int ff_h264_decode_ref_pic_list_reordering(H264Context *h, H264SliceContext *sl)

{

    int list, index, pic_structure;



    print_short_term(h);

    print_long_term(h);



    for (list = 0; list < sl->list_count; list++) {

        memcpy(sl->ref_list[list], h->default_ref_list[list], sl->ref_count[list] * sizeof(sl->ref_list[0][0]));



        if (get_bits1(&sl->gb)) {    // ref_pic_list_modification_flag_l[01]

            int pred = h->curr_pic_num;



            for (index = 0; ; index++) {

                unsigned int modification_of_pic_nums_idc = get_ue_golomb_31(&sl->gb);

                unsigned int pic_id;

                int i;

                H264Picture *ref = NULL;



                if (modification_of_pic_nums_idc == 3)

                    break;



                if (index >= sl->ref_count[list]) {

                    av_log(h->avctx, AV_LOG_ERROR, "reference count overflow\n");

                    return -1;

                }



                switch (modification_of_pic_nums_idc) {

                case 0:

                case 1: {

                    const unsigned int abs_diff_pic_num = get_ue_golomb(&sl->gb) + 1;

                    int frame_num;



                    if (abs_diff_pic_num > h->max_pic_num) {

                        av_log(h->avctx, AV_LOG_ERROR,

                               "abs_diff_pic_num overflow\n");

                        return AVERROR_INVALIDDATA;

                    }



                    if (modification_of_pic_nums_idc == 0)

                        pred -= abs_diff_pic_num;

                    else

                        pred += abs_diff_pic_num;

                    pred &= h->max_pic_num - 1;



                    frame_num = pic_num_extract(h, pred, &pic_structure);



                    for (i = h->short_ref_count - 1; i >= 0; i--) {

                        ref = h->short_ref[i];

                        assert(ref->reference);

                        assert(!ref->long_ref);

                        if (ref->frame_num == frame_num &&

                            (ref->reference & pic_structure))

                            break;

                    }

                    if (i >= 0)

                        ref->pic_id = pred;

                    break;

                }

                case 2: {

                    int long_idx;

                    pic_id = get_ue_golomb(&sl->gb); // long_term_pic_idx



                    long_idx = pic_num_extract(h, pic_id, &pic_structure);



                    if (long_idx > 31) {

                        av_log(h->avctx, AV_LOG_ERROR,

                               "long_term_pic_idx overflow\n");

                        return AVERROR_INVALIDDATA;

                    }

                    ref = h->long_ref[long_idx];

                    assert(!(ref && !ref->reference));

                    if (ref && (ref->reference & pic_structure)) {

                        ref->pic_id = pic_id;

                        assert(ref->long_ref);

                        i = 0;

                    } else {

                        i = -1;

                    }

                    break;

                }

                default:

                    av_log(h->avctx, AV_LOG_ERROR,

                           "illegal modification_of_pic_nums_idc %u\n",

                           modification_of_pic_nums_idc);

                    return AVERROR_INVALIDDATA;

                }



                if (i < 0) {

                    av_log(h->avctx, AV_LOG_ERROR,

                           "reference picture missing during reorder\n");

                    memset(&sl->ref_list[list][index], 0, sizeof(sl->ref_list[0][0])); // FIXME

                } else {

                    for (i = index; i + 1 < sl->ref_count[list]; i++) {

                        if (sl->ref_list[list][i].parent &&

                            ref->long_ref == sl->ref_list[list][i].parent->long_ref &&

                            ref->pic_id   == sl->ref_list[list][i].pic_id)

                            break;

                    }

                    for (; i > index; i--) {

                        sl->ref_list[list][i] = sl->ref_list[list][i - 1];

                    }

                    ref_from_h264pic(&sl->ref_list[list][index], ref);

                    if (FIELD_PICTURE(h)) {

                        pic_as_field(&sl->ref_list[list][index], pic_structure);

                    }

                }

            }

        }

    }

    for (list = 0; list < sl->list_count; list++) {

        for (index = 0; index < sl->ref_count[list]; index++) {

            if (   !sl->ref_list[list][index].parent

                || (!FIELD_PICTURE(h) && (sl->ref_list[list][index].reference&3) != 3)) {

                int i;

                av_log(h->avctx, AV_LOG_ERROR, "Missing reference picture, default is %d\n", h->default_ref_list[list][0].poc);

                for (i = 0; i < FF_ARRAY_ELEMS(h->last_pocs); i++)

                    h->last_pocs[i] = INT_MIN;

                if (h->default_ref_list[list][0].parent

                    && !(!FIELD_PICTURE(h) && (h->default_ref_list[list][0].reference&3) != 3))

                    sl->ref_list[list][index] = h->default_ref_list[list][0];

                else

                    return -1;

            }

            av_assert0(av_buffer_get_ref_count(sl->ref_list[list][index].parent->f->buf[0]) > 0);

        }

    }



    return 0;

}
