/*
  * H.26L/H.264/AVC/JVT/14496-10/... reference picture handling
  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**

  * @file

  * H.264 / AVC / MPEG4 part10  reference picture handling.
  * @author Michael Niedermayer <michaelni@gmx.at>
  */
 

 #include "libavutil/avassert.h"

 #include "internal.h"
 #include "avcodec.h"
 #include "h264.h"
 #include "golomb.h"
 
 #include <assert.h>
 

 #define COPY_PICTURE(dst, src) \
 do {\
     *(dst) = *(src);\
     (dst)->f.extended_data = (dst)->f.data;\
     (dst)->tf.f = &(dst)->f;\
 } while (0)
 

 
 static void pic_as_field(Picture *pic, const int parity){
     int i;
     for (i = 0; i < 4; ++i) {
         if (parity == PICT_BOTTOM_FIELD)

             pic->f.data[i] += pic->f.linesize[i];

         pic->reference      = parity;

         pic->f.linesize[i] *= 2;

     }
     pic->poc= pic->field_poc[parity == PICT_BOTTOM_FIELD];
 }
 

 static int split_field_copy(Picture *dest, Picture *src, int parity, int id_add)
 {

     int match = !!(src->reference & parity);

 
     if (match) {

         COPY_PICTURE(dest, src);

         if (parity != PICT_FRAME) {

             pic_as_field(dest, parity);
             dest->pic_id *= 2;
             dest->pic_id += id_add;
         }
     }
 
     return match;
 }
 

 static int build_def_list(Picture *def, Picture **in, int len, int is_long, int sel)
 {
     int  i[2] = { 0 };
     int index = 0;

     while (i[0] < len || i[1] < len) {
         while (i[0] < len && !(in[i[0]] && (in[i[0]]->reference & sel)))

             i[0]++;

         while (i[1] < len && !(in[i[1]] && (in[i[1]]->reference & (sel ^ 3))))

             i[1]++;

         if (i[0] < len) {
             in[i[0]]->pic_id = is_long ? i[0] : in[i[0]]->frame_num;
             split_field_copy(&def[index++], in[i[0]++], sel, 1);

         }

         if (i[1] < len) {
             in[i[1]]->pic_id = is_long ? i[1] : in[i[1]]->frame_num;
             split_field_copy(&def[index++], in[i[1]++], sel ^ 3, 0);

         }
     }
 
     return index;
 }
 

 static int add_sorted(Picture **sorted, Picture **src, int len, int limit, int dir)
 {

     int i, best_poc;

     int out_i = 0;

     for (;;) {
         best_poc = dir ? INT_MIN : INT_MAX;

         for (i = 0; i < len; i++) {
             const int poc = src[i]->poc;
             if (((poc > limit) ^ dir) && ((poc < best_poc) ^ dir)) {
                 best_poc      = poc;
                 sorted[out_i] = src[i];

             }
         }

         if (best_poc == (dir ? INT_MIN : INT_MAX))

             break;

         limit = sorted[out_i++]->poc - dir;

     }
     return out_i;
 }
 

 int ff_h264_fill_default_ref_list(H264Context *h)
 {

     int i, len;
 

     if (h->slice_type_nos == AV_PICTURE_TYPE_B) {

         Picture *sorted[32];
         int cur_poc, list;
         int lens[2];
 

         if (FIELD_PICTURE(h))

             cur_poc = h->cur_pic_ptr->field_poc[h->picture_structure == PICT_BOTTOM_FIELD];

         else

             cur_poc = h->cur_pic_ptr->poc;
 
         for (list = 0; list < 2; list++) {
             len  = add_sorted(sorted,       h->short_ref, h->short_ref_count, cur_poc, 1 ^ list);
             len += add_sorted(sorted + len, h->short_ref, h->short_ref_count, cur_poc, 0 ^ list);

             av_assert0(len <= 32);

             len  = build_def_list(h->default_ref_list[list],       sorted,      len, 0, h->picture_structure);
             len += build_def_list(h->default_ref_list[list] + len, h->long_ref, 16,  1, h->picture_structure);

             av_assert0(len <= 32);

 
             if (len < h->ref_count[list])
                 memset(&h->default_ref_list[list][len], 0, sizeof(Picture) * (h->ref_count[list] - len));
             lens[list] = len;

