/*

 * Copyright (c) 2020, Alliance for Open Media. All rights reserved.

 *

 * This source code is subject to the terms of the BSD 2 Clause License and

 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License

 * was not distributed with this source code in the LICENSE file, you can

 * obtain it at www.aomedia.org/license/software. If the Alliance for Open

 * Media Patent License 1.0 was not distributed with this source code in the

 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.

 */

#include "av1/common/reconinter.h"

#include "av1/encoder/encodemv.h"

#include "av1/encoder/encoder.h"

#include "av1/encoder/interp_search.h"

#include "av1/encoder/mcomp.h"

#include "av1/encoder/motion_search_facade.h"

#include "av1/encoder/partition_strategy.h"

#include "av1/encoder/reconinter_enc.h"

#include "av1/encoder/tpl_model.h"

#include "av1/encoder/tx_search.h"

#define RIGHT_SHIFT_MV(x) (((x) + 3 + ((x) >= 0)) >> 3)

typedef struct {

  int_mv fmv;

  int weight;

} cand_mv_t;

static int compare_weight(const void *a, const void *b) {

  const int diff = ((cand_mv_t *)a)->weight - ((cand_mv_t *)b)->weight;

  if (diff < 0)

    return 1;

  else if (diff > 0)

    return -1;

  return 0;

}

// Allow more mesh searches for screen content type on the ARF.

static int use_fine_search_interval(const AV1_COMP *const cpi) {

  return cpi->is_screen_content_type &&

         cpi->ppi->gf_group.update_type[cpi->gf_frame_index] == ARF_UPDATE &&

         cpi->oxcf.speed <= 2;

}

// Iterate through the tpl and collect the mvs to be used as candidates

static inline void get_mv_candidate_from_tpl(const AV1_COMP *const cpi,

                                             const MACROBLOCK *x,

                                             BLOCK_SIZE bsize, int ref,

                                             cand_mv_t *cand, int *cand_count,

                                             int *total_cand_weight) {

  const SuperBlockEnc *sb_enc = &x->sb_enc;

  if (!sb_enc->tpl_data_count) {

    return;

  }

  const AV1_COMMON *cm = &cpi->common;

  const MACROBLOCKD *xd = &x->e_mbd;

  const int mi_row = xd->mi_row;

  const int mi_col = xd->mi_col;

  const BLOCK_SIZE tpl_bsize =

      convert_length_to_bsize(cpi->ppi->tpl_data.tpl_bsize_1d);

  const int tplw = mi_size_wide[tpl_bsize];

  const int tplh = mi_size_high[tpl_bsize];

  const int nw = mi_size_wide[bsize] / tplw;

  const int nh = mi_size_high[bsize] / tplh;

  if (nw >= 1 && nh >= 1) {

    const int of_h = mi_row % mi_size_high[cm->seq_params->sb_size];

    const int of_w = mi_col % mi_size_wide[cm->seq_params->sb_size];

    const int start = of_h / tplh * sb_enc->tpl_stride + of_w / tplw;

    int valid = 1;

    // Assign large weight to start_mv, so it is always tested.

    cand[0].weight = nw * nh;

    for (int k = 0; k < nh; k++) {

      for (int l = 0; l < nw; l++) {

        const int_mv mv =

            sb_enc

                ->tpl_mv[start + k * sb_enc->tpl_stride + l][ref - LAST_FRAME];

        if (mv.as_int == INVALID_MV) {

          valid = 0;

          break;

        }

        const FULLPEL_MV fmv = { GET_MV_RAWPEL(mv.as_mv.row),

                                 GET_MV_RAWPEL(mv.as_mv.col) };

        int unique = 1;

        for (int m = 0; m < *cand_count; m++) {

          if (RIGHT_SHIFT_MV(fmv.row) ==

                  RIGHT_SHIFT_MV(cand[m].fmv.as_fullmv.row) &&

              RIGHT_SHIFT_MV(fmv.col) ==

                  RIGHT_SHIFT_MV(cand[m].fmv.as_fullmv.col)) {

            unique = 0;

            cand[m].weight++;

            break;

          }

        }

        if (unique) {

          cand[*cand_count].fmv.as_fullmv = fmv;

          cand[*cand_count].weight = 1;

          (*cand_count)++;

        }

      }

      if (!valid) break;

    }

    if (valid) {

      *total_cand_weight = 2 * nh * nw;

      if (*cand_count > 2)

        qsort(cand, *cand_count, sizeof(cand[0]), &compare_weight);

    }

  }

}

void av1_single_motion_search(const AV1_COMP *const cpi, MACROBLOCK *x,

                              BLOCK_SIZE bsize, int ref_idx, int *rate_mv,

                              int search_range, inter_mode_info *mode_info,

                              int_mv *best_mv,

                              struct HandleInterModeArgs *const args) {

  MACROBLOCKD *xd = &x->e_mbd;

  const AV1_COMMON *cm = &cpi->common;

  const MotionVectorSearchParams *mv_search_params = &cpi->mv_search_params;

  const int num_planes = av1_num_planes(cm);

