Function dds_mod 

pub unsafe extern "C" fn dds_mod(
    phase_acc: *mut u32,
    phase_rate: i32,
    scale: i16,
    phase: i32,
) -> i16

\brief Generate an integer tone sample, with modulation. \param phase_acc A pointer to a phase accumulator value. \param phase_rate The phase increment to be applied. \param scale The scaling factor. \param phase The phase offset. \return The signal amplitude, between -32767 and 32767.