Vendor dependencies

Let's see how I like this workflow.
This commit is contained in:
John Doty 2022-12-19 08:27:18 -08:00
parent 34d1830413
commit 9c435dc440
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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 exponential distribution.
use {Rng, Rand};
use distributions::{ziggurat, ziggurat_tables, Sample, IndependentSample};
/// A wrapper around an `f64` to generate Exp(1) random numbers.
///
/// See `Exp` for the general exponential distribution.
///
/// Implemented via the ZIGNOR variant[1] of the Ziggurat method. The
/// exact description in the paper was adjusted to use tables for the
/// exponential distribution rather than normal.
///
/// [1]: Jurgen A. Doornik (2005). [*An Improved Ziggurat Method to
/// Generate Normal Random
/// Samples*](http://www.doornik.com/research/ziggurat.pdf). Nuffield
/// College, Oxford
///
/// # Example
///
/// ```rust
/// use rand::distributions::exponential::Exp1;
///
/// let Exp1(x) = rand::random();
/// println!("{}", x);
/// ```
#[derive(Clone, Copy, Debug)]
pub struct Exp1(pub f64);
// This could be done via `-rng.gen::<f64>().ln()` but that is slower.
impl Rand for Exp1 {
#[inline]
fn rand<R:Rng>(rng: &mut R) -> Exp1 {
#[inline]
fn pdf(x: f64) -> f64 {
(-x).exp()
}
#[inline]
fn zero_case<R:Rng>(rng: &mut R, _u: f64) -> f64 {
ziggurat_tables::ZIG_EXP_R - rng.gen::<f64>().ln()
}
Exp1(ziggurat(rng, false,
&ziggurat_tables::ZIG_EXP_X,
&ziggurat_tables::ZIG_EXP_F,
pdf, zero_case))
}
}
/// The exponential distribution `Exp(lambda)`.
///
/// This distribution has density function: `f(x) = lambda *
/// exp(-lambda * x)` for `x > 0`.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{Exp, IndependentSample};
///
/// let exp = Exp::new(2.0);
/// let v = exp.ind_sample(&mut rand::thread_rng());
/// println!("{} is from a Exp(2) distribution", v);
/// ```
#[derive(Clone, Copy, Debug)]
pub struct Exp {
/// `lambda` stored as `1/lambda`, since this is what we scale by.
lambda_inverse: f64
}
impl Exp {
/// Construct a new `Exp` with the given shape parameter
/// `lambda`. Panics if `lambda <= 0`.
#[inline]
pub fn new(lambda: f64) -> Exp {
assert!(lambda > 0.0, "Exp::new called with `lambda` <= 0");
Exp { lambda_inverse: 1.0 / lambda }
}
}
impl Sample<f64> for Exp {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl IndependentSample<f64> for Exp {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
let Exp1(n) = rng.gen::<Exp1>();
n * self.lambda_inverse
}
}
#[cfg(test)]
mod test {
use distributions::{Sample, IndependentSample};
use super::Exp;
#[test]
fn test_exp() {
let mut exp = Exp::new(10.0);
let mut rng = ::test::rng();
for _ in 0..1000 {
assert!(exp.sample(&mut rng) >= 0.0);
assert!(exp.ind_sample(&mut rng) >= 0.0);
}
}
#[test]
#[should_panic]
fn test_exp_invalid_lambda_zero() {
Exp::new(0.0);
}
#[test]
#[should_panic]
fn test_exp_invalid_lambda_neg() {
Exp::new(-10.0);
}
}

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vendor/rand/src/distributions/gamma.rs vendored Normal file
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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.
//
// ignore-lexer-test FIXME #15679
//! The Gamma and derived distributions.
use self::GammaRepr::*;
use self::ChiSquaredRepr::*;
use {Rng, Open01};
use super::normal::StandardNormal;
use super::{IndependentSample, Sample, Exp};
/// The Gamma distribution `Gamma(shape, scale)` distribution.
///
/// The density function of this distribution is
///
/// ```text
/// f(x) = x^(k - 1) * exp(-x / θ) / (Γ(k) * θ^k)
/// ```
///
/// where `Γ` is the Gamma function, `k` is the shape and `θ` is the
/// scale and both `k` and `θ` are strictly positive.
///
/// The algorithm used is that described by Marsaglia & Tsang 2000[1],
/// falling back to directly sampling from an Exponential for `shape
/// == 1`, and using the boosting technique described in [1] for
/// `shape < 1`.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{IndependentSample, Gamma};
///
/// let gamma = Gamma::new(2.0, 5.0);
/// let v = gamma.ind_sample(&mut rand::thread_rng());
/// println!("{} is from a Gamma(2, 5) distribution", v);
/// ```
///
/// [1]: George Marsaglia and Wai Wan Tsang. 2000. "A Simple Method
/// for Generating Gamma Variables" *ACM Trans. Math. Softw.* 26, 3
/// (September 2000),
/// 363-372. DOI:[10.1145/358407.358414](http://doi.acm.org/10.1145/358407.358414)
#[derive(Clone, Copy, Debug)]
pub struct Gamma {
repr: GammaRepr,
}
#[derive(Clone, Copy, Debug)]
enum GammaRepr {
Large(GammaLargeShape),
One(Exp),
Small(GammaSmallShape)
}
// These two helpers could be made public, but saving the
// match-on-Gamma-enum branch from using them directly (e.g. if one
// knows that the shape is always > 1) doesn't appear to be much
// faster.
/// Gamma distribution where the shape parameter is less than 1.
///
/// Note, samples from this require a compulsory floating-point `pow`
/// call, which makes it significantly slower than sampling from a
/// gamma distribution where the shape parameter is greater than or
/// equal to 1.
///
/// See `Gamma` for sampling from a Gamma distribution with general
/// shape parameters.
#[derive(Clone, Copy, Debug)]
struct GammaSmallShape {
inv_shape: f64,
large_shape: GammaLargeShape
}
/// Gamma distribution where the shape parameter is larger than 1.
///
/// See `Gamma` for sampling from a Gamma distribution with general
/// shape parameters.
#[derive(Clone, Copy, Debug)]
struct GammaLargeShape {
scale: f64,
c: f64,
d: f64
}
impl Gamma {
/// Construct an object representing the `Gamma(shape, scale)`
/// distribution.
///
/// Panics if `shape <= 0` or `scale <= 0`.
#[inline]
pub fn new(shape: f64, scale: f64) -> Gamma {
assert!(shape > 0.0, "Gamma::new called with shape <= 0");
assert!(scale > 0.0, "Gamma::new called with scale <= 0");
let repr = if shape == 1.0 {
One(Exp::new(1.0 / scale))
} else if shape < 1.0 {
Small(GammaSmallShape::new_raw(shape, scale))
} else {
Large(GammaLargeShape::new_raw(shape, scale))
};
Gamma { repr: repr }
}
}
impl GammaSmallShape {
fn new_raw(shape: f64, scale: f64) -> GammaSmallShape {
GammaSmallShape {
inv_shape: 1. / shape,
large_shape: GammaLargeShape::new_raw(shape + 1.0, scale)
}
}
}
impl GammaLargeShape {
fn new_raw(shape: f64, scale: f64) -> GammaLargeShape {
let d = shape - 1. / 3.;
GammaLargeShape {
scale: scale,
c: 1. / (9. * d).sqrt(),
d: d
}
}
}
impl Sample<f64> for Gamma {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl Sample<f64> for GammaSmallShape {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl Sample<f64> for GammaLargeShape {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl IndependentSample<f64> for Gamma {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
match self.repr {
Small(ref g) => g.ind_sample(rng),
One(ref g) => g.ind_sample(rng),
Large(ref g) => g.ind_sample(rng),
}
}
}
impl IndependentSample<f64> for GammaSmallShape {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
let Open01(u) = rng.gen::<Open01<f64>>();
self.large_shape.ind_sample(rng) * u.powf(self.inv_shape)
}
}
impl IndependentSample<f64> for GammaLargeShape {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
loop {
let StandardNormal(x) = rng.gen::<StandardNormal>();
let v_cbrt = 1.0 + self.c * x;
if v_cbrt <= 0.0 { // a^3 <= 0 iff a <= 0
continue
}
let v = v_cbrt * v_cbrt * v_cbrt;
let Open01(u) = rng.gen::<Open01<f64>>();
let x_sqr = x * x;
if u < 1.0 - 0.0331 * x_sqr * x_sqr ||
u.ln() < 0.5 * x_sqr + self.d * (1.0 - v + v.ln()) {
return self.d * v * self.scale
}
}
}
}
/// The chi-squared distribution `χ²(k)`, where `k` is the degrees of
/// freedom.
///
/// For `k > 0` integral, this distribution is the sum of the squares
/// of `k` independent standard normal random variables. For other
/// `k`, this uses the equivalent characterisation
/// `χ²(k) = Gamma(k/2, 2)`.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{ChiSquared, IndependentSample};
///
/// let chi = ChiSquared::new(11.0);
/// let v = chi.ind_sample(&mut rand::thread_rng());
/// println!("{} is from a χ²(11) distribution", v)
/// ```
#[derive(Clone, Copy, Debug)]
pub struct ChiSquared {
repr: ChiSquaredRepr,
}
#[derive(Clone, Copy, Debug)]
enum ChiSquaredRepr {
// k == 1, Gamma(alpha, ..) is particularly slow for alpha < 1,
// e.g. when alpha = 1/2 as it would be for this case, so special-
// casing and using the definition of N(0,1)^2 is faster.
DoFExactlyOne,
DoFAnythingElse(Gamma),
}
impl ChiSquared {
/// Create a new chi-squared distribution with degrees-of-freedom
/// `k`. Panics if `k < 0`.
pub fn new(k: f64) -> ChiSquared {
let repr = if k == 1.0 {
DoFExactlyOne
} else {
assert!(k > 0.0, "ChiSquared::new called with `k` < 0");
DoFAnythingElse(Gamma::new(0.5 * k, 2.0))
};
ChiSquared { repr: repr }
}
}
impl Sample<f64> for ChiSquared {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl IndependentSample<f64> for ChiSquared {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
match self.repr {
DoFExactlyOne => {
// k == 1 => N(0,1)^2
let StandardNormal(norm) = rng.gen::<StandardNormal>();
norm * norm
}
DoFAnythingElse(ref g) => g.ind_sample(rng)
}
}
}
/// The Fisher F distribution `F(m, n)`.
///
/// This distribution is equivalent to the ratio of two normalised
/// chi-squared distributions, that is, `F(m,n) = (χ²(m)/m) /
/// (χ²(n)/n)`.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{FisherF, IndependentSample};
///
/// let f = FisherF::new(2.0, 32.0);
/// let v = f.ind_sample(&mut rand::thread_rng());
/// println!("{} is from an F(2, 32) distribution", v)
/// ```
#[derive(Clone, Copy, Debug)]
pub struct FisherF {
numer: ChiSquared,
denom: ChiSquared,
// denom_dof / numer_dof so that this can just be a straight
// multiplication, rather than a division.
dof_ratio: f64,
}
impl FisherF {
/// Create a new `FisherF` distribution, with the given
/// parameter. Panics if either `m` or `n` are not positive.
pub fn new(m: f64, n: f64) -> FisherF {
assert!(m > 0.0, "FisherF::new called with `m < 0`");
assert!(n > 0.0, "FisherF::new called with `n < 0`");
FisherF {
numer: ChiSquared::new(m),
denom: ChiSquared::new(n),
dof_ratio: n / m
}
}
}
impl Sample<f64> for FisherF {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl IndependentSample<f64> for FisherF {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
self.numer.ind_sample(rng) / self.denom.ind_sample(rng) * self.dof_ratio
}
}
/// The Student t distribution, `t(nu)`, where `nu` is the degrees of
/// freedom.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{StudentT, IndependentSample};
///
/// let t = StudentT::new(11.0);
/// let v = t.ind_sample(&mut rand::thread_rng());
/// println!("{} is from a t(11) distribution", v)
/// ```
#[derive(Clone, Copy, Debug)]
pub struct StudentT {
chi: ChiSquared,
dof: f64
}
impl StudentT {
/// Create a new Student t distribution with `n` degrees of
/// freedom. Panics if `n <= 0`.
pub fn new(n: f64) -> StudentT {
assert!(n > 0.0, "StudentT::new called with `n <= 0`");
StudentT {
chi: ChiSquared::new(n),
dof: n
}
}
}
impl Sample<f64> for StudentT {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl IndependentSample<f64> for StudentT {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
let StandardNormal(norm) = rng.gen::<StandardNormal>();
norm * (self.dof / self.chi.ind_sample(rng)).sqrt()
}
}
#[cfg(test)]
mod test {
use distributions::{Sample, IndependentSample};
use super::{ChiSquared, StudentT, FisherF};
#[test]
fn test_chi_squared_one() {
let mut chi = ChiSquared::new(1.0);
let mut rng = ::test::rng();
for _ in 0..1000 {
chi.sample(&mut rng);
chi.ind_sample(&mut rng);
}
}
#[test]
fn test_chi_squared_small() {
let mut chi = ChiSquared::new(0.5);
let mut rng = ::test::rng();
for _ in 0..1000 {
chi.sample(&mut rng);
chi.ind_sample(&mut rng);
}
}
#[test]
fn test_chi_squared_large() {
let mut chi = ChiSquared::new(30.0);
let mut rng = ::test::rng();
for _ in 0..1000 {
chi.sample(&mut rng);
chi.ind_sample(&mut rng);
}
}
#[test]
#[should_panic]
fn test_chi_squared_invalid_dof() {
ChiSquared::new(-1.0);
}
#[test]
fn test_f() {
let mut f = FisherF::new(2.0, 32.0);
let mut rng = ::test::rng();
for _ in 0..1000 {
f.sample(&mut rng);
f.ind_sample(&mut rng);
}
}
#[test]
fn test_t() {
let mut t = StudentT::new(11.0);
let mut rng = ::test::rng();
for _ in 0..1000 {
t.sample(&mut rng);
t.ind_sample(&mut rng);
}
}
}

