Using CDFs for read_partition special case Test results: akiyo -0.05% bowing -0.072% bridge -0.042% bus -0.156% coastguard -0.645% container -0.087% deadline 0.007% flower 0.02% football -0.009% foreman 0.03% hall 0.087% highway -0.041% husky -0.031% mad900 0.015% mobile -0.007% mother 0.012% news 0.039% pamphlet 0.061% paris -0.003% sign -0.148% silent 0.003% students -0.009% tempete -0.061% waterfall 0.666 Change-Id: I96c2fd3a6fbc5f8e5cf7f3b881ef89335e58d5ac

diff --git a/av1/common/onyxc_int.h b/av1/common/onyxc_int.h
index e966a12..29690d2 100644
--- a/av1/common/onyxc_int.h
+++ b/av1/common/onyxc_int.h

@@ -895,6 +895,43 @@
 }
 #endif
 
+static INLINE aom_cdf_prob cdf_element_prob(const aom_cdf_prob *cdf,
+                                            size_t element) {
+#if CONFIG_EC_SMALLMUL
+  return (element > 0 ? cdf[element - 1] : CDF_PROB_TOP) - cdf[element];
+#else
+  return cdf[element] - (element > 0 ? cdf[element - 1] : 0);
+#endif
+}
+
+static INLINE void partition_gather_horz_alike(aom_cdf_prob *out,
+                                               const aom_cdf_prob *const in) {
+  out[0] = CDF_PROB_TOP;
+  out[0] -= cdf_element_prob(in, PARTITION_HORZ);
+  out[0] -= cdf_element_prob(in, PARTITION_SPLIT);
+#if CONFIG_EXT_PARTITION_TYPES
+  out[0] -= cdf_element_prob(in, PARTITION_HORZ_A);
+  out[0] -= cdf_element_prob(in, PARTITION_HORZ_B);
+  out[0] -= cdf_element_prob(in, PARTITION_VERT_A);
+#endif
+  out[0] = AOM_ICDF(out[0]);
+  out[1] = AOM_ICDF(CDF_PROB_TOP);
+}
+
+static INLINE void partition_gather_vert_alike(aom_cdf_prob *out,
+                                               const aom_cdf_prob *const in) {
+  out[0] = CDF_PROB_TOP;
+  out[0] -= cdf_element_prob(in, PARTITION_VERT);
+  out[0] -= cdf_element_prob(in, PARTITION_SPLIT);
+#if CONFIG_EXT_PARTITION_TYPES
+  out[0] -= cdf_element_prob(in, PARTITION_HORZ_A);
+  out[0] -= cdf_element_prob(in, PARTITION_VERT_A);
+  out[0] -= cdf_element_prob(in, PARTITION_VERT_B);
+#endif
+  out[0] = AOM_ICDF(out[0]);
+  out[1] = AOM_ICDF(CDF_PROB_TOP);
+}
+
 #if CONFIG_EXT_PARTITION_TYPES
 static INLINE void update_ext_partition_context(MACROBLOCKD *xd, int mi_row,
                                                 int mi_col, BLOCK_SIZE subsize,

diff --git a/av1/decoder/decodeframe.c b/av1/decoder/decodeframe.c
index e0fb51b..39368e0 100644
--- a/av1/decoder/decodeframe.c
+++ b/av1/decoder/decodeframe.c

@@ -2139,13 +2139,8 @@
 #if CONFIG_UNPOISON_PARTITION_CTX
   const int ctx =
       partition_plane_context(xd, mi_row, mi_col, has_rows, has_cols, bsize);
-  const aom_prob *const probs =
-      ctx < PARTITION_CONTEXTS ? cm->fc->partition_prob[ctx] : NULL;
-  FRAME_COUNTS *const counts = ctx < PARTITION_CONTEXTS ? xd->counts : NULL;
 #else
   const int ctx = partition_plane_context(xd, mi_row, mi_col, bsize);
-  const aom_prob *const probs = cm->fc->partition_prob[ctx];
-  FRAME_COUNTS *const counts = xd->counts;
 #endif
   PARTITION_TYPE p;
   FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
@@ -2164,15 +2159,22 @@
                                         ACCT_STR);
 #endif  // CONFIG_EXT_PARTITION_TYPES
   } else if (!has_rows && has_cols) {
-    p = aom_read(r, probs[1], ACCT_STR) ? PARTITION_SPLIT : PARTITION_HORZ;
+    assert(bsize > BLOCK_8X8);
+    aom_cdf_prob cdf[2];
+    partition_gather_vert_alike(cdf, partition_cdf);
+    assert(cdf[1] == AOM_ICDF(CDF_PROB_TOP));
+    p = aom_read_cdf(r, cdf, 2, ACCT_STR) ? PARTITION_SPLIT : PARTITION_HORZ;
+    // gather cols
   } else if (has_rows && !has_cols) {
-    p = aom_read(r, probs[2], ACCT_STR) ? PARTITION_SPLIT : PARTITION_VERT;
+    assert(bsize > BLOCK_8X8);
+    aom_cdf_prob cdf[2];
+    partition_gather_horz_alike(cdf, partition_cdf);
+    assert(cdf[1] == AOM_ICDF(CDF_PROB_TOP));
+    p = aom_read_cdf(r, cdf, 2, ACCT_STR) ? PARTITION_SPLIT : PARTITION_VERT;
   } else {
     p = PARTITION_SPLIT;
   }
 
-  if (counts) ++counts->partition[ctx][p];
-
   return p;
 }
 

diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index cbb78da..201d97f 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c

@@ -2873,13 +2873,6 @@
 #endif
                                                 bsize)
                       : 0;
-#if CONFIG_UNPOISON_PARTITION_CTX
-  const aom_prob *const probs =
-      ctx < PARTITION_CONTEXTS ? cm->fc->partition_prob[ctx] : NULL;
-#else
-  const aom_prob *const probs = cm->fc->partition_prob[ctx];
-#endif
-
   FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
   (void)cm;
 
@@ -2896,10 +2889,16 @@
 #endif  // CONFIG_EXT_PARTITION_TYPES
   } else if (!has_rows && has_cols) {
     assert(p == PARTITION_SPLIT || p == PARTITION_HORZ);
-    aom_write(w, p == PARTITION_SPLIT, probs[1]);
+    assert(bsize > BLOCK_8X8);
+    aom_cdf_prob cdf[2];
+    partition_gather_vert_alike(cdf, ec_ctx->partition_cdf[ctx]);
+    aom_write_cdf(w, p == PARTITION_SPLIT, cdf, 2);
   } else if (has_rows && !has_cols) {
     assert(p == PARTITION_SPLIT || p == PARTITION_VERT);
-    aom_write(w, p == PARTITION_SPLIT, probs[2]);
+    assert(bsize > BLOCK_8X8);
+    aom_cdf_prob cdf[2];
+    partition_gather_horz_alike(cdf, ec_ctx->partition_cdf[ctx]);
+    aom_write_cdf(w, p == PARTITION_SPLIT, cdf, 2);
   } else {
     assert(p == PARTITION_SPLIT);
   }