/*

 * 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"

#include "hevcdec.h"

#include "progressframe.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(HEVCLocalContext *lc, int x0, int y0,

                                     int nPbW, int nPbH, int log2_ctb_size)

{

    int x0b = av_zero_extend(x0, log2_ctb_size);

    int y0b = av_zero_extend(y0, log2_ctb_size);

    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->na.cand_left && lc->na.cand_up : lc->ctb_up_left_flag;

    lc->na.cand_up_right_sap =

            (x0b + nPbW == 1 << log2_ctb_size) ?

                    lc->ctb_up_right_flag && !y0b : lc->na.cand_up;

    lc->na.cand_up_right =

            lc->na.cand_up_right_sap

                     && (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 av_always_inline int

z_scan_block_avail(const HEVCPPS *pps, const HEVCSPS *sps,

                   int xCurr, int yCurr, int xN, int yN)

{

#define MIN_TB_ADDR_ZS(x, y)                                            \

    pps->min_tb_addr_zs[(y) * (sps->tb_mask+2) + (x)]

    int xCurr_ctb = xCurr >> sps->log2_ctb_size;

    int yCurr_ctb = yCurr >> sps->log2_ctb_size;

    int xN_ctb    = xN    >> sps->log2_ctb_size;

    int yN_ctb    = yN    >> sps->log2_ctb_size;

    if( yN_ctb < yCurr_ctb || xN_ctb < xCurr_ctb )

        return 1;

    else {

        int Curr = MIN_TB_ADDR_ZS((xCurr >> sps->log2_min_tb_size) & sps->tb_mask,

                (yCurr >> sps->log2_min_tb_size) & sps->tb_mask);

        int N    = MIN_TB_ADDR_ZS((xN >> sps->log2_min_tb_size) & sps->tb_mask,

                (yN >> sps->log2_min_tb_size) & sps->tb_mask);

        return N <= Curr;

    }

}

//check if the two luma locations belong to the same motion estimation region

static av_always_inline int is_diff_mer(const HEVCPPS *pps, int xN, int yN, int xP, int yP)

{

    uint8_t plevel = pps->log2_parallel_merge_level;

    return xN >> plevel == xP >> plevel &&

           yN >> plevel == yP >> plevel;

}

#define MATCH_MV(x) (AV_RN32A(&A.x) == AV_RN32A(&B.x))

#define MATCH(x) (A.x == B.x)

// check if the mv's and refidx are the same between A and B

static av_always_inline int compare_mv_ref_idx(struct MvField A, struct MvField B)

{

    int a_pf = A.pred_flag;

    int b_pf = B.pred_flag;

    if (a_pf == b_pf) {

        if (a_pf == PF_BI) {

            return MATCH(ref_idx[0]) && MATCH_MV(mv[0]) &&

                   MATCH(ref_idx[1]) && MATCH_MV(mv[1]);

        } else if (a_pf == PF_L0) {

            return MATCH(ref_idx[0]) && MATCH_MV(mv[0]);

        } else if (a_pf == PF_L1) {

            return MATCH(ref_idx[1]) && MATCH_MV(mv[1]);

        }

    }

    return 0;

}

static av_always_inline void mv_scale(Mv *dst, const Mv *src, int td, int tb)

{

    int tx, scale_factor;

    td = av_clip_int8(td);

    tb = av_clip_int8(tb);

    tx = (0x4000 + abs(td / 2)) / td;

    scale_factor = av_clip_intp2((tb * tx + 32) >> 6, 12);

    dst->x = av_clip_int16((scale_factor * src->x + 127 +

                           (scale_factor * src->x < 0)) >> 8);

    dst->y = av_clip_int16((scale_factor * src->y + 127 +

                           (scale_factor * src->y < 0)) >> 8);

}

static int check_mvset(Mv *mvLXCol, const Mv *mvCol,

                       int colPic, int poc,

                       const RefPicList *refPicList, int X, int refIdxLx,

                       const 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 (cur_lt || col_poc_diff == cur_poc_diff || !col_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(const HEVCContext *s, MvField temp_col,

                                         int refIdxLx, Mv *mvLXCol, int X,

                                         int colPic, const RefPicList *refPicList_col)

