libvpx: Pull from upstream

source/libvpx/vp9/common/vp9_tile_common.c

Index: source/libvpx/vp9/common/vp9_tile_common.c
===================================================================
--- source/libvpx/vp9/common/vp9_tile_common.c	(revision 240950)
+++ source/libvpx/vp9/common/vp9_tile_common.c	(working copy)
@@ -15,46 +15,37 @@
 #define MIN_TILE_WIDTH_B64 4
 #define MAX_TILE_WIDTH_B64 64
 
-static int to_sbs(n_mis) {
-  return mi_cols_aligned_to_sb(n_mis) >> MI_BLOCK_SIZE_LOG2;
+static int get_tile_offset(int idx, int mis, int log2) {
+  const int sb_cols = mi_cols_aligned_to_sb(mis) >> MI_BLOCK_SIZE_LOG2;
+  const int offset = ((idx * sb_cols) >> log2) << MI_BLOCK_SIZE_LOG2;
+  return MIN(offset, mis);
 }
 
-static void get_tile_offsets(int *min_tile_off, int *max_tile_off,
-                             int tile_idx, int log2_n_tiles, int n_mis) {
-  const int n_sbs = to_sbs(n_mis);
-  const int sb_off1 =  (tile_idx      * n_sbs) >> log2_n_tiles;
-  const int sb_off2 = ((tile_idx + 1) * n_sbs) >> log2_n_tiles;
-
-  *min_tile_off = MIN(sb_off1 << 3, n_mis);
-  *max_tile_off = MIN(sb_off2 << 3, n_mis);
+void vp9_tile_init(TileInfo *tile, const VP9_COMMON *cm, int row, int col) {
+  tile->mi_row_start = get_tile_offset(row, cm->mi_rows, cm->log2_tile_rows);
+  tile->mi_row_end = get_tile_offset(row + 1, cm->mi_rows, cm->log2_tile_rows);
+  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_idx, int col_idx) {
-  get_tile_offsets(&tile->mi_row_start, &tile->mi_row_end,
-                   row_idx, cm->log2_tile_rows, cm->mi_rows);
-  get_tile_offsets(&tile->mi_col_start, &tile->mi_col_end,
-                   col_idx, cm->log2_tile_cols, cm->mi_cols);
-}
-
 void vp9_get_tile_n_bits(int mi_cols,
                          int *min_log2_tile_cols, int *max_log2_tile_cols) {
-  const int sb_cols = to_sbs(mi_cols);
-  int min_log2_n_tiles, max_log2_n_tiles;
+  const int sb_cols = mi_cols_aligned_to_sb(mi_cols) >> MI_BLOCK_SIZE_LOG2;
+  int min_log2 = 0, max_log2 = 0;
 
-  for (max_log2_n_tiles = 0;
-       (sb_cols >> max_log2_n_tiles) >= MIN_TILE_WIDTH_B64;
-       max_log2_n_tiles++) {}
-  max_log2_n_tiles--;
-  if (max_log2_n_tiles <  0)
-    max_log2_n_tiles = 0;
+  // max
+  while ((sb_cols >> max_log2) >= MIN_TILE_WIDTH_B64)
+    ++max_log2;
+  --max_log2;
+  if (max_log2 < 0)
+    max_log2 = 0;
 
-  for (min_log2_n_tiles = 0;
-       (MAX_TILE_WIDTH_B64 << min_log2_n_tiles) < sb_cols;
-       min_log2_n_tiles++) {}
+  // min
+  while ((MAX_TILE_WIDTH_B64 << min_log2) < sb_cols)
+    ++min_log2;
 
-  assert(min_log2_n_tiles <= max_log2_n_tiles);
+  assert(min_log2 <= max_log2);
 
-  *min_log2_tile_cols = min_log2_n_tiles;
-  *max_log2_tile_cols = max_log2_n_tiles;
+  *min_log2_tile_cols = min_log2;
+  *max_log2_tile_cols = max_log2;
 }