text: /*
   *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #include "./vpx_dsp_rtcd.h"
  #include "vp9/common/vp9_filter.h"
  #include "vp9/common/vp9_scale.h"
  #include "vpx_dsp/vpx_filter.h"
  
  static INLINE int scaled_x(int val, const struct scale_factors *sf) {
    return (int)((int64_t)val * sf->x_scale_fp >> REF_SCALE_SHIFT);
  }
  
  static INLINE int scaled_y(int val, const struct scale_factors *sf) {
    return (int)((int64_t)val * sf->y_scale_fp >> REF_SCALE_SHIFT);
  }
  
  static int unscaled_value(int val, const struct scale_factors *sf) {
    (void) sf;
    return val;
  }
  
  static int get_fixed_point_scale_factor(int other_size, int this_size) {
    // Calculate scaling factor once for each reference frame
    // and use fixed point scaling factors in decoding and encoding routines.
    // Hardware implementations can calculate scale factor in device driver
    // and use multiplication and shifting on hardware instead of division.
    return (other_size << REF_SCALE_SHIFT) / this_size;
  }
  
  MV32 vp9_scale_mv(const MV *mv, int x, int y, const struct scale_factors *sf) {
    const int x_off_q4 = scaled_x(x << SUBPEL_BITS, sf) & SUBPEL_MASK;
    const int y_off_q4 = scaled_y(y << SUBPEL_BITS, sf) & SUBPEL_MASK;
    const MV32 res = {
      scaled_y(mv->row, sf) + y_off_q4,
      scaled_x(mv->col, sf) + x_off_q4
    };
    return res;
  }
  
  #if CONFIG_VP9_HIGHBITDEPTH
  void vp9_setup_scale_factors_for_frame(struct scale_factors *sf,
                                         int other_w, int other_h,
                                         int this_w, int this_h,
                                         int use_highbd) {
  #else
  void vp9_setup_scale_factors_for_frame(struct scale_factors *sf,
                                         int other_w, int other_h,
                                         int this_w, int this_h) {
  #endif
    if (!valid_ref_frame_size(other_w, other_h, this_w, this_h)) {
      sf->x_scale_fp = REF_INVALID_SCALE;
      sf->y_scale_fp = REF_INVALID_SCALE;
      return;
    }
  
    sf->x_scale_fp = get_fixed_point_scale_factor(other_w, this_w);
    sf->y_scale_fp = get_fixed_point_scale_factor(other_h, this_h);
    sf->x_step_q4 = scaled_x(16, sf);
    sf->y_step_q4 = scaled_y(16, sf);
  
    if (vp9_is_scaled(sf)) {
      sf->scale_value_x = scaled_x;
      sf->scale_value_y = scaled_y;
    } else {
      sf->scale_value_x = unscaled_value;
      sf->scale_value_y = unscaled_value;
    }
  
    // TODO(agrange): Investigate the best choice of functions to use here
    // for EIGHTTAP_SMOOTH. Since it is not interpolating, need to choose what
    // to do at full-pel offsets. The current selection, where the filter is
    // applied in one direction only, and not at all for 0,0, seems to give the
    // best quality, but it may be worth trying an additional mode that does
    // do the filtering on full-pel.
  
    if (sf->x_step_q4 == 16) {
      if (sf->y_step_q4 == 16) {
        // No scaling in either direction.
        sf->predict[0][0][0] = vpx_convolve_copy;
        sf->predict[0][0][1] = vpx_convolve_avg;
        sf->predict[0][1][0] = vpx_convolve8_vert;
        sf->predict[0][1][1] = vpx_convolve8_avg_vert;
        sf->predict[1][0][0] = vpx_convolve8_horiz;
        sf->predict[1][0][1] = vpx_convolve8_avg_horiz;
      } else {
        // No scaling in x direction. Must always scale in the y direction.
        sf->predict[0][0][0] = vpx_scaled_vert;
        sf->predict[0][0][1] = vpx_scaled_avg_vert;
        sf->predict[0][1][0] = vpx_scaled_vert;
        sf->predict[0][1][1] = vpx_scaled_avg_vert;
        sf->predict[1][0][0] = vpx_scaled_2d;
        sf->predict[1][0][1] = vpx_scaled_avg_2d;
      }
    } else {
      if (sf->y_step_q4 == 16) {
        // No scaling in the y direction. Must always scale in the x direction.
        sf->predict[0][0][0] = vpx_scaled_horiz;
        sf->predict[0][0][1] = vpx_scaled_avg_horiz;
        sf->predict[0][1][0] = vpx_scaled_2d;
        sf->predict[0][1][1] = vpx_scaled_avg_2d;
        sf->predict[1][0][0] = vpx_scaled_horiz;
        sf->predict[1][0][1] = vpx_scaled_avg_horiz;
      } else {
        // Must always scale in both directions.
        sf->predict[0][0][0] = vpx_scaled_2d;
        sf->predict[0][0][1] = vpx_scaled_avg_2d;
        sf->predict[0][1][0] = vpx_scaled_2d;
        sf->predict[0][1][1] = vpx_scaled_avg_2d;
        sf->predict[1][0][0] = vpx_scaled_2d;
        sf->predict[1][0][1] = vpx_scaled_avg_2d;
      }
    }
  
