FastRandom

Namespace: Box.Utils

A fast, non-cryptographic PRNG based on xoroshiro128+. Suitable for games and simulations where speed is critical. Provides global Instance seeded from system entropy or custom seed.

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Constructors

internal FastRandom()

Initialize with a seed derived from Environment.TickCount64 via cryptographic-quality mixing. Automatically sets Instance if not already assigned.

internal FastRandom(ulong seed)

Initialize with a user-provided 64-bit seed. Instance is set on first construction.

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Properties

Name	Type	Description
static FastRandom Instance	FastRandom	Singleton instance, set on first constructed instance.

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Methods

Signature	Description
void SetSeed(ulong seed)	Reseed the generator with a new 64-bit value.
int NextInt()	Return a non-negative int in [0, int.MaxValue].
int NextInt(int max)	Return int in [0, max). max must be > 0.
int NextInt(int min, int max)	Return int in [min, max). min < max required.
long NextLong()	Return a non-negative long in [0, long.MaxValue].
long NextLong(long max)	Return long in [0, max). max must be > 0.
long NextLong(long min, long max)	Return long in [min, max). min < max required.
double NextDouble()	Return double in [0.0, 1.0).
double NextDouble(double max)	Return double in [0.0, max). max must be > 0.
double NextDouble(double min, double max)	Return double in [min, max). min < max required.
float NextFloat()	Return float in [0.0f, 1.0f).
float NextFloat(float max)	Return float in [0.0f, max). max must be > 0.
float NextFloat(float min, float max)	Return float in [min, max). min < max required.
bool NextBool()	Return a random boolean (true or false).
int Range(int min, int max)	Return int in inclusive range [min, max]. min <= max required.
long Range(long min, long max)	Return long in inclusive range [min, max]. min <= max required.
double Range(double min, double max)	Return double in half-open range [min, max). min < max required.
float Range(float min, float max)	Return float in half-open range [min, max). min < max required.

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Usage Example

// Ensure the global instance is initialized
var rand = new FastRandom();

// Reseed if desired
rand.SetSeed(123456789UL);

int a = rand.NextInt();             // e.g. 123456
int b = rand.NextInt(10);           // [0,10)
int c = rand.NextInt(5, 15);        // [5,15)
long x = rand.NextLong();           // non-negative long
bool flag = rand.NextBool();        // true or false
float f = rand.NextFloat(0.5f, 2.0f); // [0.5,2.0)
double d = rand.Range(0.0, 100.0);  // [0.0,100.0)