         }
 

         if (lens[0] == lens[1] && lens[1] > 1) {

             for (i = 0; h->default_ref_list[0][i].f.data[0] == h->default_ref_list[1][i].f.data[0] && i < lens[0]; i++);

             if (i == lens[0]) {
                 Picture tmp;
                 COPY_PICTURE(&tmp, &h->default_ref_list[1][0]);
                 COPY_PICTURE(&h->default_ref_list[1][0], &h->default_ref_list[1][1]);
                 COPY_PICTURE(&h->default_ref_list[1][1], &tmp);
             }

         }

     } else {
         len  = build_def_list(h->default_ref_list[0],       h->short_ref, h->short_ref_count, 0, h->picture_structure);
         len += build_def_list(h->default_ref_list[0] + len, h-> long_ref, 16,                 1, h->picture_structure);

         av_assert0(len <= 32);

         if (len < h->ref_count[0])
             memset(&h->default_ref_list[0][len], 0, sizeof(Picture) * (h->ref_count[0] - len));

     }
 #ifdef TRACE

     for (i = 0; i < h->ref_count[0]; i++) {
         tprintf(h->avctx, "List0: %s fn:%d 0x%p\n",
                 (h->default_ref_list[0][i].long_ref ? "LT" : "ST"),
                 h->default_ref_list[0][i].pic_id,
                 h->default_ref_list[0][i].f.data[0]);

     }

     if (h->slice_type_nos == AV_PICTURE_TYPE_B) {
         for (i = 0; i < h->ref_count[1]; i++) {
             tprintf(h->avctx, "List1: %s fn:%d 0x%p\n",
                     (h->default_ref_list[1][i].long_ref ? "LT" : "ST"),
                     h->default_ref_list[1][i].pic_id,
                     h->default_ref_list[1][i].f.data[0]);

         }
     }
 #endif
     return 0;
 }
 
 static void print_short_term(H264Context *h);
 static void print_long_term(H264Context *h);
 
 /**
  * Extract structure information about the picture described by pic_num in
  * the current decoding context (frame or field). Note that pic_num is
  * picture number without wrapping (so, 0<=pic_num<max_pic_num).
  * @param pic_num picture number for which to extract structure information
  * @param structure one of PICT_XXX describing structure of picture
  *                      with pic_num
  * @return frame number (short term) or long term index of picture
  *         described by pic_num
  */

 static int pic_num_extract(H264Context *h, int pic_num, int *structure)
 {

     *structure = h->picture_structure;

     if (FIELD_PICTURE(h)) {

         if (!(pic_num & 1))
             /* opposite field */
             *structure ^= PICT_FRAME;
         pic_num >>= 1;
     }
 
     return pic_num;
 }
 

 int ff_h264_decode_ref_pic_list_reordering(H264Context *h)
 {

     int list, index, pic_structure, i;

 
     print_short_term(h);
     print_long_term(h);
 

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

         for (i = 0; i < h->ref_count[list]; i++)
             COPY_PICTURE(&h->ref_list[list][i], &h->default_ref_list[list][i]);

         if (get_bits1(&h->gb)) {
             int pred = h->curr_pic_num;

             for (index = 0; ; index++) {
                 unsigned int reordering_of_pic_nums_idc = get_ue_golomb_31(&h->gb);

                 unsigned int pic_id;
                 int i;
                 Picture *ref = NULL;
 

                 if (reordering_of_pic_nums_idc == 3)

                     break;
 

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

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

                     return -1;
                 }
 

                 if (reordering_of_pic_nums_idc < 3) {
                     if (reordering_of_pic_nums_idc < 2) {
                         const unsigned int abs_diff_pic_num = get_ue_golomb(&h->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 -1;
                         }
 

