/*

 * VVC motion vector decoder

 *

 * Copyright (C) 2023 Nuo Mi

 * Copyright (C) 2022 Xu Mu

 * 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 "ctu.h"

#include "data.h"

#include "refs.h"

#include "mvs.h"

#define IS_SAME_MV(a, b) (AV_RN64A(a) == AV_RN64A(b))

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

static av_always_inline int is_same_mer(const VVCFrameContext *fc, const int xN, const int yN, const int xP, const int yP)

{

    const uint8_t plevel = fc->ps.sps->log2_parallel_merge_level;

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

           yN >> plevel == yP >> plevel;

}

//return true if we have same mvs and ref_idxs

static av_always_inline int compare_mv_ref_idx(const MvField *n, const MvField *o)

{

    if (!o || n->pred_flag != o->pred_flag)

        return 0;

    for (int i = 0; i < 2; i++) {

        PredFlag mask = i + 1;

        if (n->pred_flag & mask) {

            const int same_ref_idx = n->ref_idx[i] == o->ref_idx[i];

            const int same_mv = IS_SAME_MV(n->mv + i, o->mv + i);

            if (!same_ref_idx || !same_mv)

                return 0;

        }

    }

    return 1;

}

// 8.5.2.15 Temporal motion buffer compression process for collocated motion vectors

static av_always_inline void mv_compression(Mv *motion)

{

    int mv[2] = {motion->x, motion->y};

    for (int i = 0; i < 2; i++) {

        const int s = mv[i] >> 17;

        const int f = av_log2((mv[i] ^ s) | 31) - 4;

        const int mask  = (-1 * (1 << f)) >> 1;

        const int round = (1 << f) >> 2;

        mv[i] = (mv[i] + round) & mask;

    }

    motion->x = mv[0];

    motion->y = mv[1];

}

void ff_vvc_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) >> 1)) / td;

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

    dst->x = av_clip_intp2((scale_factor * src->x + 127 +

                           (scale_factor * src->x < 0)) >> 8, 17);

    dst->y = av_clip_intp2((scale_factor * src->y + 127 +

                           (scale_factor * src->y < 0)) >> 8, 17);

}

//part of 8.5.2.12 Derivation process for collocated motion vectors

static int check_mvset(Mv *mvLXCol, 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].refs[refIdxLx].is_lt;

    int col_lt = refPicList_col[listCol].refs[refidxCol].is_lt;

    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].refs[refidxCol].poc;

    cur_poc_diff = poc    - refPicList[X].refs[refIdxLx].poc;

    mv_compression(mvCol);

    if (cur_lt || col_poc_diff == cur_poc_diff) {

        mvLXCol->x = av_clip_intp2(mvCol->x, 17);

        mvLXCol->y = av_clip_intp2(mvCol->y, 17);

    } else {

        ff_vvc_mv_scale(mvLXCol, mvCol, col_poc_diff, cur_poc_diff);

    }

    return 1;

}

#define CHECK_MVSET(l)                                          \

    check_mvset(mvLXCol, temp_col.mv + l,                       \

                colPic, fc->ps.ph.poc,                          \

                refPicList, X, refIdxLx,                        \

                refPicList_col, L ## l, temp_col.ref_idx[l])

//derive NoBackwardPredFlag

int ff_vvc_no_backward_pred_flag(const VVCLocalContext *lc)

{

    int check_diffpicount = 0;

    int i, j;

    const RefPicList *rpl = lc->sc->rpl;

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

        for (i = 0; i < lc->sc->sh.r->num_ref_idx_active[j]; i++) {

            if (rpl[j].refs[i].poc > lc->fc->ps.ph.poc) {

                check_diffpicount++;

                break;

            }

        }

    }

    return !check_diffpicount;

}

//8.5.2.12 Derivation process for collocated motion vectors

static int derive_temporal_colocated_mvs(const VVCLocalContext *lc, MvField temp_col,

                                         int refIdxLx, Mv *mvLXCol, int X,

                                         int colPic, const RefPicList *refPicList_col, int sb_flag)

{

    const VVCFrameContext *fc   = lc->fc;

    const SliceContext *sc      = lc->sc;

    RefPicList* refPicList      = sc->rpl;

    if (temp_col.pred_flag == PF_INTRA ||

        temp_col.pred_flag == PF_IBC   ||

        temp_col.pred_flag == PF_PLT)

        return 0;

    if (sb_flag){

        if (X == 0) {

            if (temp_col.pred_flag & PF_L0)

                return CHECK_MVSET(0);

            else if (ff_vvc_no_backward_pred_flag(lc) && (temp_col.pred_flag & PF_L1))

                return CHECK_MVSET(1);

        } else {

            if (temp_col.pred_flag & PF_L1)

                return CHECK_MVSET(1);

            else if (ff_vvc_no_backward_pred_flag(lc) && (temp_col.pred_flag & PF_L0))

                return CHECK_MVSET(0);

        }

    } else {

        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) {

            if (ff_vvc_no_backward_pred_flag(lc)) {

                if (X == 0)

                    return CHECK_MVSET(0);

                else

                    return CHECK_MVSET(1);

            } else {

                if (!lc->sc->sh.r->sh_collocated_from_l0_flag)

                    return CHECK_MVSET(0);

                else

                    return CHECK_MVSET(1);

            }

        }

    }

    return 0;

}

#define TAB_MVF(x, y)                                                   \

    tab_mvf[((y) >> MIN_PU_LOG2) * min_pu_width + ((x) >> MIN_PU_LOG2)]