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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.
//! Sampling from random distributions.
//!
//! This is a generalization of `Rand` to allow parameters to control the
//! exact properties of the generated values, e.g. the mean and standard
//! deviation of a normal distribution. The `Sample` trait is the most
//! general, and allows for generating values that change some state
//! internally. The `IndependentSample` trait is for generating values
//! that do not need to record state.
use core::marker;
use {Rng, Rand};
pub use self::range::Range;
#[cfg(feature="std")]
pub use self::gamma::{Gamma, ChiSquared, FisherF, StudentT};
#[cfg(feature="std")]
pub use self::normal::{Normal, LogNormal};
#[cfg(feature="std")]
pub use self::exponential::Exp;
pub mod range;
#[cfg(feature="std")]
pub mod gamma;
#[cfg(feature="std")]
pub mod normal;
#[cfg(feature="std")]
pub mod exponential;
#[cfg(feature="std")]
mod ziggurat_tables;
/// Types that can be used to create a random instance of `Support`.
pub trait Sample<Support> {
/// Generate a random value of `Support`, using `rng` as the
/// source of randomness.
fn sample<R: Rng>(&mut self, rng: &mut R) -> Support;
}
/// `Sample`s that do not require keeping track of state.
///
/// Since no state is recorded, each sample is (statistically)
/// independent of all others, assuming the `Rng` used has this
/// property.
// FIXME maybe having this separate is overkill (the only reason is to
// take &self rather than &mut self)? or maybe this should be the
// trait called `Sample` and the other should be `DependentSample`.
pub trait IndependentSample<Support>: Sample<Support> {
/// Generate a random value.
fn ind_sample<R: Rng>(&self, &mut R) -> Support;
}
/// A wrapper for generating types that implement `Rand` via the
/// `Sample` & `IndependentSample` traits.
#[derive(Debug)]
pub struct RandSample<Sup> {
_marker: marker::PhantomData<fn() -> Sup>,
}
impl<Sup> Copy for RandSample<Sup> {}
impl<Sup> Clone for RandSample<Sup> {
fn clone(&self) -> Self { *self }
}
impl<Sup: Rand> Sample<Sup> for RandSample<Sup> {
fn sample<R: Rng>(&mut self, rng: &mut R) -> Sup { self.ind_sample(rng) }
}
impl<Sup: Rand> IndependentSample<Sup> for RandSample<Sup> {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> Sup {
rng.gen()
}
}
impl<Sup> RandSample<Sup> {
pub fn new() -> RandSample<Sup> {
RandSample { _marker: marker::PhantomData }
}
}
/// A value with a particular weight for use with `WeightedChoice`.
#[derive(Copy, Clone, Debug)]
pub struct Weighted<T> {
/// The numerical weight of this item
pub weight: u32,
/// The actual item which is being weighted
pub item: T,
}
/// A distribution that selects from a finite collection of weighted items.
///
/// Each item has an associated weight that influences how likely it
/// is to be chosen: higher weight is more likely.
///
/// The `Clone` restriction is a limitation of the `Sample` and
/// `IndependentSample` traits. Note that `&T` is (cheaply) `Clone` for
/// all `T`, as is `u32`, so one can store references or indices into
/// another vector.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{Weighted, WeightedChoice, IndependentSample};
///
/// let mut items = vec!(Weighted { weight: 2, item: 'a' },
/// Weighted { weight: 4, item: 'b' },
/// Weighted { weight: 1, item: 'c' });
/// let wc = WeightedChoice::new(&mut items);
/// let mut rng = rand::thread_rng();
/// for _ in 0..16 {
/// // on average prints 'a' 4 times, 'b' 8 and 'c' twice.
/// println!("{}", wc.ind_sample(&mut rng));
/// }
/// ```
#[derive(Debug)]
pub struct WeightedChoice<'a, T:'a> {
items: &'a mut [Weighted<T>],
weight_range: Range<u32>
}
impl<'a, T: Clone> WeightedChoice<'a, T> {
/// Create a new `WeightedChoice`.
///
/// Panics if:
///
/// - `items` is empty
/// - the total weight is 0
/// - the total weight is larger than a `u32` can contain.
pub fn new(items: &'a mut [Weighted<T>]) -> WeightedChoice<'a, T> {
// strictly speaking, this is subsumed by the total weight == 0 case
assert!(!items.is_empty(), "WeightedChoice::new called with no items");
let mut running_total: u32 = 0;
// we convert the list from individual weights to cumulative
// weights so we can binary search. This *could* drop elements
// with weight == 0 as an optimisation.
for item in items.iter_mut() {
running_total = match running_total.checked_add(item.weight) {
Some(n) => n,
None => panic!("WeightedChoice::new called with a total weight \
larger than a u32 can contain")
};
item.weight = running_total;
}
assert!(running_total != 0, "WeightedChoice::new called with a total weight of 0");
WeightedChoice {
items: items,
// we're likely to be generating numbers in this range
// relatively often, so might as well cache it
weight_range: Range::new(0, running_total)
}
}
}
impl<'a, T: Clone> Sample<T> for WeightedChoice<'a, T> {
fn sample<R: Rng>(&mut self, rng: &mut R) -> T { self.ind_sample(rng) }
}
impl<'a, T: Clone> IndependentSample<T> for WeightedChoice<'a, T> {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> T {
// we want to find the first element that has cumulative
// weight > sample_weight, which we do by binary since the
// cumulative weights of self.items are sorted.
// choose a weight in [0, total_weight)
let sample_weight = self.weight_range.ind_sample(rng);
// short circuit when it's the first item
if sample_weight < self.items[0].weight {
return self.items[0].item.clone();
}
let mut idx = 0;
let mut modifier = self.items.len();
// now we know that every possibility has an element to the
// left, so we can just search for the last element that has
// cumulative weight <= sample_weight, then the next one will
// be "it". (Note that this greatest element will never be the
// last element of the vector, since sample_weight is chosen
// in [0, total_weight) and the cumulative weight of the last
// one is exactly the total weight.)
while modifier > 1 {
let i = idx + modifier / 2;
if self.items[i].weight <= sample_weight {
// we're small, so look to the right, but allow this
// exact element still.
idx = i;
// we need the `/ 2` to round up otherwise we'll drop
// the trailing elements when `modifier` is odd.
modifier += 1;
} else {
// otherwise we're too big, so go left. (i.e. do
// nothing)
}
modifier /= 2;
}
return self.items[idx + 1].item.clone();
}
}
/// Sample a random number using the Ziggurat method (specifically the
/// ZIGNOR variant from Doornik 2005). Most of the arguments are
/// directly from the paper:
///
/// * `rng`: source of randomness
/// * `symmetric`: whether this is a symmetric distribution, or one-sided with P(x < 0) = 0.
/// * `X`: the $x_i$ abscissae.
/// * `F`: precomputed values of the PDF at the $x_i$, (i.e. $f(x_i)$)
/// * `F_DIFF`: precomputed values of $f(x_i) - f(x_{i+1})$
/// * `pdf`: the probability density function
/// * `zero_case`: manual sampling from the tail when we chose the
/// bottom box (i.e. i == 0)
// the perf improvement (25-50%) is definitely worth the extra code
// size from force-inlining.
#[cfg(feature="std")]
#[inline(always)]
fn ziggurat<R: Rng, P, Z>(
rng: &mut R,
symmetric: bool,
x_tab: ziggurat_tables::ZigTable,
f_tab: ziggurat_tables::ZigTable,
mut pdf: P,
mut zero_case: Z)
-> f64 where P: FnMut(f64) -> f64, Z: FnMut(&mut R, f64) -> f64 {
const SCALE: f64 = (1u64 << 53) as f64;
loop {
// reimplement the f64 generation as an optimisation suggested
// by the Doornik paper: we have a lot of precision-space
// (i.e. there are 11 bits of the 64 of a u64 to use after
// creating a f64), so we might as well reuse some to save
// generating a whole extra random number. (Seems to be 15%
// faster.)
//
// This unfortunately misses out on the benefits of direct
// floating point generation if an RNG like dSMFT is
// used. (That is, such RNGs create floats directly, highly
// efficiently and overload next_f32/f64, so by not calling it
// this may be slower than it would be otherwise.)
// FIXME: investigate/optimise for the above.
let bits: u64 = rng.gen();
let i = (bits & 0xff) as usize;
let f = (bits >> 11) as f64 / SCALE;
// u is either U(-1, 1) or U(0, 1) depending on if this is a
// symmetric distribution or not.
let u = if symmetric {2.0 * f - 1.0} else {f};
let x = u * x_tab[i];
let test_x = if symmetric { x.abs() } else {x};
// algebraically equivalent to |u| < x_tab[i+1]/x_tab[i] (or u < x_tab[i+1]/x_tab[i])
if test_x < x_tab[i + 1] {
return x;
}
if i == 0 {
return zero_case(rng, u);
}
// algebraically equivalent to f1 + DRanU()*(f0 - f1) < 1
if f_tab[i + 1] + (f_tab[i] - f_tab[i + 1]) * rng.gen::<f64>() < pdf(x) {
return x;
}
}
}
#[cfg(test)]
mod tests {
use {Rng, Rand};
use super::{RandSample, WeightedChoice, Weighted, Sample, IndependentSample};
#[derive(PartialEq, Debug)]
struct ConstRand(usize);
impl Rand for ConstRand {
fn rand<R: Rng>(_: &mut R) -> ConstRand {
ConstRand(0)
}
}
// 0, 1, 2, 3, ...
struct CountingRng { i: u32 }
impl Rng for CountingRng {
fn next_u32(&mut self) -> u32 {
self.i += 1;
self.i - 1
}
fn next_u64(&mut self) -> u64 {
self.next_u32() as u64
}
}
#[test]
fn test_rand_sample() {
let mut rand_sample = RandSample::<ConstRand>::new();
assert_eq!(rand_sample.sample(&mut ::test::rng()), ConstRand(0));
assert_eq!(rand_sample.ind_sample(&mut ::test::rng()), ConstRand(0));
}
#[test]
fn test_weighted_choice() {
// this makes assumptions about the internal implementation of
// WeightedChoice, specifically: it doesn't reorder the items,
// it doesn't do weird things to the RNG (so 0 maps to 0, 1 to
// 1, internally; modulo a modulo operation).
macro_rules! t {
($items:expr, $expected:expr) => {{
let mut items = $items;
let wc = WeightedChoice::new(&mut items);
let expected = $expected;
let mut rng = CountingRng { i: 0 };
for &val in expected.iter() {
assert_eq!(wc.ind_sample(&mut rng), val)
}
}}
}
t!(vec!(Weighted { weight: 1, item: 10}), [10]);
// skip some
t!(vec!(Weighted { weight: 0, item: 20},
Weighted { weight: 2, item: 21},
Weighted { weight: 0, item: 22},
Weighted { weight: 1, item: 23}),
[21,21, 23]);
// different weights
t!(vec!(Weighted { weight: 4, item: 30},
Weighted { weight: 3, item: 31}),
[30,30,30,30, 31,31,31]);
// check that we're binary searching
// correctly with some vectors of odd
// length.
t!(vec!(Weighted { weight: 1, item: 40},
Weighted { weight: 1, item: 41},
Weighted { weight: 1, item: 42},
Weighted { weight: 1, item: 43},
Weighted { weight: 1, item: 44}),
[40, 41, 42, 43, 44]);
t!(vec!(Weighted { weight: 1, item: 50},
Weighted { weight: 1, item: 51},
Weighted { weight: 1, item: 52},
Weighted { weight: 1, item: 53},
Weighted { weight: 1, item: 54},
Weighted { weight: 1, item: 55},
Weighted { weight: 1, item: 56}),
[50, 51, 52, 53, 54, 55, 56]);
}
#[test]
fn test_weighted_clone_initialization() {
let initial : Weighted<u32> = Weighted {weight: 1, item: 1};
let clone = initial.clone();
assert_eq!(initial.weight, clone.weight);
assert_eq!(initial.item, clone.item);
}
#[test] #[should_panic]
fn test_weighted_clone_change_weight() {
let initial : Weighted<u32> = Weighted {weight: 1, item: 1};
let mut clone = initial.clone();
clone.weight = 5;
assert_eq!(initial.weight, clone.weight);
}
#[test] #[should_panic]
fn test_weighted_clone_change_item() {
let initial : Weighted<u32> = Weighted {weight: 1, item: 1};
let mut clone = initial.clone();
clone.item = 5;
assert_eq!(initial.item, clone.item);
}
#[test] #[should_panic]
fn test_weighted_choice_no_items() {
WeightedChoice::<isize>::new(&mut []);
}
#[test] #[should_panic]
fn test_weighted_choice_zero_weight() {
WeightedChoice::new(&mut [Weighted { weight: 0, item: 0},
Weighted { weight: 0, item: 1}]);
}
#[test] #[should_panic]
fn test_weighted_choice_weight_overflows() {
let x = ::std::u32::MAX / 2; // x + x + 2 is the overflow
WeightedChoice::new(&mut [Weighted { weight: x, item: 0 },
Weighted { weight: 1, item: 1 },
Weighted { weight: x, item: 2 },
Weighted { weight: 1, item: 3 }]);
}
}

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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 normal and derived distributions.
use {Rng, Rand, Open01};
use distributions::{ziggurat, ziggurat_tables, Sample, IndependentSample};
/// A wrapper around an `f64` to generate N(0, 1) random numbers
/// (a.k.a. a standard normal, or Gaussian).
///
/// See `Normal` for the general normal distribution.
///
/// Implemented via the ZIGNOR variant[1] of the Ziggurat method.
///
/// [1]: Jurgen A. Doornik (2005). [*An Improved Ziggurat Method to
/// Generate Normal Random
/// Samples*](http://www.doornik.com/research/ziggurat.pdf). Nuffield
/// College, Oxford
///
/// # Example
///
/// ```rust
/// use rand::distributions::normal::StandardNormal;
///
/// let StandardNormal(x) = rand::random();
/// println!("{}", x);
/// ```
#[derive(Clone, Copy, Debug)]
pub struct StandardNormal(pub f64);
impl Rand for StandardNormal {
fn rand<R:Rng>(rng: &mut R) -> StandardNormal {
#[inline]
fn pdf(x: f64) -> f64 {
(-x*x/2.0).exp()
}
#[inline]
fn zero_case<R:Rng>(rng: &mut R, u: f64) -> f64 {
// compute a random number in the tail by hand
// strange initial conditions, because the loop is not
// do-while, so the condition should be true on the first
// run, they get overwritten anyway (0 < 1, so these are
// good).
let mut x = 1.0f64;
let mut y = 0.0f64;
while -2.0 * y < x * x {
let Open01(x_) = rng.gen::<Open01<f64>>();
let Open01(y_) = rng.gen::<Open01<f64>>();
x = x_.ln() / ziggurat_tables::ZIG_NORM_R;
y = y_.ln();
}
if u < 0.0 { x - ziggurat_tables::ZIG_NORM_R } else { ziggurat_tables::ZIG_NORM_R - x }
}
StandardNormal(ziggurat(
rng,
true, // this is symmetric
&ziggurat_tables::ZIG_NORM_X,
&ziggurat_tables::ZIG_NORM_F,
pdf, zero_case))
}
}
/// The normal distribution `N(mean, std_dev**2)`.
///
/// This uses the ZIGNOR variant of the Ziggurat method, see
/// `StandardNormal` for more details.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{Normal, IndependentSample};
///
/// // mean 2, standard deviation 3
/// let normal = Normal::new(2.0, 3.0);
/// let v = normal.ind_sample(&mut rand::thread_rng());
/// println!("{} is from a N(2, 9) distribution", v)
/// ```
#[derive(Clone, Copy, Debug)]
pub struct Normal {
mean: f64,
std_dev: f64,
}
impl Normal {
/// Construct a new `Normal` distribution with the given mean and
/// standard deviation.
///
/// # Panics
///
/// Panics if `std_dev < 0`.
#[inline]
pub fn new(mean: f64, std_dev: f64) -> Normal {
assert!(std_dev >= 0.0, "Normal::new called with `std_dev` < 0");
Normal {
mean: mean,
std_dev: std_dev
}
}
}
impl Sample<f64> for Normal {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl IndependentSample<f64> for Normal {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
let StandardNormal(n) = rng.gen::<StandardNormal>();
self.mean + self.std_dev * n
}
}
/// The log-normal distribution `ln N(mean, std_dev**2)`.
///
/// If `X` is log-normal distributed, then `ln(X)` is `N(mean,
/// std_dev**2)` distributed.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{LogNormal, IndependentSample};
///
/// // mean 2, standard deviation 3
/// let log_normal = LogNormal::new(2.0, 3.0);
/// let v = log_normal.ind_sample(&mut rand::thread_rng());
/// println!("{} is from an ln N(2, 9) distribution", v)
/// ```
#[derive(Clone, Copy, Debug)]
pub struct LogNormal {
norm: Normal
}
impl LogNormal {
/// Construct a new `LogNormal` distribution with the given mean
/// and standard deviation.
///
/// # Panics
///
/// Panics if `std_dev < 0`.
#[inline]
pub fn new(mean: f64, std_dev: f64) -> LogNormal {
assert!(std_dev >= 0.0, "LogNormal::new called with `std_dev` < 0");
LogNormal { norm: Normal::new(mean, std_dev) }
}
}
impl Sample<f64> for LogNormal {
fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
}
impl IndependentSample<f64> for LogNormal {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
self.norm.ind_sample(rng).exp()
}
}
#[cfg(test)]
mod tests {
use distributions::{Sample, IndependentSample};
use super::{Normal, LogNormal};
#[test]
fn test_normal() {
let mut norm = Normal::new(10.0, 10.0);
let mut rng = ::test::rng();
for _ in 0..1000 {
norm.sample(&mut rng);
norm.ind_sample(&mut rng);
}
}
#[test]
#[should_panic]
fn test_normal_invalid_sd() {
Normal::new(10.0, -1.0);
}
#[test]
fn test_log_normal() {
let mut lnorm = LogNormal::new(10.0, 10.0);
let mut rng = ::test::rng();
for _ in 0..1000 {
lnorm.sample(&mut rng);
lnorm.ind_sample(&mut rng);
}
}
#[test]
#[should_panic]
fn test_log_normal_invalid_sd() {
LogNormal::new(10.0, -1.0);
}
}

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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.
//! Generating numbers between two others.
// this is surprisingly complicated to be both generic & correct
use core::num::Wrapping as w;
use Rng;
use distributions::{Sample, IndependentSample};
/// Sample values uniformly between two bounds.
///
/// This gives a uniform distribution (assuming the RNG used to sample
/// it is itself uniform & the `SampleRange` implementation for the
/// given type is correct), even for edge cases like `low = 0u8`,
/// `high = 170u8`, for which a naive modulo operation would return
/// numbers less than 85 with double the probability to those greater
/// than 85.
///
/// Types should attempt to sample in `[low, high)`, i.e., not
/// including `high`, but this may be very difficult. All the
/// primitive integer types satisfy this property, and the float types
/// normally satisfy it, but rounding may mean `high` can occur.
///
/// # Example
///
/// ```rust
/// use rand::distributions::{IndependentSample, Range};
///
/// fn main() {
/// let between = Range::new(10, 10000);
/// let mut rng = rand::thread_rng();
/// let mut sum = 0;
/// for _ in 0..1000 {
/// sum += between.ind_sample(&mut rng);
/// }
/// println!("{}", sum);
/// }
/// ```
#[derive(Clone, Copy, Debug)]
pub struct Range<X> {
low: X,
range: X,
accept_zone: X
}
impl<X: SampleRange + PartialOrd> Range<X> {
/// Create a new `Range` instance that samples uniformly from
/// `[low, high)`. Panics if `low >= high`.
pub fn new(low: X, high: X) -> Range<X> {
assert!(low < high, "Range::new called with `low >= high`");
SampleRange::construct_range(low, high)
}
}
impl<Sup: SampleRange> Sample<Sup> for Range<Sup> {
#[inline]
fn sample<R: Rng>(&mut self, rng: &mut R) -> Sup { self.ind_sample(rng) }
}
impl<Sup: SampleRange> IndependentSample<Sup> for Range<Sup> {
fn ind_sample<R: Rng>(&self, rng: &mut R) -> Sup {
SampleRange::sample_range(self, rng)
}
}
/// The helper trait for types that have a sensible way to sample
/// uniformly between two values. This should not be used directly,
/// and is only to facilitate `Range`.
pub trait SampleRange : Sized {
/// Construct the `Range` object that `sample_range`
/// requires. This should not ever be called directly, only via
/// `Range::new`, which will check that `low < high`, so this
/// function doesn't have to repeat the check.
fn construct_range(low: Self, high: Self) -> Range<Self>;
/// Sample a value from the given `Range` with the given `Rng` as
/// a source of randomness.
fn sample_range<R: Rng>(r: &Range<Self>, rng: &mut R) -> Self;
}
macro_rules! integer_impl {
($ty:ty, $unsigned:ident) => {
impl SampleRange for $ty {
// we play free and fast with unsigned vs signed here
// (when $ty is signed), but that's fine, since the
// contract of this macro is for $ty and $unsigned to be
// "bit-equal", so casting between them is a no-op & a
// bijection.
#[inline]
fn construct_range(low: $ty, high: $ty) -> Range<$ty> {
let range = (w(high as $unsigned) - w(low as $unsigned)).0;
let unsigned_max: $unsigned = ::core::$unsigned::MAX;
// this is the largest number that fits into $unsigned
// that `range` divides evenly, so, if we've sampled
// `n` uniformly from this region, then `n % range` is
// uniform in [0, range)
let zone = unsigned_max - unsigned_max % range;
Range {
low: low,
range: range as $ty,
accept_zone: zone as $ty
}
}
#[inline]
fn sample_range<R: Rng>(r: &Range<$ty>, rng: &mut R) -> $ty {
loop {
// rejection sample
let v = rng.gen::<$unsigned>();
// until we find something that fits into the
// region which r.range evenly divides (this will
// be uniformly distributed)
if v < r.accept_zone as $unsigned {
// and return it, with some adjustments
return (w(r.low) + w((v % r.range as $unsigned) as $ty)).0;
}
}
}
}
}
}
integer_impl! { i8, u8 }
integer_impl! { i16, u16 }
integer_impl! { i32, u32 }
integer_impl! { i64, u64 }
#[cfg(feature = "i128_support")]
integer_impl! { i128, u128 }
integer_impl! { isize, usize }
integer_impl! { u8, u8 }
integer_impl! { u16, u16 }
integer_impl! { u32, u32 }
integer_impl! { u64, u64 }
#[cfg(feature = "i128_support")]
integer_impl! { u128, u128 }
integer_impl! { usize, usize }
macro_rules! float_impl {
($ty:ty) => {
impl SampleRange for $ty {
fn construct_range(low: $ty, high: $ty) -> Range<$ty> {
Range {
low: low,
range: high - low,
accept_zone: 0.0 // unused
}
}
fn sample_range<R: Rng>(r: &Range<$ty>, rng: &mut R) -> $ty {
r.low + r.range * rng.gen::<$ty>()
}
}
}
}
float_impl! { f32 }
float_impl! { f64 }
#[cfg(test)]
mod tests {
use distributions::{Sample, IndependentSample};
use super::Range as Range;
#[should_panic]
#[test]
fn test_range_bad_limits_equal() {
Range::new(10, 10);
}
#[should_panic]
#[test]
fn test_range_bad_limits_flipped() {
Range::new(10, 5);
}
#[test]
fn test_integers() {
let mut rng = ::test::rng();
macro_rules! t {
($($ty:ident),*) => {{
$(
let v: &[($ty, $ty)] = &[(0, 10),
(10, 127),
(::core::$ty::MIN, ::core::$ty::MAX)];
for &(low, high) in v.iter() {
let mut sampler: Range<$ty> = Range::new(low, high);
for _ in 0..1000 {
let v = sampler.sample(&mut rng);
assert!(low <= v && v < high);
let v = sampler.ind_sample(&mut rng);
assert!(low <= v && v < high);
}
}
)*
}}
}
#[cfg(not(feature = "i128_support"))]
t!(i8, i16, i32, i64, isize,
u8, u16, u32, u64, usize);
#[cfg(feature = "i128_support")]
t!(i8, i16, i32, i64, i128, isize,
u8, u16, u32, u64, u128, usize);
}
#[test]
fn test_floats() {
let mut rng = ::test::rng();
macro_rules! t {
($($ty:ty),*) => {{
$(
let v: &[($ty, $ty)] = &[(0.0, 100.0),
(-1e35, -1e25),
(1e-35, 1e-25),
(-1e35, 1e35)];
for &(low, high) in v.iter() {
let mut sampler: Range<$ty> = Range::new(low, high);
for _ in 0..1000 {
let v = sampler.sample(&mut rng);
assert!(low <= v && v < high);
let v = sampler.ind_sample(&mut rng);
assert!(low <= v && v < high);
}
}
)*
}}
}
t!(f32, f64)
}
}

