text: /*****************************************************************************
   * mvpred.c: motion vector prediction
   *****************************************************************************
   * Copyright (C) 2003-2011 x264 project
   *
   * Authors: Loren Merritt <lorenm@u.washington.edu>
   *          Jason Garrett-Glaser <darkshikari@gmail.com>
   *          Laurent Aimar <fenrir@via.ecp.fr>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program 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 General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA.
   *
   * This program is also available under a commercial proprietary license.
   * For more information, contact us at licensing@x264.com.
   *****************************************************************************/
  
  #include "common.h"
  
  void x264_mb_predict_mv( x264_t *h, int i_list, int idx, int i_width, int16_t mvp[2] )
  {
      const int i8 = x264_scan8[idx];
      const int i_ref= h->mb.cache.ref[i_list][i8];
      int     i_refa = h->mb.cache.ref[i_list][i8 - 1];
      int16_t *mv_a  = h->mb.cache.mv[i_list][i8 - 1];
      int     i_refb = h->mb.cache.ref[i_list][i8 - 8];
      int16_t *mv_b  = h->mb.cache.mv[i_list][i8 - 8];
      int     i_refc = h->mb.cache.ref[i_list][i8 - 8 + i_width];
      int16_t *mv_c  = h->mb.cache.mv[i_list][i8 - 8 + i_width];
  
      // Partitions not yet reached in scan order are unavailable.
      if( (idx&3) >= 2 + (i_width&1) || i_refc == -2 )
      {
          i_refc = h->mb.cache.ref[i_list][i8 - 8 - 1];
          mv_c   = h->mb.cache.mv[i_list][i8 - 8 - 1];
  
          if( SLICE_MBAFF
              && h->mb.cache.ref[i_list][x264_scan8[0]-1] != -2
              && MB_INTERLACED != h->mb.field[h->mb.i_mb_left_xy[0]] )
          {
              if( idx == 2 )
              {
                  mv_c = h->mb.cache.topright_mv[i_list][0];
                  i_refc = h->mb.cache.topright_ref[i_list][0];
              }
              else if( idx == 8 )
              {
                  mv_c = h->mb.cache.topright_mv[i_list][1];
                  i_refc = h->mb.cache.topright_ref[i_list][1];
              }
              else if( idx == 10 )
              {
                  mv_c = h->mb.cache.topright_mv[i_list][2];
                  i_refc = h->mb.cache.topright_ref[i_list][2];
              }
          }
      }
      if( h->mb.i_partition == D_16x8 )
      {
          if( idx == 0 )
          {
              if( i_refb == i_ref )
              {
                  CP32( mvp, mv_b );
                  return;
              }
          }
          else
          {
              if( i_refa == i_ref )
              {
                  CP32( mvp, mv_a );
                  return;
              }
          }
      }
      else if( h->mb.i_partition == D_8x16 )
      {
          if( idx == 0 )
          {
              if( i_refa == i_ref )
              {
                  CP32( mvp, mv_a );
                  return;
              }
          }
          else
          {
              if( i_refc == i_ref )
              {
                  CP32( mvp, mv_c );
                  return;
              }
          }
      }
  
      int i_count = (i_refa == i_ref) + (i_refb == i_ref) + (i_refc == i_ref);
  
      if( i_count > 1 )
      {
  median:
          x264_median_mv( mvp, mv_a, mv_b, mv_c );
      }
      else if( i_count == 1 )
      {
          if( i_refa == i_ref )
              CP32( mvp, mv_a );
          else if( i_refb == i_ref )
              CP32( mvp, mv_b );
          else
              CP32( mvp, mv_c );
      }
      else if( i_refb == -2 && i_refc == -2 && i_refa != -2 )
          CP32( mvp, mv_a );
      else
          goto median;
  }
  