{

    const RefPicList *refPicList = s->cur_frame->refPicList;

    if (temp_col.pred_flag == PF_INTRA)

        return 0;

    if (!(temp_col.pred_flag & PF_L0))

        return CHECK_MVSET(1);

    else if (temp_col.pred_flag == PF_L0)

        return CHECK_MVSET(0);

    else if (temp_col.pred_flag == PF_BI) {

        int check_diffpicount = 0;

        int i, j;

        for (j = 0; j < 2; j++) {

            for (i = 0; i < refPicList[j].nb_refs; i++) {

                if (refPicList[j].list[i] > s->poc) {

                    check_diffpicount++;

                    break;

                }

            }

        }

        if (!check_diffpicount) {

            if (X==0)

                return CHECK_MVSET(0);

            else

                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) >> sps->log2_min_pu_size),                        \

            ((y ## v) >> sps->log2_min_pu_size))

#define DERIVE_TEMPORAL_COLOCATED_MVS                                   \

    derive_temporal_colocated_mvs(s, temp_col,                          \

                                  refIdxLx, mvLXCol, X, colPic,         \

                                  ff_hevc_get_ref_list(ref, x, y))

/*

 * 8.5.3.1.7  temporal luma motion vector prediction

 */

static int temporal_luma_motion_vector(const HEVCContext *s, const HEVCSPS *sps,

                                       int x0, int y0,

                                       int nPbW, int nPbH, int refIdxLx,

                                       Mv *mvLXCol, int X)

{

    const MvField *tab_mvf;

    MvField temp_col;

    int x, y, x_pu, y_pu;

    int min_pu_width = sps->min_pu_width;

    int availableFlagLXCol = 0;

    int colPic;

    const HEVCFrame *ref = s->collocated_ref;

    if (!ref) {

        memset(mvLXCol, 0, sizeof(*mvLXCol));

        return 0;

    }

    tab_mvf = ref->tab_mvf;

    colPic  = ref->poc;

    //bottom right collocated motion vector

    x = x0 + nPbW;

    y = y0 + nPbH;

    if (tab_mvf &&

        (y0 >> sps->log2_ctb_size) == (y >> sps->log2_ctb_size) &&

        y < sps->height &&

        x < sps->width) {

        x                 &= ~15;

        y                 &= ~15;

        if (s->avctx->active_thread_type == FF_THREAD_FRAME)

            ff_progress_frame_await(&ref->tf, y);

        x_pu               = x >> sps->log2_min_pu_size;

        y_pu               = y >> 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                 &= ~15;

        y                 &= ~15;

        if (s->avctx->active_thread_type == FF_THREAD_FRAME)

            ff_progress_frame_await(&ref->tf, y);

        x_pu               = x >> sps->log2_min_pu_size;

        y_pu               = y >> 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).pred_flag == PF_INTRA))

#define PRED_BLOCK_AVAILABLE(v)                                 \

    z_scan_block_avail(pps, sps, x0, y0, x ## v, y ## v)

#define COMPARE_MV_REFIDX(a, b)                                 \

    compare_mv_ref_idx(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(HEVCLocalContext *lc, const HEVCContext *s,

                                            const HEVCPPS *pps, const HEVCSPS *sps,

                                            int x0, int y0,

                                            int nPbW, int nPbH,

                                            int log2_cb_size,

                                            int singleMCLFlag, int part_idx,

                                            int merge_idx,

                                            struct MvField mergecandlist[])

{

    const RefPicList *refPicList = s->cur_frame->refPicList;

    const MvField *tab_mvf       = s->cur_frame->tab_mvf;

    const int min_pu_width = 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 xB1    = x0 + nPbW - 1;

    const int yB1    = y0 - 1;

    const int xB0    = x0 + nPbW;

    const int yB0    = y0 - 1;

    const int xA0    = x0 - 1;

    const int yA0    = y0 + nPbH;

    const int xB2    = x0 - 1;

    const int yB2    = y0 - 1;

    const int nb_refs = (s->sh.slice_type == HEVC_SLICE_P) ?