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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.
// Tables for distributions which are sampled using the ziggurat
// algorithm. Autogenerated by `ziggurat_tables.py`.
pub type ZigTable = &'static [f64; 257];
pub const ZIG_NORM_R: f64 = 3.654152885361008796;
pub static ZIG_NORM_X: [f64; 257] =
[3.910757959537090045, 3.654152885361008796, 3.449278298560964462, 3.320244733839166074,
3.224575052047029100, 3.147889289517149969, 3.083526132001233044, 3.027837791768635434,
2.978603279880844834, 2.934366867207854224, 2.894121053612348060, 2.857138730872132548,
2.822877396825325125, 2.790921174000785765, 2.760944005278822555, 2.732685359042827056,
2.705933656121858100, 2.680514643284522158, 2.656283037575502437, 2.633116393630324570,
2.610910518487548515, 2.589575986706995181, 2.569035452680536569, 2.549221550323460761,
2.530075232158516929, 2.511544441625342294, 2.493583041269680667, 2.476149939669143318,
2.459208374333311298, 2.442725318198956774, 2.426670984935725972, 2.411018413899685520,
2.395743119780480601, 2.380822795170626005, 2.366237056715818632, 2.351967227377659952,
2.337996148795031370, 2.324308018869623016, 2.310888250599850036, 2.297723348901329565,
2.284800802722946056, 2.272108990226823888, 2.259637095172217780, 2.247375032945807760,
2.235313384928327984, 2.223443340090905718, 2.211756642882544366, 2.200245546609647995,
2.188902771624720689, 2.177721467738641614, 2.166695180352645966, 2.155817819875063268,
2.145083634046203613, 2.134487182844320152, 2.124023315687815661, 2.113687150684933957,
2.103474055713146829, 2.093379631137050279, 2.083399693996551783, 2.073530263516978778,
2.063767547809956415, 2.054107931648864849, 2.044547965215732788, 2.035084353727808715,
2.025713947862032960, 2.016433734904371722, 2.007240830558684852, 1.998132471356564244,
1.989106007615571325, 1.980158896898598364, 1.971288697931769640, 1.962493064942461896,
1.953769742382734043, 1.945116560006753925, 1.936531428273758904, 1.928012334050718257,
1.919557336591228847, 1.911164563769282232, 1.902832208548446369, 1.894558525668710081,
1.886341828534776388, 1.878180486290977669, 1.870072921069236838, 1.862017605397632281,
1.854013059758148119, 1.846057850283119750, 1.838150586580728607, 1.830289919680666566,
1.822474540091783224, 1.814703175964167636, 1.806974591348693426, 1.799287584547580199,
1.791640986550010028, 1.784033659547276329, 1.776464495522344977, 1.768932414909077933,
1.761436365316706665, 1.753975320315455111, 1.746548278279492994, 1.739154261283669012,
1.731792314050707216, 1.724461502945775715, 1.717160915015540690, 1.709889657069006086,
1.702646854797613907, 1.695431651932238548, 1.688243209434858727, 1.681080704722823338,
1.673943330923760353, 1.666830296159286684, 1.659740822855789499, 1.652674147080648526,
1.645629517902360339, 1.638606196773111146, 1.631603456932422036, 1.624620582830568427,
1.617656869570534228, 1.610711622367333673, 1.603784156023583041, 1.596873794420261339,
1.589979870021648534, 1.583101723393471438, 1.576238702733332886, 1.569390163412534456,
1.562555467528439657, 1.555733983466554893, 1.548925085471535512, 1.542128153226347553,
1.535342571438843118, 1.528567729435024614, 1.521803020758293101, 1.515047842773992404,
1.508301596278571965, 1.501563685112706548, 1.494833515777718391, 1.488110497054654369,
1.481394039625375747, 1.474683555695025516, 1.467978458615230908, 1.461278162507407830,
1.454582081885523293, 1.447889631277669675, 1.441200224845798017, 1.434513276002946425,
1.427828197027290358, 1.421144398672323117, 1.414461289772464658, 1.407778276843371534,
1.401094763676202559, 1.394410150925071257, 1.387723835686884621, 1.381035211072741964,
1.374343665770030531, 1.367648583594317957, 1.360949343030101844, 1.354245316759430606,
1.347535871177359290, 1.340820365893152122, 1.334098153216083604, 1.327368577624624679,
1.320630975217730096, 1.313884673146868964, 1.307128989027353860, 1.300363230327433728,
1.293586693733517645, 1.286798664489786415, 1.279998415710333237, 1.273185207661843732,
1.266358287014688333, 1.259516886060144225, 1.252660221891297887, 1.245787495544997903,
1.238897891102027415, 1.231990574742445110, 1.225064693752808020, 1.218119375481726552,
1.211153726239911244, 1.204166830140560140, 1.197157747875585931, 1.190125515422801650,
1.183069142678760732, 1.175987612011489825, 1.168879876726833800, 1.161744859441574240,
1.154581450355851802, 1.147388505416733873, 1.140164844363995789, 1.132909248648336975,
1.125620459211294389, 1.118297174115062909, 1.110938046009249502, 1.103541679420268151,
1.096106627847603487, 1.088631390649514197, 1.081114409698889389, 1.073554065787871714,
1.065948674757506653, 1.058296483326006454, 1.050595664586207123, 1.042844313139370538,
1.035040439828605274, 1.027181966030751292, 1.019266717460529215, 1.011292417434978441,
1.003256679539591412, 0.995156999629943084, 0.986990747093846266, 0.978755155288937750,
0.970447311058864615, 0.962064143217605250, 0.953602409875572654, 0.945058684462571130,
0.936429340280896860, 0.927710533396234771, 0.918898183643734989, 0.909987953490768997,
0.900975224455174528, 0.891855070726792376, 0.882622229578910122, 0.873271068082494550,
0.863795545546826915, 0.854189171001560554, 0.844444954902423661, 0.834555354079518752,
0.824512208745288633, 0.814306670128064347, 0.803929116982664893, 0.793369058833152785,
0.782615023299588763, 0.771654424216739354, 0.760473406422083165, 0.749056662009581653,
0.737387211425838629, 0.725446140901303549, 0.713212285182022732, 0.700661841097584448,
0.687767892786257717, 0.674499822827436479, 0.660822574234205984, 0.646695714884388928,
0.632072236375024632, 0.616896989996235545, 0.601104617743940417, 0.584616766093722262,
0.567338257040473026, 0.549151702313026790, 0.529909720646495108, 0.509423329585933393,
0.487443966121754335, 0.463634336771763245, 0.437518402186662658, 0.408389134588000746,
0.375121332850465727, 0.335737519180459465, 0.286174591747260509, 0.215241895913273806,
0.000000000000000000];
pub static ZIG_NORM_F: [f64; 257] =
[0.000477467764586655, 0.001260285930498598, 0.002609072746106363, 0.004037972593371872,
0.005522403299264754, 0.007050875471392110, 0.008616582769422917, 0.010214971439731100,
0.011842757857943104, 0.013497450601780807, 0.015177088307982072, 0.016880083152595839,
0.018605121275783350, 0.020351096230109354, 0.022117062707379922, 0.023902203305873237,
0.025705804008632656, 0.027527235669693315, 0.029365939758230111, 0.031221417192023690,
0.033093219458688698, 0.034980941461833073, 0.036884215688691151, 0.038802707404656918,
0.040736110656078753, 0.042684144916619378, 0.044646552251446536, 0.046623094902089664,
0.048613553216035145, 0.050617723861121788, 0.052635418276973649, 0.054666461325077916,
0.056710690106399467, 0.058767952921137984, 0.060838108349751806, 0.062921024437977854,
0.065016577971470438, 0.067124653828023989, 0.069245144397250269, 0.071377949059141965,
0.073522973714240991, 0.075680130359194964, 0.077849336702372207, 0.080030515814947509,
0.082223595813495684, 0.084428509570654661, 0.086645194450867782, 0.088873592068594229,
0.091113648066700734, 0.093365311913026619, 0.095628536713353335, 0.097903279039215627,
0.100189498769172020, 0.102487158942306270, 0.104796225622867056, 0.107116667775072880,
0.109448457147210021, 0.111791568164245583, 0.114145977828255210, 0.116511665626037014,
0.118888613443345698, 0.121276805485235437, 0.123676228202051403, 0.126086870220650349,
0.128508722280473636, 0.130941777174128166, 0.133386029692162844, 0.135841476571757352,
0.138308116449064322, 0.140785949814968309, 0.143274978974047118, 0.145775208006537926,
0.148286642733128721, 0.150809290682410169, 0.153343161060837674, 0.155888264725064563,
0.158444614156520225, 0.161012223438117663, 0.163591108232982951, 0.166181285765110071,
0.168782774801850333, 0.171395595638155623, 0.174019770082499359, 0.176655321444406654,
0.179302274523530397, 0.181960655600216487, 0.184630492427504539, 0.187311814224516926,
0.190004651671193070, 0.192709036904328807, 0.195425003514885592, 0.198152586546538112,
0.200891822495431333, 0.203642749311121501, 0.206405406398679298, 0.209179834621935651,
0.211966076307852941, 0.214764175252008499, 0.217574176725178370, 0.220396127481011589,
0.223230075764789593, 0.226076071323264877, 0.228934165415577484, 0.231804410825248525,
0.234686861873252689, 0.237581574432173676, 0.240488605941449107, 0.243408015423711988,
0.246339863502238771, 0.249284212419516704, 0.252241126056943765, 0.255210669955677150,
0.258192911338648023, 0.261187919133763713, 0.264195763998317568, 0.267216518344631837,
0.270250256366959984, 0.273297054069675804, 0.276356989296781264, 0.279430141762765316,
0.282516593084849388, 0.285616426816658109, 0.288729728483353931, 0.291856585618280984,
0.294997087801162572, 0.298151326697901342, 0.301319396102034120, 0.304501391977896274,
0.307697412505553769, 0.310907558127563710, 0.314131931597630143, 0.317370638031222396,
0.320623784958230129, 0.323891482377732021, 0.327173842814958593, 0.330470981380537099,
0.333783015832108509, 0.337110066638412809, 0.340452257045945450, 0.343809713148291340,
0.347182563958251478, 0.350570941482881204, 0.353974980801569250, 0.357394820147290515,
0.360830600991175754, 0.364282468130549597, 0.367750569780596226, 0.371235057669821344,
0.374736087139491414, 0.378253817247238111, 0.381788410875031348, 0.385340034841733958,
0.388908860020464597, 0.392495061461010764, 0.396098818517547080, 0.399720314981931668,
0.403359739222868885, 0.407017284331247953, 0.410693148271983222, 0.414387534042706784,
0.418100649839684591, 0.421832709231353298, 0.425583931339900579, 0.429354541031341519,
0.433144769114574058, 0.436954852549929273, 0.440785034667769915, 0.444635565397727750,
0.448506701509214067, 0.452398706863882505, 0.456311852680773566, 0.460246417814923481,
0.464202689050278838, 0.468180961407822172, 0.472181538469883255, 0.476204732721683788,
0.480250865911249714, 0.484320269428911598, 0.488413284707712059, 0.492530263646148658,
0.496671569054796314, 0.500837575128482149, 0.505028667945828791, 0.509245245998136142,
0.513487720749743026, 0.517756517232200619, 0.522052074674794864, 0.526374847174186700,
0.530725304406193921, 0.535103932383019565, 0.539511234259544614, 0.543947731192649941,
0.548413963257921133, 0.552910490428519918, 0.557437893621486324, 0.561996775817277916,
0.566587763258951771, 0.571211506738074970, 0.575868682975210544, 0.580559996103683473,
0.585286179266300333, 0.590047996335791969, 0.594846243770991268, 0.599681752622167719,
0.604555390700549533, 0.609468064928895381, 0.614420723892076803, 0.619414360609039205,
0.624450015550274240, 0.629528779928128279, 0.634651799290960050, 0.639820277456438991,
0.645035480824251883, 0.650298743114294586, 0.655611470583224665, 0.660975147780241357,
0.666391343912380640, 0.671861719900766374, 0.677388036222513090, 0.682972161648791376,
0.688616083008527058, 0.694321916130032579, 0.700091918140490099, 0.705928501336797409,
0.711834248882358467, 0.717811932634901395, 0.723864533472881599, 0.729995264565802437,
0.736207598131266683, 0.742505296344636245, 0.748892447223726720, 0.755373506511754500,
0.761953346841546475, 0.768637315803334831, 0.775431304986138326, 0.782341832659861902,
0.789376143571198563, 0.796542330428254619, 0.803849483176389490, 0.811307874318219935,
0.818929191609414797, 0.826726833952094231, 0.834716292992930375, 0.842915653118441077,
0.851346258465123684, 0.860033621203008636, 0.869008688043793165, 0.878309655816146839,
0.887984660763399880, 0.898095921906304051, 0.908726440060562912, 0.919991505048360247,
0.932060075968990209, 0.945198953453078028, 0.959879091812415930, 0.977101701282731328,
1.000000000000000000];
pub const ZIG_EXP_R: f64 = 7.697117470131050077;
pub static ZIG_EXP_X: [f64; 257] =
[8.697117470131052741, 7.697117470131050077, 6.941033629377212577, 6.478378493832569696,
6.144164665772472667, 5.882144315795399869, 5.666410167454033697, 5.482890627526062488,
5.323090505754398016, 5.181487281301500047, 5.054288489981304089, 4.938777085901250530,
4.832939741025112035, 4.735242996601741083, 4.644491885420085175, 4.559737061707351380,
4.480211746528421912, 4.405287693473573185, 4.334443680317273007, 4.267242480277365857,
4.203313713735184365, 4.142340865664051464, 4.084051310408297830, 4.028208544647936762,
3.974606066673788796, 3.923062500135489739, 3.873417670399509127, 3.825529418522336744,
3.779270992411667862, 3.734528894039797375, 3.691201090237418825, 3.649195515760853770,
3.608428813128909507, 3.568825265648337020, 3.530315889129343354, 3.492837654774059608,
3.456332821132760191, 3.420748357251119920, 3.386035442460300970, 3.352149030900109405,
3.319047470970748037, 3.286692171599068679, 3.255047308570449882, 3.224079565286264160,
3.193757903212240290, 3.164053358025972873, 3.134938858084440394, 3.106389062339824481,
3.078380215254090224, 3.050890016615455114, 3.023897504455676621, 2.997382949516130601,
2.971327759921089662, 2.945714394895045718, 2.920526286512740821, 2.895747768600141825,
2.871364012015536371, 2.847360965635188812, 2.823725302450035279, 2.800444370250737780,
2.777506146439756574, 2.754899196562344610, 2.732612636194700073, 2.710636095867928752,
2.688959688741803689, 2.667573980773266573, 2.646469963151809157, 2.625639026797788489,
2.605072938740835564, 2.584763820214140750, 2.564704126316905253, 2.544886627111869970,
2.525304390037828028, 2.505950763528594027, 2.486819361740209455, 2.467904050297364815,
2.449198932978249754, 2.430698339264419694, 2.412396812688870629, 2.394289099921457886,
2.376370140536140596, 2.358635057409337321, 2.341079147703034380, 2.323697874390196372,
2.306486858283579799, 2.289441870532269441, 2.272558825553154804, 2.255833774367219213,
2.239262898312909034, 2.222842503111036816, 2.206569013257663858, 2.190438966723220027,
2.174449009937774679, 2.158595893043885994, 2.142876465399842001, 2.127287671317368289,
2.111826546019042183, 2.096490211801715020, 2.081275874393225145, 2.066180819490575526,
2.051202409468584786, 2.036338080248769611, 2.021585338318926173, 2.006941757894518563,
1.992404978213576650, 1.977972700957360441, 1.963642687789548313, 1.949412758007184943,
1.935280786297051359, 1.921244700591528076, 1.907302480018387536, 1.893452152939308242,
1.879691795072211180, 1.866019527692827973, 1.852433515911175554, 1.838931967018879954,
1.825513128903519799, 1.812175288526390649, 1.798916770460290859, 1.785735935484126014,
1.772631179231305643, 1.759600930889074766, 1.746643651946074405, 1.733757834985571566,
1.720942002521935299, 1.708194705878057773, 1.695514524101537912, 1.682900062917553896,
1.670349953716452118, 1.657862852574172763, 1.645437439303723659, 1.633072416535991334,
1.620766508828257901, 1.608518461798858379, 1.596327041286483395, 1.584191032532688892,
1.572109239386229707, 1.560080483527888084, 1.548103603714513499, 1.536177455041032092,
1.524300908219226258, 1.512472848872117082, 1.500692176842816750, 1.488957805516746058,
1.477268661156133867, 1.465623682245745352, 1.454021818848793446, 1.442462031972012504,
1.430943292938879674, 1.419464582769983219, 1.408024891569535697, 1.396623217917042137,
1.385258568263121992, 1.373929956328490576, 1.362636402505086775, 1.351376933258335189,
1.340150580529504643, 1.328956381137116560, 1.317793376176324749, 1.306660610415174117,
1.295557131686601027, 1.284481990275012642, 1.273434238296241139, 1.262412929069615330,
1.251417116480852521, 1.240445854334406572, 1.229498195693849105, 1.218573192208790124,
1.207669893426761121, 1.196787346088403092, 1.185924593404202199, 1.175080674310911677,
1.164254622705678921, 1.153445466655774743, 1.142652227581672841, 1.131873919411078511,
1.121109547701330200, 1.110358108727411031, 1.099618588532597308, 1.088889961938546813,
1.078171191511372307, 1.067461226479967662, 1.056759001602551429, 1.046063435977044209,
1.035373431790528542, 1.024687873002617211, 1.014005623957096480, 1.003325527915696735,
0.992646405507275897, 0.981967053085062602, 0.971286240983903260, 0.960602711668666509,
0.949915177764075969, 0.939222319955262286, 0.928522784747210395, 0.917815182070044311,
0.907098082715690257, 0.896370015589889935, 0.885629464761751528, 0.874874866291025066,
0.864104604811004484, 0.853317009842373353, 0.842510351810368485, 0.831682837734273206,
0.820832606554411814, 0.809957724057418282, 0.799056177355487174, 0.788125868869492430,
0.777164609759129710, 0.766170112735434672, 0.755139984181982249, 0.744071715500508102,
0.732962673584365398, 0.721810090308756203, 0.710611050909655040, 0.699362481103231959,
0.688061132773747808, 0.676703568029522584, 0.665286141392677943, 0.653804979847664947,
0.642255960424536365, 0.630634684933490286, 0.618936451394876075, 0.607156221620300030,
0.595288584291502887, 0.583327712748769489, 0.571267316532588332, 0.559100585511540626,
0.546820125163310577, 0.534417881237165604, 0.521885051592135052, 0.509211982443654398,
0.496388045518671162, 0.483401491653461857, 0.470239275082169006, 0.456886840931420235,
0.443327866073552401, 0.429543940225410703, 0.415514169600356364, 0.401214678896277765,
0.386617977941119573, 0.371692145329917234, 0.356399760258393816, 0.340696481064849122,
0.324529117016909452, 0.307832954674932158, 0.290527955491230394, 0.272513185478464703,
0.253658363385912022, 0.233790483059674731, 0.212671510630966620, 0.189958689622431842,
0.165127622564187282, 0.137304980940012589, 0.104838507565818778, 0.063852163815001570,
0.000000000000000000];
pub static ZIG_EXP_F: [f64; 257] =
[0.000167066692307963, 0.000454134353841497, 0.000967269282327174, 0.001536299780301573,
0.002145967743718907, 0.002788798793574076, 0.003460264777836904, 0.004157295120833797,
0.004877655983542396, 0.005619642207205489, 0.006381905937319183, 0.007163353183634991,
0.007963077438017043, 0.008780314985808977, 0.009614413642502212, 0.010464810181029981,
0.011331013597834600, 0.012212592426255378, 0.013109164931254991, 0.014020391403181943,
0.014945968011691148, 0.015885621839973156, 0.016839106826039941, 0.017806200410911355,
0.018786700744696024, 0.019780424338009740, 0.020787204072578114, 0.021806887504283581,
0.022839335406385240, 0.023884420511558174, 0.024942026419731787, 0.026012046645134221,
0.027094383780955803, 0.028188948763978646, 0.029295660224637411, 0.030414443910466622,
0.031545232172893622, 0.032687963508959555, 0.033842582150874358, 0.035009037697397431,
0.036187284781931443, 0.037377282772959382, 0.038578995503074871, 0.039792391023374139,
0.041017441380414840, 0.042254122413316254, 0.043502413568888197, 0.044762297732943289,
0.046033761076175184, 0.047316792913181561, 0.048611385573379504, 0.049917534282706379,
0.051235237055126281, 0.052564494593071685, 0.053905310196046080, 0.055257689676697030,
0.056621641283742870, 0.057997175631200659, 0.059384305633420280, 0.060783046445479660,
0.062193415408541036, 0.063615431999807376, 0.065049117786753805, 0.066494496385339816,
0.067951593421936643, 0.069420436498728783, 0.070901055162371843, 0.072393480875708752,
0.073897746992364746, 0.075413888734058410, 0.076941943170480517, 0.078481949201606435,
0.080033947542319905, 0.081597980709237419, 0.083174093009632397, 0.084762330532368146,
0.086362741140756927, 0.087975374467270231, 0.089600281910032886, 0.091237516631040197,
0.092887133556043569, 0.094549189376055873, 0.096223742550432825, 0.097910853311492213,
0.099610583670637132, 0.101322997425953631, 0.103048160171257702, 0.104786139306570145,
0.106537004050001632, 0.108300825451033755, 0.110077676405185357, 0.111867631670056283,
0.113670767882744286, 0.115487163578633506, 0.117316899211555525, 0.119160057175327641,
0.121016721826674792, 0.122886979509545108, 0.124770918580830933, 0.126668629437510671,
0.128580204545228199, 0.130505738468330773, 0.132445327901387494, 0.134399071702213602,
0.136367070926428829, 0.138349428863580176, 0.140346251074862399, 0.142357645432472146,
0.144383722160634720, 0.146424593878344889, 0.148480375643866735, 0.150551185001039839,
0.152637142027442801, 0.154738369384468027, 0.156854992369365148, 0.158987138969314129,
0.161134939917591952, 0.163298528751901734, 0.165478041874935922, 0.167673618617250081,
0.169885401302527550, 0.172113535315319977, 0.174358169171353411, 0.176619454590494829,
0.178897546572478278, 0.181192603475496261, 0.183504787097767436, 0.185834262762197083,
0.188181199404254262, 0.190545769663195363, 0.192928149976771296, 0.195328520679563189,
0.197747066105098818, 0.200183974691911210, 0.202639439093708962, 0.205113656293837654,
0.207606827724221982, 0.210119159388988230, 0.212650861992978224, 0.215202151075378628,
0.217773247148700472, 0.220364375843359439, 0.222975768058120111, 0.225607660116683956,
0.228260293930716618, 0.230933917169627356, 0.233628783437433291, 0.236345152457059560,
0.239083290262449094, 0.241843469398877131, 0.244625969131892024, 0.247431075665327543,
0.250259082368862240, 0.253110290015629402, 0.255985007030415324, 0.258883549749016173,
0.261806242689362922, 0.264753418835062149, 0.267725419932044739, 0.270722596799059967,
0.273745309652802915, 0.276793928448517301, 0.279868833236972869, 0.282970414538780746,
0.286099073737076826, 0.289255223489677693, 0.292439288161892630, 0.295651704281261252,
0.298892921015581847, 0.302163400675693528, 0.305463619244590256, 0.308794066934560185,
0.312155248774179606, 0.315547685227128949, 0.318971912844957239, 0.322428484956089223,
0.325917972393556354, 0.329440964264136438, 0.332998068761809096, 0.336589914028677717,
0.340217149066780189, 0.343880444704502575, 0.347580494621637148, 0.351318016437483449,
0.355093752866787626, 0.358908472948750001, 0.362762973354817997, 0.366658079781514379,
0.370594648435146223, 0.374573567615902381, 0.378595759409581067, 0.382662181496010056,
0.386773829084137932, 0.390931736984797384, 0.395136981833290435, 0.399390684475231350,
0.403694012530530555, 0.408048183152032673, 0.412454465997161457, 0.416914186433003209,
0.421428728997616908, 0.425999541143034677, 0.430628137288459167, 0.435316103215636907,
0.440065100842354173, 0.444876873414548846, 0.449753251162755330, 0.454696157474615836,
0.459707615642138023, 0.464789756250426511, 0.469944825283960310, 0.475175193037377708,
0.480483363930454543, 0.485871987341885248, 0.491343869594032867, 0.496901987241549881,
0.502549501841348056, 0.508289776410643213, 0.514126393814748894, 0.520063177368233931,
0.526104213983620062, 0.532253880263043655, 0.538516872002862246, 0.544898237672440056,
0.551403416540641733, 0.558038282262587892, 0.564809192912400615, 0.571723048664826150,
0.578787358602845359, 0.586010318477268366, 0.593400901691733762, 0.600968966365232560,
0.608725382079622346, 0.616682180915207878, 0.624852738703666200, 0.633251994214366398,
0.641896716427266423, 0.650805833414571433, 0.660000841079000145, 0.669506316731925177,
0.679350572264765806, 0.689566496117078431, 0.700192655082788606, 0.711274760805076456,
0.722867659593572465, 0.735038092431424039, 0.747868621985195658, 0.761463388849896838,
0.775956852040116218, 0.791527636972496285, 0.808421651523009044, 0.826993296643051101,
0.847785500623990496, 0.871704332381204705, 0.900469929925747703, 0.938143680862176477,
1.000000000000000000];

