int ff_h264_decode_ref_pic_marking(const H264Context *h, H264SliceContext *sl,
                                   GetBitContext *gb)
{
    int i;
    MMCO *mmco = sl->mmco;
    int nb_mmco = 0;

    if (h->nal_unit_type == NAL_IDR_SLICE) { // FIXME fields
        skip_bits1(gb); // broken_link
        if (get_bits1(gb)) {
            mmco[0].opcode   = MMCO_LONG;
            mmco[0].long_arg = 0;
            nb_mmco          = 1;
        }
        sl->explicit_ref_marking = 1;
    } else {
        sl->explicit_ref_marking = get_bits1(gb);
        if (sl->explicit_ref_marking) {
            for (i = 0; i < MAX_MMCO_COUNT; i++) {
                MMCOOpcode opcode = get_ue_golomb_31(gb);

                mmco[i].opcode = opcode;
                if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG) {
                    mmco[i].short_pic_num =
                        (h->curr_pic_num - get_ue_golomb(gb) - 1) &
                            (h->max_pic_num - 1);
#if 0
                    if (mmco[i].short_pic_num >= h->short_ref_count ||
                        !h->short_ref[mmco[i].short_pic_num]) {
                        av_log(s->avctx, AV_LOG_ERROR,
                               "illegal short ref in memory management control "
                               "operation %d\n", mmco);
                        return -1;
                    }
#endif
                }
                if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
                    opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG) {
                    unsigned int long_arg = get_ue_golomb_31(gb);
                    if (long_arg >= 32 ||
                        (long_arg >= 16 && !(opcode == MMCO_SET_MAX_LONG &&
                                             long_arg == 16) &&
                         !(opcode == MMCO_LONG2UNUSED && FIELD_PICTURE(h)))) {
                        av_log(h->avctx, AV_LOG_ERROR,
                               "illegal long ref in memory management control "
                               "operation %d\n", opcode);
                        return -1;
                    }
                    mmco[i].long_arg = long_arg;
                }

                if (opcode > (unsigned) MMCO_LONG) {
                    av_log(h->avctx, AV_LOG_ERROR,
                           "illegal memory management control operation %d\n",
                           opcode);
                    return -1;
                }
                if (opcode == MMCO_END)
                    break;
            }
            nb_mmco = i;
        }
    }

    sl->nb_mmco = nb_mmco;

    return 0;
}