                         if (reordering_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;
                     } else {

                         int long_idx;

                         pic_id = get_ue_golomb(&h->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 -1;
                         }
                         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;

                         }
                     }
 
                     if (i < 0) {

                         av_log(h->avctx, AV_LOG_ERROR, "reference picture missing during reorder\n");

                         memset(&h->ref_list[list][index], 0, sizeof(Picture)); //FIXME
                     } else {

                         for (i = index; i + 1 < h->ref_count[list]; i++) {
                             if (ref->long_ref == h->ref_list[list][i].long_ref &&
                                 ref->pic_id   == h->ref_list[list][i].pic_id)

                                 break;
                         }

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

                             COPY_PICTURE(&h->ref_list[list][i], &h->ref_list[list][i - 1]);

                         }

                         COPY_PICTURE(&h->ref_list[list][index], ref);

                         if (FIELD_PICTURE(h)) {

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

                 } else {

                     av_log(h->avctx, AV_LOG_ERROR, "illegal reordering_of_pic_nums_idc\n");

                     return -1;
                 }
             }
         }
     }

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

             if (   !h->ref_list[list][index].f.data[0]

                 || (!FIELD_PICTURE(h) && (h->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].f.data[0]

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

                     COPY_PICTURE(&h->ref_list[list][index], &h->default_ref_list[list][0]);

                 else
                     return -1;
             }

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

         }
     }
 
     return 0;
 }
 

 void ff_h264_fill_mbaff_ref_list(H264Context *h)
 {

     int list, i, j;

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

         for (i = 0; i < h->ref_count[list]; i++) {

             Picture *frame = &h->ref_list[list][i];

             Picture *field = &h->ref_list[list][16 + 2 * i];

             COPY_PICTURE(field, frame);

             for (j = 0; j < 3; j++)

                 field[0].f.linesize[j] <<= 1;

             field[0].reference = PICT_TOP_FIELD;

             field[0].poc       = field[0].field_poc[0];

             COPY_PICTURE(field + 1, field);

             for (j = 0; j < 3; j++)

                 field[1].f.data[j] += frame->f.linesize[j];

             field[1].reference = PICT_BOTTOM_FIELD;

             field[1].poc       = field[1].field_poc[1];

             h->luma_weight[16 + 2 * i][list][0] = h->luma_weight[16 + 2 * i + 1][list][0] = h->luma_weight[i][list][0];
             h->luma_weight[16 + 2 * i][list][1] = h->luma_weight[16 + 2 * i + 1][list][1] = h->luma_weight[i][list][1];
             for (j = 0; j < 2; j++) {
                 h->chroma_weight[16 + 2 * i][list][j][0] = h->chroma_weight[16 + 2 * i + 1][list][j][0] = h->chroma_weight[i][list][j][0];
                 h->chroma_weight[16 + 2 * i][list][j][1] = h->chroma_weight[16 + 2 * i + 1][list][j][1] = h->chroma_weight[i][list][j][1];

             }
         }
     }
 }
 
 /**
  * Mark a picture as no longer needed for reference. The refmask
  * argument allows unreferencing of individual fields or the whole frame.
  * If the picture becomes entirely unreferenced, but is being held for
  * display purposes, it is marked as such.
  * @param refmask mask of fields to unreference; the mask is bitwise
  *                anded with the reference marking of pic
  * @return non-zero if pic becomes entirely unreferenced (except possibly
  *         for display purposes) zero if one of the fields remains in
  *         reference
  */

 static inline int unreference_pic(H264Context *h, Picture *pic, int refmask)
 {

     int i;

     if (pic->reference &= refmask) {

         return 0;
     } else {
         for(i = 0; h->delayed_pic[i]; i++)
             if(pic == h->delayed_pic[i]){

                 pic->reference = DELAYED_PIC_REF;