  void x264_mb_predict_mv_16x16( x264_t *h, int i_list, int i_ref, int16_t mvp[2] )
  {
      int     i_refa = h->mb.cache.ref[i_list][X264_SCAN8_0 - 1];
      int16_t *mv_a  = h->mb.cache.mv[i_list][X264_SCAN8_0 - 1];
      int     i_refb = h->mb.cache.ref[i_list][X264_SCAN8_0 - 8];
      int16_t *mv_b  = h->mb.cache.mv[i_list][X264_SCAN8_0 - 8];
      int     i_refc = h->mb.cache.ref[i_list][X264_SCAN8_0 - 8 + 4];
      int16_t *mv_c  = h->mb.cache.mv[i_list][X264_SCAN8_0 - 8 + 4];
      if( i_refc == -2 )
      {
          i_refc = h->mb.cache.ref[i_list][X264_SCAN8_0 - 8 - 1];
          mv_c   = h->mb.cache.mv[i_list][X264_SCAN8_0 - 8 - 1];
      }
  
      int i_count = (i_refa == i_ref) + (i_refb == i_ref) + (i_refc == i_ref);
  
      if( i_count > 1 )
      {
  median:
          x264_median_mv( mvp, mv_a, mv_b, mv_c );
      }
      else if( i_count == 1 )
      {
          if( i_refa == i_ref )
              CP32( mvp, mv_a );
          else if( i_refb == i_ref )
              CP32( mvp, mv_b );
          else
              CP32( mvp, mv_c );
      }
      else if( i_refb == -2 && i_refc == -2 && i_refa != -2 )
          CP32( mvp, mv_a );
      else
          goto median;
  }
  
  
  void x264_mb_predict_mv_pskip( x264_t *h, int16_t mv[2] )
  {
      int     i_refa = h->mb.cache.ref[0][X264_SCAN8_0 - 1];
      int     i_refb = h->mb.cache.ref[0][X264_SCAN8_0 - 8];
      int16_t *mv_a  = h->mb.cache.mv[0][X264_SCAN8_0 - 1];
      int16_t *mv_b  = h->mb.cache.mv[0][X264_SCAN8_0 - 8];
  
      if( i_refa == -2 || i_refb == -2 ||
          !( i_refa | M32( mv_a ) ) ||
          !( i_refb | M32( mv_b ) ) )
      {
          M32( mv ) = 0;
      }
      else
          x264_mb_predict_mv_16x16( h, 0, 0, mv );
  }
  
  static int x264_mb_predict_mv_direct16x16_temporal( x264_t *h )
  {
      int mb_x = h->mb.i_mb_x;
      int mb_y = h->mb.i_mb_y;
      int mb_xy = h->mb.i_mb_xy;
      int type_col[2] = { h->fref[1][0]->mb_type[mb_xy], h->fref[1][0]->mb_type[mb_xy] };
      int partition_col[2] = { h->fref[1][0]->mb_partition[mb_xy], h->fref[1][0]->mb_partition[mb_xy] };
      int preshift = MB_INTERLACED;
      int postshift = MB_INTERLACED;
      int offset = 1;
      int yshift = 1;
      h->mb.i_partition = partition_col[0];
      if( PARAM_INTERLACED && h->fref[1][0]->field[mb_xy] != MB_INTERLACED )
      {
          if( MB_INTERLACED )
          {
              mb_y = h->mb.i_mb_y&~1;
              mb_xy = mb_x + h->mb.i_mb_stride * mb_y;
              type_col[0] = h->fref[1][0]->mb_type[mb_xy];
              type_col[1] = h->fref[1][0]->mb_type[mb_xy + h->mb.i_mb_stride];
              partition_col[0] = h->fref[1][0]->mb_partition[mb_xy];
              partition_col[1] = h->fref[1][0]->mb_partition[mb_xy + h->mb.i_mb_stride];
              preshift = 0;
              yshift = 0;
  
