libvpx: Pull from upstream

source/libvpx/vp9/common/vp9_tile_common.c

 /*
  *  Copyright (c) 2010 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.
  */
 
@@ skipping 18 matching lines @@
 void vp9_tile_set_col(TileInfo *tile, const VP9_COMMON *cm, int col) {
   tile->mi_col_start = get_tile_offset(col, cm->mi_cols, cm->log2_tile_cols);
   tile->mi_col_end = get_tile_offset(col + 1, cm->mi_cols, cm->log2_tile_cols);
 }
 
 void vp9_tile_init(TileInfo *tile, const VP9_COMMON *cm, int row, int col) {
   vp9_tile_set_row(tile, cm, row);
   vp9_tile_set_col(tile, cm, col);
 }
 
+static int get_min_log2_tile_cols(const int sb64_cols) {
+  int min_log2 = 0;
+  while ((MAX_TILE_WIDTH_B64 << min_log2) < sb64_cols)
+    ++min_log2;
+  return min_log2;
+}
+
+static int get_max_log2_tile_cols(const int sb64_cols) {
+  int max_log2 = 1;
+  while ((sb64_cols >> max_log2) >= MIN_TILE_WIDTH_B64)
+    ++max_log2;
+  return max_log2 - 1;
+}
+
 void vp9_get_tile_n_bits(int mi_cols,
                          int *min_log2_tile_cols, int *max_log2_tile_cols) {
-  const int sb_cols = mi_cols_aligned_to_sb(mi_cols) >> MI_BLOCK_SIZE_LOG2;
-  int min_log2 = 0, max_log2 = 0;
-
-  // max
-  while ((sb_cols >> max_log2) >= MIN_TILE_WIDTH_B64)
-    ++max_log2;
-  --max_log2;
-  if (max_log2 < 0)
-    max_log2 = 0;
-
-  // min
-  while ((MAX_TILE_WIDTH_B64 << min_log2) < sb_cols)
-    ++min_log2;
-
-  assert(min_log2 <= max_log2);
-
-  *min_log2_tile_cols = min_log2;
-  *max_log2_tile_cols = max_log2;
+  const int sb64_cols = mi_cols_aligned_to_sb(mi_cols) >> MI_BLOCK_SIZE_LOG2;
+  *min_log2_tile_cols = get_min_log2_tile_cols(sb64_cols);
+  *max_log2_tile_cols = get_max_log2_tile_cols(sb64_cols);
+  assert(*min_log2_tile_cols <= *max_log2_tile_cols);
 }