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// Copyright 2017 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.
//
// Based on jitterentropy-library, http://www.chronox.de/jent.html.
// Copyright Stephan Mueller <smueller@chronox.de>, 2014 - 2017.
//
// With permission from Stephan Mueller to relicense the Rust translation under
// the MIT license.
//! Non-physical true random number generator based on timing jitter.
use Rng;
use core::{fmt, mem, ptr};
#[cfg(feature="std")]
use std::sync::atomic::{AtomicUsize, ATOMIC_USIZE_INIT, Ordering};
const MEMORY_BLOCKS: usize = 64;
const MEMORY_BLOCKSIZE: usize = 32;
const MEMORY_SIZE: usize = MEMORY_BLOCKS * MEMORY_BLOCKSIZE;
/// A true random number generator based on jitter in the CPU execution time,
/// and jitter in memory access time.
///
/// This is a true random number generator, as opposed to pseudo-random
/// generators. Random numbers generated by `JitterRng` can be seen as fresh
/// entropy. A consequence is that is orders of magnitude slower than `OsRng`
/// and PRNGs (about 10^3 .. 10^6 slower).
///
/// There are very few situations where using this RNG is appropriate. Only very
/// few applications require true entropy. A normal PRNG can be statistically
/// indistinguishable, and a cryptographic PRNG should also be as impossible to
/// predict.
///
/// Use of `JitterRng` is recommended for initializing cryptographic PRNGs when
/// `OsRng` is not available.
///
/// This implementation is based on
/// [Jitterentropy](http://www.chronox.de/jent.html) version 2.1.0.
//
// Note: the C implementation relies on being compiled without optimizations.
// This implementation goes through lengths to make the compiler not optimise
// out what is technically dead code, but that does influence timing jitter.
pub struct JitterRng {
data: u64, // Actual random number
// Number of rounds to run the entropy collector per 64 bits
rounds: u32,
// Timer and previous time stamp, used by `measure_jitter`
timer: fn() -> u64,
prev_time: u64,
// Deltas used for the stuck test
last_delta: i64,
last_delta2: i64,
// Memory for the Memory Access noise source
mem_prev_index: usize,
mem: [u8; MEMORY_SIZE],
// Make `next_u32` not waste 32 bits
data_remaining: Option<u32>,
}
// Custom Debug implementation that does not expose the internal state
impl fmt::Debug for JitterRng {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "JitterRng {{}}")
}
}
/// An error that can occur when `test_timer` fails.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TimerError {
/// No timer available.
NoTimer,
/// Timer too coarse to use as an entropy source.
CoarseTimer,
/// Timer is not monotonically increasing.
NotMonotonic,
/// Variations of deltas of time too small.
TinyVariantions,
/// Too many stuck results (indicating no added entropy).
TooManyStuck,
#[doc(hidden)]
__Nonexhaustive,
}
impl TimerError {
fn description(&self) -> &'static str {
match *self {
TimerError::NoTimer => "no timer available",
TimerError::CoarseTimer => "coarse timer",
TimerError::NotMonotonic => "timer not monotonic",
TimerError::TinyVariantions => "time delta variations too small",
TimerError::TooManyStuck => "too many stuck results",
TimerError::__Nonexhaustive => unreachable!(),
}
}
}
impl fmt::Display for TimerError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.description())
}
}
#[cfg(feature="std")]
impl ::std::error::Error for TimerError {
fn description(&self) -> &str {
self.description()
}
}
// Initialise to zero; must be positive
#[cfg(feature="std")]
static JITTER_ROUNDS: AtomicUsize = ATOMIC_USIZE_INIT;
impl JitterRng {
/// Create a new `JitterRng`.
/// Makes use of `std::time` for a timer.
///
/// During initialization CPU execution timing jitter is measured a few
/// hundred times. If this does not pass basic quality tests, an error is
/// returned. The test result is cached to make subsequent calls faster.
#[cfg(feature="std")]
pub fn new() -> Result<JitterRng, TimerError> {
let mut ec = JitterRng::new_with_timer(platform::get_nstime);
let mut rounds = JITTER_ROUNDS.load(Ordering::Relaxed) as u32;
if rounds == 0 {
// No result yet: run test.
// This allows the timer test to run multiple times; we don't care.
rounds = ec.test_timer()?;
JITTER_ROUNDS.store(rounds as usize, Ordering::Relaxed);
}
ec.set_rounds(rounds);
Ok(ec)
}
/// Create a new `JitterRng`.
/// A custom timer can be supplied, making it possible to use `JitterRng` in
/// `no_std` environments.
///
/// The timer must have nanosecond precision.
///
/// This method is more low-level than `new()`. It is the responsibility of
/// the caller to run `test_timer` before using any numbers generated with
/// `JitterRng`, and optionally call `set_rounds()`.
pub fn new_with_timer(timer: fn() -> u64) -> JitterRng {
let mut ec = JitterRng {
data: 0,
rounds: 64,
timer: timer,
prev_time: 0,
last_delta: 0,
last_delta2: 0,
mem_prev_index: 0,
mem: [0; MEMORY_SIZE],
data_remaining: None,
};
// Fill `data`, `prev_time`, `last_delta` and `last_delta2` with
// non-zero values.
ec.prev_time = timer();
ec.gen_entropy();
// Do a single read from `self.mem` to make sure the Memory Access noise
// source is not optimised out.
// Note: this read is important, it effects optimisations for the entire
// module!
black_box(ec.mem[0]);
ec
}
/// Configures how many rounds are used to generate each 64-bit value.
/// This must be greater than zero, and has a big impact on performance
/// and output quality.
///
/// `new_with_timer` conservatively uses 64 rounds, but often less rounds
/// can be used. The `test_timer()` function returns the minimum number of
/// rounds required for full strength (platform dependent), so one may use
/// `rng.set_rounds(rng.test_timer()?);` or cache the value.
pub fn set_rounds(&mut self, rounds: u32) {
assert!(rounds > 0);
self.rounds = rounds;
}
// Calculate a random loop count used for the next round of an entropy
// collection, based on bits from a fresh value from the timer.
//
// The timer is folded to produce a number that contains at most `n_bits`
// bits.
//
// Note: A constant should be added to the resulting random loop count to
// prevent loops that run 0 times.
#[inline(never)]
fn random_loop_cnt(&mut self, n_bits: u32) -> u32 {
let mut rounds = 0;
let mut time = (self.timer)();
// Mix with the current state of the random number balance the random
// loop counter a bit more.
time ^= self.data;
// We fold the time value as much as possible to ensure that as many
// bits of the time stamp are included as possible.
let folds = (64 + n_bits - 1) / n_bits;
let mask = (1 << n_bits) - 1;
for _ in 0..folds {
rounds ^= time & mask;
time = time >> n_bits;
}
rounds as u32
}
// CPU jitter noise source
// Noise source based on the CPU execution time jitter
//
// This function injects the individual bits of the time value into the
// entropy pool using an LFSR.
//
// The code is deliberately inefficient with respect to the bit shifting.
// This function not only acts as folding operation, but this function's
// execution is used to measure the CPU execution time jitter. Any change to
// the loop in this function implies that careful retesting must be done.
#[inline(never)]
fn lfsr_time(&mut self, time: u64, var_rounds: bool) {
fn lfsr(mut data: u64, time: u64) -> u64{
for i in 1..65 {
let mut tmp = time << (64 - i);
tmp = tmp >> (64 - 1);
// Fibonacci LSFR with polynomial of
// x^64 + x^61 + x^56 + x^31 + x^28 + x^23 + 1 which is
// primitive according to
// http://poincare.matf.bg.ac.rs/~ezivkovm/publications/primpol1.pdf
// (the shift values are the polynomial values minus one
// due to counting bits from 0 to 63). As the current
// position is always the LSB, the polynomial only needs
// to shift data in from the left without wrap.
data ^= tmp;
data ^= (data >> 63) & 1;
data ^= (data >> 60) & 1;
data ^= (data >> 55) & 1;
data ^= (data >> 30) & 1;
data ^= (data >> 27) & 1;
data ^= (data >> 22) & 1;
data = data.rotate_left(1);
}
data
}
// Note: in the reference implementation only the last round effects
// `self.data`, all the other results are ignored. To make sure the
// other rounds are not optimised out, we first run all but the last
// round on a throw-away value instead of the real `self.data`.
let mut lfsr_loop_cnt = 0;
if var_rounds { lfsr_loop_cnt = self.random_loop_cnt(4) };
let mut throw_away: u64 = 0;
for _ in 0..lfsr_loop_cnt {
throw_away = lfsr(throw_away, time);
}
black_box(throw_away);
self.data = lfsr(self.data, time);
}
// Memory Access noise source
// This is a noise source based on variations in memory access times
//
// This function performs memory accesses which will add to the timing
// variations due to an unknown amount of CPU wait states that need to be
// added when accessing memory. The memory size should be larger than the L1
// caches as outlined in the documentation and the associated testing.
//
// The L1 cache has a very high bandwidth, albeit its access rate is usually
// slower than accessing CPU registers. Therefore, L1 accesses only add
// minimal variations as the CPU has hardly to wait. Starting with L2,
// significant variations are added because L2 typically does not belong to
// the CPU any more and therefore a wider range of CPU wait states is
// necessary for accesses. L3 and real memory accesses have even a wider
// range of wait states. However, to reliably access either L3 or memory,
// the `self.mem` memory must be quite large which is usually not desirable.
#[inline(never)]
fn memaccess(&mut self, var_rounds: bool) {
let mut acc_loop_cnt = 128;
if var_rounds { acc_loop_cnt += self.random_loop_cnt(4) };
let mut index = self.mem_prev_index;
for _ in 0..acc_loop_cnt {
// Addition of memblocksize - 1 to index with wrap around logic to
// ensure that every memory location is hit evenly.
// The modulus also allows the compiler to remove the indexing
// bounds check.
index = (index + MEMORY_BLOCKSIZE - 1) % MEMORY_SIZE;
// memory access: just add 1 to one byte
// memory access implies read from and write to memory location
let tmp = self.mem[index];
self.mem[index] = tmp.wrapping_add(1);
}
self.mem_prev_index = index;
}
// Stuck test by checking the:
// - 1st derivation of the jitter measurement (time delta)
// - 2nd derivation of the jitter measurement (delta of time deltas)
// - 3rd derivation of the jitter measurement (delta of delta of time
// deltas)
//
// All values must always be non-zero.
// This test is a heuristic to see whether the last measurement holds
// entropy.
fn stuck(&mut self, current_delta: i64) -> bool {
let delta2 = self.last_delta - current_delta;
let delta3 = delta2 - self.last_delta2;
self.last_delta = current_delta;
self.last_delta2 = delta2;
current_delta == 0 || delta2 == 0 || delta3 == 0
}
// This is the heart of the entropy generation: calculate time deltas and
// use the CPU jitter in the time deltas. The jitter is injected into the
// entropy pool.
//
// Ensure that `self.prev_time` is primed before using the output of this
// function. This can be done by calling this function and not using its
// result.
fn measure_jitter(&mut self) -> Option<()> {
// Invoke one noise source before time measurement to add variations
self.memaccess(true);
// Get time stamp and calculate time delta to previous
// invocation to measure the timing variations
let time = (self.timer)();
// Note: wrapping_sub combined with a cast to `i64` generates a correct
// delta, even in the unlikely case this is a timer that is not strictly
// monotonic.
let current_delta = time.wrapping_sub(self.prev_time) as i64;
self.prev_time = time;
// Call the next noise source which also injects the data
self.lfsr_time(current_delta as u64, true);
// Check whether we have a stuck measurement (i.e. does the last
// measurement holds entropy?).
if self.stuck(current_delta) { return None };
// Rotate the data buffer by a prime number (any odd number would
// do) to ensure that every bit position of the input time stamp
// has an even chance of being merged with a bit position in the
// entropy pool. We do not use one here as the adjacent bits in
// successive time deltas may have some form of dependency. The
// chosen value of 7 implies that the low 7 bits of the next
// time delta value is concatenated with the current time delta.
self.data = self.data.rotate_left(7);
Some(())
}
// Shuffle the pool a bit by mixing some value with a bijective function
// (XOR) into the pool.
//
// The function generates a mixer value that depends on the bits set and
// the location of the set bits in the random number generated by the
// entropy source. Therefore, based on the generated random number, this
// mixer value can have 2^64 different values. That mixer value is
// initialized with the first two SHA-1 constants. After obtaining the
// mixer value, it is XORed into the random number.
//
// The mixer value is not assumed to contain any entropy. But due to the
// XOR operation, it can also not destroy any entropy present in the
// entropy pool.
#[inline(never)]
fn stir_pool(&mut self) {
// This constant is derived from the first two 32 bit initialization
// vectors of SHA-1 as defined in FIPS 180-4 section 5.3.1
// The order does not really matter as we do not rely on the specific
// numbers. We just pick the SHA-1 constants as they have a good mix of
// bit set and unset.
const CONSTANT: u64 = 0x67452301efcdab89;
// The start value of the mixer variable is derived from the third
// and fourth 32 bit initialization vector of SHA-1 as defined in
// FIPS 180-4 section 5.3.1
let mut mixer = 0x98badcfe10325476;
// This is a constant time function to prevent leaking timing
// information about the random number.
// The normal code is:
// ```
// for i in 0..64 {
// if ((self.data >> i) & 1) == 1 { mixer ^= CONSTANT; }
// }
// ```
// This is a bit fragile, as LLVM really wants to use branches here, and
// we rely on it to not recognise the opportunity.
for i in 0..64 {
let apply = (self.data >> i) & 1;
let mask = !apply.wrapping_sub(1);
mixer ^= CONSTANT & mask;
mixer = mixer.rotate_left(1);
}
self.data ^= mixer;
}
fn gen_entropy(&mut self) -> u64 {
// Prime `self.prev_time`, and run the noice sources to make sure the
// first loop round collects the expected entropy.
let _ = self.measure_jitter();
for _ in 0..self.rounds {
// If a stuck measurement is received, repeat measurement
// Note: we do not guard against an infinite loop, that would mean
// the timer suddenly became broken.
while self.measure_jitter().is_none() {}
}
self.stir_pool();
self.data
}
/// Basic quality tests on the timer, by measuring CPU timing jitter a few
/// hundred times.
///
/// If succesful, this will return the estimated number of rounds necessary
/// to collect 64 bits of entropy. Otherwise a `TimerError` with the cause
/// of the failure will be returned.
pub fn test_timer(&mut self) -> Result<u32, TimerError> {
// We could add a check for system capabilities such as `clock_getres`
// or check for `CONFIG_X86_TSC`, but it does not make much sense as the
// following sanity checks verify that we have a high-resolution timer.
#[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))]
return Err(TimerError::NoTimer);
let mut delta_sum = 0;
let mut old_delta = 0;
let mut time_backwards = 0;
let mut count_mod = 0;
let mut count_stuck = 0;
// TESTLOOPCOUNT needs some loops to identify edge systems.
// 100 is definitely too little.
const TESTLOOPCOUNT: u64 = 300;
const CLEARCACHE: u64 = 100;
for i in 0..(CLEARCACHE + TESTLOOPCOUNT) {
// Measure time delta of core entropy collection logic
let time = (self.timer)();
self.memaccess(true);
self.lfsr_time(time, true);
let time2 = (self.timer)();
// Test whether timer works
if time == 0 || time2 == 0 {
return Err(TimerError::NoTimer);
}
let delta = time2.wrapping_sub(time) as i64;
// Test whether timer is fine grained enough to provide delta even
// when called shortly after each other -- this implies that we also
// have a high resolution timer
if delta == 0 {
return Err(TimerError::CoarseTimer);
}
// Up to here we did not modify any variable that will be
// evaluated later, but we already performed some work. Thus we
// already have had an impact on the caches, branch prediction,
// etc. with the goal to clear it to get the worst case
// measurements.
if i < CLEARCACHE { continue; }
if self.stuck(delta) { count_stuck += 1; }
// Test whether we have an increasing timer.
if !(time2 > time) { time_backwards += 1; }
// Count the number of times the counter increases in steps of 100ns
// or greater.
if (delta % 100) == 0 { count_mod += 1; }
// Ensure that we have a varying delta timer which is necessary for
// the calculation of entropy -- perform this check only after the
// first loop is executed as we need to prime the old_delta value
delta_sum += (delta - old_delta).abs() as u64;
old_delta = delta;
}
// We allow the time to run backwards for up to three times.
// This can happen if the clock is being adjusted by NTP operations.
// If such an operation just happens to interfere with our test, it
// should not fail. The value of 3 should cover the NTP case being
// performed during our test run.
if time_backwards > 3 {
return Err(TimerError::NotMonotonic);
}
// Test that the available amount of entropy per round does not get to
// low. We expect 1 bit of entropy per round as a reasonable minimum
// (although less is possible, it means the collector loop has to run
// much more often).
// `assert!(delta_average >= log2(1))`
// `assert!(delta_sum / TESTLOOPCOUNT >= 1)`
// `assert!(delta_sum >= TESTLOOPCOUNT)`
if delta_sum < TESTLOOPCOUNT {
return Err(TimerError::TinyVariantions);
}
// Ensure that we have variations in the time stamp below 100 for at
// least 10% of all checks -- on some platforms, the counter increments
// in multiples of 100, but not always
if count_mod > (TESTLOOPCOUNT * 9 / 10) {
return Err(TimerError::CoarseTimer);
}
// If we have more than 90% stuck results, then this Jitter RNG is
// likely to not work well.
if count_stuck > (TESTLOOPCOUNT * 9 / 10) {
return Err(TimerError::TooManyStuck);
}
// Estimate the number of `measure_jitter` rounds necessary for 64 bits
// of entropy.
//
// We don't try very hard to come up with a good estimate of the
// available bits of entropy per round here for two reasons:
// 1. Simple estimates of the available bits (like Shannon entropy) are
// too optimistic.
// 2) Unless we want to waste a lot of time during intialization, there
// only a small number of samples are available.
//
// Therefore we use a very simple and conservative estimate:
// `let bits_of_entropy = log2(delta_average) / 2`.
//
// The number of rounds `measure_jitter` should run to collect 64 bits
// of entropy is `64 / bits_of_entropy`.
//
// To have smaller rounding errors, intermediate values are multiplied
// by `FACTOR`. To compensate for `log2` and division rounding down,
// add 1.
let delta_average = delta_sum / TESTLOOPCOUNT;
// println!("delta_average: {}", delta_average);
const FACTOR: u32 = 3;
fn log2(x: u64) -> u32 { 64 - x.leading_zeros() }
// pow(δ, FACTOR) must be representable; if you have overflow reduce FACTOR
Ok(64 * 2 * FACTOR / (log2(delta_average.pow(FACTOR)) + 1))
}
/// Statistical test: return the timer delta of one normal run of the
/// `JitterEntropy` entropy collector.
///
/// Setting `var_rounds` to `true` will execute the memory access and the
/// CPU jitter noice sources a variable amount of times (just like a real
/// `JitterEntropy` round).
///
/// Setting `var_rounds` to `false` will execute the noice sources the
/// minimal number of times. This can be used to measure the minimum amount
/// of entropy one round of entropy collector can collect in the worst case.
///
/// # Example
///
/// Use `timer_stats` to run the [NIST SP 800-90B Entropy Estimation Suite]
/// (https://github.com/usnistgov/SP800-90B_EntropyAssessment).
///
/// This is the recommended way to test the quality of `JitterRng`. It
/// should be run before using the RNG on untested hardware, after changes
/// that could effect how the code is optimised, and after major compiler
/// compiler changes, like a new LLVM version.
///
/// First generate two files `jitter_rng_var.bin` and `jitter_rng_var.min`.
///
/// Execute `python noniid_main.py -v jitter_rng_var.bin 8`, and validate it
/// with `restart.py -v jitter_rng_var.bin 8 <min-entropy>`.
/// This number is the expected amount of entropy that is at least available
/// for each round of the entropy collector. This number should be greater
/// than the amount estimated with `64 / test_timer()`.
///
/// Execute `python noniid_main.py -v -u 4 jitter_rng_var.bin 4`, and
/// validate it with `restart.py -v -u 4 jitter_rng_var.bin 4 <min-entropy>`.
/// This number is the expected amount of entropy that is available in the
/// last 4 bits of the timer delta after running noice sources. Note that
/// a value of 3.70 is the minimum estimated entropy for true randomness.
///
/// Execute `python noniid_main.py -v -u 4 jitter_rng_var.bin 4`, and
/// validate it with `restart.py -v -u 4 jitter_rng_var.bin 4 <min-entropy>`.
/// This number is the expected amount of entropy that is available to the
/// entropy collecter if both noice sources only run their minimal number of
/// times. This measures the absolute worst-case, and gives a lower bound
/// for the available entropy.
///
/// ```rust,no_run
/// use rand::JitterRng;
///
/// # use std::error::Error;
/// # use std::fs::File;
/// # use std::io::Write;
/// #
/// # fn try_main() -> Result<(), Box<Error>> {
/// fn get_nstime() -> u64 {
/// use std::time::{SystemTime, UNIX_EPOCH};
///
/// let dur = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
/// // The correct way to calculate the current time is
/// // `dur.as_secs() * 1_000_000_000 + dur.subsec_nanos() as u64`
/// // But this is faster, and the difference in terms of entropy is
/// // negligible (log2(10^9) == 29.9).
/// dur.as_secs() << 30 | dur.subsec_nanos() as u64
/// }
///
/// // Do not initialize with `JitterRng::new`, but with `new_with_timer`.
/// // 'new' always runst `test_timer`, and can therefore fail to
/// // initialize. We want to be able to get the statistics even when the
/// // timer test fails.
/// let mut rng = JitterRng::new_with_timer(get_nstime);
///
/// // 1_000_000 results are required for the NIST SP 800-90B Entropy
/// // Estimation Suite
/// // FIXME: this number is smaller here, otherwise the Doc-test is too slow
/// const ROUNDS: usize = 10_000;
/// let mut deltas_variable: Vec<u8> = Vec::with_capacity(ROUNDS);
/// let mut deltas_minimal: Vec<u8> = Vec::with_capacity(ROUNDS);
///
/// for _ in 0..ROUNDS {
/// deltas_variable.push(rng.timer_stats(true) as u8);
/// deltas_minimal.push(rng.timer_stats(false) as u8);
/// }
///
/// // Write out after the statistics collection loop, to not disturb the
/// // test results.
/// File::create("jitter_rng_var.bin")?.write(&deltas_variable)?;
/// File::create("jitter_rng_min.bin")?.write(&deltas_minimal)?;
/// #
/// # Ok(())
/// # }
/// #
/// # fn main() {
/// # try_main().unwrap();
/// # }
/// ```
#[cfg(feature="std")]
pub fn timer_stats(&mut self, var_rounds: bool) -> i64 {
let time = platform::get_nstime();
self.memaccess(var_rounds);
self.lfsr_time(time, var_rounds);
let time2 = platform::get_nstime();
time2.wrapping_sub(time) as i64
}
}
#[cfg(feature="std")]
mod platform {
#[cfg(not(any(target_os = "macos", target_os = "ios", target_os = "windows", all(target_arch = "wasm32", not(target_os = "emscripten")))))]
pub fn get_nstime() -> u64 {
use std::time::{SystemTime, UNIX_EPOCH};
let dur = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
// The correct way to calculate the current time is
// `dur.as_secs() * 1_000_000_000 + dur.subsec_nanos() as u64`
// But this is faster, and the difference in terms of entropy is negligible
// (log2(10^9) == 29.9).
dur.as_secs() << 30 | dur.subsec_nanos() as u64
}
#[cfg(any(target_os = "macos", target_os = "ios"))]
pub fn get_nstime() -> u64 {
extern crate libc;
// On Mac OS and iOS std::time::SystemTime only has 1000ns resolution.
// We use `mach_absolute_time` instead. This provides a CPU dependent unit,
// to get real nanoseconds the result should by multiplied by numer/denom
// from `mach_timebase_info`.
// But we are not interested in the exact nanoseconds, just entropy. So we
// use the raw result.
unsafe { libc::mach_absolute_time() }
}
#[cfg(target_os = "windows")]
pub fn get_nstime() -> u64 {
extern crate winapi;
unsafe {
let mut t = super::mem::zeroed();
winapi::um::profileapi::QueryPerformanceCounter(&mut t);
*t.QuadPart() as u64
}
}
#[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))]
pub fn get_nstime() -> u64 {
unreachable!()
}
}
// A function that is opaque to the optimizer to assist in avoiding dead-code
// elimination. Taken from `bencher`.
fn black_box<T>(dummy: T) -> T {
unsafe {
let ret = ptr::read_volatile(&dummy);
mem::forget(dummy);
ret
}
}
impl Rng for JitterRng {
fn next_u32(&mut self) -> u32 {
// We want to use both parts of the generated entropy
if let Some(high) = self.data_remaining.take() {
high
} else {
let data = self.next_u64();
self.data_remaining = Some((data >> 32) as u32);
data as u32
}
}
fn next_u64(&mut self) -> u64 {
self.gen_entropy()
}
fn fill_bytes(&mut self, dest: &mut [u8]) {
let mut left = dest;
while left.len() >= 8 {
let (l, r) = {left}.split_at_mut(8);
left = r;
let chunk: [u8; 8] = unsafe {
mem::transmute(self.next_u64().to_le())
};
l.copy_from_slice(&chunk);
}
let n = left.len();
if n > 0 {
let chunk: [u8; 8] = unsafe {
mem::transmute(self.next_u64().to_le())
};
left.copy_from_slice(&chunk[..n]);
}
}
}
// There are no tests included because (1) this is an "external" RNG, so output
// is not reproducible and (2) `test_timer` *will* fail on some platforms.

