uchar64 computeAbsDiff(
    const uchar64& i_Ref,
    const uchar64& i_Act,
    const cqSInt16 i_lightingOffset)
{
    auto diff = [](
        const uchar32 i_ref,
        const uchar32 i_act,
        const cqSInt16 i_lightingOffset)
    {
        const short32 short_ref = c7x::convert<short32>(i_ref);
        const short32 short_act = c7x::convert<short32>(i_act);
        return __abs(short_act - (short_ref + short32(i_lightingOffset)));
    };

    auto odd  = diff(i_Ref.odd(),  i_Act.odd(),  i_lightingOffset);
    auto even = diff(i_Ref.even(), i_Act.even(), i_lightingOffset);
    return __pack_usat(odd, even);
}