23, 456, 7890, 12345];
- let mut rng: Isaac64Rng = SeedableRng::from_seed(seed);
- let mut clone = rng.clone();
- for _ in 0..16 {
- assert_eq!(rng.next_u64(), clone.next_u64());
- }
- }
-}
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