/*

  * HEVC video decoder

  *
  * Copyright (C) 2012 - 2013 Guillaume Martres
  * Copyright (C) 2013 Anand Meher Kotra
  *
  * 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
  */
 
 #include "hevc.h"
 
 static const uint8_t l0_l1_cand_idx[12][2] = {
     { 0, 1, },
     { 1, 0, },
     { 0, 2, },
     { 2, 0, },
     { 1, 2, },
     { 2, 1, },
     { 0, 3, },
     { 3, 0, },
     { 1, 3, },
     { 3, 1, },
     { 2, 3, },
     { 3, 2, },
 };
 

 void ff_hevc_set_neighbour_available(HEVCContext *s, int x0, int y0,
                                      int nPbW, int nPbH)

 {

     HEVCLocalContext *lc = s->HEVClc;

     int x0b = x0 & ((1 << s->sps->log2_ctb_size) - 1);
     int y0b = y0 & ((1 << s->sps->log2_ctb_size) - 1);
 
     lc->na.cand_up       = (lc->ctb_up_flag   || y0b);
     lc->na.cand_left     = (lc->ctb_left_flag || x0b);
     lc->na.cand_up_left  = (!x0b && !y0b) ? lc->ctb_up_left_flag : lc->na.cand_left && lc->na.cand_up;
     lc->na.cand_up_right_sap =
             ((x0b + nPbW) == (1 << s->sps->log2_ctb_size)) ?
                     lc->ctb_up_right_flag && !y0b : lc->na.cand_up;
     lc->na.cand_up_right =
             ((x0b + nPbW) == (1 << s->sps->log2_ctb_size) ?
                     lc->ctb_up_right_flag && !y0b : lc->na.cand_up )
                      && (x0 + nPbW) < lc->end_of_tiles_x;
     lc->na.cand_bottom_left = ((y0 + nPbH) >= lc->end_of_tiles_y) ? 0 : lc->na.cand_left;
 }
 
 /*
  * 6.4.1 Derivation process for z-scan order block availability
  */
 static int z_scan_block_avail(HEVCContext *s, int xCurr, int yCurr,
                               int xN, int yN)
 {
 #define MIN_TB_ADDR_ZS(x, y)                                            \
     s->pps->min_tb_addr_zs[(y) * s->sps->min_tb_width + (x)]

     int Curr = MIN_TB_ADDR_ZS(xCurr >> s->sps->log2_min_tb_size,
                               yCurr >> s->sps->log2_min_tb_size);

     int N;
 

     if (xN < 0 || yN < 0 ||
         xN >= s->sps->width ||
         yN >= s->sps->height)

         return 0;
 

     N = MIN_TB_ADDR_ZS(xN >> s->sps->log2_min_tb_size,
                        yN >> s->sps->log2_min_tb_size);

 
     return N <= Curr;
 }
 
 static int same_prediction_block(HEVCLocalContext *lc, int log2_cb_size,
                                  int x0, int y0, int nPbW, int nPbH,
                                  int xA1, int yA1, int partIdx)
 {
     return !(nPbW << 1 == 1 << log2_cb_size &&
              nPbH << 1 == 1 << log2_cb_size && partIdx == 1 &&
              lc->cu.x + nPbW > xA1 &&
              lc->cu.y + nPbH <= yA1);
 }
 
 /*
  * 6.4.2 Derivation process for prediction block availability
  */
 static int check_prediction_block_available(HEVCContext *s, int log2_cb_size,
                                             int x0, int y0, int nPbW, int nPbH,
                                             int xA1, int yA1, int partIdx)
 {

     HEVCLocalContext *lc = s->HEVClc;

 
     if (lc->cu.x < xA1 && lc->cu.y < yA1 &&
         (lc->cu.x + (1 << log2_cb_size)) > xA1 &&
         (lc->cu.y + (1 << log2_cb_size)) > yA1)
         return same_prediction_block(lc, log2_cb_size, x0, y0,
                                      nPbW, nPbH, xA1, yA1, partIdx);
     else
         return z_scan_block_avail(s, x0, y0, xA1, yA1);
 }
 
 //check if the two luma locations belong to the same mostion estimation region
 static int isDiffMER(HEVCContext *s, int xN, int yN, int xP, int yP)
 {
     uint8_t plevel = s->pps->log2_parallel_merge_level;
 
     return xN >> plevel == xP >> plevel &&
            yN >> plevel == yP >> plevel;
 }
 
 #define MATCH(x) (A.x == B.x)
 