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// Copyright 2013-2015 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.
//! Interfaces to the operating system provided random number
//! generators.
use std::{io, fmt};
#[cfg(not(target_env = "sgx"))]
use std::mem;
use Rng;
/// A random number generator that retrieves randomness straight from
/// the operating system. Platform sources:
///
/// - Unix-like systems (Linux, Android, Mac OSX): read directly from
/// `/dev/urandom`, or from `getrandom(2)` system call if available.
/// - OpenBSD: calls `getentropy(2)`
/// - FreeBSD: uses the `kern.arandom` `sysctl(2)` mib
/// - Windows: calls `RtlGenRandom`, exported from `advapi32.dll` as
/// `SystemFunction036`.
/// - iOS: calls SecRandomCopyBytes as /dev/(u)random is sandboxed.
/// - PNaCl: calls into the `nacl-irt-random-0.1` IRT interface.
///
/// This usually does not block. On some systems (e.g. FreeBSD, OpenBSD,
/// Max OS X, and modern Linux) this may block very early in the init
/// process, if the CSPRNG has not been seeded yet.[1]
///
/// [1] See <https://www.python.org/dev/peps/pep-0524/> for a more
/// in-depth discussion.
pub struct OsRng(imp::OsRng);
impl OsRng {
/// Create a new `OsRng`.
pub fn new() -> io::Result<OsRng> {
imp::OsRng::new().map(OsRng)
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 { self.0.next_u32() }
fn next_u64(&mut self) -> u64 { self.0.next_u64() }
fn fill_bytes(&mut self, v: &mut [u8]) { self.0.fill_bytes(v) }
}
impl fmt::Debug for OsRng {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "OsRng {{}}")
}
}
#[cfg(not(target_env = "sgx"))]
fn next_u32(fill_buf: &mut FnMut(&mut [u8])) -> u32 {
let mut buf: [u8; 4] = [0; 4];
fill_buf(&mut buf);
unsafe { mem::transmute::<[u8; 4], u32>(buf) }
}
#[cfg(not(target_env = "sgx"))]
fn next_u64(fill_buf: &mut FnMut(&mut [u8])) -> u64 {
let mut buf: [u8; 8] = [0; 8];
fill_buf(&mut buf);
unsafe { mem::transmute::<[u8; 8], u64>(buf) }
}
#[cfg(all(unix, not(target_os = "ios"),
not(target_os = "nacl"),
not(target_os = "freebsd"),
not(target_os = "fuchsia"),
not(target_os = "openbsd"),
not(target_os = "redox")))]
mod imp {
extern crate libc;
use super::{next_u32, next_u64};
use self::OsRngInner::*;
use std::io;
use std::fs::File;
use Rng;
use read::ReadRng;
#[cfg(all(target_os = "linux",
any(target_arch = "x86_64",
target_arch = "x86",
target_arch = "arm",
target_arch = "aarch64",
target_arch = "powerpc")))]
fn getrandom(buf: &mut [u8]) -> libc::c_long {
extern "C" {
fn syscall(number: libc::c_long, ...) -> libc::c_long;
}
#[cfg(target_arch = "x86_64")]
const NR_GETRANDOM: libc::c_long = 318;
#[cfg(target_arch = "x86")]
const NR_GETRANDOM: libc::c_long = 355;
#[cfg(target_arch = "arm")]
const NR_GETRANDOM: libc::c_long = 384;
#[cfg(target_arch = "aarch64")]
const NR_GETRANDOM: libc::c_long = 278;
#[cfg(target_arch = "powerpc")]
const NR_GETRANDOM: libc::c_long = 359;
unsafe {
syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), 0)
}
}
#[cfg(not(all(target_os = "linux",
any(target_arch = "x86_64",
target_arch = "x86",
target_arch = "arm",
target_arch = "aarch64",
target_arch = "powerpc"))))]
fn getrandom(_buf: &mut [u8]) -> libc::c_long { -1 }
fn getrandom_fill_bytes(v: &mut [u8]) {
let mut read = 0;
let len = v.len();
while read < len {
let result = getrandom(&mut v[read..]);
if result == -1 {
let err = io::Error::last_os_error();
if err.kind() == io::ErrorKind::Interrupted {
continue
} else {
panic!("unexpected getrandom error: {}", err);
}
} else {
read += result as usize;
}
}
}
#[cfg(all(target_os = "linux",
any(target_arch = "x86_64",
target_arch = "x86",
target_arch = "arm",
target_arch = "aarch64",
target_arch = "powerpc")))]
fn is_getrandom_available() -> bool {
use std::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering};
use std::sync::{Once, ONCE_INIT};
static CHECKER: Once = ONCE_INIT;
static AVAILABLE: AtomicBool = ATOMIC_BOOL_INIT;
CHECKER.call_once(|| {
let mut buf: [u8; 0] = [];
let result = getrandom(&mut buf);
let available = if result == -1 {
let err = io::Error::last_os_error().raw_os_error();
err != Some(libc::ENOSYS)
} else {
true
};
AVAILABLE.store(available, Ordering::Relaxed);
});
AVAILABLE.load(Ordering::Relaxed)
}
#[cfg(not(all(target_os = "linux",
any(target_arch = "x86_64",
target_arch = "x86",
target_arch = "arm",
target_arch = "aarch64",
target_arch = "powerpc"))))]
fn is_getrandom_available() -> bool { false }
pub struct OsRng {
inner: OsRngInner,
}
enum OsRngInner {
OsGetrandomRng,
OsReadRng(ReadRng<File>),
}
impl OsRng {
pub fn new() -> io::Result<OsRng> {
if is_getrandom_available() {
return Ok(OsRng { inner: OsGetrandomRng });
}
let reader = try!(File::open("/dev/urandom"));
let reader_rng = ReadRng::new(reader);
Ok(OsRng { inner: OsReadRng(reader_rng) })
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
match self.inner {
OsGetrandomRng => next_u32(&mut getrandom_fill_bytes),
OsReadRng(ref mut rng) => rng.next_u32(),
}
}
fn next_u64(&mut self) -> u64 {
match self.inner {
OsGetrandomRng => next_u64(&mut getrandom_fill_bytes),
OsReadRng(ref mut rng) => rng.next_u64(),
}
}
fn fill_bytes(&mut self, v: &mut [u8]) {
match self.inner {
OsGetrandomRng => getrandom_fill_bytes(v),
OsReadRng(ref mut rng) => rng.fill_bytes(v)
}
}
}
}
#[cfg(target_os = "ios")]
mod imp {
extern crate libc;
use super::{next_u32, next_u64};
use std::io;
use Rng;
use self::libc::{c_int, size_t};
#[derive(Debug)]
pub struct OsRng;
enum SecRandom {}
#[allow(non_upper_case_globals)]
const kSecRandomDefault: *const SecRandom = 0 as *const SecRandom;
#[link(name = "Security", kind = "framework")]
extern {
fn SecRandomCopyBytes(rnd: *const SecRandom,
count: size_t, bytes: *mut u8) -> c_int;
}
impl OsRng {
pub fn new() -> io::Result<OsRng> {
Ok(OsRng)
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
next_u32(&mut |v| self.fill_bytes(v))
}
fn next_u64(&mut self) -> u64 {
next_u64(&mut |v| self.fill_bytes(v))
}
fn fill_bytes(&mut self, v: &mut [u8]) {
let ret = unsafe {
SecRandomCopyBytes(kSecRandomDefault, v.len() as size_t, v.as_mut_ptr())
};
if ret == -1 {
panic!("couldn't generate random bytes: {}", io::Error::last_os_error());
}
}
}
}
#[cfg(target_os = "freebsd")]
mod imp {
extern crate libc;
use std::{io, ptr};
use Rng;
use super::{next_u32, next_u64};
#[derive(Debug)]
pub struct OsRng;
impl OsRng {
pub fn new() -> io::Result<OsRng> {
Ok(OsRng)
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
next_u32(&mut |v| self.fill_bytes(v))
}
fn next_u64(&mut self) -> u64 {
next_u64(&mut |v| self.fill_bytes(v))
}
fn fill_bytes(&mut self, v: &mut [u8]) {
let mib = [libc::CTL_KERN, libc::KERN_ARND];
// kern.arandom permits a maximum buffer size of 256 bytes
for s in v.chunks_mut(256) {
let mut s_len = s.len();
let ret = unsafe {
libc::sysctl(mib.as_ptr(), mib.len() as libc::c_uint,
s.as_mut_ptr() as *mut _, &mut s_len,
ptr::null(), 0)
};
if ret == -1 || s_len != s.len() {
panic!("kern.arandom sysctl failed! (returned {}, s.len() {}, oldlenp {})",
ret, s.len(), s_len);
}
}
}
}
}
#[cfg(target_os = "openbsd")]
mod imp {
extern crate libc;
use std::io;
use Rng;
use super::{next_u32, next_u64};
#[derive(Debug)]
pub struct OsRng;
impl OsRng {
pub fn new() -> io::Result<OsRng> {
Ok(OsRng)
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
next_u32(&mut |v| self.fill_bytes(v))
}
fn next_u64(&mut self) -> u64 {
next_u64(&mut |v| self.fill_bytes(v))
}
fn fill_bytes(&mut self, v: &mut [u8]) {
// getentropy(2) permits a maximum buffer size of 256 bytes
for s in v.chunks_mut(256) {
let ret = unsafe {
libc::getentropy(s.as_mut_ptr() as *mut libc::c_void, s.len())
};
if ret == -1 {
let err = io::Error::last_os_error();
panic!("getentropy failed: {}", err);
}
}
}
}
}
#[cfg(target_os = "redox")]
mod imp {
use std::io;
use std::fs::File;
use Rng;
use read::ReadRng;
#[derive(Debug)]
pub struct OsRng {
inner: ReadRng<File>,
}
impl OsRng {
pub fn new() -> io::Result<OsRng> {
let reader = try!(File::open("rand:"));
let reader_rng = ReadRng::new(reader);
Ok(OsRng { inner: reader_rng })
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
self.inner.next_u32()
}
fn next_u64(&mut self) -> u64 {
self.inner.next_u64()
}
fn fill_bytes(&mut self, v: &mut [u8]) {
self.inner.fill_bytes(v)
}
}
}
#[cfg(target_os = "fuchsia")]
mod imp {
extern crate fuchsia_cprng;
use std::io;
use Rng;
use super::{next_u32, next_u64};
#[derive(Debug)]
pub struct OsRng;
impl OsRng {
pub fn new() -> io::Result<OsRng> {
Ok(OsRng)
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
next_u32(&mut |v| self.fill_bytes(v))
}
fn next_u64(&mut self) -> u64 {
next_u64(&mut |v| self.fill_bytes(v))
}
fn fill_bytes(&mut self, v: &mut [u8]) {
fuchsia_cprng::cprng_draw(v);
}
}
}
#[cfg(windows)]
mod imp {
extern crate winapi;
use std::io;
use Rng;
use super::{next_u32, next_u64};
use self::winapi::shared::minwindef::ULONG;
use self::winapi::um::ntsecapi::RtlGenRandom;
use self::winapi::um::winnt::PVOID;
#[derive(Debug)]
pub struct OsRng;
impl OsRng {
pub fn new() -> io::Result<OsRng> {
Ok(OsRng)
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
next_u32(&mut |v| self.fill_bytes(v))
}
fn next_u64(&mut self) -> u64 {
next_u64(&mut |v| self.fill_bytes(v))
}
fn fill_bytes(&mut self, v: &mut [u8]) {
// RtlGenRandom takes an ULONG (u32) for the length so we need to
// split up the buffer.
for slice in v.chunks_mut(<ULONG>::max_value() as usize) {
let ret = unsafe {
RtlGenRandom(slice.as_mut_ptr() as PVOID, slice.len() as ULONG)
};
if ret == 0 {
panic!("couldn't generate random bytes: {}",
io::Error::last_os_error());
}
}
}
}
}
#[cfg(target_os = "nacl")]
mod imp {
extern crate libc;
use std::io;
use std::mem;
use Rng;
use super::{next_u32, next_u64};
#[derive(Debug)]
pub struct OsRng(extern fn(dest: *mut libc::c_void,
bytes: libc::size_t,
read: *mut libc::size_t) -> libc::c_int);
extern {
fn nacl_interface_query(name: *const libc::c_char,
table: *mut libc::c_void,
table_size: libc::size_t) -> libc::size_t;
}
const INTERFACE: &'static [u8] = b"nacl-irt-random-0.1\0";
#[repr(C)]
struct NaClIRTRandom {
get_random_bytes: Option<extern fn(dest: *mut libc::c_void,
bytes: libc::size_t,
read: *mut libc::size_t) -> libc::c_int>,
}
impl OsRng {
pub fn new() -> io::Result<OsRng> {
let mut iface = NaClIRTRandom {
get_random_bytes: None,
};
let result = unsafe {
nacl_interface_query(INTERFACE.as_ptr() as *const _,
mem::transmute(&mut iface),
mem::size_of::<NaClIRTRandom>() as libc::size_t)
};
if result != 0 {
assert!(iface.get_random_bytes.is_some());
let result = OsRng(iface.get_random_bytes.take().unwrap());
Ok(result)
} else {
let error = io::ErrorKind::NotFound;
let error = io::Error::new(error, "IRT random interface missing");
Err(error)
}
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
next_u32(&mut |v| self.fill_bytes(v))
}
fn next_u64(&mut self) -> u64 {
next_u64(&mut |v| self.fill_bytes(v))
}
fn fill_bytes(&mut self, v: &mut [u8]) {
let mut read = 0;
loop {
let mut r: libc::size_t = 0;
let len = v.len();
let error = (self.0)(v[read..].as_mut_ptr() as *mut _,
(len - read) as libc::size_t,
&mut r as *mut _);
assert!(error == 0, "`get_random_bytes` failed!");
read += r as usize;
if read >= v.len() { break; }
}
}
}
}
#[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))]
mod imp {
use std::io;
use Rng;
#[derive(Debug)]
pub struct OsRng;
impl OsRng {
pub fn new() -> io::Result<OsRng> {
Err(io::Error::new(io::ErrorKind::Other, "Not supported"))
}
}
impl Rng for OsRng {
fn next_u32(&mut self) -> u32 {
panic!("Not supported")
}
}
}
#[cfg(target_env = "sgx")]
mod imp {
use rdrand::RdRand;
use std::io;
use rand_core::RngCore;
pub struct OsRng{
gen: RdRand
}
impl OsRng {
pub fn new() -> io::Result<OsRng> {
match RdRand::new() {
Ok(rng) => Ok(OsRng { gen: rng }),
Err(_) => Err(io::Error::new(io::ErrorKind::Other, "Not supported"))
}
}
pub(crate) fn next_u32(&mut self) -> u32 {
match self.gen.try_next_u32() {
Some(n) => n,
None => panic!("Non-recoverable hardware failure has occured")
}
}
pub(crate) fn next_u64(&mut self) -> u64 {
match self.gen.try_next_u64() {
Some(n) => n,
None => panic!("Non-recoverable hardware failure has occured")
}
}
pub(crate) fn fill_bytes(&mut self, v: &mut [u8]) {
match self.gen.try_fill_bytes(v) {
Ok(_) => {},
Err(_) => panic!("Non-recoverable hardware failure has occured")
}
}
}
}
#[cfg(test)]
mod test {
use std::sync::mpsc::channel;
use Rng;
use OsRng;
use std::thread;
#[test]
fn test_os_rng() {
let mut r = OsRng::new().unwrap();
r.next_u32();
r.next_u64();
let mut v = [0u8; 1000];
r.fill_bytes(&mut v);
}
#[test]
fn test_os_rng_tasks() {
let mut txs = vec!();
for _ in 0..20 {
let (tx, rx) = channel();
txs.push(tx);
thread::spawn(move|| {
// wait until all the tasks are ready to go.
rx.recv().unwrap();
// deschedule to attempt to interleave things as much
// as possible (XXX: is this a good test?)
let mut r = OsRng::new().unwrap();
thread::yield_now();
let mut v = [0u8; 1000];
for _ in 0..100 {
r.next_u32();
thread::yield_now();
r.next_u64();
thread::yield_now();
r.fill_bytes(&mut v);
thread::yield_now();
}
});
}
// start all the tasks
for tx in txs.iter() {
tx.send(()).unwrap();
}
}
}