#define TAB_MVF_PU(v)                                                   \

    TAB_MVF(x ## v, y ## v)

#define TAB_CP_MV(lx, x, y)                                              \

    fc->tab.cp_mv[lx][((((y) >> min_cb_log2_size) * min_cb_width + ((x) >> min_cb_log2_size)) ) * MAX_CONTROL_POINTS]

#define DERIVE_TEMPORAL_COLOCATED_MVS(sb_flag)                          \

    derive_temporal_colocated_mvs(lc, temp_col,                          \

                                  refIdxLx, mvLXCol, X, colPic,         \

                                  ff_vvc_get_ref_list(fc, ref, x, y), sb_flag)

//8.5.2.11 Derivation process for temporal luma motion vector prediction

static int temporal_luma_motion_vector(const VVCLocalContext *lc,

    const int refIdxLx, Mv *mvLXCol, const int X, int check_center, int sb_flag)

{

    const VVCFrameContext *fc = lc->fc;

    const VVCSPS *sps         = fc->ps.sps;

    const VVCPPS *pps         = fc->ps.pps;

    const CodingUnit *cu      = lc->cu;

    const int subpic_idx      = lc->sc->sh.r->curr_subpic_idx;

    int x, y, x_end, y_end, colPic, availableFlagLXCol = 0;

    int min_pu_width = fc->ps.pps->min_pu_width;

    VVCFrame *ref = fc->ref->collocated_ref;

    MvField *tab_mvf;

    MvField temp_col;

    if (!ref) {

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

        return 0;

    }

    if (!fc->ps.ph.r->ph_temporal_mvp_enabled_flag || (cu->cb_width * cu->cb_height <= 32))

        return 0;

    tab_mvf = ref->tab_dmvr_mvf;

    colPic  = ref->poc;

    //bottom right collocated motion vector

    x = cu->x0 + cu->cb_width;

    y = cu->y0 + cu->cb_height;

    x_end = pps->subpic_x[subpic_idx] + pps->subpic_width[subpic_idx];

    y_end = pps->subpic_y[subpic_idx] + pps->subpic_height[subpic_idx];

    if (tab_mvf &&

        (cu->y0 >> sps->ctb_log2_size_y) == (y >> sps->ctb_log2_size_y) &&

        x < x_end && y < y_end) {

        x                 &= ~7;

        y                 &= ~7;

        temp_col           = TAB_MVF(x, y);

        availableFlagLXCol = DERIVE_TEMPORAL_COLOCATED_MVS(sb_flag);

    }

    if (check_center) {

        // derive center collocated motion vector

        if (tab_mvf && !availableFlagLXCol) {

            x                  = cu->x0 + (cu->cb_width >> 1);

            y                  = cu->y0 + (cu->cb_height >> 1);

            x                 &= ~7;

            y                 &= ~7;

            temp_col           = TAB_MVF(x, y);

            availableFlagLXCol = DERIVE_TEMPORAL_COLOCATED_MVS(sb_flag);

        }

    }

    return availableFlagLXCol;

}

void ff_vvc_set_mvf(const VVCLocalContext *lc, const int x0, const int y0, const int w, const int h, const MvField *mvf)

{

    const VVCFrameContext *fc   = lc->fc;

    MvField *tab_mvf            = fc->tab.mvf;

    const int min_pu_width      = fc->ps.pps->min_pu_width;

    const int min_pu_size       = 1 << MIN_PU_LOG2;

    for (int dy = 0; dy < h; dy += min_pu_size) {

        for (int dx = 0; dx < w; dx += min_pu_size) {

            const int x = x0 + dx;

            const int y = y0 + dy;

            TAB_MVF(x, y) = *mvf;

        }

    }

}

void ff_vvc_set_intra_mvf(const VVCLocalContext *lc, const bool dmvr, const PredFlag pf, const bool ciip_flag)

{

    const VVCFrameContext *fc   = lc->fc;

    const CodingUnit *cu        = lc->cu;

    MvField *tab_mvf            = dmvr ? fc->ref->tab_dmvr_mvf : fc->tab.mvf;

    const int min_pu_width      = fc->ps.pps->min_pu_width;

    const int min_pu_size       = 1 << MIN_PU_LOG2;

    for (int dy = 0; dy < cu->cb_height; dy += min_pu_size) {

        for (int dx = 0; dx < cu->cb_width; dx += min_pu_size) {

            const int x = cu->x0 + dx;

            const int y = cu->y0 + dy;

            MvField *mv = &TAB_MVF(x, y);

            mv->pred_flag = pf;

            mv->ciip_flag = ciip_flag;

        }

    }

}

//cbProfFlagLX from 8.5.5.9 Derivation process for motion vector arrays from affine control point motion vectors

static int derive_cb_prof_flag_lx(const VVCLocalContext *lc, const PredictionUnit* pu, int lx, int is_fallback)

{

    const MotionInfo* mi    = &pu->mi;

    const Mv* cp_mv         = &mi->mv[lx][0];

    if (lc->fc->ps.ph.r->ph_prof_disabled_flag || is_fallback)

        return 0;

    if (mi->motion_model_idc == MOTION_4_PARAMS_AFFINE) {

        if (IS_SAME_MV(cp_mv, cp_mv + 1))

            return 0;

    }

    if (mi->motion_model_idc == MOTION_6_PARAMS_AFFINE) {

        if (IS_SAME_MV(cp_mv, cp_mv + 1) && IS_SAME_MV(cp_mv, cp_mv + 2))

            return 0;

    }

    if (lc->sc->rpl[lx].refs[mi->ref_idx[lx]].is_scaled)

        return 0;

    return 1;

