static void effecte_karplus_strong(mod_channel *ch)
{
    if (mod_tick == 0)
    {
        if (ch->sample > 0)
        {
            MODULE_SAMPLE *s = &source->samples[ch->sample - 1];

            signed char *sample_loop_data = &source->sample_data[s->offset + s->loop_start];

            unsigned int loop_length = s->loop_length - 2;
            unsigned int loop_length_counter = loop_length;

            /* interpolate whole sample loop each row */
            while (loop_length_counter--)
            {
                *sample_loop_data = (*sample_loop_data + *(sample_loop_data + 1)) / 2;
                sample_loop_data++;
            }

            /* interpolate with: last sample in loop + first sample in loop */
            *sample_loop_data = (*sample_loop_data + *(sample_loop_data - loop_length)) / 2;
        }
    }

    return;
}