  MB_MODE_INFO *mbmi = xd->mi[0];

  struct buf_2d backup_yv12[MAX_MB_PLANE] = { { 0, 0, 0, 0, 0 } };

  int bestsme = INT_MAX;

  const int ref = mbmi->ref_frame[ref_idx];

  const YV12_BUFFER_CONFIG *scaled_ref_frame =

      av1_get_scaled_ref_frame(cpi, ref);

  const int mi_row = xd->mi_row;

  const int mi_col = xd->mi_col;

  const MvCosts *mv_costs = x->mv_costs;

  if (scaled_ref_frame) {

    // Swap out the reference frame for a version that's been scaled to

    // match the resolution of the current frame, allowing the existing

    // full-pixel motion search code to be used without additional

    // modifications.

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

      backup_yv12[i] = xd->plane[i].pre[ref_idx];

    }

    av1_setup_pre_planes(xd, ref_idx, scaled_ref_frame, mi_row, mi_col, NULL,

                         num_planes);

  }

  // Work out the size of the first step in the mv step search.

  // 0 here is maximum length first step. 1 is AOMMAX >> 1 etc.

  int step_param;

  if (cpi->sf.mv_sf.auto_mv_step_size && cm->show_frame) {

    // Take the weighted average of the step_params based on the last frame's

    // max mv magnitude and that based on the best ref mvs of the current

    // block for the given reference.

    step_param = (av1_init_search_range(x->max_mv_context[ref]) +

                  mv_search_params->mv_step_param) /

                 2;

  } else {

    step_param = mv_search_params->mv_step_param;

  }

  const MV ref_mv = av1_get_ref_mv(x, ref_idx).as_mv;

  FULLPEL_MV start_mv;

  if (mbmi->motion_mode != SIMPLE_TRANSLATION)

    start_mv = get_fullmv_from_mv(&mbmi->mv[0].as_mv);

  else

    start_mv = get_fullmv_from_mv(&ref_mv);

  const FULLPEL_MV fullpel_ref_mv = start_mv;

  // cand stores start_mv and all possible MVs in a SB.

  cand_mv_t cand[MAX_TPL_BLK_IN_SB * MAX_TPL_BLK_IN_SB + 1];

  av1_zero(cand);

  cand[0].fmv.as_fullmv = start_mv;

  int cnt = 1;

  int total_weight = 0;

  if (!cpi->sf.mv_sf.full_pixel_search_level &&

      mbmi->motion_mode == SIMPLE_TRANSLATION) {

    get_mv_candidate_from_tpl(cpi, x, bsize, ref, cand, &cnt, &total_weight);

  }

  const int cand_cnt = AOMMIN(2, cnt);

  // TODO(any): Test the speed feature for OBMC_CAUSAL mode.

  if (cpi->sf.mv_sf.skip_fullpel_search_using_startmv_refmv &&

      mbmi->motion_mode == SIMPLE_TRANSLATION) {

    for (int cand_idx = 0; cand_idx < cand_cnt; cand_idx++) {

      int_mv *fmv_cand = &cand[cand_idx].fmv;

      int skip_cand_mv = 0;

      // Check difference between mvs in the stack and candidate mv.

      for (int stack_idx = 0; stack_idx < args->start_mv_cnt; stack_idx++) {

        uint8_t this_ref_mv_idx = args->ref_mv_idx_stack[stack_idx];

        const int this_newmv_valid =

            args->single_newmv_valid[this_ref_mv_idx][ref];

        if (!this_newmv_valid && this_ref_mv_idx != mbmi->ref_mv_idx) continue;

        const FULLPEL_MV *fmv_stack = &args->start_mv_stack[stack_idx];

        const int start_mv_row_diff =

            abs(fmv_stack->row - fmv_cand->as_fullmv.row);

        const int start_mv_col_diff =

            abs(fmv_stack->col - fmv_cand->as_fullmv.col);

        if (mbmi->mode == NEAR_NEWMV || mbmi->mode == NEW_NEARMV) {

          assert(has_second_ref(mbmi));

          this_ref_mv_idx += 1;

        }

        const MV this_ref_mv =

            av1_get_ref_mv_from_stack(ref_idx, mbmi->ref_frame, this_ref_mv_idx,

                                      &x->mbmi_ext)

                .as_mv;

        assert(IMPLIES(args->ref_mv_idx_stack[stack_idx] == mbmi->ref_mv_idx,

                       this_ref_mv.row == ref_mv.row));

        assert(IMPLIES(args->ref_mv_idx_stack[stack_idx] == mbmi->ref_mv_idx,

                       this_ref_mv.col == ref_mv.col));

        const FULLPEL_MV this_fullpel_ref_mv = get_fullmv_from_mv(&this_ref_mv);

        const int ref_mv_row_diff =

            abs(this_fullpel_ref_mv.row - fullpel_ref_mv.row);

        const int ref_mv_col_diff =

            abs(this_fullpel_ref_mv.col - fullpel_ref_mv.col);

        if (cpi->sf.mv_sf.skip_fullpel_search_using_startmv_refmv >= 2) {

          // Prunes the current start_mv candidate, if the absolute mv

          // difference of both row and column are <= 1.