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// Copyright 2014 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 ChaCha random number generator.
use core::num::Wrapping as w;
use {Rng, SeedableRng, Rand};
#[allow(bad_style)]
type w32 = w<u32>;
const KEY_WORDS : usize = 8; // 8 words for the 256-bit key
const STATE_WORDS : usize = 16;
const CHACHA_ROUNDS: u32 = 20; // Cryptographically secure from 8 upwards as of this writing
/// A random number generator that uses the ChaCha20 algorithm [1].
///
/// The ChaCha algorithm is widely accepted as suitable for
/// cryptographic purposes, but this implementation has not been
/// verified as such. Prefer a generator like `OsRng` that defers to
/// the operating system for cases that need high security.
///
/// [1]: D. J. Bernstein, [*ChaCha, a variant of
/// Salsa20*](http://cr.yp.to/chacha.html)
#[derive(Copy, Clone, Debug)]
pub struct ChaChaRng {
buffer: [w32; STATE_WORDS], // Internal buffer of output
state: [w32; STATE_WORDS], // Initial state
index: usize, // Index into state
}
static EMPTY: ChaChaRng = ChaChaRng {
buffer: [w(0); STATE_WORDS],
state: [w(0); STATE_WORDS],
index: STATE_WORDS
};
macro_rules! quarter_round{
($a: expr, $b: expr, $c: expr, $d: expr) => {{
$a = $a + $b; $d = $d ^ $a; $d = w($d.0.rotate_left(16));
$c = $c + $d; $b = $b ^ $c; $b = w($b.0.rotate_left(12));
$a = $a + $b; $d = $d ^ $a; $d = w($d.0.rotate_left( 8));
$c = $c + $d; $b = $b ^ $c; $b = w($b.0.rotate_left( 7));
}}
}
macro_rules! double_round{
($x: expr) => {{
// Column round
quarter_round!($x[ 0], $x[ 4], $x[ 8], $x[12]);
quarter_round!($x[ 1], $x[ 5], $x[ 9], $x[13]);
quarter_round!($x[ 2], $x[ 6], $x[10], $x[14]);
quarter_round!($x[ 3], $x[ 7], $x[11], $x[15]);
// Diagonal round
quarter_round!($x[ 0], $x[ 5], $x[10], $x[15]);
quarter_round!($x[ 1], $x[ 6], $x[11], $x[12]);
quarter_round!($x[ 2], $x[ 7], $x[ 8], $x[13]);
quarter_round!($x[ 3], $x[ 4], $x[ 9], $x[14]);
}}
}
#[inline]
fn core(output: &mut [w32; STATE_WORDS], input: &[w32; STATE_WORDS]) {
*output = *input;
for _ in 0..CHACHA_ROUNDS / 2 {
double_round!(output);
}
for i in 0..STATE_WORDS {
output[i] = output[i] + input[i];
}
}
impl ChaChaRng {
/// Create an ChaCha random number generator using the default
/// fixed key of 8 zero words.
///
/// # Examples
///
/// ```rust
/// use rand::{Rng, ChaChaRng};
///
/// let mut ra = ChaChaRng::new_unseeded();
/// println!("{:?}", ra.next_u32());
/// println!("{:?}", ra.next_u32());
/// ```
///
/// Since this equivalent to a RNG with a fixed seed, repeated executions
/// of an unseeded RNG will produce the same result. This code sample will
/// consistently produce:
///
/// - 2917185654
/// - 2419978656
pub fn new_unseeded() -> ChaChaRng {
let mut rng = EMPTY;
rng.init(&[0; KEY_WORDS]);
rng
}
/// Sets the internal 128-bit ChaCha counter to
/// a user-provided value. This permits jumping
/// arbitrarily ahead (or backwards) in the pseudorandom stream.
///
/// Since the nonce words are used to extend the counter to 128 bits,
/// users wishing to obtain the conventional ChaCha pseudorandom stream
/// associated with a particular nonce can call this function with
/// arguments `0, desired_nonce`.
///
/// # Examples
///
/// ```rust
/// use rand::{Rng, ChaChaRng};
///
/// let mut ra = ChaChaRng::new_unseeded();
/// ra.set_counter(0u64, 1234567890u64);
/// println!("{:?}", ra.next_u32());
/// println!("{:?}", ra.next_u32());
/// ```
pub fn set_counter(&mut self, counter_low: u64, counter_high: u64) {
self.state[12] = w((counter_low >> 0) as u32);
self.state[13] = w((counter_low >> 32) as u32);
self.state[14] = w((counter_high >> 0) as u32);
self.state[15] = w((counter_high >> 32) as u32);
self.index = STATE_WORDS; // force recomputation
}
/// Initializes `self.state` with the appropriate key and constants
///
/// We deviate slightly from the ChaCha specification regarding
/// the nonce, which is used to extend the counter to 128 bits.
/// This is provably as strong as the original cipher, though,
/// since any distinguishing attack on our variant also works
/// against ChaCha with a chosen-nonce. See the XSalsa20 [1]
/// security proof for a more involved example of this.
///
/// The modified word layout is:
/// ```text
/// constant constant constant constant
/// key key key key
/// key key key key
/// counter counter counter counter
/// ```
/// [1]: Daniel J. Bernstein. [*Extending the Salsa20
/// nonce.*](http://cr.yp.to/papers.html#xsalsa)
fn init(&mut self, key: &[u32; KEY_WORDS]) {
self.state[0] = w(0x61707865);
self.state[1] = w(0x3320646E);
self.state[2] = w(0x79622D32);
self.state[3] = w(0x6B206574);
for i in 0..KEY_WORDS {
self.state[4+i] = w(key[i]);
}
self.state[12] = w(0);
self.state[13] = w(0);
self.state[14] = w(0);
self.state[15] = w(0);
self.index = STATE_WORDS;
}
/// Refill the internal output buffer (`self.buffer`)
fn update(&mut self) {
core(&mut self.buffer, &self.state);
self.index = 0;
// update 128-bit counter
self.state[12] = self.state[12] + w(1);
if self.state[12] != w(0) { return };
self.state[13] = self.state[13] + w(1);
if self.state[13] != w(0) { return };
self.state[14] = self.state[14] + w(1);
if self.state[14] != w(0) { return };
self.state[15] = self.state[15] + w(1);
}
}
impl Rng for ChaChaRng {
#[inline]
fn next_u32(&mut self) -> u32 {
if self.index == STATE_WORDS {
self.update();
}
let value = self.buffer[self.index % STATE_WORDS];
self.index += 1;
value.0
}
}
impl<'a> SeedableRng<&'a [u32]> for ChaChaRng {
fn reseed(&mut self, seed: &'a [u32]) {
// reset state
self.init(&[0u32; KEY_WORDS]);
// set key in place
let key = &mut self.state[4 .. 4+KEY_WORDS];
for (k, s) in key.iter_mut().zip(seed.iter()) {
*k = w(*s);
}
}
/// Create a ChaCha generator from a seed,
/// obtained from a variable-length u32 array.
/// Only up to 8 words are used; if less than 8
/// words are used, the remaining are set to zero.
fn from_seed(seed: &'a [u32]) -> ChaChaRng {
let mut rng = EMPTY;
rng.reseed(seed);
rng
}
}
impl Rand for ChaChaRng {
fn rand<R: Rng>(other: &mut R) -> ChaChaRng {
let mut key : [u32; KEY_WORDS] = [0; KEY_WORDS];
for word in key.iter_mut() {
*word = other.gen();
}
SeedableRng::from_seed(&key[..])
}
}
#[cfg(test)]
mod test {
use {Rng, SeedableRng};
use super::ChaChaRng;
#[test]
fn test_rng_rand_seeded() {
let s = ::test::rng().gen_iter::<u32>().take(8).collect::<Vec<u32>>();
let mut ra: ChaChaRng = SeedableRng::from_seed(&s[..]);
let mut rb: ChaChaRng = SeedableRng::from_seed(&s[..]);
assert!(::test::iter_eq(ra.gen_ascii_chars().take(100),
rb.gen_ascii_chars().take(100)));
}
#[test]
fn test_rng_seeded() {
let seed : &[_] = &[0,1,2,3,4,5,6,7];
let mut ra: ChaChaRng = SeedableRng::from_seed(seed);
let mut rb: ChaChaRng = SeedableRng::from_seed(seed);
assert!(::test::iter_eq(ra.gen_ascii_chars().take(100),
rb.gen_ascii_chars().take(100)));
}
#[test]
fn test_rng_reseed() {
let s = ::test::rng().gen_iter::<u32>().take(8).collect::<Vec<u32>>();
let mut r: ChaChaRng = 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_true_values() {
// Test vectors 1 and 2 from
// http://tools.ietf.org/html/draft-nir-cfrg-chacha20-poly1305-04
let seed : &[_] = &[0u32; 8];
let mut ra: ChaChaRng = SeedableRng::from_seed(seed);
let v = (0..16).map(|_| ra.next_u32()).collect::<Vec<_>>();
assert_eq!(v,
vec!(0xade0b876, 0x903df1a0, 0xe56a5d40, 0x28bd8653,
0xb819d2bd, 0x1aed8da0, 0xccef36a8, 0xc70d778b,
0x7c5941da, 0x8d485751, 0x3fe02477, 0x374ad8b8,
0xf4b8436a, 0x1ca11815, 0x69b687c3, 0x8665eeb2));
let v = (0..16).map(|_| ra.next_u32()).collect::<Vec<_>>();
assert_eq!(v,
vec!(0xbee7079f, 0x7a385155, 0x7c97ba98, 0x0d082d73,
0xa0290fcb, 0x6965e348, 0x3e53c612, 0xed7aee32,
0x7621b729, 0x434ee69c, 0xb03371d5, 0xd539d874,
0x281fed31, 0x45fb0a51, 0x1f0ae1ac, 0x6f4d794b));
let seed : &[_] = &[0,1,2,3,4,5,6,7];
let mut ra: ChaChaRng = SeedableRng::from_seed(seed);
// Store the 17*i-th 32-bit word,
// i.e., the i-th word of the i-th 16-word block
let mut v : Vec<u32> = Vec::new();
for _ in 0..16 {
v.push(ra.next_u32());
for _ in 0..16 {
ra.next_u32();
}
}
assert_eq!(v,
vec!(0xf225c81a, 0x6ab1be57, 0x04d42951, 0x70858036,
0x49884684, 0x64efec72, 0x4be2d186, 0x3615b384,
0x11cfa18e, 0xd3c50049, 0x75c775f6, 0x434c6530,
0x2c5bad8f, 0x898881dc, 0x5f1c86d9, 0xc1f8e7f4));
}
#[test]
fn test_rng_clone() {
let seed : &[_] = &[0u32; 8];
let mut rng: ChaChaRng = 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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// 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 random number generator.
#![allow(non_camel_case_types)]
use core::slice;
use core::iter::repeat;
use core::num::Wrapping as w;
use core::fmt;
use {Rng, SeedableRng, Rand};
#[allow(bad_style)]
type w32 = w<u32>;
const RAND_SIZE_LEN: usize = 8;
const RAND_SIZE: u32 = 1 << RAND_SIZE_LEN;
const RAND_SIZE_USIZE: usize = 1 << RAND_SIZE_LEN;
/// A random number generator that uses the ISAAC algorithm[1].
///
/// 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 IsaacRng {
cnt: u32,
rsl: [w32; RAND_SIZE_USIZE],
mem: [w32; RAND_SIZE_USIZE],
a: w32,
b: w32,
c: w32,
}
static EMPTY: IsaacRng = IsaacRng {
cnt: 0,
rsl: [w(0); RAND_SIZE_USIZE],
mem: [w(0); RAND_SIZE_USIZE],
a: w(0), b: w(0), c: w(0),
};
impl IsaacRng {
/// Create an ISAAC random number generator using the default
/// fixed seed.
pub fn new_unseeded() -> IsaacRng {
let mut rng = EMPTY;
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) {
let mut a = w(0x9e3779b9);
let mut b = a;
let mut c = a;
let mut d = a;
let mut e = a;
let mut f = a;
let mut g = a;
let mut h = a;
macro_rules! mix {
() => {{
a=a^(b<<11); d=d+a; b=b+c;
b=b^(c>>2); e=e+b; c=c+d;
c=c^(d<<8); f=f+c; d=d+e;
d=d^(e>>16); g=g+d; e=e+f;
e=e^(f<<10); h=h+e; f=f+g;
f=f^(g>>4); a=a+f; g=g+h;
g=g^(h<<8); b=b+g; h=h+a;
h=h^(a>>9); c=c+h; a=a+b;
}}
}
for _ in 0..4 {
mix!();
}
if use_rsl {
macro_rules! memloop {
($arr:expr) => {{
for i in (0..RAND_SIZE_USIZE/8).map(|i| i * 8) {
a=a+$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+$arr[i+7];
mix!();
self.mem[i ]=a; self.mem[i+1]=b;
self.mem[i+2]=c; self.mem[i+3]=d;
self.mem[i+4]=e; self.mem[i+5]=f;
self.mem[i+6]=g; self.mem[i+7]=h;
}
}}
}
memloop!(self.rsl);
memloop!(self.mem);
} else {
for i in (0..RAND_SIZE_USIZE/8).map(|i| i * 8) {
mix!();
self.mem[i ]=a; self.mem[i+1]=b;
self.mem[i+2]=c; self.mem[i+3]=d;
self.mem[i+4]=e; self.mem[i+5]=f;
self.mem[i+6]=g; self.mem[i+7]=h;
}
}
self.isaac();
}
/// Refills the output buffer (`self.rsl`)
#[inline]
fn isaac(&mut self) {
self.c = self.c + w(1);
// abbreviations
let mut a = self.a;
let mut b = self.b + self.c;
const MIDPOINT: usize = RAND_SIZE_USIZE / 2;
macro_rules! ind {
($x:expr) => ( self.mem[($x >> 2usize).0 as usize & (RAND_SIZE_USIZE - 1)] )
}
let r = [(0, MIDPOINT), (MIDPOINT, 0)];
for &(mr_offset, m2_offset) in r.iter() {
macro_rules! rngstepp {
($j:expr, $shift:expr) => {{
let base = $j;
let mix = a << $shift;
let x = self.mem[base + mr_offset];
a = (a ^ mix) + self.mem[base + m2_offset];
let y = ind!(x) + a + b;
self.mem[base + mr_offset] = y;
b = ind!(y >> RAND_SIZE_LEN) + x;
self.rsl[base + mr_offset] = b;
}}
}
macro_rules! rngstepn {
($j:expr, $shift:expr) => {{
let base = $j;
let mix = a >> $shift;
let x = self.mem[base + mr_offset];
a = (a ^ mix) + self.mem[base + m2_offset];
let y = ind!(x) + a + b;
self.mem[base + mr_offset] = y;
b = ind!(y >> RAND_SIZE_LEN) + x;
self.rsl[base + mr_offset] = b;
}}
}
for i in (0..MIDPOINT/4).map(|i| i * 4) {
rngstepp!(i + 0, 13);
rngstepn!(i + 1, 6);
rngstepp!(i + 2, 2);
rngstepn!(i + 3, 16);
}
}
self.a = a;
self.b = b;
self.cnt = RAND_SIZE;
}
}
// Cannot be derived because [u32; 256] does not implement Clone
impl Clone for IsaacRng {
fn clone(&self) -> IsaacRng {
*self
}
}
impl Rng for IsaacRng {
#[inline]
fn next_u32(&mut self) -> u32 {
if self.cnt == 0 {
// make some more numbers
self.isaac();
}
self.cnt -= 1;
// self.cnt is at most RAND_SIZE, but that is before the
// subtraction above. We want to index without bounds
// checking, but this could lead to incorrect code if someone
// misrefactors, so we check, sometimes.
//
// (Changes here should be reflected in Isaac64Rng.next_u64.)
debug_assert!(self.cnt < RAND_SIZE);
// (the % is cheaply telling the optimiser that we're always
// in bounds, without unsafe. NB. this is a power of two, so
// it optimises to a bitwise mask).
self.rsl[(self.cnt % RAND_SIZE) as usize].0
}
}
impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
fn reseed(&mut self, seed: &'a [u32]) {
// 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(0u32));
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 [u32]) -> IsaacRng {
let mut rng = EMPTY;
rng.reseed(seed);
rng
}
}
impl Rand for IsaacRng {
fn rand<R: Rng>(other: &mut R) -> IsaacRng {
let mut ret = EMPTY;
unsafe {
let ptr = ret.rsl.as_mut_ptr() as *mut u8;
let slice = slice::from_raw_parts_mut(ptr, RAND_SIZE_USIZE * 4);
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 IsaacRng {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "IsaacRng {{}}")
}
}
#[cfg(test)]
mod test {
use {Rng, SeedableRng};
use super::IsaacRng;
#[test]
fn test_rng_32_rand_seeded() {
let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
let mut ra: IsaacRng = SeedableRng::from_seed(&s[..]);
let mut rb: IsaacRng = SeedableRng::from_seed(&s[..]);
assert!(::test::iter_eq(ra.gen_ascii_chars().take(100),
rb.gen_ascii_chars().take(100)));
}
#[test]
fn test_rng_32_seeded() {
let seed: &[_] = &[1, 23, 456, 7890, 12345];
let mut ra: IsaacRng = SeedableRng::from_seed(seed);
let mut rb: IsaacRng = SeedableRng::from_seed(seed);
assert!(::test::iter_eq(ra.gen_ascii_chars().take(100),
rb.gen_ascii_chars().take(100)));
}
#[test]
fn test_rng_32_reseed() {
let s = ::test::rng().gen_iter::<u32>().take(256).collect::<Vec<u32>>();
let mut r: IsaacRng = 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_32_true_values() {
let seed: &[_] = &[1, 23, 456, 7890, 12345];
let mut ra: IsaacRng = SeedableRng::from_seed(seed);
// Regression test that isaac is actually using the above vector
let v = (0..10).map(|_| ra.next_u32()).collect::<Vec<_>>();
assert_eq!(v,
vec!(2558573138, 873787463, 263499565, 2103644246, 3595684709,
4203127393, 264982119, 2765226902, 2737944514, 3900253796));
let seed: &[_] = &[12345, 67890, 54321, 9876];
let mut rb: IsaacRng = SeedableRng::from_seed(seed);
// skip forward to the 10000th number
for _ in 0..10000 { rb.next_u32(); }
let v = (0..10).map(|_| rb.next_u32()).collect::<Vec<_>>();
assert_eq!(v,
vec!(3676831399, 3183332890, 2834741178, 3854698763, 2717568474,
1576568959, 3507990155, 179069555, 141456972, 2478885421));
}
}