              if( (IS_INTRA(type_col[0]) || partition_col[0] == D_16x16) &&
                  (IS_INTRA(type_col[1]) || partition_col[1] == D_16x16) &&
                  partition_col[0] != D_8x8 )
                  h->mb.i_partition = D_16x8;
              else
                  h->mb.i_partition = D_8x8;
          }
          else
          {
              int cur_poc = h->fdec->i_poc + h->fdec->i_delta_poc[MB_INTERLACED&h->mb.i_mb_y&1];
              int col_parity = abs(h->fref[1][0]->i_poc + h->fref[1][0]->i_delta_poc[0] - cur_poc)
                            >= abs(h->fref[1][0]->i_poc + h->fref[1][0]->i_delta_poc[1] - cur_poc);
              mb_y = (h->mb.i_mb_y&~1) + col_parity;
              mb_xy = mb_x + h->mb.i_mb_stride * mb_y;
              type_col[0] = type_col[1] = h->fref[1][0]->mb_type[mb_xy];
              partition_col[0] = partition_col[1] = h->fref[1][0]->mb_partition[mb_xy];
              preshift = 1;
              yshift = 2;
              h->mb.i_partition = partition_col[0];
          }
          offset = 0;
      }
      int i_mb_4x4 = 16 * h->mb.i_mb_stride * mb_y + 4 * mb_x;
      int i_mb_8x8 =  4 * h->mb.i_mb_stride * mb_y + 2 * mb_x;
  
      x264_macroblock_cache_ref( h, 0, 0, 4, 4, 1, 0 );
  
      /* Don't do any checks other than the ones we have to, based
       * on the size of the colocated partitions.
       * Depends on the enum order: D_8x8, D_16x8, D_8x16, D_16x16 */
      int max_i8 = (D_16x16 - h->mb.i_partition) + 1;
      int step = (h->mb.i_partition == D_16x8) + 1;
      int width = 4 >> ((D_16x16 - h->mb.i_partition)&1);
      int height = 4 >> ((D_16x16 - h->mb.i_partition)>>1);
      for( int i8 = 0; i8 < max_i8; i8 += step )
      {
          int x8 = i8&1;
          int y8 = i8>>1;
          int ypart = (SLICE_MBAFF && h->fref[1][0]->field[mb_xy] != MB_INTERLACED) ?
                      MB_INTERLACED ? y8*6 : 2*(h->mb.i_mb_y&1) + y8 :
                      3*y8;
  
          if( IS_INTRA( type_col[y8] ) )
          {
              x264_macroblock_cache_ref( h, 2*x8, 2*y8, width, height, 0, 0 );
              x264_macroblock_cache_mv(  h, 2*x8, 2*y8, width, height, 0, 0 );
              x264_macroblock_cache_mv(  h, 2*x8, 2*y8, width, height, 1, 0 );
              continue;
          }
  
          int i_part_8x8 = i_mb_8x8 + x8 + (ypart>>1) * h->mb.i_b8_stride;
          int i_ref1_ref = h->fref[1][0]->ref[0][i_part_8x8];
          int i_ref = (map_col_to_list0(i_ref1_ref>>preshift) << postshift) + (offset&i_ref1_ref&MB_INTERLACED);
  
          if( i_ref >= 0 )
          {
              int dist_scale_factor = h->mb.dist_scale_factor[i_ref][0];
              int16_t *mv_col = h->fref[1][0]->mv[0][i_mb_4x4 + 3*x8 + ypart * h->mb.i_b4_stride];
              int16_t mv_y = (mv_col[1]<<yshift)/2;
              int l0x = ( dist_scale_factor * mv_col[0] + 128 ) >> 8;
              int l0y = ( dist_scale_factor * mv_y + 128 ) >> 8;
              if( h->param.i_threads > 1 && (l0y > h->mb.mv_max_spel[1] || l0y-mv_y > h->mb.mv_max_spel[1]) )
                  return 0;
              x264_macroblock_cache_ref( h, 2*x8, 2*y8, width, height, 0, i_ref );
              x264_macroblock_cache_mv( h, 2*x8, 2*y8, width, height, 0, pack16to32_mask(l0x, l0y) );
              x264_macroblock_cache_mv( h, 2*x8, 2*y8, width, height, 1, pack16to32_mask(l0x-mv_col[0], l0y-mv_y) );
          }
          else
          {
              /* the collocated ref isn't in the current list0 */
              /* FIXME: we might still be able to use direct_8x8 on some partitions */
              /* FIXME: with B-pyramid + extensive ref list reordering
               *   (not currently used), we would also have to check
               *   l1mv1 like in spatial mode */
              return 0;
          }
      }
  