          if (start_mv_row_diff <= 1 && start_mv_col_diff <= 1 &&

              ref_mv_row_diff <= 1 && ref_mv_col_diff <= 1) {

            skip_cand_mv = 1;

            break;

          }

        } else if (cpi->sf.mv_sf.skip_fullpel_search_using_startmv_refmv >= 1) {

          // Prunes the current start_mv candidate, if the sum of the absolute

          // mv difference of row and column is <= 1.

          if ((start_mv_row_diff + start_mv_col_diff <= 1) &&

              (ref_mv_row_diff + ref_mv_col_diff <= 1)) {

            skip_cand_mv = 1;

            break;

          }

        }

      }

      if (skip_cand_mv) {

        // Mark the candidate mv as invalid so that motion search gets skipped.

        cand[cand_idx].fmv.as_int = INVALID_MV;

      } else {

        // Store start_mv candidate and corresponding ref_mv_idx of full-pel

        // search in the mv stack.

        assert(args->start_mv_cnt < MAX_REF_MV_SEARCH * 2);

        args->start_mv_stack[args->start_mv_cnt] = fmv_cand->as_fullmv;

        args->ref_mv_idx_stack[args->start_mv_cnt] = mbmi->ref_mv_idx;

        args->start_mv_cnt++;

      }

    }

  }

  // Hot fix for asan complaints when resize mode is on. When resize mode is on,

  // the stride of the reference frame can be different from indicated by

  // MotionVectorSearchParams::search_site_cfg. When this happens, we need to

  // readjust the stride.

  const MV_SPEED_FEATURES *mv_sf = &cpi->sf.mv_sf;

  const SEARCH_METHODS search_method =

      av1_get_default_mv_search_method(x, mv_sf, bsize);

  const search_site_config *src_search_site_cfg =

      av1_get_search_site_config(cpi, x, search_method);

  // Further reduce the search range.

  if (search_range < INT_MAX) {

    const search_site_config *search_site_cfg =

        &src_search_site_cfg[search_method_lookup[search_method]];

    // Max step_param is search_site_cfg->num_search_steps.

    if (search_range < 1) {

      step_param = search_site_cfg->num_search_steps;

    } else {

      while (search_site_cfg->radius[search_site_cfg->num_search_steps -

                                     step_param - 1] > (search_range << 1) &&

             search_site_cfg->num_search_steps - step_param - 1 > 0)

        step_param++;

    }

  }

  int cost_list[5];

  FULLPEL_MV_STATS best_mv_stats;

  int_mv second_best_mv;

  best_mv->as_int = second_best_mv.as_int = INVALID_MV;

  // Allow more mesh searches for screen content type on the ARF.

  const int fine_search_interval = use_fine_search_interval(cpi);

  FULLPEL_MOTION_SEARCH_PARAMS full_ms_params;

  switch (mbmi->motion_mode) {

    case SIMPLE_TRANSLATION: {

      // Perform a search with the top 2 candidates

      int sum_weight = 0;

      for (int m = 0; m < cand_cnt; m++) {

        int_mv smv = cand[m].fmv;

        FULLPEL_MV this_best_mv, this_second_best_mv;

        FULLPEL_MV_STATS this_mv_stats;

        if (smv.as_int == INVALID_MV) continue;

        av1_make_default_fullpel_ms_params(

            &full_ms_params, cpi, x, bsize, &ref_mv, smv.as_fullmv,

            src_search_site_cfg, search_method, fine_search_interval);

        const int thissme =

            av1_full_pixel_search(smv.as_fullmv, &full_ms_params, step_param,

                                  cond_cost_list(cpi, cost_list), &this_best_mv,

                                  &this_mv_stats, &this_second_best_mv);

        if (thissme < bestsme) {

          bestsme = thissme;

          best_mv->as_fullmv = this_best_mv;

          best_mv_stats = this_mv_stats;

          second_best_mv.as_fullmv = this_second_best_mv;

        }

        sum_weight += cand[m].weight;

        if (4 * sum_weight > 3 * total_weight) break;

      }

    } break;

    case OBMC_CAUSAL:

      av1_make_default_fullpel_ms_params(&full_ms_params, cpi, x, bsize,

                                         &ref_mv, start_mv, src_search_site_cfg,

                                         search_method, fine_search_interval);

      bestsme = av1_obmc_full_pixel_search(start_mv, &full_ms_params,

                                           step_param, &best_mv->as_fullmv);

      break;

    default: assert(0 && "Invalid motion mode!\n");

  }

  if (best_mv->as_int == INVALID_MV) return;

  if (scaled_ref_frame) {

    // Swap back the original buffers for subpel motion search.

