DadDrivers::cDryWet

Namespace: DadDrivers::cDryWet
Files: cDryWet.h / cDryWet.cpp
Directory: DAD_FORGE/Drivers
Description: Dry/wet mix control class with smooth crossfade for audio effects

📋 Class Description

The cDryWet class manages the dry/wet ratio control in audio processing, enabling smooth transitions between BYPASS, OFF, and ON states. The dry channel is controlled by a hardware component (PGA2310/PGA2311) via SPI, while the wet channel is managed by the user application. The class implements an equal-power crossfade function (sin/cos) to maintain constant perceived volume during transitions.

The class inherits from DadGUI::iGUI_EventListener, an interface for intercepting GUI events. It implements the virtual methods on_GUI_FastUpdate() for fast redundant processing and on_GUI_RT_Process() for real-time audio loop operations.

🔗 External Dependencies

Global Variables and Driver Objects Used

Variable / Object	Type	Source	Role
`__SoftSPI`	`cSoftSPI*`	`extern in cDryWet.cpp`	Software SPI driver used to transmit gain values to the PGA2310/PGA2311 via the SPI bus. Transmits the calculated volume index to both channels (L/R) of the PGA converter.
`__GUI_EventManager`	`cGUI_EventManager*`	`extern in GUI_Event.h`	Central GUI event manager that triggers `on_GUI_FastUpdate()` and `on_GUI_RT_Process()` callbacks during user interface updates.

🎯 Enumerations and Associated Structures

eDryWetState_t

Element / Variable	Value	Description
`bypass`	0	BYPASS state: complete silent signal
`off`	1	OFF state: effect disabled, dry signal at maximum volume
`on`	2	ON state: effect active with configured dry/wet mix

📚 Public Methods

Init

Element	Details
Method	`void Init(float MinDry, float MaxDry, float TimeChange)`
Description	Initializes dry/wet mix parameters and defines gain ranges for the hardware channel. Configures transition duration for fades between states.
Parameter(s)
`MinDry`	Minimum dry channel gain in dB (hardware range: -95.5 to 31.5 dB)
`MaxDry`	Maximum dry channel gain in dB (hardware range: -95.5 to 31.5 dB)
`TimeChange`	Complete transition duration for a fade between two states, in seconds
Return	None

on_GUI_FastUpdate

Element	Details
Method	`void on_GUI_FastUpdate()`
Description	Updates the target mix state based on ON/OFF/BYPASS status. Determines whether the fade should go to 0% wet (OFF), user mix (ON), or complete silence (BYPASS).
Parameter(s)	None
Return	None

on_GUI_RT_Process

Element	Details
Method	`void on_GUI_RT_Process()`
Description	Performs smooth crossfading between dry and wet signals by progressively adjusting the mix value. Calculates dry and wet gains using a sin/cos function to maintain constant perceived volume. Automatically transmits the new gain to the hardware channel via SPI when necessary.
Parameter(s)	None
Return	None

setMix

Element	Details
Method	`void setMix(float Mix)`
Description	Sets the target mix level as a percentage (0.0 = fully dry, 100.0 = fully wet). Automatically converts the percentage to a normalized value (0-1) and updates the target state if the effect is ON.
Parameter(s)
`Mix`	Mix level as a percentage (0.0 to 100.0). 0% = dry only signal, 50% = equal mix, 100% = wet only signal
Return	None

setNormalizedMix

Element	Details
Method	`void setNormalizedMix(float Mix)`
Description	Sets the target mix level as a normalized value (0.0 = fully dry, 1.0 = fully wet). Used directly by the application for precise ratio control.
Parameter(s)
`Mix`	Normalized mix level (0.0 to 1.0). 0.0 = dry only signal, 0.5 = equal mix, 1.0 = wet only signal
Return	None

FadeToOn

Element	Details
Method	`void FadeToOn()`
Description	Initiates fade to ON state (effect active).
Parameter(s)	None
Return	None

FadeToOff

Element	Details
Method	`void FadeToOff()`
Description	Initiates fade to OFF state (effect disabled). The mix will return to 0% wet (fully dry) with progressive fading.
Parameter(s)	None
Return	None

FadeToBypass

Element	Details
Method	`void FadeToBypass()`
Description	Initiates fade to BYPASS state (complete silence). All channels are reduced to zero during the transition.
Parameter(s)	None
Return	None

getState

Element	Details
Method	`uint8_t getState()`
Description	Returns the current state of the class after all fades are completed. Useful for checking if dry/wet processing is active or disabled.
Parameter(s)	None
Return	`uint8_t` value corresponding to the `eDryWetState_t` enumeration (0=bypass, 1=off, 2=on)

getGainWet

Element	Details
Method	`float getGainWet()`
Description	Returns the current wet gain value (0.0 to 1.0). Useful for the user application that needs to apply this gain to the wet signal before final mixing.
Parameter(s)	None
Return	`float` value representing the current wet gain (0.0 = silent, 1.0 = full volume)

🔒 Protected/Private Methods

No protected or private methods.

📦 Data Members (Variables)

Public Variables

No public variables.

Protected/Private Variables

Member	Type	Description
`m_OldComputedDryGain`	`float`	Previous computed dry gain for change detection (avoids unnecessary hardware updates)
`m_CurrentWetGain`	`float`	Current wet gain (0.0 to 1.0), calculated from the current mix value
`m_CurrentDryGain`	`float`	Current dry gain (0.0 to 1.0), calculated from the current mix value
`m_CurrentMix`	`float`	Current mix value during fade (progresses toward target)
`m_TargetMix`	`float`	Target mix value (determined by ON/OFF/BYPASS state or setMix)
`m_UserMix`	`float`	User-defined mix parameter (used only when effect is in ON state)
`m_PreviousMix`	`float`	Previous mix value for change detection in real-time processing
`m_MixIncrement`	`float`	Mix increment per sample for smooth transitions (RT_TIME / TimeChange)
`m_MinDry`	`float`	Minimum dry gain (PGA2310/11 hardware index, range -95.5 to 31.5 dB)
`m_MaxDry`	`float`	Maximum dry gain (PGA2310/11 hardware index, range -95.5 to 31.5 dB)
`m_OldDryVolumeIndex`	`uint32_t`	Previous hardware volume index to avoid unnecessary SPI transmissions
`m_State`	`eDryWetState_t`	Target state (bypass, off, or on) defined by the GUI application
`m_CurrentState`	`eDryWetState_t`	Actual current state after all fades are completed

💡 Usage Example

#include "DadDrivers/cDryWet.h"

using namespace DadDrivers;

int main()
{
    // cDryWet class initialization
    // Range: -60.0dB to 0.0dB, transition in 2 seconds
    cDryWet dryWet;
    dryWet.Init(-60.0f, 0.0f, 2.0f);

    dryWet.setMix(50.0f);   // Set mix to 50% (equal)
    
    // Based on effect state change, the GUI calls:
    
    dryWet.FadeToOn();      // Activate effect with fade
    // Wait for fade to complete
    while(dryWet.getState() != eDryWetState_t::on);

    // or 

    dryWet.FadeToOff();     // Deactivate effect with fade
    // Wait for fade to complete
    while(dryWet.getState() != eDryWetState_t::off);
    // 100% Dry, 0% Wet
    
    // or

    dryWet.FadeToBypass();  // Mute
    // Wait for fade to complete
    while(dryWet.getState() != eDryWetState_t::bypass);
    // 0% Dry, 0% Wet
    
    ...

    // In main audio loop 
    float in, out;
    while(1) {
        ...
        ...
        float gainWet = dryWet.getGainWet();
        out = in * gainWet;
    }

    return 0;
}