shithub: libvpx

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Refactor the block decode code to make it simpler.

Change-Id: I0f983cb821ad7ec6fbefe7895cb8124a8fa39df6

--- a/vp9/common/vp9_blockd.c

+++ b/vp9/common/vp9_blockd.c

@@ -50,39 +50,25 @@

   const int num_4x4_w = num_4x4_blocks_wide_lookup[plane_bsize];

   const int num_4x4_h = num_4x4_blocks_high_lookup[plane_bsize];

   const int step = 1 << (tx_size << 1);

-  int i;

+  int i = 0, r, c;

   // If mb_to_right_edge is < 0 we are in a situation in which

   // the current block size extends into the UMV and we won't

   // visit the sub blocks that are wholly within the UMV.

-  if (xd->mb_to_right_edge < 0 || xd->mb_to_bottom_edge < 0) {

-    int r, c;

+  const int max_blocks_wide = num_4x4_w + (xd->mb_to_right_edge >= 0 ? 0 :

+      xd->mb_to_right_edge >> (5 + pd->subsampling_x));

+  const int max_blocks_high = num_4x4_h + (xd->mb_to_bottom_edge >= 0 ? 0 :

+      xd->mb_to_bottom_edge >> (5 + pd->subsampling_x));

-    int max_blocks_wide = num_4x4_w;

-    int max_blocks_high = num_4x4_h;

-

-    // xd->mb_to_right_edge is in units of pixels * 8.  This converts

-    // it to 4x4 block sizes.

-    if (xd->mb_to_right_edge < 0)

-      max_blocks_wide += (xd->mb_to_right_edge >> (5 + pd->subsampling_x));

-

-    if (xd->mb_to_bottom_edge < 0)

-      max_blocks_high += (xd->mb_to_bottom_edge >> (5 + pd->subsampling_y));

-

-    i = 0;

-    // Unlike the normal case - in here we have to keep track of the

-    // row and column of the blocks we use so that we know if we are in

-    // the unrestricted motion border.

-    for (r = 0; r < num_4x4_h; r += (1 << tx_size)) {

-      for (c = 0; c < num_4x4_w; c += (1 << tx_size)) {

-        if (r < max_blocks_high && c < max_blocks_wide)

-          visit(plane, i, plane_bsize, tx_size, arg);

-        i += step;

-      }

+  // Keep track of the row and column of the blocks we use so that we know

+  // if we are in the unrestricted motion border.

+  for (r = 0; r < max_blocks_high; r += (1 << tx_size)) {

+    for (c = 0; c < num_4x4_w; c += (1 << tx_size)) {

+      // Skip visiting the sub blocks that are wholly within the UMV.

+      if (c < max_blocks_wide)

+        visit(plane, i, plane_bsize, tx_size, arg);

+      i += step;

     }

-  } else {

-    for (i = 0; i < num_4x4_w * num_4x4_h; i += step)

-      visit(plane, i, plane_bsize, tx_size, arg);

   }

 }