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      1 /*
      2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #include "vp9/common/vp9_tile_common.h"
     12 
     13 #define MIN_TILE_WIDTH_B64 4
     14 #define MAX_TILE_WIDTH_B64 64
     15 
     16 static int to_sbs(n_mis) {
     17   return mi_cols_aligned_to_sb(n_mis) >> MI_BLOCK_SIZE_LOG2;
     18 }
     19 
     20 static void vp9_get_tile_offsets(int *min_tile_off, int *max_tile_off,
     21                                  int tile_idx, int log2_n_tiles, int n_mis) {
     22   const int n_sbs = to_sbs(n_mis);
     23   const int sb_off1 =  (tile_idx      * n_sbs) >> log2_n_tiles;
     24   const int sb_off2 = ((tile_idx + 1) * n_sbs) >> log2_n_tiles;
     25 
     26   *min_tile_off = MIN(sb_off1 << 3, n_mis);
     27   *max_tile_off = MIN(sb_off2 << 3, n_mis);
     28 }
     29 
     30 void vp9_get_tile_col_offsets(VP9_COMMON *cm, int tile_col_idx) {
     31   vp9_get_tile_offsets(&cm->cur_tile_mi_col_start, &cm->cur_tile_mi_col_end,
     32                        tile_col_idx, cm->log2_tile_cols, cm->mi_cols);
     33 }
     34 
     35 void vp9_get_tile_row_offsets(VP9_COMMON *cm, int tile_row_idx) {
     36   vp9_get_tile_offsets(&cm->cur_tile_mi_row_start, &cm->cur_tile_mi_row_end,
     37                        tile_row_idx, cm->log2_tile_rows, cm->mi_rows);
     38 }
     39 
     40 
     41 void vp9_get_tile_n_bits(int mi_cols,
     42                          int *min_log2_tile_cols, int *max_log2_tile_cols) {
     43   const int sb_cols = to_sbs(mi_cols);
     44   int min_log2_n_tiles, max_log2_n_tiles;
     45 
     46   for (max_log2_n_tiles = 0;
     47        (sb_cols >> max_log2_n_tiles) >= MIN_TILE_WIDTH_B64;
     48        max_log2_n_tiles++) {}
     49   max_log2_n_tiles--;
     50   if (max_log2_n_tiles <  0)
     51     max_log2_n_tiles = 0;
     52 
     53   for (min_log2_n_tiles = 0;
     54        (MAX_TILE_WIDTH_B64 << min_log2_n_tiles) < sb_cols;
     55        min_log2_n_tiles++) {}
     56 
     57   assert(min_log2_n_tiles <= max_log2_n_tiles);
     58 
     59   *min_log2_tile_cols = min_log2_n_tiles;
     60   *max_log2_tile_cols = max_log2_n_tiles;
     61 }
     62