}

typedef struct SubblockParams {

    int d_hor_x;

    int d_ver_x;

    int d_hor_y;

    int d_ver_y;

    int mv_scale_hor;

    int mv_scale_ver;

    int is_fallback;

    int cb_width;

    int cb_height;

} SubblockParams;

static int is_fallback_mode(const SubblockParams *sp, const PredFlag pred_flag)

{

    const int a = 4 * (2048 + sp->d_hor_x);

    const int b = 4 * sp->d_hor_y;

    const int c = 4 * (2048 + sp->d_ver_y);

    const int d = 4 * sp->d_ver_x;

    if (pred_flag == PF_BI) {

        const int max_w4 = FFMAX(0, FFMAX(a, FFMAX(b, a + b)));

        const int min_w4 = FFMIN(0, FFMIN(a, FFMIN(b, a + b)));

        const int max_h4 = FFMAX(0, FFMAX(c, FFMAX(d, c + d)));

        const int min_h4 = FFMIN(0, FFMIN(c, FFMIN(d, c + d)));

        const int bx_wx4 = ((max_w4 - min_w4) >> 11) + 9;

        const int bx_hx4 = ((max_h4 - min_h4) >> 11) + 9;

        return bx_wx4 * bx_hx4 > 225;

    } else {

        const int bx_wxh = (FFABS(a) >> 11) + 9;

        const int bx_hxh = (FFABS(d) >> 11) + 9;

        const int bx_wxv = (FFABS(b) >> 11) + 9;

        const int bx_hxv = (FFABS(c) >> 11) + 9;

        if (bx_wxh * bx_hxh <= 165 && bx_wxv * bx_hxv <= 165)

            return 0;

    }

    return 1;

}

static void init_subblock_params(SubblockParams *sp, const MotionInfo* mi,

    const int cb_width, const int cb_height, const int lx)

{

    const int log2_cbw  = av_log2(cb_width);

    const int log2_cbh  = av_log2(cb_height);

    const Mv* cp_mv     = mi->mv[lx];

    const int num_cp_mv = mi->motion_model_idc + 1;

    sp->d_hor_x = (cp_mv[1].x - cp_mv[0].x) * (1 << (MAX_CU_DEPTH - log2_cbw));

    sp->d_ver_x = (cp_mv[1].y - cp_mv[0].y) * (1 << (MAX_CU_DEPTH - log2_cbw));

    if (num_cp_mv == 3) {

        sp->d_hor_y = (cp_mv[2].x - cp_mv[0].x) * (1 << (MAX_CU_DEPTH - log2_cbh));

        sp->d_ver_y = (cp_mv[2].y - cp_mv[0].y) * (1 << (MAX_CU_DEPTH - log2_cbh));

    } else {

        sp->d_hor_y = -sp->d_ver_x;

        sp->d_ver_y = sp->d_hor_x;

    }

    sp->mv_scale_hor = (cp_mv[0].x) * (1 << MAX_CU_DEPTH);

    sp->mv_scale_ver = (cp_mv[0].y) * (1 << MAX_CU_DEPTH);

    sp->cb_width  = cb_width;

    sp->cb_height = cb_height;

    sp->is_fallback = is_fallback_mode(sp, mi->pred_flag);

}

static void derive_subblock_diff_mvs(const VVCLocalContext *lc, PredictionUnit* pu, const SubblockParams* sp, const int lx)

{

    pu->cb_prof_flag[lx] = derive_cb_prof_flag_lx(lc, pu, lx, sp->is_fallback);

    if (pu->cb_prof_flag[lx]) {

        const int dmv_limit = 1 << 5;

        const int pos_offset_x = 6 * (sp->d_hor_x + sp->d_hor_y);

        const int pos_offset_y = 6 * (sp->d_ver_x + sp->d_ver_y);

        for (int x = 0; x < AFFINE_MIN_BLOCK_SIZE; x++) {

            for (int y = 0; y < AFFINE_MIN_BLOCK_SIZE; y++) {

                LOCAL_ALIGNED_8(Mv, diff, [1]);

                diff->x = x * (sp->d_hor_x * (1 << 2)) + y * (sp->d_hor_y * (1 << 2)) - pos_offset_x;

                diff->y = x * (sp->d_ver_x * (1 << 2)) + y * (sp->d_ver_y * (1 << 2)) - pos_offset_y;

                ff_vvc_round_mv(diff, 0, 8);

                pu->diff_mv_x[lx][AFFINE_MIN_BLOCK_SIZE * y + x] = av_clip(diff->x, -dmv_limit + 1, dmv_limit - 1);

                pu->diff_mv_y[lx][AFFINE_MIN_BLOCK_SIZE * y + x] = av_clip(diff->y, -dmv_limit + 1, dmv_limit - 1);

            }

        }

    }

}

static void store_cp_mv(const VVCLocalContext *lc, const MotionInfo *mi, const int lx)

{

    VVCFrameContext *fc = lc->fc;

    const CodingUnit *cu = lc->cu;

    const int log2_min_cb_size = fc->ps.sps->min_cb_log2_size_y;

    const int min_cb_size = fc->ps.sps->min_cb_size_y;

    const int min_cb_width = fc->ps.pps->min_cb_width;

    const int num_cp_mv = mi->motion_model_idc + 1;

    for (int dy = 0; dy < cu->cb_height; dy += min_cb_size) {

        for (int dx = 0; dx < cu->cb_width; dx += min_cb_size) {

            const int x_cb = (cu->x0 + dx) >> log2_min_cb_size;

            const int y_cb = (cu->y0 + dy) >> log2_min_cb_size;

            const int offset = (y_cb * min_cb_width + x_cb) * MAX_CONTROL_POINTS;

            memcpy(&fc->tab.cp_mv[lx][offset], mi->mv[lx], sizeof(Mv) * num_cp_mv);

