summaryrefslogtreecommitdiff
path: root/rand/src/prng/isaac64.rs
diff options
context:
space:
mode:
Diffstat (limited to 'rand/src/prng/isaac64.rs')
-rw-r--r--rand/src/prng/isaac64.rs340
1 files changed, 340 insertions, 0 deletions
diff --git a/rand/src/prng/isaac64.rs b/rand/src/prng/isaac64.rs
new file mode 100644
index 0000000..b98e3fe
--- /dev/null
+++ b/rand/src/prng/isaac64.rs
@@ -0,0 +1,340 @@
+// 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());
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.46.0) at 2024-11-22 08:26:13 +0000