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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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// Copyright 2017 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.
//! Pseudo random number generators are algorithms to produce *apparently
//! random* numbers deterministically, and usually fairly quickly.
//!
//! So long as the algorithm is computationally secure, is initialised with
//! sufficient entropy (i.e. unknown by an attacker), and its internal state is
//! also protected (unknown to an attacker), the output will also be
//! *computationally secure*. Computationally Secure Pseudo Random Number
//! Generators (CSPRNGs) are thus suitable sources of random numbers for
//! cryptography. There are a couple of gotchas here, however. First, the seed
//! used for initialisation must be unknown. Usually this should be provided by
//! the operating system and should usually be secure, however this may not
//! always be the case (especially soon after startup). Second, user-space
//! memory may be vulnerable, for example when written to swap space, and after
//! forking a child process should reinitialise any user-space PRNGs. For this
//! reason it may be preferable to source random numbers directly from the OS
//! for cryptographic applications.
//!
//! PRNGs are also widely used for non-cryptographic uses: randomised
//! algorithms, simulations, games. In these applications it is usually not
//! important for numbers to be cryptographically *unguessable*, but even
//! distribution and independence from other samples (from the point of view
//! of someone unaware of the algorithm used, at least) may still be important.
//! Good PRNGs should satisfy these properties, but do not take them for
//! granted; Wikipedia's article on
//! [Pseudorandom number generators](https://en.wikipedia.org/wiki/Pseudorandom_number_generator)
//! provides some background on this topic.
//!
//! Care should be taken when seeding (initialising) PRNGs. Some PRNGs have
//! short periods for some seeds. If one PRNG is seeded from another using the
//! same algorithm, it is possible that both will yield the same sequence of
//! values (with some lag).
mod chacha;
mod isaac;
mod isaac64;
mod xorshift;
pub use self::chacha::ChaChaRng;
pub use self::isaac::IsaacRng;
pub use self::isaac64::Isaac64Rng;
pub use self::xorshift::XorShiftRng;

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// Copyright 2017 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.
//! Xorshift generators
use core::num::Wrapping as w;
use {Rng, SeedableRng, Rand};
/// An Xorshift[1] random number
/// generator.
///
/// The Xorshift algorithm is not suitable for cryptographic purposes
/// but is very fast. If you do not know for sure that it fits your
/// requirements, use a more secure one such as `IsaacRng` or `OsRng`.
///
/// [1]: Marsaglia, George (July 2003). ["Xorshift
/// RNGs"](http://www.jstatsoft.org/v08/i14/paper). *Journal of
/// Statistical Software*. Vol. 8 (Issue 14).
#[allow(missing_copy_implementations)]
#[derive(Clone, Debug)]
pub struct XorShiftRng {
x: w<u32>,
y: w<u32>,
z: w<u32>,
w: w<u32>,
}
impl XorShiftRng {
/// Creates a new XorShiftRng instance which is not seeded.
///
/// The initial values of this RNG are constants, so all generators created
/// by this function will yield the same stream of random numbers. It is
/// highly recommended that this is created through `SeedableRng` instead of
/// this function
pub fn new_unseeded() -> XorShiftRng {
XorShiftRng {
x: w(0x193a6754),
y: w(0xa8a7d469),
z: w(0x97830e05),
w: w(0x113ba7bb),
}
}
}
impl Rng for XorShiftRng {
#[inline]
fn next_u32(&mut self) -> u32 {
let x = self.x;
let t = x ^ (x << 11);
self.x = self.y;
self.y = self.z;
self.z = self.w;
let w_ = self.w;
self.w = w_ ^ (w_ >> 19) ^ (t ^ (t >> 8));
self.w.0
}
}
impl SeedableRng<[u32; 4]> for XorShiftRng {
/// Reseed an XorShiftRng. This will panic if `seed` is entirely 0.
fn reseed(&mut self, seed: [u32; 4]) {
assert!(!seed.iter().all(|&x| x == 0),
"XorShiftRng.reseed called with an all zero seed.");
self.x = w(seed[0]);
self.y = w(seed[1]);
self.z = w(seed[2]);
self.w = w(seed[3]);
}
/// Create a new XorShiftRng. This will panic if `seed` is entirely 0.
fn from_seed(seed: [u32; 4]) -> XorShiftRng {
assert!(!seed.iter().all(|&x| x == 0),
"XorShiftRng::from_seed called with an all zero seed.");
XorShiftRng {
x: w(seed[0]),
y: w(seed[1]),
z: w(seed[2]),
w: w(seed[3]),
}
}
}
impl Rand for XorShiftRng {
fn rand<R: Rng>(rng: &mut R) -> XorShiftRng {
let mut tuple: (u32, u32, u32, u32) = rng.gen();
while tuple == (0, 0, 0, 0) {
tuple = rng.gen();
}
let (x, y, z, w_) = tuple;
XorShiftRng { x: w(x), y: w(y), z: w(z), w: w(w_) }
}
}

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// Copyright 2013-2014 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 implementations of `Rand` for the built-in types.
use core::{char, mem};
use {Rand,Rng};
impl Rand for isize {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> isize {
if mem::size_of::<isize>() == 4 {
rng.gen::<i32>() as isize
} else {
rng.gen::<i64>() as isize
}
}
}
impl Rand for i8 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> i8 {
rng.next_u32() as i8
}
}
impl Rand for i16 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> i16 {
rng.next_u32() as i16
}
}
impl Rand for i32 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> i32 {
rng.next_u32() as i32
}
}
impl Rand for i64 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> i64 {
rng.next_u64() as i64
}
}
#[cfg(feature = "i128_support")]
impl Rand for i128 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> i128 {
rng.gen::<u128>() as i128
}
}
impl Rand for usize {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> usize {
if mem::size_of::<usize>() == 4 {
rng.gen::<u32>() as usize
} else {
rng.gen::<u64>() as usize
}
}
}
impl Rand for u8 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> u8 {
rng.next_u32() as u8
}
}
impl Rand for u16 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> u16 {
rng.next_u32() as u16
}
}
impl Rand for u32 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> u32 {
rng.next_u32()
}
}
impl Rand for u64 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> u64 {
rng.next_u64()
}
}
#[cfg(feature = "i128_support")]
impl Rand for u128 {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> u128 {
((rng.next_u64() as u128) << 64) | (rng.next_u64() as u128)
}
}
macro_rules! float_impls {
($mod_name:ident, $ty:ty, $mantissa_bits:expr, $method_name:ident) => {
mod $mod_name {
use {Rand, Rng, Open01, Closed01};
const SCALE: $ty = (1u64 << $mantissa_bits) as $ty;
impl Rand for $ty {
/// Generate a floating point number in the half-open
/// interval `[0,1)`.
///
/// See `Closed01` for the closed interval `[0,1]`,
/// and `Open01` for the open interval `(0,1)`.
#[inline]
fn rand<R: Rng>(rng: &mut R) -> $ty {
rng.$method_name()
}
}
impl Rand for Open01<$ty> {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> Open01<$ty> {
// add a small amount (specifically 2 bits below
// the precision of f64/f32 at 1.0), so that small
// numbers are larger than 0, but large numbers
// aren't pushed to/above 1.
Open01(rng.$method_name() + 0.25 / SCALE)
}
}
impl Rand for Closed01<$ty> {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> Closed01<$ty> {
// rescale so that 1.0 - epsilon becomes 1.0
// precisely.
Closed01(rng.$method_name() * SCALE / (SCALE - 1.0))
}
}
}
}
}
float_impls! { f64_rand_impls, f64, 53, next_f64 }
float_impls! { f32_rand_impls, f32, 24, next_f32 }
impl Rand for char {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> char {
// a char is 21 bits
const CHAR_MASK: u32 = 0x001f_ffff;
loop {
// Rejection sampling. About 0.2% of numbers with at most
// 21-bits are invalid codepoints (surrogates), so this
// will succeed first go almost every time.
match char::from_u32(rng.next_u32() & CHAR_MASK) {
Some(c) => return c,
None => {}
}
}
}
}
impl Rand for bool {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> bool {
rng.gen::<u8>() & 1 == 1
}
}
macro_rules! tuple_impl {
// use variables to indicate the arity of the tuple
($($tyvar:ident),* ) => {
// the trailing commas are for the 1 tuple
impl<
$( $tyvar : Rand ),*
> Rand for ( $( $tyvar ),* , ) {
#[inline]
fn rand<R: Rng>(_rng: &mut R) -> ( $( $tyvar ),* , ) {
(
// use the $tyvar's to get the appropriate number of
// repeats (they're not actually needed)
$(
_rng.gen::<$tyvar>()
),*
,
)
}
}
}
}
impl Rand for () {
#[inline]
fn rand<R: Rng>(_: &mut R) -> () { () }
}
tuple_impl!{A}
tuple_impl!{A, B}
tuple_impl!{A, B, C}
tuple_impl!{A, B, C, D}
tuple_impl!{A, B, C, D, E}
tuple_impl!{A, B, C, D, E, F}
tuple_impl!{A, B, C, D, E, F, G}
tuple_impl!{A, B, C, D, E, F, G, H}
tuple_impl!{A, B, C, D, E, F, G, H, I}
tuple_impl!{A, B, C, D, E, F, G, H, I, J}
tuple_impl!{A, B, C, D, E, F, G, H, I, J, K}
tuple_impl!{A, B, C, D, E, F, G, H, I, J, K, L}
macro_rules! array_impl {
{$n:expr, $t:ident, $($ts:ident,)*} => {
array_impl!{($n - 1), $($ts,)*}
impl<T> Rand for [T; $n] where T: Rand {
#[inline]
fn rand<R: Rng>(_rng: &mut R) -> [T; $n] {
[_rng.gen::<$t>(), $(_rng.gen::<$ts>()),*]
}
}
};
{$n:expr,} => {
impl<T> Rand for [T; $n] {
fn rand<R: Rng>(_rng: &mut R) -> [T; $n] { [] }
}
};
}
array_impl!{32, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T,}
impl<T:Rand> Rand for Option<T> {
#[inline]
fn rand<R: Rng>(rng: &mut R) -> Option<T> {
if rng.gen() {
Some(rng.gen())
} else {
None
}
}
}
#[cfg(test)]
mod tests {
use {Rng, thread_rng, Open01, Closed01};
struct ConstantRng(u64);
impl Rng for ConstantRng {
fn next_u32(&mut self) -> u32 {
let ConstantRng(v) = *self;
v as u32
}
fn next_u64(&mut self) -> u64 {
let ConstantRng(v) = *self;
v
}
}
#[test]
fn floating_point_edge_cases() {
// the test for exact equality is correct here.
assert!(ConstantRng(0xffff_ffff).gen::<f32>() != 1.0);
assert!(ConstantRng(0xffff_ffff_ffff_ffff).gen::<f64>() != 1.0);
}
#[test]
fn rand_open() {
// this is unlikely to catch an incorrect implementation that
// generates exactly 0 or 1, but it keeps it sane.
let mut rng = thread_rng();
for _ in 0..1_000 {
// strict inequalities
let Open01(f) = rng.gen::<Open01<f64>>();
assert!(0.0 < f && f < 1.0);
let Open01(f) = rng.gen::<Open01<f32>>();
assert!(0.0 < f && f < 1.0);
}
}
#[test]
fn rand_closed() {
let mut rng = thread_rng();
for _ in 0..1_000 {
// strict inequalities
let Closed01(f) = rng.gen::<Closed01<f64>>();
assert!(0.0 <= f && f <= 1.0);
let Closed01(f) = rng.gen::<Closed01<f32>>();
assert!(0.0 <= f && f <= 1.0);
}
}
}

