SBP_IFILTER_MASK
(sbdsp_mix_read(sc, SBP_INFILTER) & ~SBP_IFILTER_MASK) |
mixval = sbdsp_mix_read(sc, SBP_INFILTER) & ~SBP_IFILTER_MASK;
sc->in_filter = mixval & SBP_IFILTER_MASK;
sbdsp_mix_read(sc, SBP_INFILTER) & SBP_IFILTER_MASK;