        }

    }

}

//8.5.5.9 Derivation process for motion vector arrays from affine control point motion vectors

void ff_vvc_store_sb_mvs(const VVCLocalContext *lc, PredictionUnit *pu)

{

    const CodingUnit *cu = lc->cu;

    const MotionInfo *mi = &pu->mi;

    const int sbw = cu->cb_width / mi->num_sb_x;

    const int sbh = cu->cb_height / mi->num_sb_y;

    SubblockParams params[2];

    MvField mvf = {0};

    mvf.pred_flag = mi->pred_flag;

    mvf.bcw_idx = mi->bcw_idx;

    mvf.hpel_if_idx = mi->hpel_if_idx;

    for (int i = 0; i < 2; i++) {

        const PredFlag mask = i + 1;

        if (mi->pred_flag & mask) {

            store_cp_mv(lc, mi, i);

            init_subblock_params(params + i, mi, cu->cb_width, cu->cb_height, i);

            derive_subblock_diff_mvs(lc, pu, params + i, i);

            mvf.ref_idx[i] = mi->ref_idx[i];

        }

    }

    for (int sby = 0; sby < mi->num_sb_y; sby++) {

        for (int sbx = 0; sbx < mi->num_sb_x; sbx++) {

            const int x0 = cu->x0 + sbx * sbw;

            const int y0 = cu->y0 + sby * sbh;

            for (int i = 0; i < 2; i++) {

                const PredFlag mask = i + 1;

                if (mi->pred_flag & mask) {

                    const SubblockParams* sp = params + i;

                    const int x_pos_cb = sp->is_fallback ? (cu->cb_width >> 1) : (2 + (sbx << MIN_CU_LOG2));

                    const int y_pos_cb = sp->is_fallback ? (cu->cb_height >> 1) : (2 + (sby << MIN_CU_LOG2));

                    Mv *mv = mvf.mv + i;

                    mv->x = sp->mv_scale_hor + sp->d_hor_x * x_pos_cb + sp->d_hor_y * y_pos_cb;

                    mv->y = sp->mv_scale_ver + sp->d_ver_x * x_pos_cb + sp->d_ver_y * y_pos_cb;

                    ff_vvc_round_mv(mv, 0, MAX_CU_DEPTH);

                    ff_vvc_clip_mv(mv);

                }

            }

            ff_vvc_set_mvf(lc, x0, y0, sbw, sbh, &mvf);

        }

    }

}

void ff_vvc_store_gpm_mvf(const VVCLocalContext *lc, const PredictionUnit *pu)

{

    const CodingUnit *cu     = lc->cu;

    const int angle_idx      = ff_vvc_gpm_angle_idx[pu->gpm_partition_idx];

    const int distance_idx   = ff_vvc_gpm_distance_idx[pu->gpm_partition_idx];

    const int displacement_x = ff_vvc_gpm_distance_lut[angle_idx];

    const int displacement_y = ff_vvc_gpm_distance_lut[(angle_idx + 8) % 32];

    const int is_flip        = angle_idx >= 13 &&angle_idx <= 27;

    const int shift_hor      = (angle_idx % 16 == 8 || (angle_idx % 16 && cu->cb_height >= cu->cb_width)) ? 0 : 1;

    const int sign           = angle_idx < 16 ? 1 : -1;

    const int block_size     = 4;

    int offset_x = (-cu->cb_width) >> 1;

    int offset_y = (-cu->cb_height) >> 1;

    if (!shift_hor)

        offset_y += sign * ((distance_idx * cu->cb_height) >> 3);

    else

        offset_x += sign * ((distance_idx * cu->cb_width) >> 3);

    for (int y = 0; y < cu->cb_height; y += block_size) {

        for (int x = 0; x < cu->cb_width; x += block_size) {

            const int motion_idx = (((x + offset_x) * (1 << 1)) + 5) * displacement_x +

                (((y + offset_y) * (1 << 1)) + 5) * displacement_y;

            const int s_type = FFABS(motion_idx) < 32 ? 2 : (motion_idx <= 0 ? (1 - is_flip) : is_flip);

            const int pred_flag = pu->gpm_mv[0].pred_flag | pu->gpm_mv[1].pred_flag;

            const int x0 = cu->x0 + x;

            const int y0 = cu->y0 + y;

            if (!s_type)

                ff_vvc_set_mvf(lc, x0, y0, block_size, block_size, pu->gpm_mv + 0);

            else if (s_type == 1 || (s_type == 2 && pred_flag != PF_BI))

                ff_vvc_set_mvf(lc, x0, y0, block_size, block_size, pu->gpm_mv + 1);

            else {

                MvField mvf  = pu->gpm_mv[0];

                const MvField *mv1 = &pu->gpm_mv[1];

                const int lx =  mv1->pred_flag - PF_L0;

                mvf.pred_flag = PF_BI;

                mvf.ref_idx[lx] = mv1->ref_idx[lx];

                mvf.mv[lx] = mv1->mv[lx];

                ff_vvc_set_mvf(lc, x0, y0, block_size, block_size, &mvf);

            }

        }

    }

}

void ff_vvc_store_mvf(const VVCLocalContext *lc, const MvField *mvf)

