Struct rand_pcg::Lcg64Xsh32

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pub struct Lcg64Xsh32 { /* private fields */ }
Expand description

A PCG random number generator (XSH RR 64/32 (LCG) variant).

Permuted Congruential Generator with 64-bit state, internal Linear Congruential Generator, and 32-bit output via “xorshift high (bits), random rotation” output function.

This is a 64-bit LCG with explicitly chosen stream with the PCG-XSH-RR output function. This combination is the standard pcg32.

Despite the name, this implementation uses 16 bytes (128 bit) space comprising 64 bits of state and 64 bits stream selector. These are both set by SeedableRng, using a 128-bit seed.

Note that two generators with different stream parameter may be closely correlated.

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impl Lcg64Xsh32

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pub fn advance(&mut self, delta: u64)

Multi-step advance functions (jump-ahead, jump-back)

The method used here is based on Brown, “Random Number Generation with Arbitrary Stride,”, Transactions of the American Nuclear Society (Nov. 1994). The algorithm is very similar to fast exponentiation.

Even though delta is an unsigned integer, we can pass a signed integer to go backwards, it just goes “the long way round”.

Using this function is equivalent to calling next_32() delta number of times.

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pub fn new(state: u64, stream: u64) -> Self

Construct an instance compatible with PCG seed and stream.

Note that the highest bit of the stream parameter is discarded to simplify upholding internal invariants.

Note that two generators with different stream parameters may be closely correlated.

PCG specifies the following default values for both parameters:

  • state = 0xcafef00dd15ea5e5
  • stream = 0xa02bdbf7bb3c0a7

Trait Implementations§

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impl Clone for Lcg64Xsh32

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fn clone(&self) -> Lcg64Xsh32

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Lcg64Xsh32

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<'de> Deserialize<'de> for Lcg64Xsh32

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fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>
where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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impl PartialEq for Lcg64Xsh32

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fn eq(&self, other: &Lcg64Xsh32) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl RngCore for Lcg64Xsh32

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fn next_u32(&mut self) -> u32

Return the next random u32. Read more
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fn next_u64(&mut self) -> u64

Return the next random u64. Read more
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fn fill_bytes(&mut self, dest: &mut [u8])

Fill dest with random data. Read more
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impl SeedableRng for Lcg64Xsh32

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fn from_seed(seed: Self::Seed) -> Self

We use a single 127-bit seed to initialise the state and select a stream. One seed bit (lowest bit of seed[8]) is ignored.

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type Seed = [u8; 16]

Seed type, which is restricted to types mutably-dereferenceable as u8 arrays (we recommend [u8; N] for some N). Read more
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fn seed_from_u64(state: u64) -> Self

Create a new PRNG using a u64 seed. Read more
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fn from_rng(rng: impl RngCore) -> Self

Create a new PRNG seeded from an infallible Rng. Read more
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fn try_from_rng<R>(rng: R) -> Result<Self, <R as TryRngCore>::Error>
where R: TryRngCore,

Create a new PRNG seeded from a potentially fallible Rng. Read more
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fn from_os_rng() -> Self

Creates a new instance of the RNG seeded via getrandom. Read more
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fn try_from_os_rng() -> Result<Self, Error>

Creates a new instance of the RNG seeded via getrandom without unwrapping potential getrandom errors. Read more
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impl Serialize for Lcg64Xsh32

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fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>
where __S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl Eq for Lcg64Xsh32

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impl StructuralPartialEq for Lcg64Xsh32

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> DeserializeOwned for T
where T: for<'de> Deserialize<'de>,