 // check if the mv's and refidx are the same between A and B
 static int compareMVrefidx(struct MvField A, struct MvField B)
 {
     if (A.pred_flag[0] && A.pred_flag[1] && B.pred_flag[0] && B.pred_flag[1])
         return MATCH(ref_idx[0]) && MATCH(mv[0].x) && MATCH(mv[0].y) &&
                MATCH(ref_idx[1]) && MATCH(mv[1].x) && MATCH(mv[1].y);
 
     if (A.pred_flag[0] && !A.pred_flag[1] && B.pred_flag[0] && !B.pred_flag[1])
         return MATCH(ref_idx[0]) && MATCH(mv[0].x) && MATCH(mv[0].y);
 
     if (!A.pred_flag[0] && A.pred_flag[1] && !B.pred_flag[0] && B.pred_flag[1])
         return MATCH(ref_idx[1]) && MATCH(mv[1].x) && MATCH(mv[1].y);
 
     return 0;
 }
 
 static av_always_inline void mv_scale(Mv *dst, Mv *src, int td, int tb)
 {
     int tx, scale_factor;
 
     td = av_clip_int8_c(td);
     tb = av_clip_int8_c(tb);
     tx = (0x4000 + abs(td / 2)) / td;
     scale_factor = av_clip_c((tb * tx + 32) >> 6, -4096, 4095);
     dst->x = av_clip_int16_c((scale_factor * src->x + 127 +
                              (scale_factor * src->x < 0)) >> 8);
     dst->y = av_clip_int16_c((scale_factor * src->y + 127 +
                              (scale_factor * src->y < 0)) >> 8);
 }
 
 static int check_mvset(Mv *mvLXCol, Mv *mvCol,
                        int colPic, int poc,
                        RefPicList *refPicList, int X, int refIdxLx,
                        RefPicList *refPicList_col, int listCol, int refidxCol)
 {
     int cur_lt = refPicList[X].isLongTerm[refIdxLx];
     int col_lt = refPicList_col[listCol].isLongTerm[refidxCol];
     int col_poc_diff, cur_poc_diff;
 
     if (cur_lt != col_lt) {
         mvLXCol->x = 0;
         mvLXCol->y = 0;
         return 0;
     }
 
     col_poc_diff = colPic - refPicList_col[listCol].list[refidxCol];
     cur_poc_diff = poc    - refPicList[X].list[refIdxLx];
 
     if (!col_poc_diff)

         col_poc_diff = 1;  // error resilience

 
     if (cur_lt || col_poc_diff == cur_poc_diff) {
         mvLXCol->x = mvCol->x;
         mvLXCol->y = mvCol->y;
     } else {
         mv_scale(mvLXCol, mvCol, col_poc_diff, cur_poc_diff);
     }
     return 1;
 }
 

 #define CHECK_MVSET(l)                                          \
     check_mvset(mvLXCol, temp_col.mv + l,                       \
                 colPic, s->poc,                                 \
                 refPicList, X, refIdxLx,                        \
                 refPicList_col, L ## l, temp_col.ref_idx[l])

 
 // derive the motion vectors section 8.5.3.1.8
 static int derive_temporal_colocated_mvs(HEVCContext *s, MvField temp_col,

                                          int refIdxLx, Mv *mvLXCol, int X,
                                          int colPic, RefPicList *refPicList_col)

 {
     RefPicList *refPicList = s->ref->refPicList;
 
     if (temp_col.is_intra) {
         mvLXCol->x = 0;
         mvLXCol->y = 0;
         return 0;
     }
 
     if (temp_col.pred_flag[0] == 0)
         return CHECK_MVSET(1);
     else if (temp_col.pred_flag[0] == 1 && temp_col.pred_flag[1] == 0)
         return CHECK_MVSET(0);
     else if (temp_col.pred_flag[0] == 1 && temp_col.pred_flag[1] == 1) {
         int check_diffpicount = 0;
         int i = 0;
         for (i = 0; i < refPicList[0].nb_refs; i++) {
             if (refPicList[0].list[i] > s->poc)
                 check_diffpicount++;
         }
         for (i = 0; i < refPicList[1].nb_refs; i++) {
             if (refPicList[1].list[i] > s->poc)
                 check_diffpicount++;
         }
         if (check_diffpicount == 0 && X == 0)
             return CHECK_MVSET(0);
         else if (check_diffpicount == 0 && X == 1)
             return CHECK_MVSET(1);
         else {
             if (s->sh.collocated_list == L1)
                 return CHECK_MVSET(0);
             else
                 return CHECK_MVSET(1);
         }
     }
 
     return 0;
 }
 

 #define TAB_MVF(x, y)                                                   \

     tab_mvf[(y) * min_pu_width + x]

