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Parameter Mapping Module

This module provides parameter mapping with different scaling curves. Maps a normalized 0-1 input (e.g., from a knob or CV input) to a custom range with various transformation curves (linear, exponential, logarithmic, cubic).

Key Features:

Map 0-1 input to any min-max range
Multiple curve types for natural feel
Exponential curves for frequency parameters
Logarithmic curves for attenuation/volume
Cubic curves for smooth non-linear response
Audio-rate safe transformations

Usage Example:

import nimphea/hid/parameter

# Map knob value to frequency range with exponential curve
let knobValue = 0.5  # From ADC (0.0 to 1.0)
let frequency = mapParameter(knobValue, 20.0, 20000.0, EXPONENTIAL)
echo "Frequency: ", frequency, " Hz"

# Map different parameter types
let cutoff = mapParameter(0.7, 100.0, 10000.0, EXPONENTIAL)
let volume = mapParameter(0.8, 0.0, 1.0, LOGARITHMIC)
let mix = mapParameter(0.5, 0.0, 1.0, LINEAR)

Curve Types:

LINEAR: Direct proportional mapping (y = x)
EXPONENTIAL: Fast rise at high end (ideal for frequency)
LOGARITHMIC: Fast rise at low end (ideal for volume/attenuation)
CUBE: Smooth S-curve (cubic transformation)

Performance Notes:

All transformations use simple math (no table lookups)
Safe to call in audio callback
No memory allocation

Types

Curve {.importcpp: "daisy::Parameter::Curve", header: "hid/parameter.h", pure.} = enum
  LINEAR = 0, EXPONENTIAL = 1, LOGARITHMIC = 2, CUBE = 3

Parameter scaling curve types.

Values:

LINEAR: Direct proportional mapping (y = x)
EXPONENTIAL: Exponential curve (fast rise at high end)
LOGARITHMIC: Logarithmic curve (fast rise at low end)
CUBE: Cubic curve (smooth S-curve)

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Procs

proc mapParameter(input: float32; min: float32; max: float32; curve: Curve): float32 {. ...raises: [], tags: [], forbids: [].}: Map a normalized 0-1 input to a custom range with scaling curve.

Parameters:

input: Normalized input value (0.0 to 1.0)

min: Minimum output value (when input = 0.0)

max: Maximum output value (when input = 1.0)

curve: Transformation curve to apply

Returns: Mapped value in range min, max with curve applied

Note: Input values outside 0-1 are clamped.

Example:

# Exponential frequency mapping (natural feel for pitch) let freq = mapParameter(0.5, 20.0, 20000.0, EXPONENTIAL) # Logarithmic volume mapping (natural feel for amplitude) let vol = mapParameter(0.75, 0.0, 1.0, LOGARITHMIC) # Linear mix parameter let mix = mapParameter(0.5, 0.0, 1.0, LINEAR)
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proc mapParameterCube(input: float32; min: float32; max: float32): float32 {. inline, ...raises: [], tags: [], forbids: [].}: Convenience function for cubic parameter mapping.

Parameters:

input: Normalized input (0.0 to 1.0)

min: Minimum output value

max: Maximum output value

Returns: Cubic curve mapped value

Example:

let smoothParam = mapParameterCube(knobValue, 0.0, 100.0)
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proc mapParameterExp(input: float32; min: float32; max: float32): float32 {. inline, ...raises: [], tags: [], forbids: [].}: Convenience function for exponential parameter mapping.

Parameters:

input: Normalized input (0.0 to 1.0)

min: Minimum output value

max: Maximum output value

Returns: Exponentially mapped value

Example:

let cutoffFreq = mapParameterExp(knobValue, 100.0, 10000.0)
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proc mapParameterLin(input: float32; min: float32; max: float32): float32 {. inline, ...raises: [], tags: [], forbids: [].}: Convenience function for linear parameter mapping.

Parameters:

input: Normalized input (0.0 to 1.0)

min: Minimum output value

max: Maximum output value

Returns: Linearly mapped value

Example:

let mixAmount = mapParameterLin(knobValue, 0.0, 1.0)
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proc mapParameterLog(input: float32; min: float32; max: float32): float32 {. inline, ...raises: [], tags: [], forbids: [].}: Convenience function for logarithmic parameter mapping.

Parameters:

input: Normalized input (0.0 to 1.0)

min: Minimum output value

max: Maximum output value

Returns: Logarithmically mapped value

Example:

let volume = mapParameterLog(knobValue, 0.0, 1.0)
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