{

    const CodingUnit *cu = lc->cu;

    ff_vvc_set_mvf(lc, cu->x0, cu->y0, cu->cb_width, cu->cb_height, mvf);

}

void ff_vvc_store_mv(const VVCLocalContext *lc, const MotionInfo *mi)

{

    const CodingUnit *cu = lc->cu;

    MvField mvf = {0};

    mvf.hpel_if_idx = mi->hpel_if_idx;

    mvf.bcw_idx = mi->bcw_idx;

    mvf.pred_flag = mi->pred_flag;

    for (int i = 0; i < 2; i++) {

        const PredFlag mask = i + 1;

        if (mvf.pred_flag & mask) {

            mvf.mv[i] = mi->mv[i][0];

            mvf.ref_idx[i] = mi->ref_idx[i];

        }

    }

    ff_vvc_set_mvf(lc, cu->x0, cu->y0, cu->cb_width, cu->cb_height, &mvf);

}

typedef enum NeighbourIdx {

    A0,

    A1,

    A2,

    B0,

    B1,

    B2,

    B3,

    NUM_NBS,

    NB_IDX_NONE = NUM_NBS,

} NeighbourIdx;

typedef struct Neighbour {

    int x;

    int y;

    int checked;

    int available;

} Neighbour;

typedef struct NeighbourContext {

    Neighbour neighbours[NUM_NBS];

    const VVCLocalContext *lc;

} NeighbourContext;

static int is_available(const VVCFrameContext *fc, const int x0, const int y0)

{

    const VVCSPS *sps      = fc->ps.sps;

    const int x            = x0 >> sps->min_cb_log2_size_y;

    const int y            = y0 >> sps->min_cb_log2_size_y;

    const int min_cb_width = fc->ps.pps->min_cb_width;

    return SAMPLE_CTB(fc->tab.cb_width[0], x, y) != 0;

}

static int is_a0_available(const VVCLocalContext *lc, const CodingUnit *cu)

{

    const VVCFrameContext *fc   = lc->fc;

    const VVCSPS *sps           = fc->ps.sps;

    const int x0b               = av_zero_extend(cu->x0, sps->ctb_log2_size_y);

    int cand_bottom_left;

    if (!x0b && !lc->ctb_left_flag) {

        cand_bottom_left = 0;

    } else {

        const int max_y = FFMIN(fc->ps.pps->height, ((cu->y0 >> sps->ctb_log2_size_y) + 1) << sps->ctb_log2_size_y);

        if (cu->y0 + cu->cb_height >= max_y)

            cand_bottom_left = 0;

        else

            cand_bottom_left = is_available(fc, cu->x0 - 1, cu->y0 + cu->cb_height);

    }

    return cand_bottom_left;

}

static void init_neighbour_context(NeighbourContext *ctx, const VVCLocalContext *lc)

{

    const CodingUnit *cu            = lc->cu;

    const NeighbourAvailable *na    = &lc->na;

    const int x0                    = cu->x0;

    const int y0                    = cu->y0;

    const int cb_width              = cu->cb_width;

    const int cb_height             = cu->cb_height;

    const int a0_available          = is_a0_available(lc, cu);

    Neighbour neighbours[NUM_NBS] = {

        { x0 - 1,               y0 + cb_height,         !a0_available           }, //A0

        { x0 - 1,               y0 + cb_height - 1,     !na->cand_left          }, //A1

        { x0 - 1,               y0,                     !na->cand_left          }, //A2

        { x0 + cb_width,        y0 - 1,                 !na->cand_up_right      }, //B0

        { x0 + cb_width - 1,    y0 - 1,                 !na->cand_up            }, //B1

        { x0 - 1,               y0 - 1,                 !na->cand_up_left       }, //B2

        { x0,                   y0 - 1,                 !na->cand_up            }, //B3

    };

    memcpy(ctx->neighbours, neighbours, sizeof(neighbours));

    ctx->lc = lc;

}

static av_always_inline PredMode pred_flag_to_mode(PredFlag pred)

{

    static const PredMode lut[] = {

        MODE_INTRA, // PF_INTRA

        MODE_INTER, // PF_L0

        MODE_INTER, // PF_L1

        MODE_INTER, // PF_BI

        0,          // invalid

        MODE_IBC,   // PF_IBC

        0,          // invalid

        0,          // invalid

        MODE_PLT,   // PF_PLT

    };

    return lut[pred];

}

static int check_available(Neighbour *n, const VVCLocalContext *lc, const int check_mer)

{

    const VVCFrameContext *fc   = lc->fc;

    const VVCSPS *sps           = fc->ps.sps;

    const CodingUnit *cu        = lc->cu;

    const MvField *tab_mvf      = fc->tab.mvf;

    const int min_pu_width      = fc->ps.pps->min_pu_width;

    if (!n->checked) {

        n->checked = 1;

        n->available = !sps->r->sps_entropy_coding_sync_enabled_flag || ((n->x >> sps->ctb_log2_size_y) <= (cu->x0 >> sps->ctb_log2_size_y));

        n->available = n->available && is_available(fc, n->x, n->y) && cu->pred_mode == pred_flag_to_mode(TAB_MVF(n->x, n->y).pred_flag);

        if (check_mer)

            n->available = n->available && !is_same_mer(fc, n->x, n->y, cu->x0, cu->y0);

    }

    return n->available;

}

static const MvField *mv_merge_candidate(const VVCLocalContext *lc, const int x_cand, const int y_cand)