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

      xd->plane[i].pre[ref_idx] = backup_yv12[i];

    }

  }

  // Terminate search with the current ref_idx based on fullpel mv, rate cost,

  // and other know cost.

  if (cpi->sf.inter_sf.skip_newmv_in_drl >= 2 &&

      mbmi->motion_mode == SIMPLE_TRANSLATION &&

      best_mv->as_int != INVALID_MV) {

    int_mv this_mv;

    this_mv.as_mv = get_mv_from_fullmv(&best_mv->as_fullmv);

    const int ref_mv_idx = mbmi->ref_mv_idx;

    const int this_mv_rate =

        av1_mv_bit_cost(&this_mv.as_mv, &ref_mv, mv_costs->nmv_joint_cost,

                        mv_costs->mv_cost_stack, MV_COST_WEIGHT);

    mode_info[ref_mv_idx].full_search_mv.as_int = this_mv.as_int;

    mode_info[ref_mv_idx].full_mv_rate = this_mv_rate;

    mode_info[ref_mv_idx].full_mv_bestsme = bestsme;

    for (int prev_ref_idx = 0; prev_ref_idx < ref_mv_idx; ++prev_ref_idx) {

      // Check if the motion search result same as previous results

      if (this_mv.as_int == mode_info[prev_ref_idx].full_search_mv.as_int) {

        // Compare the rate cost

        const int prev_rate_cost = mode_info[prev_ref_idx].full_mv_rate +

                                   mode_info[prev_ref_idx].drl_cost;

        const int this_rate_cost =

            this_mv_rate + mode_info[ref_mv_idx].drl_cost;

        if (prev_rate_cost <= this_rate_cost) {

          // If the current rate_cost is worse than the previous rate_cost, then

          // we terminate the search. Since av1_single_motion_search is only

          // called by handle_new_mv in SIMPLE_TRANSLATION mode, we set the

          // best_mv to INVALID mv to signal that we wish to terminate search

          // for the current mode.

          best_mv->as_int = INVALID_MV;

          return;

        }

      }

      // Terminate the evaluation of current ref_mv_idx based on bestsme and

      // drl_cost.

      const int psme = mode_info[prev_ref_idx].full_mv_bestsme;

      if (psme == INT_MAX) continue;

      const int thr =

          cpi->sf.inter_sf.skip_newmv_in_drl == 3 ? (psme + (psme >> 2)) : psme;

      if (cpi->sf.inter_sf.skip_newmv_in_drl >= 3 &&

          mode_info[ref_mv_idx].full_mv_bestsme > thr &&

          mode_info[prev_ref_idx].drl_cost < mode_info[ref_mv_idx].drl_cost) {

        best_mv->as_int = INVALID_MV;

        return;

      }

    }

  }

  if (cpi->common.features.cur_frame_force_integer_mv) {

    convert_fullmv_to_mv(best_mv);

  }

  const int use_fractional_mv =

      bestsme < INT_MAX && cpi->common.features.cur_frame_force_integer_mv == 0;

  int best_mv_rate = 0;

  int mv_rate_calculated = 0;

  if (use_fractional_mv) {

    int_mv fractional_ms_list[3];

    av1_set_fractional_mv(fractional_ms_list);

    int dis; /* TODO: use dis in distortion calculation later. */

    SUBPEL_MOTION_SEARCH_PARAMS ms_params;

    av1_make_default_subpel_ms_params(&ms_params, cpi, x, bsize, &ref_mv,

                                      cost_list);

    MV subpel_start_mv = get_mv_from_fullmv(&best_mv->as_fullmv);

    assert(av1_is_subpelmv_in_range(&ms_params.mv_limits, subpel_start_mv));

    switch (mbmi->motion_mode) {

      case SIMPLE_TRANSLATION:

        if (mv_sf->use_accurate_subpel_search) {

          const int try_second = second_best_mv.as_int != INVALID_MV &&

                                 second_best_mv.as_int != best_mv->as_int &&

                                 (mv_sf->disable_second_mv <= 1);

          const int best_mv_var = mv_search_params->find_fractional_mv_step(

              xd, cm, &ms_params, subpel_start_mv, &best_mv_stats,

              &best_mv->as_mv, &dis, &x->pred_sse[ref], fractional_ms_list);

          if (try_second) {

            struct macroblockd_plane *p = xd->plane;

            const BUFFER_SET orig_dst = {

              { p[0].dst.buf, p[1].dst.buf, p[2].dst.buf },

              { p[0].dst.stride, p[1].dst.stride, p[2].dst.stride },

            };

            MV this_best_mv;

            subpel_start_mv = get_mv_from_fullmv(&second_best_mv.as_fullmv);

            if (av1_is_subpelmv_in_range(&ms_params.mv_limits,

                                         subpel_start_mv)) {

              unsigned int sse;

              const int this_var = mv_search_params->find_fractional_mv_step(

                  xd, cm, &ms_params, subpel_start_mv, NULL, &this_best_mv,

                  &dis, &sse, fractional_ms_list);

              // If cpi->sf.mv_sf.disable_second_mv is 0 and both MVs are valid,

              // use actual rd cost to choose the better MV.

              if (!mv_sf->disable_second_mv && this_var != INT32_MAX) {

                // Calculate rd cost of first MV.

