Square Wave Oscillator
Overview
The square wave oscillator programmatically generates a pulse waveform with a 50% pulse width. The basic_square_osc is not bandwidth limited, while square_osc is, using a technique called "PolyBLEP" to reduce aliasing artifacts that can occur when generating the waveform with a sharp discontinuity as the signal transitions from -1.0 to 1.0.
PolyBLEP works by precalculating a correction function that subtracts the waveform’s high-frequency components at discontinuities. This correction function is then applied to the generated waveform, effectively removing frequencies above the waveform’s Nyquist frequency to avoid aliasing artifacts.
Declaration
struct basic_square_osc
{
constexpr float operator()(phase p) const;
constexpr float operator()(phase_iterator i) const;
};
constexpr auto basic_square = basic_square_osc{};
struct square_osc
{
constexpr float operator()(phase p, phase dt) const;
constexpr float operator()(phase_iterator i) const;
};
constexpr auto square = square_osc{};Expressions
basic_square_osc is a model of BasicOscillator and implements all valid expressions of BasicOscillator. square_osc is a model of BandwidthLimitedOscillator and implements all valid expressions of BandwidthLimitedOscillator.
basic_square_osc and square_osc are stateless. The global instances basic_square and square can be used anywhere without needing to be placed in a class or struct. They are semantically equivalent to global functions.