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DSP

Constants

Name	Description
`SR`	Sample rate in Hz. Configure with `config.sample_rate(rate)`.
`INV_SR`	Inverse sample rate (`1.0 / SR`). Useful for phase increment calculations.
`PI`	Pi (3.14159…)
`TWOPI`	Two pi / tau (6.28318…). Full cycle in radians.
`CYCLE`	Current cycle position (0.0 to 1.0), derived from the transport clock.
`CPS`	Cycles per second — tempo-derived frequency (e.g. 120 BPM = 2.0 CPS).
`TIME`	Elapsed time in seconds since the signal’s epoch. Available in `dsp signal` blocks only.

SR and INV_SR are injected at runtime and reflect the actual sample rate. CYCLE and CPS are updated each sample from the transport. TIME is only available inside dsp signal blocks.

Native Functions

All built-in functions in DSP blocks are called via __native("name", ...). This makes it explicit that these are native implementations compiled to efficient graph nodes — they have no user-visible definition in Resonon code.

dsp effect FilteredOverdrive {
    param cutoff: 2000.0 range(20, 20000);
    param drive: 0.5 range(0, 1);
    fn process(left, right) -> (out_l, out_r) {
        let gain = 1.0 + 20.0 * drive;
        let l = __native("tanh", left * gain);
        let r = __native("tanh", right * gain);
        return (
            __native("svf_lp", l, cutoff, 0.707),
            __native("svf_lp", r, cutoff, 0.707)
        );
    }
}

Math Functions

Trigonometric

Function	Description
`__native("sin", x)`	Sine
`__native("cos", x)`	Cosine
`__native("tan", x)`	Tangent
`__native("tanh", x)`	Hyperbolic tangent (useful for soft clipping)

Exponential & Logarithmic

Function	Description
`__native("exp", x)`	e^x
`__native("log", x)`	Natural logarithm (ln)
`__native("log2", x)`	Base-2 logarithm
`__native("log10", x)`	Base-10 logarithm
`__native("sqrt", x)`	Square root
`__native("pow", base, exp)`	Power (base^exp)

Rounding & Clamping

Function	Description
`__native("abs", x)`	Absolute value
`__native("floor", x)`	Round down to nearest integer
`__native("ceil", x)`	Round up to nearest integer
`__native("round", x)`	Round to nearest integer
`__native("fract", x)`	Fractional part (`x - floor(x)`)
`__native("clamp", x, lo, hi)`	Clamp x to the range [lo, hi]
`__native("min", a, b)`	Minimum of two values
`__native("max", a, b)`	Maximum of two values
`__native("lerp", a, b, t)`	Linear interpolation: `a + (b - a) * t`

Pitch Conversion

Function	Description
`__native("mtof", note)`	MIDI note to frequency: `440 * 2^((note - 69) / 12)`. Accepts fractional notes for microtonal pitches (e.g. `__native("mtof", 60.5)` gives a quarter-tone above C4)
`__native("ftom", freq)`	Frequency to MIDI note: `69 + 12 * log2(freq / 440)`

Stateful DSP Functions

These functions maintain internal state across samples. Each call site gets its own independent state — the DSP compiler allocates a hidden state buffer for each __native(...) call that needs it.

Filters

Function	Description
`__native("svf_lp", signal, freq, Q)`	State Variable Filter — lowpass
`__native("svf_hp", signal, freq, Q)`	State Variable Filter — highpass
`__native("svf_bp", signal, freq, Q)`	State Variable Filter — bandpass
`__native("svf_notch", signal, freq, Q)`	State Variable Filter — notch
`__native("svf_allpass", signal, freq, Q)`	State Variable Filter — allpass
`__native("svf_peak", signal, freq, Q)`	State Variable Filter — peak (bell)
`__native("onepole", signal, coeff)`	One-pole lowpass filter

SVF filters use a topology-preserving transform (Zavalishin). freq is in Hz, Q controls resonance (0.707 = Butterworth, higher = more resonant). The sample rate is injected automatically.

onepole is a simple first-order lowpass. coeff ranges from 0 to 1 — higher values track the input faster.

Delay

Function	Description
`__native("delay", signal, samples)`	Integer sample delay (circular buffer, max 1 second)
`__native("delay_interp", signal, samples)`	Fractional delay with linear interpolation (max 1 second)

Noise & Sample-Hold

Function	Description
`__native("noise")`	White noise, range [-1.0, 1.0]
`__native("sample_hold", signal, trigger)`	Captures signal on rising edge of trigger (transition from <=0 to >0)

See Also