      return 1;
  }
  
  static ALWAYS_INLINE int x264_mb_predict_mv_direct16x16_spatial( x264_t *h, int b_interlaced )
  {
      int8_t ref[2];
      ALIGNED_ARRAY_8( int16_t, mv,[2],[2] );
      for( int i_list = 0; i_list < 2; i_list++ )
      {
          int     i_refa = h->mb.cache.ref[i_list][X264_SCAN8_0 - 1];
          int16_t *mv_a  = h->mb.cache.mv[i_list][X264_SCAN8_0 - 1];
          int     i_refb = h->mb.cache.ref[i_list][X264_SCAN8_0 - 8];
          int16_t *mv_b  = h->mb.cache.mv[i_list][X264_SCAN8_0 - 8];
          int     i_refc = h->mb.cache.ref[i_list][X264_SCAN8_0 - 8 + 4];
          int16_t *mv_c  = h->mb.cache.mv[i_list][X264_SCAN8_0 - 8 + 4];
          if( i_refc == -2 )
          {
              i_refc = h->mb.cache.ref[i_list][X264_SCAN8_0 - 8 - 1];
              mv_c   = h->mb.cache.mv[i_list][X264_SCAN8_0 - 8 - 1];
          }
  
          int i_ref = X264_MIN3( (unsigned)i_refa, (unsigned)i_refb, (unsigned)i_refc );
          if( i_ref < 0 )
          {
              i_ref = -1;
              M32( mv[i_list] ) = 0;
          }
          else
          {
              /* Same as x264_mb_predict_mv_16x16, but simplified to eliminate cases
               * not relevant to spatial direct. */
              int i_count = (i_refa == i_ref) + (i_refb == i_ref) + (i_refc == i_ref);
  
              if( i_count > 1 )
                  x264_median_mv( mv[i_list], mv_a, mv_b, mv_c );
              else
              {
                  if( i_refa == i_ref )
                      CP32( mv[i_list], mv_a );
                  else if( i_refb == i_ref )
                      CP32( mv[i_list], mv_b );
                  else
                      CP32( mv[i_list], mv_c );
              }
          }
  
          x264_macroblock_cache_ref( h, 0, 0, 4, 4, i_list, i_ref );
          x264_macroblock_cache_mv_ptr( h, 0, 0, 4, 4, i_list, mv[i_list] );
          ref[i_list] = i_ref;
      }
  
      int mb_x = h->mb.i_mb_x;
      int mb_y = h->mb.i_mb_y;
      int mb_xy = h->mb.i_mb_xy;
      int type_col[2] = { h->fref[1][0]->mb_type[mb_xy], h->fref[1][0]->mb_type[mb_xy] };
      int partition_col[2] = { h->fref[1][0]->mb_partition[mb_xy], h->fref[1][0]->mb_partition[mb_xy] };
      h->mb.i_partition = partition_col[0];
      if( b_interlaced && h->fref[1][0]->field[mb_xy] != MB_INTERLACED )
      {
          if( MB_INTERLACED )
          {
              mb_y = h->mb.i_mb_y&~1;
              mb_xy = mb_x + h->mb.i_mb_stride * mb_y;
              type_col[0] = h->fref[1][0]->mb_type[mb_xy];
              type_col[1] = h->fref[1][0]->mb_type[mb_xy + h->mb.i_mb_stride];
              partition_col[0] = h->fref[1][0]->mb_partition[mb_xy];
              partition_col[1] = h->fref[1][0]->mb_partition[mb_xy + h->mb.i_mb_stride];
  
              if( (IS_INTRA(type_col[0]) || partition_col[0] == D_16x16) &&
                  (IS_INTRA(type_col[1]) || partition_col[1] == D_16x16) &&
                  partition_col[0] != D_8x8 )
                  h->mb.i_partition = D_16x8;
              else
                  h->mb.i_partition = D_8x8;
          }
          else
          {
              int cur_poc = h->fdec->i_poc + h->fdec->i_delta_poc[MB_INTERLACED&h->mb.i_mb_y&1];
              int col_parity = abs(h->fref[1][0]->i_poc + h->fref[1][0]->i_delta_poc[0] - cur_poc)
                            >= abs(h->fref[1][0]->i_poc + h->fref[1][0]->i_delta_poc[1] - cur_poc);
              mb_y = (h->mb.i_mb_y&~1) + col_parity;
              mb_xy = mb_x + h->mb.i_mb_stride * mb_y;
              type_col[0] = type_col[1] = h->fref[1][0]->mb_type[mb_xy];
              partition_col[0] = partition_col[1] = h->fref[1][0]->mb_partition[mb_xy];
              h->mb.i_partition = partition_col[0];
          }
      }
      int i_mb_4x4 = b_interlaced ? 4 * (h->mb.i_b4_stride*mb_y + mb_x) : h->mb.i_b4_xy ;
      int i_mb_8x8 = b_interlaced ? 2 * (h->mb.i_b8_stride*mb_y + mb_x) : h->mb.i_b8_xy ;
  