                mbmi->mv[0].as_mv = best_mv->as_mv;

                av1_enc_build_inter_predictor(cm, xd, mi_row, mi_col, &orig_dst,

                                              bsize, 0, 0);

                RD_STATS this_rd_stats;

                av1_init_rd_stats(&this_rd_stats);

                av1_estimate_txfm_yrd(cpi, x, &this_rd_stats, INT64_MAX, bsize,

                                      max_txsize_rect_lookup[bsize]);

                int this_mv_rate = av1_mv_bit_cost(

                    &best_mv->as_mv, &ref_mv, mv_costs->nmv_joint_cost,

                    mv_costs->mv_cost_stack, MV_COST_WEIGHT);

                const int64_t rd =

                    RDCOST(x->rdmult, this_mv_rate + this_rd_stats.rate,

                           this_rd_stats.dist);

                // Calculate rd cost of second MV.

                mbmi->mv[0].as_mv = this_best_mv;

                av1_enc_build_inter_predictor(cm, xd, mi_row, mi_col, &orig_dst,

                                              bsize, 0, 0);

                RD_STATS tmp_rd_stats;

                av1_init_rd_stats(&tmp_rd_stats);

                av1_estimate_txfm_yrd(cpi, x, &tmp_rd_stats, INT64_MAX, bsize,

                                      max_txsize_rect_lookup[bsize]);

                int tmp_mv_rate = av1_mv_bit_cost(

                    &this_best_mv, &ref_mv, mv_costs->nmv_joint_cost,

                    mv_costs->mv_cost_stack, MV_COST_WEIGHT);

                int64_t tmp_rd =

                    RDCOST(x->rdmult, tmp_rd_stats.rate + tmp_mv_rate,

                           tmp_rd_stats.dist);

                if (tmp_rd < rd) {

                  best_mv->as_mv = this_best_mv;

                  x->pred_sse[ref] = sse;

                }

              } else {

                // If cpi->sf.mv_sf.disable_second_mv = 1, use var to decide the

                // best MV.

                if (this_var < best_mv_var) {

                  best_mv->as_mv = this_best_mv;

                  x->pred_sse[ref] = sse;

                }

              }

            }

          }

        } else {

          mv_search_params->find_fractional_mv_step(

              xd, cm, &ms_params, subpel_start_mv, &best_mv_stats,

              &best_mv->as_mv, &dis, &x->pred_sse[ref], NULL);

        }

        break;

      case OBMC_CAUSAL:

        av1_find_best_obmc_sub_pixel_tree_up(

            xd, cm, &ms_params, subpel_start_mv, NULL, &best_mv->as_mv, &dis,

            &x->pred_sse[ref], NULL);

        break;

      default: assert(0 && "Invalid motion mode!\n");

    }

    // Terminate search with the current ref_idx based on subpel mv and rate

    // cost.

    if (cpi->sf.inter_sf.skip_newmv_in_drl >= 1 && args != NULL &&

        mbmi->motion_mode == SIMPLE_TRANSLATION &&

        best_mv->as_int != INVALID_MV) {

      const int ref_mv_idx = mbmi->ref_mv_idx;

      best_mv_rate =

          av1_mv_bit_cost(&best_mv->as_mv, &ref_mv, mv_costs->nmv_joint_cost,

                          mv_costs->mv_cost_stack, MV_COST_WEIGHT);

      mv_rate_calculated = 1;

      for (int prev_ref_idx = 0; prev_ref_idx < ref_mv_idx; ++prev_ref_idx) {

        if (!args->single_newmv_valid[prev_ref_idx][ref]) continue;

        // Check if the motion vectors are the same.

        if (best_mv->as_int == args->single_newmv[prev_ref_idx][ref].as_int) {

          // Skip this evaluation if the previous one is skipped.

          if (mode_info[prev_ref_idx].skip) {

            mode_info[ref_mv_idx].skip = 1;

            break;

          }

          // Compare the rate cost that we current know.

          const int prev_rate_cost =

              args->single_newmv_rate[prev_ref_idx][ref] +

              mode_info[prev_ref_idx].drl_cost;

          const int this_rate_cost =

              best_mv_rate + mode_info[ref_mv_idx].drl_cost;

          if (prev_rate_cost <= this_rate_cost) {

            // If the current rate_cost is worse than the previous rate_cost,

            // then we terminate the search for this ref_mv_idx.

            mode_info[ref_mv_idx].skip = 1;

            break;

          }

        }

      }

    }

  }

  if (mv_rate_calculated) {

    *rate_mv = best_mv_rate;

  } else {

    *rate_mv =

        av1_mv_bit_cost(&best_mv->as_mv, &ref_mv, mv_costs->nmv_joint_cost,

                        mv_costs->mv_cost_stack, MV_COST_WEIGHT);