{

    const VVCFrameContext *fc   = lc->fc;

    const int min_pu_width      = fc->ps.pps->min_pu_width;

    const MvField* tab_mvf      = fc->tab.mvf;

    const MvField *mvf          = &TAB_MVF(x_cand, y_cand);

    return mvf;

}

static const MvField* mv_merge_from_nb(NeighbourContext *ctx, const NeighbourIdx nb)

{

    const VVCLocalContext *lc   = ctx->lc;

    Neighbour *n                = &ctx->neighbours[nb];

    if (check_available(n, lc, 1))

        return mv_merge_candidate(lc, n->x, n->y);

    return 0;

}

#define MV_MERGE_FROM_NB(nb) mv_merge_from_nb(&nctx, nb)

//8.5.2.3 Derivation process for spatial merging candidates

static int mv_merge_spatial_candidates(const VVCLocalContext *lc, const int merge_idx,

    const MvField **nb_list, MvField *cand_list, int *nb_merge_cand)

{

    const MvField *cand;

    int num_cands = 0;

    NeighbourContext nctx;

    static NeighbourIdx nbs[][2] = {

        {B1, NB_IDX_NONE },

        {A1, B1 },

        {B0, B1 },

        {A0, A1 },

    };

    init_neighbour_context(&nctx, lc);

    for (int i = 0; i < FF_ARRAY_ELEMS(nbs); i++) {

        NeighbourIdx nb    = nbs[i][0];

        NeighbourIdx old   = nbs[i][1];

        cand = nb_list[nb] = MV_MERGE_FROM_NB(nb);

        if (cand && !compare_mv_ref_idx(cand, nb_list[old])) {

            cand_list[num_cands] = *cand;

            if (merge_idx == num_cands)

                return 1;

            num_cands++;

        }

    }

    if (num_cands != 4) {

        cand = MV_MERGE_FROM_NB(B2);

        if (cand && !compare_mv_ref_idx(cand, nb_list[A1])

            && !compare_mv_ref_idx(cand, nb_list[B1])) {

            cand_list[num_cands] = *cand;

            if (merge_idx == num_cands)

                return 1;

            num_cands++;

        }

    }

    *nb_merge_cand = num_cands;

    return 0;

}

static int mv_merge_temporal_candidate(const VVCLocalContext *lc, MvField *cand)

{

    const VVCFrameContext *fc   = lc->fc;

    const CodingUnit *cu        = lc->cu;

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

    if (fc->ps.ph.r->ph_temporal_mvp_enabled_flag && (cu->cb_width * cu->cb_height > 32)) {

        int available_l0 = temporal_luma_motion_vector(lc, 0, cand->mv + 0, 0, 1, 0);

        int available_l1 = IS_B(lc->sc->sh.r) ?

            temporal_luma_motion_vector(lc, 0, cand->mv + 1, 1, 1, 0) : 0;

        cand->pred_flag = available_l0 + (available_l1 << 1);

    }

    return cand->pred_flag;

}

//8.5.2.6 Derivation process for history-based merging candidates

static int mv_merge_history_candidates(const VVCLocalContext *lc, const int merge_idx,

    const MvField **nb_list, MvField *cand_list, int *num_cands)

{

    const VVCSPS *sps       = lc->fc->ps.sps;

    const EntryPoint* ep    = lc->ep;

    for (int i = 1; i <= ep->num_hmvp && (*num_cands < sps->max_num_merge_cand - 1); i++) {

        const MvField *h = &ep->hmvp[ep->num_hmvp - i];

        const int same_motion = i <= 2 && (compare_mv_ref_idx(h, nb_list[A1]) || compare_mv_ref_idx(h, nb_list[B1]));

        if (!same_motion) {

            cand_list[*num_cands] = *h;

            if (merge_idx == *num_cands)

                return 1;

            (*num_cands)++;

        }

    }

    return 0;

}

//8.5.2.4 Derivation process for pairwise average merging candidate

static int mv_merge_pairwise_candidate(MvField *cand_list, const int num_cands, const int is_b)

{

    if (num_cands > 1) {

        const int num_ref_rists = is_b ? 2 : 1;

        const MvField* p0       = cand_list + 0;

        const MvField* p1       = cand_list + 1;

        MvField* cand           = cand_list + num_cands;

        cand->pred_flag = 0;

        for (int i = 0; i < num_ref_rists; i++) {

            PredFlag mask = i + 1;

            if (p0->pred_flag & mask) {

                cand->pred_flag |= mask;

                cand->ref_idx[i] = p0->ref_idx[i];

                if (p1->pred_flag & mask) {

                    Mv *mv = cand->mv + i;

                    mv->x = p0->mv[i].x + p1->mv[i].x;

                    mv->y = p0->mv[i].y + p1->mv[i].y;

                    ff_vvc_round_mv(mv, 0, 1);

                } else {

                    cand->mv[i] = p0->mv[i];

                }

            } else if (p1->pred_flag & mask) {

                cand->pred_flag |= mask;

                cand->mv[i] = p1->mv[i];

                cand->ref_idx[i] = p1->ref_idx[i];

            }

        }

        if (cand->pred_flag) {

            cand->hpel_if_idx = p0->hpel_if_idx == p1->hpel_if_idx ? p0->hpel_if_idx : 0;

            cand->bcw_idx = 0;

            cand->ciip_flag = 0;

            return 1;

        }

    }

    return 0;

}

//8.5.2.5 Derivation process for zero motion vector merging candidates

static void mv_merge_zero_motion_candidate(const VVCLocalContext *lc, const int merge_idx,

    MvField *cand_list, int num_cands)