      int8_t *l1ref0 = &h->fref[1][0]->ref[0][i_mb_8x8];
      int8_t *l1ref1 = &h->fref[1][0]->ref[1][i_mb_8x8];
      int16_t (*l1mv[2])[2] = { (int16_t (*)[2]) &h->fref[1][0]->mv[0][i_mb_4x4],
                                (int16_t (*)[2]) &h->fref[1][0]->mv[1][i_mb_4x4] };
  
      if( (M16( ref ) & 0x8080) == 0x8080 ) /* if( ref[0] < 0 && ref[1] < 0 ) */
      {
          x264_macroblock_cache_ref( h, 0, 0, 4, 4, 0, 0 );
          x264_macroblock_cache_ref( h, 0, 0, 4, 4, 1, 0 );
          return 1;
      }
  
      if( h->param.i_threads > 1
          && ( mv[0][1] > h->mb.mv_max_spel[1]
            || mv[1][1] > h->mb.mv_max_spel[1] ) )
      {
  #if 0
          fprintf(stderr, "direct_spatial: (%d,%d) (%d,%d) > %d \n",
                  mv[0][0], mv[0][1], mv[1][0], mv[1][1],
                  h->mb.mv_max_spel[1]);
  #endif
          return 0;
      }
  
      if( !M64( mv ) || (!b_interlaced && IS_INTRA( type_col[0] )) || (ref[0]&&ref[1]) )
          return 1;
  
      /* Don't do any checks other than the ones we have to, based
       * on the size of the colocated partitions.
       * Depends on the enum order: D_8x8, D_16x8, D_8x16, D_16x16 */
      int max_i8 = (D_16x16 - h->mb.i_partition) + 1;
      int step = (h->mb.i_partition == D_16x8) + 1;
      int width = 4 >> ((D_16x16 - h->mb.i_partition)&1);
      int height = 4 >> ((D_16x16 - h->mb.i_partition)>>1);
  
      /* col_zero_flag */
      for( int i8 = 0; i8 < max_i8; i8 += step )
      {
          const int x8 = i8&1;
          const int y8 = i8>>1;
          int ypart = (b_interlaced && h->fref[1][0]->field[mb_xy] != MB_INTERLACED) ?
                      MB_INTERLACED ? y8*6 : 2*(h->mb.i_mb_y&1) + y8 :
                      3*y8;
          int o8 = x8 + (ypart>>1) * h->mb.i_b8_stride;
          int o4 = 3*x8 + ypart * h->mb.i_b4_stride;
  
          if( b_interlaced && IS_INTRA( type_col[y8] ) )
              continue;
  
          int idx;
          if( l1ref0[o8] == 0 )
              idx = 0;
          else if( l1ref0[o8] < 0 && l1ref1[o8] == 0 )
              idx = 1;
          else
              continue;
  
          if( abs( l1mv[idx][o4][0] ) <= 1 && abs( l1mv[idx][o4][1] ) <= 1 )
          {
              if( ref[0] == 0 ) x264_macroblock_cache_mv( h, 2*x8, 2*y8, width, height, 0, 0 );
              if( ref[1] == 0 ) x264_macroblock_cache_mv( h, 2*x8, 2*y8, width, height, 1, 0 );
          }
      }
  
      return 1;
  }
  
  
  static int x264_mb_predict_mv_direct16x16_spatial_interlaced( x264_t *h )
  {
      return x264_mb_predict_mv_direct16x16_spatial( h, 1 );
  }
  