    // 2D subpel motion always gets filtered in both directions
  
    if ((sf->x_step_q4 != 16) || (sf->y_step_q4 != 16)) {
      sf->predict[1][1][0] = vpx_scaled_2d;
      sf->predict[1][1][1] = vpx_scaled_avg_2d;
    } else {
      sf->predict[1][1][0] = vpx_convolve8;
      sf->predict[1][1][1] = vpx_convolve8_avg;
    }
  
  #if CONFIG_VP9_HIGHBITDEPTH
    if (use_highbd) {
      if (sf->x_step_q4 == 16) {
        if (sf->y_step_q4 == 16) {
          // No scaling in either direction.
          sf->highbd_predict[0][0][0] = vpx_highbd_convolve_copy;
          sf->highbd_predict[0][0][1] = vpx_highbd_convolve_avg;
          sf->highbd_predict[0][1][0] = vpx_highbd_convolve8_vert;
          sf->highbd_predict[0][1][1] = vpx_highbd_convolve8_avg_vert;
          sf->highbd_predict[1][0][0] = vpx_highbd_convolve8_horiz;
          sf->highbd_predict[1][0][1] = vpx_highbd_convolve8_avg_horiz;
        } else {
          // No scaling in x direction. Must always scale in the y direction.
          sf->highbd_predict[0][0][0] = vpx_highbd_convolve8_vert;
          sf->highbd_predict[0][0][1] = vpx_highbd_convolve8_avg_vert;
          sf->highbd_predict[0][1][0] = vpx_highbd_convolve8_vert;
          sf->highbd_predict[0][1][1] = vpx_highbd_convolve8_avg_vert;
          sf->highbd_predict[1][0][0] = vpx_highbd_convolve8;
          sf->highbd_predict[1][0][1] = vpx_highbd_convolve8_avg;
        }
      } else {
        if (sf->y_step_q4 == 16) {
          // No scaling in the y direction. Must always scale in the x direction.
          sf->highbd_predict[0][0][0] = vpx_highbd_convolve8_horiz;
          sf->highbd_predict[0][0][1] = vpx_highbd_convolve8_avg_horiz;
          sf->highbd_predict[0][1][0] = vpx_highbd_convolve8;
          sf->highbd_predict[0][1][1] = vpx_highbd_convolve8_avg;
          sf->highbd_predict[1][0][0] = vpx_highbd_convolve8_horiz;
          sf->highbd_predict[1][0][1] = vpx_highbd_convolve8_avg_horiz;
        } else {
          // Must always scale in both directions.
          sf->highbd_predict[0][0][0] = vpx_highbd_convolve8;
          sf->highbd_predict[0][0][1] = vpx_highbd_convolve8_avg;
          sf->highbd_predict[0][1][0] = vpx_highbd_convolve8;
          sf->highbd_predict[0][1][1] = vpx_highbd_convolve8_avg;
          sf->highbd_predict[1][0][0] = vpx_highbd_convolve8;
          sf->highbd_predict[1][0][1] = vpx_highbd_convolve8_avg;
        }
      }
      // 2D subpel motion always gets filtered in both directions.
      sf->highbd_predict[1][1][0] = vpx_highbd_convolve8;
      sf->highbd_predict[1][1][1] = vpx_highbd_convolve8_avg;
    }
  #endif
  }
  