shithub: libvpx

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Simplifying partition context calculation.

Reversing bit order of partition_context_lookup, and modifying accordingly
update_partition_context() and partition_plane_context().

Change-Id: I64a11f1a94962a3bf217de2f50698cb781db71a5

--- a/vp9/common/vp9_common_data.c

+++ b/vp9/common/vp9_common_data.c

@@ -123,8 +123,6 @@

   TX_32X32,  // TX_MODE_SELECT

 };

-

-

 const BLOCK_SIZE ss_size_lookup[BLOCK_SIZES][2][2] = {

 //  ss_x == 0    ss_x == 0        ss_x == 1      ss_x == 1

 //  ss_y == 0    ss_y == 1        ss_y == 0      ss_y == 1

@@ -144,23 +142,23 @@

 };

 // Generates 4 bit field in which each bit set to 1 represents

-// a blocksize partition  1111 means we split 8x8, 16x16, 32x32

-// and 64x64.  0001 means we just split the 64x64...

+// a blocksize partition  1111 means we split 64x64, 32x32, 16x16

+// and 8x8.  1000 means we just split the 64x64 to 32x32

 const struct {

   PARTITION_CONTEXT above;

   PARTITION_CONTEXT left;

 } partition_context_lookup[BLOCK_SIZES]= {

-  {15, 15},  // 4X4

-  {15,  7},  // 4X8

-  {7,  15},  // 8X4

-  {7,   7},  // 8X8

-  {7,   3},  // 8X16

-  {3,   7},  // 16X8

-  {3,   3},  // 16X16

-  {3,   1},  // 16X32

-  {1,   3},  // 32X16

-  {1,   1},  // 32X32

-  {1,   0},  // 32X64

-  {0,   1},  // 64X32

-  {0,   0},  // 64X64

+  {15, 15},  // 4X4   - {0b1111, 0b1111}

+  {15, 14},  // 4X8   - {0b1111, 0b1110}

+  {14, 15},  // 8X4   - {0b1110, 0b1111}

+  {14, 14},  // 8X8   - {0b1110, 0b1110}

+  {14, 12},  // 8X16  - {0b1110, 0b1100}

+  {12, 14},  // 16X8  - {0b1100, 0b1110}

+  {12, 12},  // 16X16 - {0b1100, 0b1100}

+  {12, 8 },  // 16X32 - {0b1100, 0b1000}

+  {8,  12},  // 32X16 - {0b1000, 0b1100}

+  {8,  8 },  // 32X32 - {0b1000, 0b1000}

+  {8,  0 },  // 32X64 - {0b1000, 0b0000}

+  {0,  8 },  // 64X32 - {0b0000, 0b1000}

+  {0,  0 },  // 64X64 - {0b0000, 0b0000}

 };

--- a/vp9/common/vp9_onyxc_int.h

+++ b/vp9/common/vp9_onyxc_int.h

@@ -303,43 +303,40 @@

 static INLINE void update_partition_context(

     PARTITION_CONTEXT *above_seg_context,

     PARTITION_CONTEXT left_seg_context[8],

-    int mi_row, int mi_col,

-    BLOCK_SIZE sb_type,

-    BLOCK_SIZE sb_size) {

-  PARTITION_CONTEXT *above_ctx = above_seg_context + mi_col;

-  PARTITION_CONTEXT *left_ctx = left_seg_context + (mi_row & MI_MASK);

+    int mi_row, int mi_col, BLOCK_SIZE subsize, BLOCK_SIZE bsize) {

+  PARTITION_CONTEXT *const above_ctx = above_seg_context + mi_col;

+  PARTITION_CONTEXT *const left_ctx = left_seg_context + (mi_row & MI_MASK);

-  const int bsl = b_width_log2(sb_size), bs = (1 << bsl) / 2;

+  // num_4x4_blocks_wide_lookup[bsize] / 2

+  const int bs = num_8x8_blocks_wide_lookup[bsize];

   // update the partition context at the end notes. set partition bits

   // of block sizes larger than the current one to be one, and partition

   // bits of smaller block sizes to be zero.

-  vpx_memset(above_ctx, partition_context_lookup[sb_type].above, bs);

-  vpx_memset(left_ctx, partition_context_lookup[sb_type].left, bs);

+  vpx_memset(above_ctx, partition_context_lookup[subsize].above, bs);

+  vpx_memset(left_ctx, partition_context_lookup[subsize].left, bs);

 }

 static INLINE int partition_plane_context(

     const PARTITION_CONTEXT *above_seg_context,

     const PARTITION_CONTEXT left_seg_context[8],

-    int mi_row, int mi_col,

-    BLOCK_SIZE sb_type) {

+    int mi_row, int mi_col, BLOCK_SIZE bsize) {

   const PARTITION_CONTEXT *above_ctx = above_seg_context + mi_col;

   const PARTITION_CONTEXT *left_ctx = left_seg_context + (mi_row & MI_MASK);

-  int bsl = mi_width_log2(sb_type), bs = 1 << bsl;

+  const int bsl = mi_width_log2(bsize);

+  const int bs = 1 << bsl;

   int above = 0, left = 0, i;

-  int boffset = mi_width_log2(BLOCK_64X64) - bsl;

-  assert(mi_width_log2(sb_type) == mi_height_log2(sb_type));

+  assert(mi_width_log2(bsize) == mi_height_log2(bsize));

   assert(bsl >= 0);

-  assert(boffset >= 0);

   for (i = 0; i < bs; i++) {

     above |= above_ctx[i];

     left |= left_ctx[i];

   }

-  above = (above & (1 << boffset)) > 0;

-  left  = (left & (1 << boffset)) > 0;

+  above = (above & bs) > 0;

+  left  = (left & bs) > 0;

   return (left * 2 + above) + bsl * PARTITION_PLOFFSET;

 }