                 break;
             }
         return 1;
     }
 }
 
 /**
  * Find a Picture in the short term reference list by frame number.
  * @param frame_num frame number to search for
  * @param idx the index into h->short_ref where returned picture is found
  *            undefined if no picture found.
  * @return pointer to the found picture, or NULL if no pic with the provided
  *                 frame number is found
  */

 static Picture *find_short(H264Context *h, int frame_num, int *idx)
 {

     int i;
 

     for (i = 0; i < h->short_ref_count; i++) {
         Picture *pic = h->short_ref[i];
         if (h->avctx->debug & FF_DEBUG_MMCO)

             av_log(h->avctx, AV_LOG_DEBUG, "%d %d %p\n", i, pic->frame_num, pic);

         if (pic->frame_num == frame_num) {

             *idx = i;
             return pic;
         }
     }
     return NULL;
 }
 
 /**
  * Remove a picture from the short term reference list by its index in
  * that list.  This does no checking on the provided index; it is assumed
  * to be valid. Other list entries are shifted down.
  * @param i index into h->short_ref of picture to remove.
  */

 static void remove_short_at_index(H264Context *h, int i)
 {

     assert(i >= 0 && i < h->short_ref_count);

     h->short_ref[i] = NULL;

     if (--h->short_ref_count)

         memmove(&h->short_ref[i], &h->short_ref[i + 1],
                 (h->short_ref_count - i) * sizeof(Picture*));

 }
 
 /**
  *
  * @return the removed picture or NULL if an error occurs
  */

 static Picture *remove_short(H264Context *h, int frame_num, int ref_mask)
 {

     Picture *pic;
     int i;
 

     if (h->avctx->debug & FF_DEBUG_MMCO)

         av_log(h->avctx, AV_LOG_DEBUG, "remove short %d count %d\n", frame_num, h->short_ref_count);

 
     pic = find_short(h, frame_num, &i);

     if (pic) {
         if (unreference_pic(h, pic, ref_mask))
             remove_short_at_index(h, i);

     }
 
     return pic;
 }
 
 /**
  * Remove a picture from the long term reference list by its index in
  * that list.
  * @return the removed picture or NULL if an error occurs
  */

 static Picture *remove_long(H264Context *h, int i, int ref_mask)
 {

     Picture *pic;
 

     pic = h->long_ref[i];
     if (pic) {
         if (unreference_pic(h, pic, ref_mask)) {

             assert(h->long_ref[i]->long_ref == 1);

             h->long_ref[i]->long_ref = 0;
             h->long_ref[i]           = NULL;

             h->long_ref_count--;
         }
     }
 
     return pic;
 }
 

 void ff_h264_remove_all_refs(H264Context *h)
 {

     int i;
 

     for (i = 0; i < 16; i++) {

         remove_long(h, i, 0);
     }

     assert(h->long_ref_count == 0);

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

         unreference_pic(h, h->short_ref[i], 0);

         h->short_ref[i] = NULL;

     }

     h->short_ref_count = 0;

 
     memset(h->default_ref_list, 0, sizeof(h->default_ref_list));
     memset(h->ref_list, 0, sizeof(h->ref_list));

 }
 
 /**
  * print short term list
  */

 static void print_short_term(H264Context *h)
 {

     uint32_t i;

     if (h->avctx->debug & FF_DEBUG_MMCO) {

         av_log(h->avctx, AV_LOG_DEBUG, "short term list:\n");

         for (i = 0; i < h->short_ref_count; i++) {
             Picture *pic = h->short_ref[i];

             av_log(h->avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n",

                    i, pic->frame_num, pic->poc, pic->f.data[0]);

         }
     }
 }
 
 /**
  * print long term list
  */

 static void print_long_term(H264Context *h)
 {

     uint32_t i;

     if (h->avctx->debug & FF_DEBUG_MMCO) {

         av_log(h->avctx, AV_LOG_DEBUG, "long term list:\n");

         for (i = 0; i < 16; i++) {
             Picture *pic = h->long_ref[i];

             if (pic) {

                 av_log(h->avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n",

                        i, pic->frame_num, pic->poc, pic->f.data[0]);

