commit c7645d533dd4a0f436158b5541c35678ecb40fe2
author Hui Su <huisu@google.com> Wed Mar 21 15:51:50 2018 -0700
committer Hui Su <huisu@google.com> Thu Mar 22 02:14:04 2018 +0000
tree fb62365c720557804567df8b200cb6b93e87cede
parent 8fe9eda39e16557ae4100b25efbb06c86f87a8bb

Replace division with shift in av1_get_txb_size_index()

Encoder should be a bit faster.

Change-Id: I2f2b5eb4ca4f192c0dfe0e1935d136778a8b7ec7

av1/common/blockd.h

diff --git a/av1/common/blockd.h b/av1/common/blockd.h
index f61e40d..391706f 100644
--- a/av1/common/blockd.h
+++ b/av1/common/blockd.h
@@ -791,11 +791,12 @@
   TX_SIZE txs = max_txsize_rect_lookup[bsize];
   for (int level = 0; level < MAX_VARTX_DEPTH - 1; ++level)
     txs = sub_tx_size_map[1][txs];
-  const int tx_w = tx_size_wide_unit[txs];
-  const int tx_h = tx_size_high_unit[txs];
-  const int bw_uint = mi_size_wide[bsize];
-  const int stride = bw_uint / tx_w;
-  const int index = (blk_row / tx_h) * stride + (blk_col / tx_w);
+  const int tx_w_log2 = tx_size_wide_log2[txs] - MI_SIZE_LOG2;
+  const int tx_h_log2 = tx_size_high_log2[txs] - MI_SIZE_LOG2;
+  const int bw_log2 = b_width_log2_lookup[bsize];
+  const int stride_log2 = bw_log2 - tx_w_log2;
+  const int index =
+      ((blk_row >> tx_h_log2) << stride_log2) + (blk_col >> tx_w_log2);
   assert(index < INTER_TX_SIZE_BUF_LEN);
   return index;
 }