  }

}

int av1_joint_motion_search(const AV1_COMP *cpi, MACROBLOCK *x,

                            BLOCK_SIZE bsize, int_mv *cur_mv,

                            const uint8_t *mask, int mask_stride, int *rate_mv,

                            int allow_second_mv, int joint_me_num_refine_iter) {

  const AV1_COMMON *const cm = &cpi->common;

  const int num_planes = av1_num_planes(cm);

  const int pw = block_size_wide[bsize];

  const int ph = block_size_high[bsize];

  const int plane = 0;

  MACROBLOCKD *xd = &x->e_mbd;

  MB_MODE_INFO *mbmi = xd->mi[0];

  // This function should only ever be called for compound modes

  assert(has_second_ref(mbmi));

  const int_mv init_mv[2] = { cur_mv[0], cur_mv[1] };

  const int refs[2] = { mbmi->ref_frame[0], mbmi->ref_frame[1] };

  const MvCosts *mv_costs = x->mv_costs;

  int_mv ref_mv[2];

  int ite, ref;

  // Get the prediction block from the 'other' reference frame.

  const int_interpfilters interp_filters =

      av1_broadcast_interp_filter(EIGHTTAP_REGULAR);

  InterPredParams inter_pred_params;

  const int mi_row = xd->mi_row;

  const int mi_col = xd->mi_col;

  // Do joint motion search in compound mode to get more accurate mv.

  struct buf_2d backup_yv12[2][MAX_MB_PLANE];

  int last_besterr[2] = { INT_MAX, INT_MAX };

  const YV12_BUFFER_CONFIG *const scaled_ref_frame[2] = {

    av1_get_scaled_ref_frame(cpi, refs[0]),

    av1_get_scaled_ref_frame(cpi, refs[1])

  };

  // Prediction buffer from second frame.

  DECLARE_ALIGNED(16, uint8_t, second_pred16[MAX_SB_SQUARE * sizeof(uint16_t)]);

  uint8_t *second_pred = get_buf_by_bd(xd, second_pred16);

  int_mv best_mv, second_best_mv;

  // Allow joint search multiple times iteratively for each reference frame

  // and break out of the search loop if it couldn't find a better mv.

  for (ite = 0; ite < (2 * joint_me_num_refine_iter); ite++) {

    struct buf_2d ref_yv12[2];

    int bestsme = INT_MAX;

    int id = ite % 2;  // Even iterations search in the first reference frame,

                       // odd iterations search in the second. The predictor

                       // found for the 'other' reference frame is factored in.

    if (ite >= 2 && cur_mv[!id].as_int == init_mv[!id].as_int) {

      if (cur_mv[id].as_int == init_mv[id].as_int) {

        break;

      } else {

        int_mv cur_int_mv, init_int_mv;

        cur_int_mv.as_mv.col = cur_mv[id].as_mv.col >> 3;

        cur_int_mv.as_mv.row = cur_mv[id].as_mv.row >> 3;

        init_int_mv.as_mv.row = init_mv[id].as_mv.row >> 3;

        init_int_mv.as_mv.col = init_mv[id].as_mv.col >> 3;

        if (cur_int_mv.as_int == init_int_mv.as_int) {

          break;

        }

      }

    }

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

      ref_mv[ref] = av1_get_ref_mv(x, ref);

      // Swap out the reference frame for a version that's been scaled to

      // match the resolution of the current frame, allowing the existing

      // motion search code to be used without additional modifications.

      if (scaled_ref_frame[ref]) {

        int i;

        for (i = 0; i < num_planes; i++)

          backup_yv12[ref][i] = xd->plane[i].pre[ref];

        av1_setup_pre_planes(xd, ref, scaled_ref_frame[ref], mi_row, mi_col,

                             NULL, num_planes);

      }

    }

    assert(IMPLIES(scaled_ref_frame[0] != NULL,

                   cm->width == scaled_ref_frame[0]->y_crop_width &&

                       cm->height == scaled_ref_frame[0]->y_crop_height));

    assert(IMPLIES(scaled_ref_frame[1] != NULL,

                   cm->width == scaled_ref_frame[1]->y_crop_width &&

                       cm->height == scaled_ref_frame[1]->y_crop_height));

    // Initialize based on (possibly scaled) prediction buffers.

    ref_yv12[0] = xd->plane[plane].pre[0];

    ref_yv12[1] = xd->plane[plane].pre[1];

    av1_init_inter_params(&inter_pred_params, pw, ph, mi_row * MI_SIZE,

                          mi_col * MI_SIZE, 0, 0, xd->bd, is_cur_buf_hbd(xd), 0,

                          &cm->sf_identity, &ref_yv12[!id], interp_filters);

    inter_pred_params.conv_params = get_conv_params(0, 0, xd->bd);

    // Since we have scaled the reference frames to match the size of the

    // current frame we must use a unit scaling factor during mode selection.

    av1_enc_build_one_inter_predictor(second_pred, pw, &cur_mv[!id].as_mv,

                                      &inter_pred_params);

    // Do full-pixel compound motion search on the current reference frame.

    if (id) xd->plane[plane].pre[0] = ref_yv12[id];

    // Make motion search params

    FULLPEL_MOTION_SEARCH_PARAMS full_ms_params;