 #define TAB_MVF_PU(v)                                                   \
     TAB_MVF(x ## v ## _pu, y ## v ## _pu)

 #define DERIVE_TEMPORAL_COLOCATED_MVS                                   \
     derive_temporal_colocated_mvs(s, temp_col,                          \
                                   refIdxLx, mvLXCol, X, colPic,         \

                                   ff_hevc_get_ref_list(s, ref, x, y))

 
 /*
  * 8.5.3.1.7  temporal luma motion vector prediction
  */
 static int temporal_luma_motion_vector(HEVCContext *s, int x0, int y0,
                                        int nPbW, int nPbH, int refIdxLx,

                                        Mv *mvLXCol, int X)

 {
     MvField *tab_mvf;
     MvField temp_col;

     int x, y, x_pu, y_pu;

     int min_pu_width = s->sps->min_pu_width;

     int availableFlagLXCol = 0;
     int colPic;
 
     HEVCFrame *ref = s->ref->collocated_ref;
 
     if (!ref)
         return 0;
 
     tab_mvf = ref->tab_mvf;
     colPic  = ref->poc;
 
     //bottom right collocated motion vector

     x = x0 + nPbW;
     y = y0 + nPbH;

     if (s->threads_type == FF_THREAD_FRAME )

         ff_thread_await_progress(&ref->tf, y, 0);

     if (tab_mvf &&

         (y0 >> s->sps->log2_ctb_size) == (y >> s->sps->log2_ctb_size) &&
         y < s->sps->height &&
         x < s->sps->width) {

         x                  = ((x >> 4) << 4);
         y                  = ((y >> 4) << 4);
         x_pu               = x >> s->sps->log2_min_pu_size;
         y_pu               = y >> s->sps->log2_min_pu_size;
         temp_col           = TAB_MVF(x_pu, y_pu);

         availableFlagLXCol = DERIVE_TEMPORAL_COLOCATED_MVS;

     }
 
     // derive center collocated motion vector

     if (tab_mvf && !availableFlagLXCol) {

         x                  = x0 + (nPbW >> 1);
         y                  = y0 + (nPbH >> 1);
         x                  = ((x >> 4) << 4);
         y                  = ((y >> 4) << 4);
         x_pu               = x >> s->sps->log2_min_pu_size;
         y_pu               = y >> s->sps->log2_min_pu_size;
         temp_col           = TAB_MVF(x_pu, y_pu);

         availableFlagLXCol = DERIVE_TEMPORAL_COLOCATED_MVS;

     }
     return availableFlagLXCol;
 }
 

 #define AVAILABLE(cand, v)                                      \

     (cand && !TAB_MVF_PU(v).is_intra)
 

 #define PRED_BLOCK_AVAILABLE(v)                                 \
     check_prediction_block_available(s, log2_cb_size,           \
                                      x0, y0, nPbW, nPbH,        \
                                      x ## v, y ## v, part_idx)

 #define COMPARE_MV_REFIDX(a, b)                                 \

     compareMVrefidx(TAB_MVF_PU(a), TAB_MVF_PU(b))
 
 /*
  * 8.5.3.1.2  Derivation process for spatial merging candidates
  */
 static void derive_spatial_merge_candidates(HEVCContext *s, int x0, int y0,

                                             int nPbW, int nPbH,
                                             int log2_cb_size,

                                             int singleMCLFlag, int part_idx,
                                             struct MvField mergecandlist[])
 {

     HEVCLocalContext *lc   = s->HEVClc;

     RefPicList *refPicList = s->ref->refPicList;

     MvField *tab_mvf       = s->ref->tab_mvf;
 

     const int min_pu_width = s->sps->min_pu_width;

 
     const int cand_bottom_left = lc->na.cand_bottom_left;
     const int cand_left        = lc->na.cand_left;
     const int cand_up_left     = lc->na.cand_up_left;
     const int cand_up          = lc->na.cand_up;
     const int cand_up_right    = lc->na.cand_up_right_sap;
 
     const int xA1    = x0 - 1;
     const int yA1    = y0 + nPbH - 1;
     const int xA1_pu = xA1 >> s->sps->log2_min_pu_size;
     const int yA1_pu = yA1 >> s->sps->log2_min_pu_size;
 