{

    const VVCSPS *sps             = lc->fc->ps.sps;

    const H266RawSliceHeader *rsh = lc->sc->sh.r;

    const int num_ref_idx         = IS_P(rsh) ?

        rsh->num_ref_idx_active[L0] : FFMIN(rsh->num_ref_idx_active[L0], rsh->num_ref_idx_active[L1]);

    int zero_idx                  = 0;

    while (num_cands < sps->max_num_merge_cand) {

        MvField *cand = cand_list + num_cands;

        cand->pred_flag    = PF_L0 + (IS_B(rsh) << 1);

        AV_ZERO64(cand->mv + 0);

        AV_ZERO64(cand->mv + 1);

        cand->ref_idx[0]   = zero_idx < num_ref_idx ? zero_idx : 0;

        cand->ref_idx[1]   = zero_idx < num_ref_idx ? zero_idx : 0;

        cand->bcw_idx      = 0;

        cand->hpel_if_idx  = 0;

        if (merge_idx == num_cands)

            return;

        num_cands++;

        zero_idx++;

    }

}

static void mv_merge_mode(const VVCLocalContext *lc,  const int merge_idx, MvField *cand_list)

{

    int num_cands    = 0;

    const MvField *nb_list[NUM_NBS + 1] = { NULL };

    if (mv_merge_spatial_candidates(lc, merge_idx, nb_list, cand_list, &num_cands))

        return;

    if (mv_merge_temporal_candidate(lc, &cand_list[num_cands])) {

        if (merge_idx == num_cands)

            return;

        num_cands++;

    }

    if (mv_merge_history_candidates(lc, merge_idx, nb_list, cand_list, &num_cands))

        return;

    if (mv_merge_pairwise_candidate(cand_list, num_cands, IS_B(lc->sc->sh.r))) {

        if (merge_idx == num_cands)

            return;

        num_cands++;

    }

    mv_merge_zero_motion_candidate(lc, merge_idx, cand_list, num_cands);

}

//8.5.2.2 Derivation process for luma motion vectors for merge mode

void ff_vvc_luma_mv_merge_mode(VVCLocalContext *lc, const int merge_idx, const int ciip_flag, MvField *mv)

{

    const CodingUnit *cu = lc->cu;

    MvField cand_list[MRG_MAX_NUM_CANDS];

    ff_vvc_set_neighbour_available(lc, cu->x0, cu->y0, cu->cb_width, cu->cb_height);

    mv_merge_mode(lc, merge_idx, cand_list);

    *mv = cand_list[merge_idx];

    //ciip flag in not inhritable

    mv->ciip_flag = ciip_flag;

}

//8.5.4.2 Derivation process for luma motion vectors for geometric partitioning merge mode

void ff_vvc_luma_mv_merge_gpm(VVCLocalContext *lc, const int merge_gpm_idx[2], MvField *mv)

{

    const CodingUnit *cu = lc->cu;

    MvField cand_list[MRG_MAX_NUM_CANDS];

    const int idx[] = { merge_gpm_idx[0], merge_gpm_idx[1] + (merge_gpm_idx[1] >= merge_gpm_idx[0]) };

    ff_vvc_set_neighbour_available(lc, cu->x0, cu->y0, cu->cb_width, cu->cb_height);

    mv_merge_mode(lc, FFMAX(idx[0], idx[1]), cand_list);

    memset(mv, 0, 2 * sizeof(*mv));

    for (int i = 0; i < 2; i++) {

        int lx   = idx[i] & 1;

        int mask = lx + PF_L0;

        MvField *cand = cand_list + idx[i];

        if (!(cand->pred_flag & mask)) {

            lx   = !lx;

            mask = lx + PF_L0;

        }

        mv[i].pred_flag   = mask;

        mv[i].ref_idx[lx] = cand->ref_idx[lx];

        mv[i].mv[lx]      = cand->mv[lx];

    }

}

//8.5.5.5 Derivation process for luma affine control point motion vectors from a neighbouring block

static void affine_cps_from_nb(const VVCLocalContext *lc,

    const int x_nb, int y_nb, const int nbw, const int nbh, const int lx,

    Mv *cps, int num_cps)

{

    const VVCFrameContext *fc   = lc->fc;

    const CodingUnit *cu        = lc->cu;

    const int x0                = cu->x0;

    const int y0                = cu->y0;

    const int cb_width          = cu->cb_width;

    const int cb_height         = cu->cb_height;

    const MvField* tab_mvf      = fc->tab.mvf;

    const int min_cb_log2_size  = fc->ps.sps->min_cb_log2_size_y;

    const int min_cb_width      = fc->ps.pps->min_cb_width;

    const int log2_nbw          = ff_log2(nbw);

    const int log2_nbh          = ff_log2(nbh);

    const int is_ctb_boundary   = !((y_nb + nbh) % fc->ps.sps->ctb_size_y) && (y_nb + nbh == y0);

    const Mv *l, *r;

    int mv_scale_hor, mv_scale_ver, d_hor_x, d_ver_x, d_hor_y, d_ver_y, motion_model_idc_nb;

    if (is_ctb_boundary) {

        const int min_pu_width = fc->ps.pps->min_pu_width;

        l = &TAB_MVF(x_nb, y_nb + nbh - 1).mv[lx];

        r = &TAB_MVF(x_nb + nbw - 1, y_nb + nbh - 1).mv[lx];

    } else {

        const int x = x_nb >> min_cb_log2_size;

        const int y = y_nb >> min_cb_log2_size;

        motion_model_idc_nb  = SAMPLE_CTB(fc->tab.mmi, x, y);

        l = &TAB_CP_MV(lx, x_nb, y_nb);

        r = &TAB_CP_MV(lx, x_nb + nbw - 1, y_nb) + 1;