    FULLPEL_MV_STATS best_mv_stats;

    const MV_SPEED_FEATURES *mv_sf = &cpi->sf.mv_sf;

    const SEARCH_METHODS search_method =

        av1_get_default_mv_search_method(x, mv_sf, bsize);

    const search_site_config *src_search_sites =

        av1_get_search_site_config(cpi, x, search_method);

    // Use the mv result from the single mode as mv predictor.

    const FULLPEL_MV start_fullmv = get_fullmv_from_mv(&cur_mv[id].as_mv);

    av1_make_default_fullpel_ms_params(&full_ms_params, cpi, x, bsize,

                                       &ref_mv[id].as_mv, start_fullmv,

                                       src_search_sites, search_method,

                                       /*fine_search_interval=*/0);

    av1_set_ms_compound_refs(&full_ms_params.ms_buffers, second_pred, mask,

                             mask_stride, id);

    // Small-range full-pixel motion search.

    if (!mv_sf->disable_extensive_joint_motion_search &&

        mbmi->interinter_comp.type != COMPOUND_WEDGE) {

      bestsme = av1_full_pixel_search(start_fullmv, &full_ms_params, 5, NULL,

                                      &best_mv.as_fullmv, &best_mv_stats,

                                      &second_best_mv.as_fullmv);

    } else {

      bestsme = av1_refining_search_8p_c(&full_ms_params, start_fullmv,

                                         &best_mv.as_fullmv);

      second_best_mv = best_mv;

    }

    const int try_second = second_best_mv.as_int != INVALID_MV &&

                           second_best_mv.as_int != best_mv.as_int &&

                           allow_second_mv;

    // Restore the pointer to the first (possibly scaled) prediction buffer.

    if (id) xd->plane[plane].pre[0] = ref_yv12[0];

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

      if (scaled_ref_frame[ref]) {

        // Swap back the original buffers for subpel motion search.

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

          xd->plane[i].pre[ref] = backup_yv12[ref][i];

        }

        // Re-initialize based on unscaled prediction buffers.

        ref_yv12[ref] = xd->plane[plane].pre[ref];

      }

    }

    // Do sub-pixel compound motion search on the current reference frame.

    if (id) xd->plane[plane].pre[0] = ref_yv12[id];

    if (cpi->common.features.cur_frame_force_integer_mv) {

      convert_fullmv_to_mv(&best_mv);

    }

    if (bestsme < INT_MAX &&

        cpi->common.features.cur_frame_force_integer_mv == 0) {

      int dis; /* TODO: use dis in distortion calculation later. */

      unsigned int sse;

      SUBPEL_MOTION_SEARCH_PARAMS ms_params;

      av1_make_default_subpel_ms_params(&ms_params, cpi, x, bsize,

                                        &ref_mv[id].as_mv, NULL);

      av1_set_ms_compound_refs(&ms_params.var_params.ms_buffers, second_pred,

                               mask, mask_stride, id);

      ms_params.forced_stop = EIGHTH_PEL;

      MV start_mv = get_mv_from_fullmv(&best_mv.as_fullmv);

      assert(av1_is_subpelmv_in_range(&ms_params.mv_limits, start_mv));

      bestsme = cpi->mv_search_params.find_fractional_mv_step(

          xd, cm, &ms_params, start_mv, NULL, &best_mv.as_mv, &dis, &sse, NULL);

      if (try_second) {

        MV this_best_mv;

        MV subpel_start_mv = get_mv_from_fullmv(&second_best_mv.as_fullmv);

        if (av1_is_subpelmv_in_range(&ms_params.mv_limits, subpel_start_mv)) {

          const int thissme = cpi->mv_search_params.find_fractional_mv_step(

              xd, cm, &ms_params, subpel_start_mv, NULL, &this_best_mv, &dis,

              &sse, NULL);

          if (thissme < bestsme) {

            best_mv.as_mv = this_best_mv;

            bestsme = thissme;

          }

        }

      }

    }

    // Restore the pointer to the first prediction buffer.

    if (id) xd->plane[plane].pre[0] = ref_yv12[0];

    if (bestsme < last_besterr[id]) {

      cur_mv[id] = best_mv;

      last_besterr[id] = bestsme;

    } else {

      break;

    }

  }

  *rate_mv = 0;

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

    const int_mv curr_ref_mv = av1_get_ref_mv(x, ref);

    *rate_mv += av1_mv_bit_cost(&cur_mv[ref].as_mv, &curr_ref_mv.as_mv,

                                mv_costs->nmv_joint_cost,

                                mv_costs->mv_cost_stack, MV_COST_WEIGHT);

  }

  return AOMMIN(last_besterr[0], last_besterr[1]);

}

// Search for the best mv for one component of a compound,

// given that the other component is fixed.

int av1_compound_single_motion_search(const AV1_COMP *cpi, MACROBLOCK *x,

                                      BLOCK_SIZE bsize, MV *this_mv,

                                      const uint8_t *second_pred,

                                      const uint8_t *mask, int mask_stride,

                                      int *rate_mv, int ref_idx) {

  const AV1_COMMON *const cm = &cpi->common;

  const int num_planes = av1_num_planes(cm);