                        s->sh.nb_refs[0] : FFMIN(s->sh.nb_refs[0], s->sh.nb_refs[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;

    if (!singleMCLFlag && part_idx == 1 &&

        (lc->cu.part_mode == PART_Nx2N ||

         lc->cu.part_mode == PART_nLx2N ||

         lc->cu.part_mode == PART_nRx2N) ||

        is_diff_mer(pps, xA1, yA1, x0, y0)) {

        is_available_a1 = 0;

    } else {

        is_available_a1 = AVAILABLE(cand_left, A1);

        if (is_available_a1) {

            mergecandlist[nb_merge_cand] = TAB_MVF_PU(A1);

            if (merge_idx == 0)

                return;

            nb_merge_cand++;

        }

    }

    if (!singleMCLFlag && part_idx == 1 &&

        (lc->cu.part_mode == PART_2NxN ||

         lc->cu.part_mode == PART_2NxnU ||

         lc->cu.part_mode == PART_2NxnD) ||

        is_diff_mer(pps, xB1, yB1, x0, y0)) {

        is_available_b1 = 0;

    } else {

        is_available_b1 = AVAILABLE(cand_up, B1);

        if (is_available_b1 &&

            !(is_available_a1 && COMPARE_MV_REFIDX(B1, A1))) {

            mergecandlist[nb_merge_cand] = TAB_MVF_PU(B1);

            if (merge_idx == nb_merge_cand)

                return;

            nb_merge_cand++;

        }

    }

    // above right spatial merge candidate

    is_available_b0 = AVAILABLE(cand_up_right, B0) &&

                      xB0 < sps->width &&

                      PRED_BLOCK_AVAILABLE(B0) &&

                      !is_diff_mer(pps, xB0, yB0, x0, y0);

    if (is_available_b0 &&

        !(is_available_b1 && COMPARE_MV_REFIDX(B0, B1))) {

        mergecandlist[nb_merge_cand] = TAB_MVF_PU(B0);

        if (merge_idx == nb_merge_cand)

            return;

        nb_merge_cand++;

    }

    // left bottom spatial merge candidate

    is_available_a0 = AVAILABLE(cand_bottom_left, A0) &&

                      yA0 < sps->height &&

                      PRED_BLOCK_AVAILABLE(A0) &&

                      !is_diff_mer(pps, xA0, yA0, x0, y0);

    if (is_available_a0 &&

        !(is_available_a1 && COMPARE_MV_REFIDX(A0, A1))) {

        mergecandlist[nb_merge_cand] = TAB_MVF_PU(A0);

        if (merge_idx == nb_merge_cand)

            return;

        nb_merge_cand++;

    }

    // above left spatial merge candidate

    is_available_b2 = AVAILABLE(cand_up_left, B2) &&

                      !is_diff_mer(pps, xB2, yB2, x0, y0);

    if (is_available_b2 &&

        !(is_available_a1 && COMPARE_MV_REFIDX(B2, A1)) &&

        !(is_available_b1 && COMPARE_MV_REFIDX(B2, B1)) &&

        nb_merge_cand != 4) {

        mergecandlist[nb_merge_cand] = TAB_MVF_PU(B2);

        if (merge_idx == nb_merge_cand)

            return;

        nb_merge_cand++;

    }

    // 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 = { 0 }, mv_l1_col = { 0 };

        int available_l0 = temporal_luma_motion_vector(s, sps, x0, y0, nPbW, nPbH,

                                                       0, &mv_l0_col, 0);

        int available_l1 = (s->sh.slice_type == HEVC_SLICE_B) ?

                           temporal_luma_motion_vector(s, sps, x0, y0, nPbW, nPbH,

                                                       0, &mv_l1_col, 1) : 0;

        if (available_l0 || available_l1) {

            mergecandlist[nb_merge_cand].pred_flag = available_l0 + (available_l1 << 1);

            AV_ZERO16(mergecandlist[nb_merge_cand].ref_idx);

            mergecandlist[nb_merge_cand].mv[0]      = mv_l0_col;

            mergecandlist[nb_merge_cand].mv[1]      = mv_l1_col;

            if (merge_idx == nb_merge_cand)

                return;

            nb_merge_cand++;

        }

    }

    nb_orig_merge_cand = nb_merge_cand;

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

    if (s->sh.slice_type == HEVC_SLICE_B && 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 & PF_L0) && (l1_cand.pred_flag & PF_L1) &&