             }
         }
     }
 }
 

 static int check_opcodes(MMCO *mmco1, MMCO *mmco2, int n_mmcos)
 {
     int i;
 
     for (i = 0; i < n_mmcos; i++) {

         if (mmco1[i].opcode != mmco2[i].opcode) {
             av_log(NULL, AV_LOG_ERROR, "MMCO opcode [%d, %d] at %d mismatches between slices\n",
                    mmco1[i].opcode, mmco2[i].opcode, i);

             return -1;

         }

     }
 
     return 0;
 }

 int ff_generate_sliding_window_mmcos(H264Context *h, int first_slice)

 {
     MMCO mmco_temp[MAX_MMCO_COUNT], *mmco = first_slice ? h->mmco : mmco_temp;
     int mmco_index = 0, i;
 
     if (h->short_ref_count &&
         h->long_ref_count + h->short_ref_count >= h->sps.ref_frame_count &&

         !(FIELD_PICTURE(h) && !h->first_field && h->cur_pic_ptr->reference)) {

         mmco[0].opcode        = MMCO_SHORT2UNUSED;

         mmco[0].short_pic_num = h->short_ref[h->short_ref_count - 1]->frame_num;

         mmco_index            = 1;

         if (FIELD_PICTURE(h)) {

             mmco[0].short_pic_num *= 2;

             mmco[1].opcode         = MMCO_SHORT2UNUSED;
             mmco[1].short_pic_num  = mmco[0].short_pic_num + 1;
             mmco_index             = 2;

         }
     }

 
     if (first_slice) {
         h->mmco_index = mmco_index;
     } else if (!first_slice && mmco_index >= 0 &&
                (mmco_index != h->mmco_index ||
                 (i = check_opcodes(h->mmco, mmco_temp, mmco_index)))) {

         av_log(h->avctx, AV_LOG_ERROR,

                "Inconsistent MMCO state between slices [%d, %d]\n",
                mmco_index, h->mmco_index);

         return AVERROR_INVALIDDATA;
     }

     return 0;

 }
 

 int ff_h264_execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count)
 {

     int i, av_uninit(j);

     int pps_count;

     int current_ref_assigned = 0, err = 0;

     Picture *av_uninit(pic);
 

     if ((h->avctx->debug & FF_DEBUG_MMCO) && mmco_count == 0)

         av_log(h->avctx, AV_LOG_DEBUG, "no mmco here\n");

     for (i = 0; i < mmco_count; i++) {

         int av_uninit(structure), av_uninit(frame_num);

         if (h->avctx->debug & FF_DEBUG_MMCO)
             av_log(h->avctx, AV_LOG_DEBUG, "mmco:%d %d %d\n", h->mmco[i].opcode,
                    h->mmco[i].short_pic_num, h->mmco[i].long_arg);

         if (mmco[i].opcode == MMCO_SHORT2UNUSED ||
             mmco[i].opcode == MMCO_SHORT2LONG) {

             frame_num = pic_num_extract(h, mmco[i].short_pic_num, &structure);

             pic       = find_short(h, frame_num, &j);
             if (!pic) {
                 if (mmco[i].opcode != MMCO_SHORT2LONG ||
                     !h->long_ref[mmco[i].long_arg]    ||
                     h->long_ref[mmco[i].long_arg]->frame_num != frame_num) {

                     av_log(h->avctx, h->short_ref_count ? AV_LOG_ERROR : AV_LOG_DEBUG, "mmco: unref short failure\n");

                     err = AVERROR_INVALIDDATA;
                 }

                 continue;
             }
         }
 

         switch (mmco[i].opcode) {

         case MMCO_SHORT2UNUSED:

             if (h->avctx->debug & FF_DEBUG_MMCO)
                 av_log(h->avctx, AV_LOG_DEBUG, "mmco: unref short %d count %d\n",
                        h->mmco[i].short_pic_num, h->short_ref_count);