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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.
//! A wrapper around any Read to treat it as an RNG.
use std::io::{self, Read};
use std::mem;
use Rng;
/// An RNG that reads random bytes straight from a `Read`. This will
/// work best with an infinite reader, but this is not required.
///
/// # Panics
///
/// It will panic if it there is insufficient data to fulfill a request.
///
/// # Example
///
/// ```rust
/// use rand::{read, Rng};
///
/// let data = vec![1, 2, 3, 4, 5, 6, 7, 8];
/// let mut rng = read::ReadRng::new(&data[..]);
/// println!("{:x}", rng.gen::<u32>());
/// ```
#[derive(Debug)]
pub struct ReadRng<R> {
reader: R
}
impl<R: Read> ReadRng<R> {
/// Create a new `ReadRng` from a `Read`.
pub fn new(r: R) -> ReadRng<R> {
ReadRng {
reader: r
}
}
}
impl<R: Read> Rng for ReadRng<R> {
fn next_u32(&mut self) -> u32 {
// This is designed for speed: reading a LE integer on a LE
// platform just involves blitting the bytes into the memory
// of the u32, similarly for BE on BE; avoiding byteswapping.
let mut buf = [0; 4];
fill(&mut self.reader, &mut buf).unwrap();
unsafe { *(buf.as_ptr() as *const u32) }
}
fn next_u64(&mut self) -> u64 {
// see above for explanation.
let mut buf = [0; 8];
fill(&mut self.reader, &mut buf).unwrap();
unsafe { *(buf.as_ptr() as *const u64) }
}
fn fill_bytes(&mut self, v: &mut [u8]) {
if v.len() == 0 { return }
fill(&mut self.reader, v).unwrap();
}
}
fn fill(r: &mut Read, mut buf: &mut [u8]) -> io::Result<()> {
while buf.len() > 0 {
match try!(r.read(buf)) {
0 => return Err(io::Error::new(io::ErrorKind::Other,
"end of file reached")),
n => buf = &mut mem::replace(&mut buf, &mut [])[n..],
}
}
Ok(())
}
#[cfg(test)]
mod test {
use super::ReadRng;
use Rng;
#[test]
fn test_reader_rng_u64() {
// transmute from the target to avoid endianness concerns.
let v = vec![0u8, 0, 0, 0, 0, 0, 0, 1,
0 , 0, 0, 0, 0, 0, 0, 2,
0, 0, 0, 0, 0, 0, 0, 3];
let mut rng = ReadRng::new(&v[..]);
assert_eq!(rng.next_u64(), 1_u64.to_be());
assert_eq!(rng.next_u64(), 2_u64.to_be());
assert_eq!(rng.next_u64(), 3_u64.to_be());
}
#[test]
fn test_reader_rng_u32() {
let v = vec![0u8, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3];
let mut rng = ReadRng::new(&v[..]);
assert_eq!(rng.next_u32(), 1_u32.to_be());
assert_eq!(rng.next_u32(), 2_u32.to_be());
assert_eq!(rng.next_u32(), 3_u32.to_be());
}
#[test]
fn test_reader_rng_fill_bytes() {
let v = [1u8, 2, 3, 4, 5, 6, 7, 8];
let mut w = [0u8; 8];
let mut rng = ReadRng::new(&v[..]);
rng.fill_bytes(&mut w);
assert!(v == w);
}
#[test]
#[should_panic]
fn test_reader_rng_insufficient_bytes() {
let mut rng = ReadRng::new(&[][..]);
let mut v = [0u8; 3];
rng.fill_bytes(&mut v);
}
}

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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.
//! A wrapper around another RNG that reseeds it after it
//! generates a certain number of random bytes.
use core::default::Default;
use {Rng, SeedableRng};
/// How many bytes of entropy the underling RNG is allowed to generate
/// before it is reseeded
const DEFAULT_GENERATION_THRESHOLD: u64 = 32 * 1024;
/// A wrapper around any RNG which reseeds the underlying RNG after it
/// has generated a certain number of random bytes.
#[derive(Debug)]
pub struct ReseedingRng<R, Rsdr> {
rng: R,
generation_threshold: u64,
bytes_generated: u64,
/// Controls the behaviour when reseeding the RNG.
pub reseeder: Rsdr,
}
impl<R: Rng, Rsdr: Reseeder<R>> ReseedingRng<R, Rsdr> {
/// Create a new `ReseedingRng` with the given parameters.
///
/// # Arguments
///
/// * `rng`: the random number generator to use.
/// * `generation_threshold`: the number of bytes of entropy at which to reseed the RNG.
/// * `reseeder`: the reseeding object to use.
pub fn new(rng: R, generation_threshold: u64, reseeder: Rsdr) -> ReseedingRng<R,Rsdr> {
ReseedingRng {
rng: rng,
generation_threshold: generation_threshold,
bytes_generated: 0,
reseeder: reseeder
}
}
/// Reseed the internal RNG if the number of bytes that have been
/// generated exceed the threshold.
pub fn reseed_if_necessary(&mut self) {
if self.bytes_generated >= self.generation_threshold {
self.reseeder.reseed(&mut self.rng);
self.bytes_generated = 0;
}
}
}
impl<R: Rng, Rsdr: Reseeder<R>> Rng for ReseedingRng<R, Rsdr> {
fn next_u32(&mut self) -> u32 {
self.reseed_if_necessary();
self.bytes_generated += 4;
self.rng.next_u32()
}
fn next_u64(&mut self) -> u64 {
self.reseed_if_necessary();
self.bytes_generated += 8;
self.rng.next_u64()
}
fn fill_bytes(&mut self, dest: &mut [u8]) {
self.reseed_if_necessary();
self.bytes_generated += dest.len() as u64;
self.rng.fill_bytes(dest)
}
}
impl<S, R: SeedableRng<S>, Rsdr: Reseeder<R> + Default>
SeedableRng<(Rsdr, S)> for ReseedingRng<R, Rsdr> {
fn reseed(&mut self, (rsdr, seed): (Rsdr, S)) {
self.rng.reseed(seed);
self.reseeder = rsdr;
self.bytes_generated = 0;
}
/// Create a new `ReseedingRng` from the given reseeder and
/// seed. This uses a default value for `generation_threshold`.
fn from_seed((rsdr, seed): (Rsdr, S)) -> ReseedingRng<R, Rsdr> {
ReseedingRng {
rng: SeedableRng::from_seed(seed),
generation_threshold: DEFAULT_GENERATION_THRESHOLD,
bytes_generated: 0,
reseeder: rsdr
}
}
}
/// Something that can be used to reseed an RNG via `ReseedingRng`.
///
/// # Example
///
/// ```rust
/// use rand::{Rng, SeedableRng, StdRng};
/// use rand::reseeding::{Reseeder, ReseedingRng};
///
/// struct TickTockReseeder { tick: bool }
/// impl Reseeder<StdRng> for TickTockReseeder {
/// fn reseed(&mut self, rng: &mut StdRng) {
/// let val = if self.tick {0} else {1};
/// rng.reseed(&[val]);
/// self.tick = !self.tick;
/// }
/// }
/// fn main() {
/// let rsdr = TickTockReseeder { tick: true };
///
/// let inner = StdRng::new().unwrap();
/// let mut rng = ReseedingRng::new(inner, 10, rsdr);
///
/// // this will repeat, because it gets reseeded very regularly.
/// let s: String = rng.gen_ascii_chars().take(100).collect();
/// println!("{}", s);
/// }
///
/// ```
pub trait Reseeder<R> {
/// Reseed the given RNG.
fn reseed(&mut self, rng: &mut R);
}
/// Reseed an RNG using a `Default` instance. This reseeds by
/// replacing the RNG with the result of a `Default::default` call.
#[derive(Clone, Copy, Debug)]
pub struct ReseedWithDefault;
impl<R: Rng + Default> Reseeder<R> for ReseedWithDefault {
fn reseed(&mut self, rng: &mut R) {
*rng = Default::default();
}
}
impl Default for ReseedWithDefault {
fn default() -> ReseedWithDefault { ReseedWithDefault }
}
#[cfg(test)]
mod test {
use std::default::Default;
use std::iter::repeat;
use super::{ReseedingRng, ReseedWithDefault};
use {SeedableRng, Rng};
struct Counter {
i: u32
}
impl Rng for Counter {
fn next_u32(&mut self) -> u32 {
self.i += 1;
// very random
self.i - 1
}
}
impl Default for Counter {
fn default() -> Counter {
Counter { i: 0 }
}
}
impl SeedableRng<u32> for Counter {
fn reseed(&mut self, seed: u32) {
self.i = seed;
}
fn from_seed(seed: u32) -> Counter {
Counter { i: seed }
}
}
type MyRng = ReseedingRng<Counter, ReseedWithDefault>;
#[test]
fn test_reseeding() {
let mut rs = ReseedingRng::new(Counter {i:0}, 400, ReseedWithDefault);
let mut i = 0;
for _ in 0..1000 {
assert_eq!(rs.next_u32(), i % 100);
i += 1;
}
}
#[test]
fn test_rng_seeded() {
let mut ra: MyRng = SeedableRng::from_seed((ReseedWithDefault, 2));
let mut rb: MyRng = SeedableRng::from_seed((ReseedWithDefault, 2));
assert!(::test::iter_eq(ra.gen_ascii_chars().take(100),
rb.gen_ascii_chars().take(100)));
}
#[test]
fn test_rng_reseed() {
let mut r: MyRng = SeedableRng::from_seed((ReseedWithDefault, 3));
let string1: String = r.gen_ascii_chars().take(100).collect();
r.reseed((ReseedWithDefault, 3));
let string2: String = r.gen_ascii_chars().take(100).collect();
assert_eq!(string1, string2);
}
const FILL_BYTES_V_LEN: usize = 13579;
#[test]
fn test_rng_fill_bytes() {
let mut v = repeat(0u8).take(FILL_BYTES_V_LEN).collect::<Vec<_>>();
::test::rng().fill_bytes(&mut v);
// Sanity test: if we've gotten here, `fill_bytes` has not infinitely
// recursed.
assert_eq!(v.len(), FILL_BYTES_V_LEN);
// To test that `fill_bytes` actually did something, check that the
// average of `v` is not 0.
let mut sum = 0.0;
for &x in v.iter() {
sum += x as f64;
}
assert!(sum / v.len() as f64 != 0.0);
}
}

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// Copyright 2017 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.
//! Functions for randomly accessing and sampling sequences.
use super::Rng;
// This crate is only enabled when either std or alloc is available.
// BTreeMap is not as fast in tests, but better than nothing.
#[cfg(feature="std")] use std::collections::HashMap;
#[cfg(not(feature="std"))] use alloc::btree_map::BTreeMap;
#[cfg(not(feature="std"))] use alloc::Vec;
/// Randomly sample `amount` elements from a finite iterator.
///
/// The following can be returned:
/// - `Ok`: `Vec` of `amount` non-repeating randomly sampled elements. The order is not random.
/// - `Err`: `Vec` of all the elements from `iterable` in sequential order. This happens when the
/// length of `iterable` was less than `amount`. This is considered an error since exactly
/// `amount` elements is typically expected.
///
/// This implementation uses `O(len(iterable))` time and `O(amount)` memory.
///
/// # Example
///
/// ```rust
/// use rand::{thread_rng, seq};
///
/// let mut rng = thread_rng();
/// let sample = seq::sample_iter(&mut rng, 1..100, 5).unwrap();
/// println!("{:?}", sample);
/// ```
pub fn sample_iter<T, I, R>(rng: &mut R, iterable: I, amount: usize) -> Result<Vec<T>, Vec<T>>
where I: IntoIterator<Item=T>,
R: Rng,
{
let mut iter = iterable.into_iter();
let mut reservoir = Vec::with_capacity(amount);
reservoir.extend(iter.by_ref().take(amount));
// Continue unless the iterator was exhausted
//
// note: this prevents iterators that "restart" from causing problems.
// If the iterator stops once, then so do we.
if reservoir.len() == amount {
for (i, elem) in iter.enumerate() {
let k = rng.gen_range(0, i + 1 + amount);
if let Some(spot) = reservoir.get_mut(k) {
*spot = elem;
}
}
Ok(reservoir)
} else {
// Don't hang onto extra memory. There is a corner case where
// `amount` was much less than `len(iterable)`.
reservoir.shrink_to_fit();
Err(reservoir)
}
}
/// Randomly sample exactly `amount` values from `slice`.
///
/// The values are non-repeating and in random order.
///
/// This implementation uses `O(amount)` time and memory.
///
/// Panics if `amount > slice.len()`
///
/// # Example
///
/// ```rust
/// use rand::{thread_rng, seq};
///
/// let mut rng = thread_rng();
/// let values = vec![5, 6, 1, 3, 4, 6, 7];
/// println!("{:?}", seq::sample_slice(&mut rng, &values, 3));
/// ```
pub fn sample_slice<R, T>(rng: &mut R, slice: &[T], amount: usize) -> Vec<T>
where R: Rng,
T: Clone
{
let indices = sample_indices(rng, slice.len(), amount);
let mut out = Vec::with_capacity(amount);
out.extend(indices.iter().map(|i| slice[*i].clone()));
out
}
/// Randomly sample exactly `amount` references from `slice`.
///
/// The references are non-repeating and in random order.
///
/// This implementation uses `O(amount)` time and memory.
///
/// Panics if `amount > slice.len()`
///
/// # Example
///
/// ```rust
/// use rand::{thread_rng, seq};
///
/// let mut rng = thread_rng();
/// let values = vec![5, 6, 1, 3, 4, 6, 7];
/// println!("{:?}", seq::sample_slice_ref(&mut rng, &values, 3));
/// ```
pub fn sample_slice_ref<'a, R, T>(rng: &mut R, slice: &'a [T], amount: usize) -> Vec<&'a T>
where R: Rng
{
let indices = sample_indices(rng, slice.len(), amount);
let mut out = Vec::with_capacity(amount);
out.extend(indices.iter().map(|i| &slice[*i]));
out
}
/// Randomly sample exactly `amount` indices from `0..length`.
///
/// The values are non-repeating and in random order.
///
/// This implementation uses `O(amount)` time and memory.
///
/// This method is used internally by the slice sampling methods, but it can sometimes be useful to
/// have the indices themselves so this is provided as an alternative.
///
/// Panics if `amount > length`
pub fn sample_indices<R>(rng: &mut R, length: usize, amount: usize) -> Vec<usize>
where R: Rng,
{
if amount > length {
panic!("`amount` must be less than or equal to `slice.len()`");
}
// We are going to have to allocate at least `amount` for the output no matter what. However,
// if we use the `cached` version we will have to allocate `amount` as a HashMap as well since
// it inserts an element for every loop.
//
// Therefore, if `amount >= length / 2` then inplace will be both faster and use less memory.
// In fact, benchmarks show the inplace version is faster for length up to about 20 times
// faster than amount.
//
// TODO: there is probably even more fine-tuning that can be done here since
// `HashMap::with_capacity(amount)` probably allocates more than `amount` in practice,
// and a trade off could probably be made between memory/cpu, since hashmap operations
// are slower than array index swapping.
if amount >= length / 20 {
sample_indices_inplace(rng, length, amount)
} else {
sample_indices_cache(rng, length, amount)
}
}
/// Sample an amount of indices using an inplace partial fisher yates method.
///
/// This allocates the entire `length` of indices and randomizes only the first `amount`.
/// It then truncates to `amount` and returns.
///
/// This is better than using a HashMap "cache" when `amount >= length / 2` since it does not
/// require allocating an extra cache and is much faster.
fn sample_indices_inplace<R>(rng: &mut R, length: usize, amount: usize) -> Vec<usize>
where R: Rng,
{
debug_assert!(amount <= length);
let mut indices: Vec<usize> = Vec::with_capacity(length);
indices.extend(0..length);
for i in 0..amount {
let j: usize = rng.gen_range(i, length);
let tmp = indices[i];
indices[i] = indices[j];
indices[j] = tmp;
}
indices.truncate(amount);
debug_assert_eq!(indices.len(), amount);
indices
}
/// This method performs a partial fisher-yates on a range of indices using a HashMap
/// as a cache to record potential collisions.
///
/// The cache avoids allocating the entire `length` of values. This is especially useful when
/// `amount <<< length`, i.e. select 3 non-repeating from 1_000_000
fn sample_indices_cache<R>(
rng: &mut R,
length: usize,
amount: usize,
) -> Vec<usize>
where R: Rng,
{
debug_assert!(amount <= length);
#[cfg(feature="std")] let mut cache = HashMap::with_capacity(amount);
#[cfg(not(feature="std"))] let mut cache = BTreeMap::new();
let mut out = Vec::with_capacity(amount);
for i in 0..amount {
let j: usize = rng.gen_range(i, length);
// equiv: let tmp = slice[i];
let tmp = match cache.get(&i) {
Some(e) => *e,
None => i,
};
// equiv: slice[i] = slice[j];
let x = match cache.get(&j) {
Some(x) => *x,
None => j,
};
// equiv: slice[j] = tmp;
cache.insert(j, tmp);
// note that in the inplace version, slice[i] is automatically "returned" value
out.push(x);
}
debug_assert_eq!(out.len(), amount);
out
}
#[cfg(test)]
mod test {
use super::*;
use {thread_rng, XorShiftRng, SeedableRng};
#[test]
fn test_sample_iter() {
let min_val = 1;
let max_val = 100;
let mut r = thread_rng();
let vals = (min_val..max_val).collect::<Vec<i32>>();
let small_sample = sample_iter(&mut r, vals.iter(), 5).unwrap();
let large_sample = sample_iter(&mut r, vals.iter(), vals.len() + 5).unwrap_err();
assert_eq!(small_sample.len(), 5);
assert_eq!(large_sample.len(), vals.len());
// no randomization happens when amount >= len
assert_eq!(large_sample, vals.iter().collect::<Vec<_>>());
assert!(small_sample.iter().all(|e| {
**e >= min_val && **e <= max_val
}));
}
#[test]
fn test_sample_slice_boundaries() {
let empty: &[u8] = &[];
let mut r = thread_rng();
// sample 0 items
assert_eq!(sample_slice(&mut r, empty, 0), vec![]);
assert_eq!(sample_slice(&mut r, &[42, 2, 42], 0), vec![]);
// sample 1 item
assert_eq!(sample_slice(&mut r, &[42], 1), vec![42]);
let v = sample_slice(&mut r, &[1, 42], 1)[0];
assert!(v == 1 || v == 42);
// sample "all" the items
let v = sample_slice(&mut r, &[42, 133], 2);
assert!(v == vec![42, 133] || v == vec![133, 42]);
assert_eq!(sample_indices_inplace(&mut r, 0, 0), vec![]);
assert_eq!(sample_indices_inplace(&mut r, 1, 0), vec![]);
assert_eq!(sample_indices_inplace(&mut r, 1, 1), vec![0]);
assert_eq!(sample_indices_cache(&mut r, 0, 0), vec![]);
assert_eq!(sample_indices_cache(&mut r, 1, 0), vec![]);
assert_eq!(sample_indices_cache(&mut r, 1, 1), vec![0]);
// Make sure lucky 777's aren't lucky
let slice = &[42, 777];
let mut num_42 = 0;
let total = 1000;
for _ in 0..total {
let v = sample_slice(&mut r, slice, 1);
assert_eq!(v.len(), 1);
let v = v[0];
assert!(v == 42 || v == 777);
if v == 42 {
num_42 += 1;
}
}
let ratio_42 = num_42 as f64 / 1000 as f64;
assert!(0.4 <= ratio_42 || ratio_42 <= 0.6, "{}", ratio_42);
}
#[test]
fn test_sample_slice() {
let xor_rng = XorShiftRng::from_seed;
let max_range = 100;
let mut r = thread_rng();
for length in 1usize..max_range {
let amount = r.gen_range(0, length);
let seed: [u32; 4] = [
r.next_u32(), r.next_u32(), r.next_u32(), r.next_u32()
];
println!("Selecting indices: len={}, amount={}, seed={:?}", length, amount, seed);
// assert that the two index methods give exactly the same result
let inplace = sample_indices_inplace(
&mut xor_rng(seed), length, amount);
let cache = sample_indices_cache(
&mut xor_rng(seed), length, amount);
assert_eq!(inplace, cache);
// assert the basics work
let regular = sample_indices(
&mut xor_rng(seed), length, amount);
assert_eq!(regular.len(), amount);
assert!(regular.iter().all(|e| *e < length));
assert_eq!(regular, inplace);
// also test that sampling the slice works
let vec: Vec<usize> = (0..length).collect();
{
let result = sample_slice(&mut xor_rng(seed), &vec, amount);
assert_eq!(result, regular);
}
{
let result = sample_slice_ref(&mut xor_rng(seed), &vec, amount);
let expected = regular.iter().map(|v| v).collect::<Vec<_>>();
assert_eq!(result, expected);
}
}
}
}