                (refPicList[0].list[l0_cand.ref_idx[0]] !=

                 refPicList[1].list[l1_cand.ref_idx[1]] ||

                 AV_RN32A(&l0_cand.mv[0]) != AV_RN32A(&l1_cand.mv[1]))) {

                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    = PF_BI;

                AV_COPY32(&mergecandlist[nb_merge_cand].mv[0], &l0_cand.mv[0]);

                AV_COPY32(&mergecandlist[nb_merge_cand].mv[1], &l1_cand.mv[1]);

                if (merge_idx == nb_merge_cand)

                    return;

                nb_merge_cand++;

            }

        }

    }

    // append Zero motion vector candidates

    while (nb_merge_cand < s->sh.max_num_merge_cand) {

        mergecandlist[nb_merge_cand].pred_flag    = PF_L0 + ((s->sh.slice_type == HEVC_SLICE_B) << 1);

        AV_ZERO32(mergecandlist[nb_merge_cand].mv + 0);

        AV_ZERO32(mergecandlist[nb_merge_cand].mv + 1);

        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;

        if (merge_idx == nb_merge_cand)

            return;

        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(HEVCLocalContext *lc, const HEVCPPS *pps,

                                int x0, int y0, int nPbW,

                                int nPbH, int log2_cb_size, int part_idx,

                                int merge_idx, MvField *mv)

{

    const HEVCSPS *const  sps = pps->sps;

    const HEVCContext *const s = lc->parent;

    int singleMCLFlag = 0;

    int nCS = 1 << log2_cb_size;

    MvField mergecand_list[MRG_MAX_NUM_CANDS];

    int nPbW2 = nPbW;

    int nPbH2 = nPbH;

    if (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(lc, x0, y0, nPbW, nPbH, sps->log2_ctb_size);

    derive_spatial_merge_candidates(lc, s, pps, sps, x0, y0, nPbW, nPbH, log2_cb_size,

                                    singleMCLFlag, part_idx,

                                    merge_idx, mergecand_list);

    if (mergecand_list[merge_idx].pred_flag == PF_BI &&

        (nPbW2 + nPbH2) == 12) {

        mergecand_list[merge_idx].pred_flag = PF_L0;

    }

    *mv = mergecand_list[merge_idx];

}

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

                                        int min_pu_width, int x, int y,

                                        int elist, int ref_idx_curr, int ref_idx)

{

    const RefPicList *refPicList = s->cur_frame->refPicList;

    const MvField *tab_mvf       = s->cur_frame->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(const HEVCContext *s, const HEVCSPS *sps,

                         int x, int y, int pred_flag_index,

                         Mv *mv, int ref_idx_curr, int ref_idx)

{

    const MvField *tab_mvf = s->cur_frame->tab_mvf;

    int min_pu_width = sps->min_pu_width;

    const RefPicList *refPicList = s->cur_frame->refPicList;

    if (((TAB_MVF(x, y).pred_flag) & (1 << pred_flag_index)) &&

        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(const HEVCContext *s, const HEVCSPS *sps,

                            int x, int y, int pred_flag_index,

                            Mv *mv, int ref_idx_curr, int ref_idx)

{

    const MvField *tab_mvf = s->cur_frame->tab_mvf;

    int min_pu_width = sps->min_pu_width;

    const RefPicList *refPicList = s->cur_frame->refPicList;

    if ((TAB_MVF(x, y).pred_flag) & (1 << pred_flag_index)) {

        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 (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, sps,                                       \

                  (x ## v) >> sps->log2_min_pu_size,            \

                  (y ## v) >> sps->log2_min_pu_size,            \

                  pred, &mx, ref_idx_curr, ref_idx)

#define MP_MX_LT(v, pred, mx)                                   \

    mv_mp_mode_mx_lt(s, sps,                                    \

                     (x ## v) >> sps->log2_min_pu_size,         \

                     (y ## v) >> sps->log2_min_pu_size,         \

                     pred, &mx, ref_idx_curr, ref_idx)

void ff_hevc_luma_mv_mvp_mode(HEVCLocalContext *lc, const HEVCPPS *pps,

                              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)