             remove_short(h, frame_num, structure ^ PICT_FRAME);
             break;
         case MMCO_SHORT2LONG:
                 if (h->long_ref[mmco[i].long_arg] != pic)
                     remove_long(h, mmco[i].long_arg, 0);
 
                 remove_short_at_index(h, j);

                 h->long_ref[ mmco[i].long_arg ] = pic;
                 if (h->long_ref[mmco[i].long_arg]) {
                     h->long_ref[mmco[i].long_arg]->long_ref = 1;

                     h->long_ref_count++;
                 }
             break;
         case MMCO_LONG2UNUSED:

             j   = pic_num_extract(h, mmco[i].long_arg, &structure);

             pic = h->long_ref[j];
             if (pic) {
                 remove_long(h, j, structure ^ PICT_FRAME);

             } else if (h->avctx->debug & FF_DEBUG_MMCO)

                 av_log(h->avctx, AV_LOG_DEBUG, "mmco: unref long failure\n");

             break;
         case MMCO_LONG:
                     // Comment below left from previous code as it is an interresting note.
                     /* First field in pair is in short term list or
                      * at a different long term index.
                      * This is not allowed; see 7.4.3.3, notes 2 and 3.
                      * Report the problem and keep the pair where it is,
                      * and mark this field valid.
                      */
 

             if (h->long_ref[mmco[i].long_arg] != h->cur_pic_ptr) {

                 if (h->cur_pic_ptr->long_ref) {
                     for(j=0; j<16; j++) {
                         if(h->long_ref[j] == h->cur_pic_ptr) {
                             remove_long(h, j, 0);
                             av_log(h->avctx, AV_LOG_ERROR, "mmco: cannot assign current picture to 2 long term references\n");
                         }
                     }
                 }

                 av_assert0(!h->cur_pic_ptr->long_ref);

                 remove_long(h, mmco[i].long_arg, 0);

                 if (remove_short(h, h->cur_pic_ptr->frame_num, 0)) {
                     av_log(h->avctx, AV_LOG_ERROR, "mmco: cannot assign current picture to short and long at the same time\n");
                 }

                 h->long_ref[mmco[i].long_arg]           = h->cur_pic_ptr;
                 h->long_ref[mmco[i].long_arg]->long_ref = 1;

                 h->long_ref_count++;
             }
 

             h->cur_pic_ptr->reference |= h->picture_structure;

             current_ref_assigned = 1;

             break;
         case MMCO_SET_MAX_LONG:
             assert(mmco[i].long_arg <= 16);
             // just remove the long term which index is greater than new max

             for (j = mmco[i].long_arg; j < 16; j++) {

                 remove_long(h, j, 0);
             }
             break;
         case MMCO_RESET:

             while (h->short_ref_count) {

                 remove_short(h, h->short_ref[0]->frame_num, 0);
             }

             for (j = 0; j < 16; j++) {

                 remove_long(h, j, 0);
             }

             h->frame_num  = h->cur_pic_ptr->frame_num = 0;

             h->mmco_reset = 1;

             h->cur_pic_ptr->mmco_reset = 1;

             for (j = 0; j < MAX_DELAYED_PIC_COUNT; j++)
                 h->last_pocs[j] = INT_MIN;

             break;
         default: assert(0);
         }
     }
 
     if (!current_ref_assigned) {
         /* Second field of complementary field pair; the first field of
          * which is already referenced. If short referenced, it
          * should be first entry in short_ref. If not, it must exist
          * in long_ref; trying to put it on the short list here is an
          * error in the encoded bit stream (ref: 7.4.3.3, NOTE 2 and 3).
          */

         if (h->short_ref_count && h->short_ref[0] == h->cur_pic_ptr) {

             /* Just mark the second field valid */

             h->cur_pic_ptr->reference = PICT_FRAME;