     const int xB1    = x0 + nPbW - 1;
     const int yB1    = y0 - 1;
     const int xB1_pu = xB1 >> s->sps->log2_min_pu_size;
     const int yB1_pu = yB1 >> s->sps->log2_min_pu_size;
 
     const int xB0    = x0 + nPbW;
     const int yB0    = y0 - 1;
     const int xB0_pu = xB0 >> s->sps->log2_min_pu_size;
     const int yB0_pu = yB0 >> s->sps->log2_min_pu_size;
 
     const int xA0    = x0 - 1;
     const int yA0    = y0 + nPbH;
     const int xA0_pu = xA0 >> s->sps->log2_min_pu_size;
     const int yA0_pu = yA0 >> s->sps->log2_min_pu_size;
 
     const int xB2    = x0 - 1;
     const int yB2    = y0 - 1;
     const int xB2_pu = xB2 >> s->sps->log2_min_pu_size;
     const int yB2_pu = yB2 >> s->sps->log2_min_pu_size;
 
     const int nb_refs = (s->sh.slice_type == P_SLICE) ?
                         s->sh.nb_refs[0] : FFMIN(s->sh.nb_refs[0], s->sh.nb_refs[1]);
     int check_MER   = 1;
     int check_MER_1 = 1;

     int zero_idx = 0;

     int nb_merge_cand = 0;
     int nb_orig_merge_cand = 0;

     int is_available_a0;
     int is_available_a1;
     int is_available_b0;

     int is_available_b1;

     int is_available_b2;

     int check_B0;
     int check_A0;
 

     //first left spatial merge candidate

     is_available_a1 = AVAILABLE(cand_left, A1);
 
     if (!singleMCLFlag && part_idx == 1 &&
         (lc->cu.part_mode == PART_Nx2N ||
          lc->cu.part_mode == PART_nLx2N ||
          lc->cu.part_mode == PART_nRx2N) ||
         isDiffMER(s, xA1, yA1, x0, y0)) {
         is_available_a1 = 0;
     }
 

     if (is_available_a1)
         mergecandlist[nb_merge_cand++] = TAB_MVF_PU(A1);

 
     // above spatial merge candidate
     is_available_b1 = AVAILABLE(cand_up, B1);
 
     if (!singleMCLFlag && part_idx == 1 &&
         (lc->cu.part_mode == PART_2NxN ||
          lc->cu.part_mode == PART_2NxnU ||
          lc->cu.part_mode == PART_2NxnD) ||
         isDiffMER(s, xB1, yB1, x0, y0)) {
         is_available_b1 = 0;
     }
 
     if (is_available_a1 && is_available_b1)
         check_MER = !COMPARE_MV_REFIDX(B1, A1);
 

     if (is_available_b1 && check_MER)
         mergecandlist[nb_merge_cand++] = TAB_MVF_PU(B1);

 
     // above right spatial merge candidate
     check_MER = 1;

     check_B0  = PRED_BLOCK_AVAILABLE(B0);

     is_available_b0 = check_B0 && AVAILABLE(cand_up_right, B0);

 
     if (isDiffMER(s, xB0, yB0, x0, y0))

         is_available_b0 = 0;

     if (is_available_b1 && is_available_b0)

         check_MER = !COMPARE_MV_REFIDX(B0, B1);
 

     if (is_available_b0 && check_MER)
         mergecandlist[nb_merge_cand++] = TAB_MVF_PU(B0);

 
     // left bottom spatial merge candidate
     check_MER = 1;

     check_A0  = PRED_BLOCK_AVAILABLE(A0);

 
     is_available_a0 = check_A0 && AVAILABLE(cand_bottom_left, A0);
 
     if (isDiffMER(s, xA0, yA0, x0, y0))
         is_available_a0 = 0;
 
     if (is_available_a1 && is_available_a0)
         check_MER = !COMPARE_MV_REFIDX(A0, A1);
 

     if (is_available_a0 && check_MER)
         mergecandlist[nb_merge_cand++] = TAB_MVF_PU(A0);

 
     // above left spatial merge candidate
     check_MER = 1;
 

     is_available_b2 = AVAILABLE(cand_up_left, B2);

 
     if (isDiffMER(s, xB2, yB2, x0, y0))

         is_available_b2 = 0;

     if (is_available_a1 && is_available_b2)

         check_MER = !COMPARE_MV_REFIDX(B2, A1);
 

     if (is_available_b1 && is_available_b2)

         check_MER_1 = !COMPARE_MV_REFIDX(B2, B1);
 

     if (is_available_b2 && check_MER && check_MER_1 && nb_merge_cand != 4)
         mergecandlist[nb_merge_cand++] = TAB_MVF_PU(B2);