  MACROBLOCKD *xd = &x->e_mbd;

  MB_MODE_INFO *mbmi = xd->mi[0];

  const int ref = mbmi->ref_frame[ref_idx];

  const int_mv ref_mv = av1_get_ref_mv(x, ref_idx);

  struct macroblockd_plane *const pd = &xd->plane[0];

  const MvCosts *mv_costs = x->mv_costs;

  struct buf_2d backup_yv12[MAX_MB_PLANE];

  const YV12_BUFFER_CONFIG *const scaled_ref_frame =

      av1_get_scaled_ref_frame(cpi, ref);

  // Check that this is either an interinter or an interintra block

  assert(has_second_ref(mbmi) || (ref_idx == 0 && is_interintra_mode(mbmi)));

  // Store the first prediction buffer.

  struct buf_2d orig_yv12;

  if (ref_idx) {

    orig_yv12 = pd->pre[0];

    pd->pre[0] = pd->pre[ref_idx];

  }

  if (scaled_ref_frame) {

    // Swap out the reference frame for a version that's been scaled to

    // match the resolution of the current frame, allowing the existing

    // full-pixel motion search code to be used without additional

    // modifications.

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

      backup_yv12[i] = xd->plane[i].pre[ref_idx];

    }

    const int mi_row = xd->mi_row;

    const int mi_col = xd->mi_col;

    // The index below needs to be 0 instead of ref_idx since we assume the

    // 0th slot to be used for subsequent searches. Note that the ref_idx

    // reference buffer has been copied to the 0th slot in the code above.

    // Now we need to swap the reference frame for the 0th slot.

    av1_setup_pre_planes(xd, 0, scaled_ref_frame, mi_row, mi_col, NULL,

                         num_planes);

  }

  int bestsme = INT_MAX;

  int_mv best_mv;

  // Make motion search params

  FULLPEL_MOTION_SEARCH_PARAMS full_ms_params;

  FULLPEL_MV_STATS best_mv_stats;

  const SEARCH_METHODS search_method =

      av1_get_default_mv_search_method(x, &cpi->sf.mv_sf, bsize);

  const search_site_config *src_search_sites =

      av1_get_search_site_config(cpi, x, search_method);

  // Use the mv result from the single mode as mv predictor.

  const FULLPEL_MV start_fullmv = get_fullmv_from_mv(this_mv);

  av1_make_default_fullpel_ms_params(&full_ms_params, cpi, x, bsize,

                                     &ref_mv.as_mv, start_fullmv,

                                     src_search_sites, search_method,

                                     /*fine_search_interval=*/0);

  av1_set_ms_compound_refs(&full_ms_params.ms_buffers, second_pred, mask,

                           mask_stride, ref_idx);

  // Small-range full-pixel motion search.

  bestsme = av1_full_pixel_search(start_fullmv, &full_ms_params, 5, NULL,

                                  &best_mv.as_fullmv, &best_mv_stats, NULL);

  if (scaled_ref_frame) {

    // Swap back the original buffers for subpel motion search for the 0th slot.

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

      xd->plane[i].pre[0] = backup_yv12[i];

    }

  }

  if (cpi->common.features.cur_frame_force_integer_mv) {

    convert_fullmv_to_mv(&best_mv);

  }

  const int use_fractional_mv =

      bestsme < INT_MAX && cpi->common.features.cur_frame_force_integer_mv == 0;

  if (use_fractional_mv) {

    int dis; /* TODO: use dis in distortion calculation later. */

    unsigned int sse;

    SUBPEL_MOTION_SEARCH_PARAMS ms_params;

    av1_make_default_subpel_ms_params(&ms_params, cpi, x, bsize, &ref_mv.as_mv,

                                      NULL);

    av1_set_ms_compound_refs(&ms_params.var_params.ms_buffers, second_pred,

                             mask, mask_stride, ref_idx);

    ms_params.forced_stop = EIGHTH_PEL;

    MV start_mv = get_mv_from_fullmv(&best_mv.as_fullmv);

    assert(av1_is_subpelmv_in_range(&ms_params.mv_limits, start_mv));

    bestsme = cpi->mv_search_params.find_fractional_mv_step(

        xd, cm, &ms_params, start_mv, &best_mv_stats, &best_mv.as_mv, &dis,

        &sse, NULL);

  }

  // Restore the pointer to the first unscaled prediction buffer.

  if (ref_idx) pd->pre[0] = orig_yv12;

  if (bestsme < INT_MAX) *this_mv = best_mv.as_mv;

  *rate_mv = 0;

  *rate_mv += av1_mv_bit_cost(this_mv, &ref_mv.as_mv, mv_costs->nmv_joint_cost,

                              mv_costs->mv_cost_stack, MV_COST_WEIGHT);

  return bestsme;

}

static inline void build_second_inter_pred(const AV1_COMP *cpi, MACROBLOCK *x,

                                           BLOCK_SIZE bsize, const MV *other_mv,