rng.hpp File Reference

Deterministic randomness for modulation: a counter-free PRNG, a Gaussian draw, a stateless purpose-keyed hash, and the Ornstein-Uhlenbeck walk that every "analog drift" effect in the catalog is built from. More...

#include <algorithm>
#include <cmath>
#include <cstdint>

Go to the source code of this file.

Classes
class	pulp::signal::Xorshift32
	Xorshift32 (Marsaglia, "Xorshift RNGs", J. More...
class	pulp::signal::OuWalkT< SampleType >
	Ornstein-Uhlenbeck walk (Uhlenbeck & Ornstein, Phys. More...
class	pulp::signal::DriftT< SampleType >
	Two decorrelated OU walks presented as the two things drift is actually wired to: a pitch ratio and a unit fraction. More...

Namespaces
namespace	pulp
namespace	pulp::signal

Typedefs
using	pulp::signal::OuWalk = OuWalkT<float>
using	pulp::signal::OuWalk64 = OuWalkT<double>
using	pulp::signal::Drift = DriftT<float>
using	pulp::signal::Drift64 = DriftT<double>

Functions
constexpr std::uint64_t	pulp::signal::mix64 (std::uint64_t z)
	splitmix64 finalizer (Steele, Lea & Flood, OOPSLA 2014).
constexpr std::uint64_t	pulp::signal::mix64 (std::uint64_t seed, std::uint64_t index, std::uint64_t field=0u)
	Purpose-keyed overload used when seed, index, and field are already separate values.
float	pulp::signal::unit_from (std::uint64_t key)
	Stateless purpose-keyed draw in [0, 1).
template<typename T>
T	pulp::signal::unit_from (std::uint64_t key)
template<typename T = float>
T	pulp::signal::bipolar_from (std::uint64_t key)
constexpr std::uint64_t	pulp::signal::rng_key (std::uint64_t purpose, std::uint64_t index)
	Combine a purpose tag and an index into a key for unit_from().

Variables
constexpr std::uint64_t	pulp::signal::kGoldenGamma = 0x9E3779B97F4A7C15ull
	The 64-bit golden-ratio odd constant that splitmix64 steps its state by.

Detailed Description

Deterministic randomness for modulation: a counter-free PRNG, a Gaussian draw, a stateless purpose-keyed hash, and the Ornstein-Uhlenbeck walk that every "analog drift" effect in the catalog is built from.

RT contract: every type here is POD scalar state with no owned memory. prepare() recomputes coefficients from a sample rate and is a control-side call; seed(), reset(), next*(), and the accessors allocate nothing and are audio-thread safe.

USE: modulation that must sound alive but replay identically. Randomness in a plugin is only usable when it is reproducible — an A/B comparison, a golden-file test, and an offline bounce all have to agree with the live render. Every generator here is seeded explicitly at reset() and never reads a clock, a device id, or std::random_device. Two instances with the same seed produce bit-identical streams forever.