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C++ implementation

#pragma XOD evaluate_on_pin disable
#pragma XOD evaluate_on_pin enable input_UPD

struct State {
    TimeMs lastUpdateTime;
};

{{ GENERATED_CODE }}

void evaluate(Context ctx) {
    State* state = getState(ctx);
    if (!isInputDirty<input_UPD>(ctx)) {
        return;
    }

    TimeMs now = transactionTime();
    Number target = getValue<input_TARG>(ctx);
    Number position = getValue<output_OUT>(ctx);

    if (target == position) {
        // Already done. Store timestamp anyway so that an animation to a new
        // value would not jump at the first update
        state->lastUpdateTime = now;
        return;
    }

    Number rate = getValue<input_RATE>(ctx);
    TimeMs dtMs = now - state->lastUpdateTime;
    Number step = (Number)dtMs / 1000. * rate;

    if (target > position) {
        position = target;
    } else {
        position = max(target, position - step);
    }

    emitValue<output_OUT>(ctx, position);
    state->lastUpdateTime = now;
}

Tabular tests