         } else if (h->cur_pic_ptr->long_ref) {
             av_log(h->avctx, AV_LOG_ERROR, "illegal short term reference "
                                            "assignment for second field "
                                            "in complementary field pair "
                                            "(first field is long term)\n");

             err = AVERROR_INVALIDDATA;

         } else {

             pic = remove_short(h, h->cur_pic_ptr->frame_num, 0);
             if (pic) {

                 av_log(h->avctx, AV_LOG_ERROR, "illegal short term buffer state detected\n");

                 err = AVERROR_INVALIDDATA;

             }
 

             if (h->short_ref_count)
                 memmove(&h->short_ref[1], &h->short_ref[0],
                         h->short_ref_count * sizeof(Picture*));

             h->short_ref[0] = h->cur_pic_ptr;

             h->short_ref_count++;

             h->cur_pic_ptr->reference |= h->picture_structure;

         }
     }
 

     if (h->long_ref_count + h->short_ref_count > FFMAX(h->sps.ref_frame_count, 1)) {

 
         /* We have too many reference frames, probably due to corrupted
          * stream. Need to discard one frame. Prevents overrun of the
          * short_ref and long_ref buffers.
          */

         av_log(h->avctx, AV_LOG_ERROR,

                "number of reference frames (%d+%d) exceeds max (%d; probably "
                "corrupt input), discarding one\n",
                h->long_ref_count, h->short_ref_count, h->sps.ref_frame_count);

         err = AVERROR_INVALIDDATA;

 
         if (h->long_ref_count && !h->short_ref_count) {
             for (i = 0; i < 16; ++i)
                 if (h->long_ref[i])
                     break;
 
             assert(i < 16);
             remove_long(h, i, 0);
         } else {
             pic = h->short_ref[h->short_ref_count - 1];
             remove_short(h, pic->frame_num, 0);
         }
     }
 
     print_short_term(h);
     print_long_term(h);

     pps_count = 0;
     for (i = 0; i < FF_ARRAY_ELEMS(h->pps_buffers); i++)
         pps_count += !!h->pps_buffers[i];
 

     if (   err >= 0
         && h->long_ref_count==0

         && (h->short_ref_count<=2 || h->pps.ref_count[0] <= 1 && h->pps.ref_count[1] <= 1 && pps_count == 1)

         && h->pps.ref_count[0]<=2 + (h->picture_structure != PICT_FRAME)
         && h->cur_pic_ptr->f.pict_type == AV_PICTURE_TYPE_I){

         h->cur_pic_ptr->sync |= 1;
         if(!h->avctx->has_b_frames)

             h->sync = 2;

     }
 

     return (h->avctx->err_recognition & AV_EF_EXPLODE) ? err : 0;

 }
 

 int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb,
                                    int first_slice)
 {

     int i, ret;

     MMCO mmco_temp[MAX_MMCO_COUNT], *mmco = mmco_temp;

     int mmco_index = 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;

             mmco_index       = 1;

         }

     } else {
         if (get_bits1(gb)) { // adaptive_ref_pic_marking_mode_flag
             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 ] == NULL){
                         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;
             }

             mmco_index = i;
         } else {

             if (first_slice) {
                 ret = ff_generate_sliding_window_mmcos(h, first_slice);

                 if (ret < 0 && h->avctx->err_recognition & AV_EF_EXPLODE)

                     return ret;
             }

             mmco_index = -1;

         }
     }
 

     if (first_slice && mmco_index != -1) {

         memcpy(h->mmco, mmco_temp, sizeof(h->mmco));

         h->mmco_index = mmco_index;
     } else if (!first_slice && mmco_index >= 0 &&
                (mmco_index != h->mmco_index ||

                 check_opcodes(h->mmco, mmco_temp, mmco_index))) {

         av_log(h->avctx, AV_LOG_ERROR,

                "Inconsistent MMCO state between slices [%d, %d]\n",
                mmco_index, h->mmco_index);

         return AVERROR_INVALIDDATA;
     }
 

     return 0;
 }