 
     // temporal motion vector candidate

     if (s->sh.slice_temporal_mvp_enabled_flag &&
         nb_merge_cand < s->sh.max_num_merge_cand) {
         Mv mv_l0_col, mv_l1_col;
         int available_l0 = temporal_luma_motion_vector(s, x0, y0, nPbW, nPbH,
                                                        0, &mv_l0_col, 0);
         int available_l1 = (s->sh.slice_type == B_SLICE) ?
                            temporal_luma_motion_vector(s, x0, y0, nPbW, nPbH,
                                                        0, &mv_l1_col, 1) : 0;
 
         if (available_l0 || available_l1) {
             mergecandlist[nb_merge_cand].is_intra     = 0;
             mergecandlist[nb_merge_cand].pred_flag[0] = available_l0;
             mergecandlist[nb_merge_cand].pred_flag[1] = available_l1;
             if (available_l0) {
                 mergecandlist[nb_merge_cand].mv[0]      = mv_l0_col;
                 mergecandlist[nb_merge_cand].ref_idx[0] = 0;

             }

             if (available_l1) {
                 mergecandlist[nb_merge_cand].mv[1]      = mv_l1_col;
                 mergecandlist[nb_merge_cand].ref_idx[1] = 0;

             }

             nb_merge_cand++;

         }
     }
 

     nb_orig_merge_cand = nb_merge_cand;

 
     // combined bi-predictive merge candidates  (applies for B slices)

     if (s->sh.slice_type == B_SLICE && nb_orig_merge_cand > 1 &&
         nb_orig_merge_cand < s->sh.max_num_merge_cand) {
         int comb_idx = 0;
 
         for (comb_idx = 0; nb_merge_cand < s->sh.max_num_merge_cand &&
                            comb_idx < nb_orig_merge_cand * (nb_orig_merge_cand - 1); comb_idx++) {
             int l0_cand_idx = l0_l1_cand_idx[comb_idx][0];
             int l1_cand_idx = l0_l1_cand_idx[comb_idx][1];
             MvField l0_cand = mergecandlist[l0_cand_idx];
             MvField l1_cand = mergecandlist[l1_cand_idx];
 
             if (l0_cand.pred_flag[0] && l1_cand.pred_flag[1] &&
                 (refPicList[0].list[l0_cand.ref_idx[0]] !=
                  refPicList[1].list[l1_cand.ref_idx[1]] ||
                  l0_cand.mv[0].x != l1_cand.mv[1].x ||
                  l0_cand.mv[0].y != l1_cand.mv[1].y)) {
                 mergecandlist[nb_merge_cand].ref_idx[0]   = l0_cand.ref_idx[0];
                 mergecandlist[nb_merge_cand].ref_idx[1]   = l1_cand.ref_idx[1];
                 mergecandlist[nb_merge_cand].pred_flag[0] = 1;
                 mergecandlist[nb_merge_cand].pred_flag[1] = 1;
                 mergecandlist[nb_merge_cand].mv[0].x      = l0_cand.mv[0].x;
                 mergecandlist[nb_merge_cand].mv[0].y      = l0_cand.mv[0].y;
                 mergecandlist[nb_merge_cand].mv[1].x      = l1_cand.mv[1].x;
                 mergecandlist[nb_merge_cand].mv[1].y      = l1_cand.mv[1].y;
                 mergecandlist[nb_merge_cand].is_intra     = 0;
                 nb_merge_cand++;

             }
         }
     }
 

     // append Zero motion vector candidates
     while (nb_merge_cand < s->sh.max_num_merge_cand) {
         mergecandlist[nb_merge_cand].pred_flag[0] = 1;
         mergecandlist[nb_merge_cand].pred_flag[1] = s->sh.slice_type == B_SLICE;
         mergecandlist[nb_merge_cand].mv[0].x      = 0;
         mergecandlist[nb_merge_cand].mv[0].y      = 0;
         mergecandlist[nb_merge_cand].mv[1].x      = 0;
         mergecandlist[nb_merge_cand].mv[1].y      = 0;
         mergecandlist[nb_merge_cand].is_intra     = 0;

         mergecandlist[nb_merge_cand].ref_idx[0]   = zero_idx < nb_refs ? zero_idx : 0;
         mergecandlist[nb_merge_cand].ref_idx[1]   = zero_idx < nb_refs ? zero_idx : 0;

         nb_merge_cand++;
         zero_idx++;