  static int x264_mb_predict_mv_direct16x16_spatial_progressive( x264_t *h )
  {
      return x264_mb_predict_mv_direct16x16_spatial( h, 0 );
  }
  
  int x264_mb_predict_mv_direct16x16( x264_t *h, int *b_changed )
  {
      int b_available;
      if( h->param.analyse.i_direct_mv_pred == X264_DIRECT_PRED_NONE )
          return 0;
      else if( h->sh.b_direct_spatial_mv_pred )
      {
          if( SLICE_MBAFF )
              b_available = x264_mb_predict_mv_direct16x16_spatial_interlaced( h );
          else
              b_available = x264_mb_predict_mv_direct16x16_spatial_progressive( h );
      }
      else
          b_available = x264_mb_predict_mv_direct16x16_temporal( h );
  
      if( b_changed != NULL && b_available )
      {
          int changed;
  
          changed  = M32( h->mb.cache.direct_mv[0][0] ) ^ M32( h->mb.cache.mv[0][x264_scan8[0]] );
          changed |= M32( h->mb.cache.direct_mv[1][0] ) ^ M32( h->mb.cache.mv[1][x264_scan8[0]] );
          changed |= h->mb.cache.direct_ref[0][0] ^ h->mb.cache.ref[0][x264_scan8[0]];
          changed |= h->mb.cache.direct_ref[1][0] ^ h->mb.cache.ref[1][x264_scan8[0]];
          if( !changed && h->mb.i_partition != D_16x16 )
          {
              changed |= M32( h->mb.cache.direct_mv[0][3] ) ^ M32( h->mb.cache.mv[0][x264_scan8[12]] );
              changed |= M32( h->mb.cache.direct_mv[1][3] ) ^ M32( h->mb.cache.mv[1][x264_scan8[12]] );
              changed |= h->mb.cache.direct_ref[0][3] ^ h->mb.cache.ref[0][x264_scan8[12]];
              changed |= h->mb.cache.direct_ref[1][3] ^ h->mb.cache.ref[1][x264_scan8[12]];
          }
          if( !changed && h->mb.i_partition == D_8x8 )
          {
              changed |= M32( h->mb.cache.direct_mv[0][1] ) ^ M32( h->mb.cache.mv[0][x264_scan8[4]] );
              changed |= M32( h->mb.cache.direct_mv[1][1] ) ^ M32( h->mb.cache.mv[1][x264_scan8[4]] );
              changed |= M32( h->mb.cache.direct_mv[0][2] ) ^ M32( h->mb.cache.mv[0][x264_scan8[8]] );
              changed |= M32( h->mb.cache.direct_mv[1][2] ) ^ M32( h->mb.cache.mv[1][x264_scan8[8]] );
              changed |= h->mb.cache.direct_ref[0][1] ^ h->mb.cache.ref[0][x264_scan8[4]];
              changed |= h->mb.cache.direct_ref[1][1] ^ h->mb.cache.ref[1][x264_scan8[4]];
              changed |= h->mb.cache.direct_ref[0][2] ^ h->mb.cache.ref[0][x264_scan8[8]];
              changed |= h->mb.cache.direct_ref[1][2] ^ h->mb.cache.ref[1][x264_scan8[8]];
          }
          *b_changed = changed;
          if( !changed )
              return b_available;
      }
  
      /* cache ref & mv */
      if( b_available )
          for( int l = 0; l < 2; l++ )
          {
              CP32( h->mb.cache.direct_mv[l][0], h->mb.cache.mv[l][x264_scan8[ 0]] );
              CP32( h->mb.cache.direct_mv[l][1], h->mb.cache.mv[l][x264_scan8[ 4]] );
              CP32( h->mb.cache.direct_mv[l][2], h->mb.cache.mv[l][x264_scan8[ 8]] );
              CP32( h->mb.cache.direct_mv[l][3], h->mb.cache.mv[l][x264_scan8[12]] );
              h->mb.cache.direct_ref[l][0] = h->mb.cache.ref[l][x264_scan8[ 0]];
              h->mb.cache.direct_ref[l][1] = h->mb.cache.ref[l][x264_scan8[ 4]];
              h->mb.cache.direct_ref[l][2] = h->mb.cache.ref[l][x264_scan8[ 8]];
              h->mb.cache.direct_ref[l][3] = h->mb.cache.ref[l][x264_scan8[12]];
              h->mb.cache.direct_partition = h->mb.i_partition;
          }
  