    }

    mv_scale_hor = l->x * (1 << 7);

    mv_scale_ver = l->y * (1 << 7);

    d_hor_x = (r->x - l->x) * (1 << (7 - log2_nbw));

    d_ver_x = (r->y - l->y) * (1 << (7 - log2_nbw));

    if (!is_ctb_boundary && motion_model_idc_nb == MOTION_6_PARAMS_AFFINE) {

        const Mv* lb = &TAB_CP_MV(lx, x_nb, y_nb + nbh - 1) + 2;

        d_hor_y = (lb->x - l->x) * (1 << (7 - log2_nbh));

        d_ver_y = (lb->y - l->y) * (1 << (7 - log2_nbh));

    } else {

        d_hor_y = -d_ver_x;

        d_ver_y = d_hor_x;

    }

    if (is_ctb_boundary) {

        y_nb = y0;

    }

    cps[0].x = mv_scale_hor + d_hor_x * (x0 - x_nb)  + d_hor_y * (y0 - y_nb);

    cps[0].y = mv_scale_ver + d_ver_x * (x0 - x_nb)  + d_ver_y * (y0 - y_nb);

    cps[1].x = mv_scale_hor + d_hor_x * (x0 + cb_width - x_nb)  + d_hor_y * (y0 - y_nb);

    cps[1].y = mv_scale_ver + d_ver_x * (x0 + cb_width - x_nb)  + d_ver_y * (y0 - y_nb);

    if (num_cps == 3) {

        cps[2].x = mv_scale_hor + d_hor_x * (x0 - x_nb)  + d_hor_y * (y0 + cb_height - y_nb);

        cps[2].y = mv_scale_ver + d_ver_x * (x0 - x_nb)  + d_ver_y * (y0 + cb_height - y_nb);

    }

    for (int i = 0; i < num_cps; i++) {

        ff_vvc_round_mv(cps + i, 0, 7);

        ff_vvc_clip_mv(cps + i);

    }

}

//derive affine neighbour's position, width and height,

static int affine_neighbour_cb(const VVCFrameContext *fc, const int x_nb, const int y_nb, int *x_cb, int *y_cb, int *cbw, int *cbh)

{

    const int log2_min_cb_size  = fc->ps.sps->min_cb_log2_size_y;

    const int min_cb_width      = fc->ps.pps->min_cb_width;

    const int x                 = x_nb >> log2_min_cb_size;

    const int y                 = y_nb >> log2_min_cb_size;

    const int motion_model_idc  = SAMPLE_CTB(fc->tab.mmi, x, y);

    if (motion_model_idc) {

        *x_cb = SAMPLE_CTB(fc->tab.cb_pos_x[0],  x, y);

        *y_cb = SAMPLE_CTB(fc->tab.cb_pos_y[0],  x, y);

        *cbw  = SAMPLE_CTB(fc->tab.cb_width[0],  x, y);

        *cbh  = SAMPLE_CTB(fc->tab.cb_height[0], x, y);

    }

    return motion_model_idc;

}

//part of 8.5.5.2 Derivation process for motion vectors and reference indices in subblock merge mode

static int affine_merge_candidate(const VVCLocalContext *lc, const int x_cand, const int y_cand, MotionInfo* mi)

{

    const VVCFrameContext *fc = lc->fc;

    int x, y, w, h, motion_model_idc;

    motion_model_idc = affine_neighbour_cb(fc, x_cand, y_cand, &x, &y, &w, &h);

    if (motion_model_idc) {

        const int min_pu_width = fc->ps.pps->min_pu_width;

        const MvField* tab_mvf = fc->tab.mvf;

        const MvField *mvf = &TAB_MVF(x, y);

        mi->bcw_idx   = mvf->bcw_idx;

        mi->pred_flag = mvf->pred_flag;

        for (int i = 0; i < 2; i++) {

            PredFlag mask = i + 1;

            if (mi->pred_flag & mask) {

                affine_cps_from_nb(lc, x, y, w, h, i, &mi->mv[i][0], motion_model_idc + 1);

            }

            mi->ref_idx[i] = mvf->ref_idx[i];

        }

        mi->motion_model_idc = motion_model_idc;

    }

    return motion_model_idc;

}

static int affine_merge_from_nbs(NeighbourContext *ctx, const NeighbourIdx *nbs, const int num_nbs, MotionInfo* cand)

{

    const VVCLocalContext *lc = ctx->lc;

    for (int i = 0; i < num_nbs; i++) {

        Neighbour *n = &ctx->neighbours[nbs[i]];

        if (check_available(n, lc, 1) && affine_merge_candidate(lc, n->x, n->y, cand))

            return 1;

    }

    return 0;

}

#define AFFINE_MERGE_FROM_NBS(nbs) affine_merge_from_nbs(&nctx, nbs, FF_ARRAY_ELEMS(nbs), mi)

static const MvField* derive_corner_mvf(NeighbourContext *ctx, const NeighbourIdx *neighbour, const int num_neighbour)

{

    const VVCFrameContext *fc   = ctx->lc->fc;

    const MvField *tab_mvf      = fc->tab.mvf;

    const int min_pu_width      = fc->ps.pps->min_pu_width;

    for (int i = 0; i < num_neighbour; i++) {

        Neighbour *n = &ctx->neighbours[neighbour[i]];

        if (check_available(n, ctx->lc, 1)) {

            return &TAB_MVF(n->x, n->y);