     }
 }
 
 /*
  * 8.5.3.1.1 Derivation process of luma Mvs for merge mode
  */
 void ff_hevc_luma_mv_merge_mode(HEVCContext *s, int x0, int y0, int nPbW,
                                 int nPbH, int log2_cb_size, int part_idx,
                                 int merge_idx, MvField *mv)
 {
     int singleMCLFlag = 0;
     int nCS = 1 << log2_cb_size;
     struct MvField mergecand_list[MRG_MAX_NUM_CANDS] = { { { { 0 } } } };
     int nPbW2 = nPbW;
     int nPbH2 = nPbH;

     HEVCLocalContext *lc = s->HEVClc;

 
     if (s->pps->log2_parallel_merge_level > 2 && nCS == 8) {
         singleMCLFlag = 1;

         x0            = lc->cu.x;
         y0            = lc->cu.y;
         nPbW          = nCS;
         nPbH          = nCS;
         part_idx      = 0;

     }
 
     ff_hevc_set_neighbour_available(s, x0, y0, nPbW, nPbH);
     derive_spatial_merge_candidates(s, x0, y0, nPbW, nPbH, log2_cb_size,
                                     singleMCLFlag, part_idx, mergecand_list);
 
     if (mergecand_list[merge_idx].pred_flag[0] == 1 &&
         mergecand_list[merge_idx].pred_flag[1] == 1 &&
         (nPbW2 + nPbH2) == 12) {

         mergecand_list[merge_idx].ref_idx[1]   = -1;

         mergecand_list[merge_idx].pred_flag[1] = 0;
     }
 
     *mv = mergecand_list[merge_idx];
 }
 

 static av_always_inline void dist_scale(HEVCContext *s, Mv *mv,

                                         int min_pu_width, int x, int y,

                                         int elist, int ref_idx_curr, int ref_idx)
 {
     RefPicList *refPicList = s->ref->refPicList;

     MvField *tab_mvf       = s->ref->tab_mvf;
     int ref_pic_elist      = refPicList[elist].list[TAB_MVF(x, y).ref_idx[elist]];
     int ref_pic_curr       = refPicList[ref_idx_curr].list[ref_idx];

     if (ref_pic_elist != ref_pic_curr) {
         int poc_diff = s->poc - ref_pic_elist;
         if (!poc_diff)
             poc_diff = 1;
         mv_scale(mv, mv, poc_diff, s->poc - ref_pic_curr);
     }

 }
 
 static int mv_mp_mode_mx(HEVCContext *s, int x, int y, int pred_flag_index,
                          Mv *mv, int ref_idx_curr, int ref_idx)
 {
     MvField *tab_mvf = s->ref->tab_mvf;

     int min_pu_width = s->sps->min_pu_width;

 
     RefPicList *refPicList = s->ref->refPicList;
 
     if (TAB_MVF(x, y).pred_flag[pred_flag_index] == 1 &&
         refPicList[pred_flag_index].list[TAB_MVF(x, y).ref_idx[pred_flag_index]] == refPicList[ref_idx_curr].list[ref_idx]) {
         *mv = TAB_MVF(x, y).mv[pred_flag_index];
         return 1;
     }
     return 0;
 }
 
 static int mv_mp_mode_mx_lt(HEVCContext *s, int x, int y, int pred_flag_index,
                             Mv *mv, int ref_idx_curr, int ref_idx)
 {
     MvField *tab_mvf = s->ref->tab_mvf;

     int min_pu_width = s->sps->min_pu_width;

 
     RefPicList *refPicList = s->ref->refPicList;

     int currIsLongTerm     = refPicList[ref_idx_curr].isLongTerm[ref_idx];

 
     int colIsLongTerm =
         refPicList[pred_flag_index].isLongTerm[(TAB_MVF(x, y).ref_idx[pred_flag_index])];
 

     if (TAB_MVF(x, y).pred_flag[pred_flag_index] &&
         colIsLongTerm == currIsLongTerm) {

         *mv = TAB_MVF(x, y).mv[pred_flag_index];
         if (!currIsLongTerm)

             dist_scale(s, mv, min_pu_width, x, y,
                        pred_flag_index, ref_idx_curr, ref_idx);

         return 1;
     }
     return 0;
 }
 

 #define MP_MX(v, pred, mx)                                      \

     mv_mp_mode_mx(s, x ## v ## _pu, y ## v ## _pu, pred,        \
                   &mx, ref_idx_curr, ref_idx)

