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Clamp decoded feature data

Not all segment feature data elements are full-range powers of two, so
there are values that can be encoded that are invalid. Add a new function
to clamp values to the maximum allowed.

Change-Id: Ie47cb80ef2d54292e6b8db9f699c57214a915bc4

--- a/vp9/common/vp9_seg_common.c

+++ b/vp9/common/vp9_seg_common.c

@@ -8,11 +8,13 @@

  *  be found in the AUTHORS file in the root of the source tree.

  */

+#include <assert.h>

+#include "vp9/common/vp9_blockd.h"

 #include "vp9/common/vp9_seg_common.h"

 static const int segfeaturedata_signed[SEG_LVL_MAX] = { 1, 1, 0, 0, 0, 0 };

-static const int seg_feature_data_bits[SEG_LVL_MAX] =

-                 { QINDEX_BITS, 6, 4, 5, 8, 2 };

+static const int seg_feature_data_max[SEG_LVL_MAX] =

+                 { MAXQ, 63, 0xf, MB_MODE_COUNT - 1, 255, TX_SIZE_MAX - 1};

 // These functions provide access to new segment level features.

 // Eventually these function may be "optimized out" but for the moment,

@@ -45,8 +47,8 @@

   xd->segment_feature_mask[segment_id] &= ~(1 << feature_id);

 }

-int vp9_seg_feature_data_bits(SEG_LVL_FEATURES feature_id) {

-  return seg_feature_data_bits[feature_id];

+int vp9_seg_feature_data_max(SEG_LVL_FEATURES feature_id) {

+  return seg_feature_data_max[feature_id];

 }

 int vp9_is_segfeature_signed(SEG_LVL_FEATURES feature_id) {

@@ -63,6 +65,12 @@

                      int segment_id,

                      SEG_LVL_FEATURES feature_id,

                      int seg_data) {

+  assert(seg_data <= seg_feature_data_max[feature_id]);

+  if (seg_data < 0) {

+    assert(segfeaturedata_signed[feature_id]);

+    assert(-seg_data <= seg_feature_data_max[feature_id]);

+  }

+

   xd->segment_feature_data[segment_id][feature_id] = seg_data;

 }

--- a/vp9/common/vp9_seg_common.h

+++ b/vp9/common/vp9_seg_common.h

@@ -29,7 +29,7 @@

                             int segment_id,

                             SEG_LVL_FEATURES feature_id);

-int vp9_seg_feature_data_bits(SEG_LVL_FEATURES feature_id);

+int vp9_seg_feature_data_max(SEG_LVL_FEATURES feature_id);

 int vp9_is_segfeature_signed(SEG_LVL_FEATURES feature_id);

--- a/vp9/decoder/vp9_dboolhuff.c

+++ b/vp9/decoder/vp9_dboolhuff.c

@@ -98,3 +98,15 @@

   }

   return word;

 }

+

+int vp9_decode_unsigned_max(BOOL_DECODER *br, int max) {

+  int data = 0, bit = 0, lmax = max;

+

+  while (lmax) {

+    data |= decode_bool(br, 128) << bit++;

+    lmax >>= 1;

+  }

+  if (data > max)

+    return max;

+  return data;

+}

--- a/vp9/decoder/vp9_dboolhuff.h

+++ b/vp9/decoder/vp9_dboolhuff.h

@@ -150,4 +150,6 @@

   return 0;

 }

+extern int vp9_decode_unsigned_max(BOOL_DECODER *br, int max);

+

 #endif

--- a/vp9/decoder/vp9_decodframe.c

+++ b/vp9/decoder/vp9_decodframe.c

@@ -1134,13 +1134,13 @@

             // Update the feature data and mask

             vp9_enable_segfeature(xd, i, j);

-            data = (signed char)vp9_read_literal(

-                     &header_bc, vp9_seg_feature_data_bits(j));

+            data = vp9_decode_unsigned_max(&header_bc,

+                                           vp9_seg_feature_data_max(j));

             // Is the segment data signed..

             if (vp9_is_segfeature_signed(j)) {

               if (vp9_read_bit(&header_bc))

-                data = - data;

+                data = -data;

             }

           } else

             data = 0;

--- a/vp9/encoder/vp9_bitstream.c

+++ b/vp9/encoder/vp9_bitstream.c

@@ -1911,19 +1911,19 @@

               // Encode the relevant feature data

               if (Data < 0) {

                 Data = - Data;

-                vp9_write_literal(&header_bc, Data,

-                                  vp9_seg_feature_data_bits(j));

+                vp9_encode_unsigned_max(&header_bc, Data,

+                                        vp9_seg_feature_data_max(j));

                 vp9_write_bit(&header_bc, 1);

               } else {

-                vp9_write_literal(&header_bc, Data,

-                                  vp9_seg_feature_data_bits(j));

+                vp9_encode_unsigned_max(&header_bc, Data,

+                                        vp9_seg_feature_data_max(j));

                 vp9_write_bit(&header_bc, 0);

               }

             }

             // Unsigned data element so no sign bit needed

             else

-              vp9_write_literal(&header_bc, Data,

-                                vp9_seg_feature_data_bits(j));

+              vp9_encode_unsigned_max(&header_bc, Data,

+                                      vp9_seg_feature_data_max(j));

           } else

             vp9_write_bit(&header_bc, 0);

         }

--- a/vp9/encoder/vp9_boolhuff.c

+++ b/vp9/encoder/vp9_boolhuff.c

@@ -8,7 +8,7 @@

  *  be found in the AUTHORS file in the root of the source tree.

  */

-

+#include <assert.h>

 #include "vp9_boolhuff.h"

 #if defined(SECTIONBITS_OUTPUT)

@@ -62,6 +62,15 @@

   for (bit = bits - 1; bit >= 0; bit--)

     encode_bool(br, (1 & (data >> bit)), 0x80);

+}

+

+void vp9_encode_unsigned_max(BOOL_CODER *br, int data, int max) {

+  assert(data <= max);

+  while (max) {

+    encode_bool(br, data & 1, 128);

+    data >>= 1;

+    max >>= 1;

+  }

 }

 int vp9_recenter_nonneg(int v, int m) {

--- a/vp9/encoder/vp9_boolhuff.h

+++ b/vp9/encoder/vp9_boolhuff.h

@@ -37,6 +37,7 @@

 extern void vp9_start_encode(BOOL_CODER *bc, unsigned char *buffer);

 extern void vp9_encode_value(BOOL_CODER *br, int data, int bits);

+extern void vp9_encode_unsigned_max(BOOL_CODER *br, int data, int max);

 extern void vp9_stop_encode(BOOL_CODER *bc);

 extern const unsigned int vp9_prob_cost[256];

-- 

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