# Struct rand_pcg::Lcg64Xsh32

source ·
[−]`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.

## Implementations

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.

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

This method tests for `self`

and `other`

values to be equal, and is used
by `==`

. Read more

This method tests for `!=`

.

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.

Seed type, which is restricted to types mutably-dereferenceable as `u8`

arrays (we recommend `[u8; N]`

for some `N`

). Read more

Create a new PRNG using a `u64`

seed. Read more

Create a new PRNG seeded from another `Rng`

. Read more

## Auto Trait Implementations

### impl RefUnwindSafe for Lcg64Xsh32

### impl Send for Lcg64Xsh32

### impl Sync for Lcg64Xsh32

### impl Unpin for Lcg64Xsh32

### impl UnwindSafe for Lcg64Xsh32

## Blanket Implementations

Mutably borrows from an owned value. Read more