 #define MP_MX_LT(v, pred, mx)                                   \

     mv_mp_mode_mx_lt(s, x ## v ## _pu, y ## v ## _pu, pred,     \
                      &mx, ref_idx_curr, ref_idx)

 
 void ff_hevc_luma_mv_mvp_mode(HEVCContext *s, int x0, int y0, int nPbW,
                               int nPbH, int log2_cb_size, int part_idx,
                               int merge_idx, MvField *mv,
                               int mvp_lx_flag, int LX)
 {

     HEVCLocalContext *lc = s->HEVClc;

     MvField *tab_mvf = s->ref->tab_mvf;
     int isScaledFlag_L0 = 0;
     int availableFlagLXA0 = 0;
     int availableFlagLXB0 = 0;
     int numMVPCandLX = 0;

     int min_pu_width = s->sps->min_pu_width;

 
     int xA0, yA0;
     int xA0_pu, yA0_pu;
     int is_available_a0;
 
     int xA1, yA1;
     int xA1_pu, yA1_pu;
     int is_available_a1;
 
     int xB0, yB0;
     int xB0_pu, yB0_pu;
     int is_available_b0;
 
     int xB1, yB1;
     int xB1_pu = 0, yB1_pu = 0;
     int is_available_b1 = 0;
 
     int xB2, yB2;
     int xB2_pu = 0, yB2_pu = 0;
     int is_available_b2 = 0;
     Mv mvpcand_list[2] = { { 0 } };
     Mv mxA = { 0 };
     Mv mxB = { 0 };
     int ref_idx_curr = 0;
     int ref_idx = 0;
     int pred_flag_index_l0;
     int pred_flag_index_l1;
     int x0b = x0 & ((1 << s->sps->log2_ctb_size) - 1);
     int y0b = y0 & ((1 << s->sps->log2_ctb_size) - 1);
 
     int cand_up = (lc->ctb_up_flag || y0b);
     int cand_left = (lc->ctb_left_flag || x0b);
     int cand_up_left =
             (!x0b && !y0b) ? lc->ctb_up_left_flag : cand_left && cand_up;
     int cand_up_right =
             (x0b + nPbW == (1 << s->sps->log2_ctb_size) ||
              x0  + nPbW >= lc->end_of_tiles_x) ? lc->ctb_up_right_flag && !y0b
                                                : cand_up;
     int cand_bottom_left = (y0 + nPbH >= lc->end_of_tiles_y) ? 0 : cand_left;
 
     ref_idx_curr       = LX;
     ref_idx            = mv->ref_idx[LX];
     pred_flag_index_l0 = LX;
     pred_flag_index_l1 = !LX;
 
     // left bottom spatial candidate
     xA0 = x0 - 1;
     yA0 = y0 + nPbH;
     xA0_pu = xA0 >> s->sps->log2_min_pu_size;
     yA0_pu = yA0 >> s->sps->log2_min_pu_size;
 

     is_available_a0 = PRED_BLOCK_AVAILABLE(A0) && AVAILABLE(cand_bottom_left, A0);

 
     //left spatial merge candidate

     xA1    = x0 - 1;
     yA1    = y0 + nPbH - 1;

     xA1_pu = xA1 >> s->sps->log2_min_pu_size;
     yA1_pu = yA1 >> s->sps->log2_min_pu_size;
 
     is_available_a1 = AVAILABLE(cand_left, A1);

     if (is_available_a0 || is_available_a1)

         isScaledFlag_L0 = 1;
 
     if (is_available_a0) {
         availableFlagLXA0 = MP_MX(A0, pred_flag_index_l0, mxA);
         if (!availableFlagLXA0)
             availableFlagLXA0 = MP_MX(A0, pred_flag_index_l1, mxA);
     }
 
     if (is_available_a1 && !availableFlagLXA0) {
         availableFlagLXA0 = MP_MX(A1, pred_flag_index_l0, mxA);
         if (!availableFlagLXA0)
             availableFlagLXA0 = MP_MX(A1, pred_flag_index_l1, mxA);
     }
 
     if (is_available_a0 && !availableFlagLXA0) {
         availableFlagLXA0 = MP_MX_LT(A0, pred_flag_index_l0, mxA);
         if (!availableFlagLXA0)
             availableFlagLXA0 = MP_MX_LT(A0, pred_flag_index_l1, mxA);
     }
 
     if (is_available_a1 && !availableFlagLXA0) {
         availableFlagLXA0 = MP_MX_LT(A1, pred_flag_index_l0, mxA);
         if (!availableFlagLXA0)
             availableFlagLXA0 = MP_MX_LT(A1, pred_flag_index_l1, mxA);
     }
 