      return b_available;
  }
  
  /* This just improves encoder performance, it's not part of the spec */
  void x264_mb_predict_mv_ref16x16( x264_t *h, int i_list, int i_ref, int16_t mvc[9][2], int *i_mvc )
  {
      int16_t (*mvr)[2] = h->mb.mvr[i_list][i_ref];
      int i = 0;
  
  #define SET_MVP(mvp) \
      { \
          CP32( mvc[i], mvp ); \
          i++; \
      }
  
  #define SET_IMVP(xy) \
      if( xy >= 0 ) \
      { \
          int shift = 1 + MB_INTERLACED - h->mb.field[xy]; \
          int16_t *mvp = h->mb.mvr[i_list][i_ref<<1>>shift][xy]; \
          mvc[i][0] = mvp[0]; \
          mvc[i][1] = mvp[1]<<1>>shift; \
          i++; \
      }
  
      /* b_direct */
      if( h->sh.i_type == SLICE_TYPE_B
          && h->mb.cache.ref[i_list][x264_scan8[12]] == i_ref )
      {
          SET_MVP( h->mb.cache.mv[i_list][x264_scan8[12]] );
      }
  
      if( i_ref == 0 && h->frames.b_have_lowres )
      {
          int idx = i_list ? h->fref[1][0]->i_frame-h->fenc->i_frame-1
                           : h->fenc->i_frame-h->fref[0][0]->i_frame-1;
          if( idx <= h->param.i_bframe )
          {
              int16_t (*lowres_mv)[2] = h->fenc->lowres_mvs[i_list][idx];
              if( lowres_mv[0][0] != 0x7fff )
              {
                  M32( mvc[i] ) = (M32( lowres_mv[h->mb.i_mb_xy] )*2)&0xfffeffff;
                  i++;
              }
          }
      }
  
      /* spatial predictors */
      if( SLICE_MBAFF )
      {
          SET_IMVP( h->mb.i_mb_left_xy[0] );
          SET_IMVP( h->mb.i_mb_top_xy );
          SET_IMVP( h->mb.i_mb_topleft_xy );
          SET_IMVP( h->mb.i_mb_topright_xy );
      }
      else
      {
          SET_MVP( mvr[h->mb.i_mb_left_xy[0]] );
          SET_MVP( mvr[h->mb.i_mb_top_xy] );
          SET_MVP( mvr[h->mb.i_mb_topleft_xy] );
          SET_MVP( mvr[h->mb.i_mb_topright_xy] );
      }
  #undef SET_IMVP
  #undef SET_MVP
  
      /* temporal predictors */
      if( h->fref[0][0]->i_ref[0] > 0 )
      {
          x264_frame_t *l0 = h->fref[0][0];
          int field = h->mb.i_mb_y&1;
          int curpoc = h->fdec->i_poc + h->fdec->i_delta_poc[field];
          int refpoc = h->fref[i_list][i_ref>>SLICE_MBAFF]->i_poc;
          refpoc += l0->i_delta_poc[field^(i_ref&1)];
  
  #define SET_TMVP( dx, dy ) \
          { \
              int mb_index = h->mb.i_mb_xy + dx + dy*h->mb.i_mb_stride; \
              int scale = (curpoc - refpoc) * l0->inv_ref_poc[MB_INTERLACED&field]; \
              mvc[i][0] = (l0->mv16x16[mb_index][0]*scale + 128) >> 8; \
              mvc[i][1] = (l0->mv16x16[mb_index][1]*scale + 128) >> 8; \
              i++; \
          }
  
          SET_TMVP(0,0);
          if( h->mb.i_mb_x < h->mb.i_mb_width-1 )
              SET_TMVP(1,0);
          if( h->mb.i_mb_y < h->mb.i_mb_height-1 )
              SET_TMVP(0,1);
  #undef SET_TMVP
      }
  
      *i_mvc = i;
  }
  