{

    const HEVCSPS *const  sps = pps->sps;

    const HEVCContext *const s = lc->parent;

    const MvField *const tab_mvf = s->cur_frame->tab_mvf;

    int isScaledFlag_L0 = 0;

    int availableFlagLXA0 = 1;

    int availableFlagLXB0 = 1;

    int numMVPCandLX = 0;

    int min_pu_width = sps->min_pu_width;

    int xA0, yA0;

    int is_available_a0;

    int xA1, yA1;

    int is_available_a1;

    int xB0, yB0;

    int is_available_b0;

    int xB1, yB1;

    int is_available_b1;

    int xB2, yB2;

    int is_available_b2;

    Mv mvpcand_list[2] = { { 0 } };

    Mv mxA;

    Mv mxB;

    int ref_idx_curr;

    int ref_idx = 0;

    int pred_flag_index_l0;

    int pred_flag_index_l1;

    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;

    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;

    is_available_a0 = AVAILABLE(cand_bottom_left, A0) &&

                      yA0 < sps->height &&

                      PRED_BLOCK_AVAILABLE(A0);

    //left spatial merge candidate

    xA1    = x0 - 1;

    yA1    = y0 + nPbH - 1;

    is_available_a1 = AVAILABLE(cand_left, A1);

    if (is_available_a0 || is_available_a1)

        isScaledFlag_L0 = 1;

    if (is_available_a0) {

        if (MP_MX(A0, pred_flag_index_l0, mxA)) {

            goto b_candidates;

        }

        if (MP_MX(A0, pred_flag_index_l1, mxA)) {

            goto b_candidates;

        }

    }

    if (is_available_a1) {

        if (MP_MX(A1, pred_flag_index_l0, mxA)) {

            goto b_candidates;

        }

        if (MP_MX(A1, pred_flag_index_l1, mxA)) {

            goto b_candidates;

        }

    }

    if (is_available_a0) {

        if (MP_MX_LT(A0, pred_flag_index_l0, mxA)) {

            goto b_candidates;

        }

        if (MP_MX_LT(A0, pred_flag_index_l1, mxA)) {

            goto b_candidates;

        }

    }

    if (is_available_a1) {

        if (MP_MX_LT(A1, pred_flag_index_l0, mxA)) {

            goto b_candidates;

        }

        if (MP_MX_LT(A1, pred_flag_index_l1, mxA)) {

            goto b_candidates;

        }

    }

    availableFlagLXA0 = 0;

b_candidates:

    // B candidates

    // above right spatial merge candidate

    xB0    = x0 + nPbW;

    yB0    = y0 - 1;

    is_available_b0 =  AVAILABLE(cand_up_right, B0) &&

                       xB0 < sps->width &&

                       PRED_BLOCK_AVAILABLE(B0);

    // above spatial merge candidate

    xB1    = x0 + nPbW - 1;

    yB1    = y0 - 1;

    is_available_b1 = AVAILABLE(cand_up, B1);

    // above left spatial merge candidate

    xB2 = x0 - 1;

    yB2 = y0 - 1;

    is_available_b2 = AVAILABLE(cand_up_left, B2);

    // above right spatial merge candidate

    if (is_available_b0) {

        if (MP_MX(B0, pred_flag_index_l0, mxB)) {

            goto scalef;

        }

        if (MP_MX(B0, pred_flag_index_l1, mxB)) {

            goto scalef;

        }

    }

    // above spatial merge candidate

    if (is_available_b1) {

        if (MP_MX(B1, pred_flag_index_l0, mxB)) {

            goto scalef;

        }

        if (MP_MX(B1, pred_flag_index_l1, mxB)) {

            goto scalef;

        }

    }

    // above left spatial merge candidate

    if (is_available_b2) {

        if (MP_MX(B2, pred_flag_index_l0, mxB)) {

            goto scalef;

        }

        if (MP_MX(B2, pred_flag_index_l1, mxB)) {

            goto scalef;

        }

    }

    availableFlagLXB0 = 0;

scalef:

    if (!isScaledFlag_L0) {

        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 &&

        mvp_lx_flag == numMVPCandLX) {

        Mv mv_col;

        int available_col = temporal_luma_motion_vector(s, sps, x0, y0, nPbW,

                                                        nPbH, ref_idx,

                                                        &mv_col, LX);

        if (available_col)

            mvpcand_list[numMVPCandLX++] = mv_col;

    }

    mv->mv[LX] = mvpcand_list[mvp_lx_flag];

}