libvpx: Pull from upstream

source/libvpx/vp9/common/vp9_scale.c

Index: source/libvpx/vp9/common/vp9_scale.c
===================================================================
--- source/libvpx/vp9/common/vp9_scale.c	(revision 0)
+++ source/libvpx/vp9/common/vp9_scale.c	(revision 0)
@@ -0,0 +1,146 @@
+/*
+ *  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 "./vp9_rtcd.h"
+#include "vp9/common/vp9_filter.h"
+#include "vp9/common/vp9_scale.h"
+
+static INLINE int scaled_x(int val, const struct scale_factors *scale) {
+  return val * scale->x_scale_fp >> REF_SCALE_SHIFT;
+}
+
+static INLINE int scaled_y(int val, const struct scale_factors *scale) {
+  return val * scale->y_scale_fp >> REF_SCALE_SHIFT;
+}
+
+static int unscaled_value(int val, const struct scale_factors *scale) {
+  (void) scale;
+  return val;
+}
+
+static MV32 scaled_mv(const MV *mv, const struct scale_factors *scale) {
+  const MV32 res = {
+    scaled_y(mv->row, scale) + scale->y_offset_q4,
+    scaled_x(mv->col, scale) + scale->x_offset_q4
+  };
+  return res;
+}
+
+static MV32 unscaled_mv(const MV *mv, const struct scale_factors *scale) {
+  const MV32 res = {
+    mv->row,
+    mv->col
+  };
+  return res;
+}
+
+static void set_offsets_with_scaling(struct scale_factors *scale,
+                                     int row, int col) {
+  scale->x_offset_q4 = scaled_x(col << SUBPEL_BITS, scale) & SUBPEL_MASK;
+  scale->y_offset_q4 = scaled_y(row << SUBPEL_BITS, scale) & SUBPEL_MASK;
+}
+
+static void set_offsets_without_scaling(struct scale_factors *scale,
+                                        int row, int col) {
+  scale->x_offset_q4 = 0;
+  scale->y_offset_q4 = 0;
+}
+
+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;
+}
+
+static int check_scale_factors(int other_w, int other_h,
+                               int this_w, int this_h) {
+  return 2 * this_w >= other_w &&
+         2 * this_h >= other_h &&
+         this_w <= 16 * other_w &&
+         this_h <= 16 * other_h;
+}
+
+void vp9_setup_scale_factors_for_frame(struct scale_factors *scale,
+                                       int other_w, int other_h,
+                                       int this_w, int this_h) {
+  if (!check_scale_factors(other_w, other_h, this_w, this_h)) {
+    scale->x_scale_fp = REF_INVALID_SCALE;
+    scale->y_scale_fp = REF_INVALID_SCALE;
+    return;
+  }
+
+  scale->x_scale_fp = get_fixed_point_scale_factor(other_w, this_w);
+  scale->y_scale_fp = get_fixed_point_scale_factor(other_h, this_h);
+  scale->x_step_q4 = scaled_x(16, scale);
+  scale->y_step_q4 = scaled_y(16, scale);
+  scale->x_offset_q4 = 0;  // calculated per block
+  scale->y_offset_q4 = 0;  // calculated per block
+
+  if (vp9_is_scaled(scale)) {
+    scale->scale_value_x = scaled_x;
+    scale->scale_value_y = scaled_y;
+    scale->set_scaled_offsets = set_offsets_with_scaling;
+    scale->scale_mv = scaled_mv;
+  } else {
+    scale->scale_value_x = unscaled_value;
+    scale->scale_value_y = unscaled_value;
+    scale->set_scaled_offsets = set_offsets_without_scaling;
+    scale->scale_mv = unscaled_mv;
+  }
+
+  // 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 (scale->x_step_q4 == 16) {
+    if (scale->y_step_q4 == 16) {
+      // No scaling in either direction.
+      scale->predict[0][0][0] = vp9_convolve_copy;
+      scale->predict[0][0][1] = vp9_convolve_avg;
+      scale->predict[0][1][0] = vp9_convolve8_vert;
+      scale->predict[0][1][1] = vp9_convolve8_avg_vert;
+      scale->predict[1][0][0] = vp9_convolve8_horiz;
+      scale->predict[1][0][1] = vp9_convolve8_avg_horiz;
+    } else {
+      // No scaling in x direction. Must always scale in the y direction.
+      scale->predict[0][0][0] = vp9_convolve8_vert;
+      scale->predict[0][0][1] = vp9_convolve8_avg_vert;
+      scale->predict[0][1][0] = vp9_convolve8_vert;
+      scale->predict[0][1][1] = vp9_convolve8_avg_vert;
+      scale->predict[1][0][0] = vp9_convolve8;
+      scale->predict[1][0][1] = vp9_convolve8_avg;
+    }
+  } else {
+    if (scale->y_step_q4 == 16) {
+      // No scaling in the y direction. Must always scale in the x direction.
+      scale->predict[0][0][0] = vp9_convolve8_horiz;
+      scale->predict[0][0][1] = vp9_convolve8_avg_horiz;
+      scale->predict[0][1][0] = vp9_convolve8;
+      scale->predict[0][1][1] = vp9_convolve8_avg;
+      scale->predict[1][0][0] = vp9_convolve8_horiz;
+      scale->predict[1][0][1] = vp9_convolve8_avg_horiz;
+    } else {
+      // Must always scale in both directions.
+      scale->predict[0][0][0] = vp9_convolve8;
+      scale->predict[0][0][1] = vp9_convolve8_avg;
+      scale->predict[0][1][0] = vp9_convolve8;
+      scale->predict[0][1][1] = vp9_convolve8_avg;
+      scale->predict[1][0][0] = vp9_convolve8;
+      scale->predict[1][0][1] = vp9_convolve8_avg;
+    }
+  }
+  // 2D subpel motion always gets filtered in both directions
+  scale->predict[1][1][0] = vp9_convolve8;
+  scale->predict[1][1][1] = vp9_convolve8_avg;
+}