class

Crowbar::PRNG

High-performance, deterministic 64-bit pseudo-random number generator. Uses Xoshiro256++ seeded via SplitMix64 for uniform statistical properties, long period (2^256 - 1), and complete reproducibility across platforms.

Constructors

new(seed : UInt64 = PRNG.default_seed)

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Class methods

default_seed

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Instance methods

choice(array : Array(T)) : T forall T

Random element from array

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choice?(array : Array(T)) : T | Nil forall T

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next_u32

Generate next 32-bit unsigned integer

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next_u64

Generate next raw 64-bit unsigned integer using Xoshiro256++

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rand(max : Int) : Int32

Random integer in [0, max)

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rand(range : Range(Int32, Int32)) : Int32

Random integer within inclusive range (e.g. 1..10) or exclusive range (e.g. 0...5)

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rand_bool(prob : Float64 = 0.5) : Bool

Returns true with probability p (default 0.5)

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rand_float

Random Float64 in [0.0, 1.0)

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rand_log(max_power : Int32 = 14) : Int32

Log-scale random distribution (useful for repeats, burst lengths, and byte counts) Generates values from 1 up to 2^max_power with logarithmic bias towards smaller values

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sample(array : Array(T), count : Int32) : Array(T) forall T

Reservoir sample or simple sample

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seed

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seed=(new_seed : UInt64)

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seek(offset : Int) : Nil

Fast-forwards PRNG state by offset iterations

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shuffle(array : Array(T)) : Array(T) forall T