     // B candidates
     // above right spatial merge candidate

     xB0    = x0 + nPbW;
     yB0    = y0 - 1;

     xB0_pu = xB0 >> s->sps->log2_min_pu_size;
     yB0_pu = yB0 >> s->sps->log2_min_pu_size;
 

     is_available_b0 = PRED_BLOCK_AVAILABLE(B0) && AVAILABLE(cand_up_right, B0);

 
     if (is_available_b0) {
         availableFlagLXB0 = MP_MX(B0, pred_flag_index_l0, mxB);
         if (!availableFlagLXB0)
             availableFlagLXB0 = MP_MX(B0, pred_flag_index_l1, mxB);
     }
 
     if (!availableFlagLXB0) {
         // above spatial merge candidate

         xB1    = x0 + nPbW - 1;
         yB1    = y0 - 1;

         xB1_pu = xB1 >> s->sps->log2_min_pu_size;
         yB1_pu = yB1 >> s->sps->log2_min_pu_size;
 
         is_available_b1 = AVAILABLE(cand_up, B1);
 
         if (is_available_b1) {
             availableFlagLXB0 = MP_MX(B1, pred_flag_index_l0, mxB);
             if (!availableFlagLXB0)
                 availableFlagLXB0 = MP_MX(B1, pred_flag_index_l1, mxB);
         }
     }
 
     if (!availableFlagLXB0) {
         // above left spatial merge candidate
         xB2 = x0 - 1;
         yB2 = y0 - 1;
         xB2_pu = xB2 >> s->sps->log2_min_pu_size;
         yB2_pu = yB2 >> s->sps->log2_min_pu_size;
         is_available_b2 = AVAILABLE(cand_up_left, B2);
 
         if (is_available_b2) {
             availableFlagLXB0 = MP_MX(B2, pred_flag_index_l0, mxB);
             if (!availableFlagLXB0)
                 availableFlagLXB0 = MP_MX(B2, pred_flag_index_l1, mxB);
         }
     }
 
     if (isScaledFlag_L0 == 0) {
         if (availableFlagLXB0) {
             availableFlagLXA0 = 1;
             mxA = mxB;
         }
         availableFlagLXB0 = 0;
 
         // XB0 and L1
         if (is_available_b0) {
             availableFlagLXB0 = MP_MX_LT(B0, pred_flag_index_l0, mxB);
             if (!availableFlagLXB0)
                 availableFlagLXB0 = MP_MX_LT(B0, pred_flag_index_l1, mxB);
         }
 
         if (is_available_b1 && !availableFlagLXB0) {
             availableFlagLXB0 = MP_MX_LT(B1, pred_flag_index_l0, mxB);
             if (!availableFlagLXB0)
                 availableFlagLXB0 = MP_MX_LT(B1, pred_flag_index_l1, mxB);
         }
 
         if (is_available_b2 && !availableFlagLXB0) {
             availableFlagLXB0 = MP_MX_LT(B2, pred_flag_index_l0, mxB);
             if (!availableFlagLXB0)
                 availableFlagLXB0 = MP_MX_LT(B2, pred_flag_index_l1, mxB);
         }
     }
 

     if (availableFlagLXA0)
         mvpcand_list[numMVPCandLX++] = mxA;

     if (availableFlagLXB0 && (!availableFlagLXA0 || mxA.x != mxB.x || mxA.y != mxB.y))
         mvpcand_list[numMVPCandLX++] = mxB;

     //temporal motion vector prediction candidate
     if (numMVPCandLX < 2 && s->sh.slice_temporal_mvp_enabled_flag) {
         Mv mv_col;
         int available_col = temporal_luma_motion_vector(s, x0, y0, nPbW,

                                                         nPbH, ref_idx,
                                                         &mv_col, LX);

         if (available_col)
             mvpcand_list[numMVPCandLX++] = mv_col;

     }
 

     // insert zero motion vectors when the number of available candidates are less than 2
     while (numMVPCandLX < 2)
         mvpcand_list[numMVPCandLX++] = (Mv){ 0, 0 };

 
     mv->mv[LX].x = mvpcand_list[mvp_lx_flag].x;
     mv->mv[LX].y = mvpcand_list[mvp_lx_flag].y;
 }