libvpx: Pull from upstream

source/libvpx/vp9/decoder/vp9_decodemv.c

 /*
   Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 12 matching lines @@
 #include "vp9/decoder/vp9_decodemv.h"
 #include "vp9/decoder/vp9_decodframe.h"
 #include "vp9/decoder/vp9_onyxd_int.h"
 #include "vp9/decoder/vp9_dsubexp.h"
 #include "vp9/decoder/vp9_treereader.h"
 
 static MB_PREDICTION_MODE read_intra_mode(vp9_reader *r, const vp9_prob *p) {
   return (MB_PREDICTION_MODE)treed_read(r, vp9_intra_mode_tree, p);
 }
 
-static MB_PREDICTION_MODE read_inter_mode(vp9_reader *r, const vp9_prob *p) {
-  return (MB_PREDICTION_MODE)treed_read(r, vp9_inter_mode_tree, p);
+static MB_PREDICTION_MODE read_inter_mode(VP9_COMMON *cm, vp9_reader *r,
+                                          uint8_t context) {
+  MB_PREDICTION_MODE mode = treed_read(r, vp9_inter_mode_tree,
+                            cm->fc.inter_mode_probs[context]);
+  ++cm->counts.inter_mode[context][inter_mode_offset(mode)];
+  return mode;
 }
 
 static int read_segment_id(vp9_reader *r, const struct segmentation *seg) {
   return treed_read(r, vp9_segment_tree, seg->tree_probs);
 }
 
 static TX_SIZE read_selected_tx_size(VP9_COMMON *cm, MACROBLOCKD *xd,
-                                     BLOCK_SIZE_TYPE bsize, vp9_reader *r) {
+                                     BLOCK_SIZE bsize, vp9_reader *r) {
   const uint8_t context = vp9_get_pred_context_tx_size(xd);
   const vp9_prob *tx_probs = get_tx_probs(bsize, context, &cm->fc.tx_probs);
   TX_SIZE tx_size = vp9_read(r, tx_probs[0]);
-  if (tx_size != TX_4X4 && bsize >= BLOCK_SIZE_MB16X16) {
+  if (tx_size != TX_4X4 && bsize >= BLOCK_16X16) {
     tx_size += vp9_read(r, tx_probs[1]);
-    if (tx_size != TX_8X8 && bsize >= BLOCK_SIZE_SB32X32)
+    if (tx_size != TX_8X8 && bsize >= BLOCK_32X32)
       tx_size += vp9_read(r, tx_probs[2]);
   }
 
   update_tx_counts(bsize, context, tx_size, &cm->counts.tx);
   return tx_size;
 }
 
 static TX_SIZE read_tx_size(VP9D_COMP *pbi, TX_MODE tx_mode,
-                            BLOCK_SIZE_TYPE bsize, int select_cond,
+                            BLOCK_SIZE bsize, int allow_select,
                             vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
 
-  if (tx_mode == TX_MODE_SELECT && bsize >= BLOCK_SIZE_SB8X8 && select_cond)
+  if (allow_select && tx_mode == TX_MODE_SELECT && bsize >= BLOCK_8X8)
     return read_selected_tx_size(cm, xd, bsize, r);
-  else if (tx_mode >= ALLOW_32X32 && bsize >= BLOCK_SIZE_SB32X32)
+  else if (tx_mode >= ALLOW_32X32 && bsize >= BLOCK_32X32)
     return TX_32X32;
-  else if (tx_mode >= ALLOW_16X16 && bsize >= BLOCK_SIZE_MB16X16)
+  else if (tx_mode >= ALLOW_16X16 && bsize >= BLOCK_16X16)
     return TX_16X16;
-  else if (tx_mode >= ALLOW_8X8 && bsize >= BLOCK_SIZE_SB8X8)
+  else if (tx_mode >= ALLOW_8X8 && bsize >= BLOCK_8X8)
     return TX_8X8;
   else
     return TX_4X4;
 }
 
-static void set_segment_id(VP9_COMMON *cm, BLOCK_SIZE_TYPE bsize,
+static void set_segment_id(VP9_COMMON *cm, BLOCK_SIZE bsize,
                            int mi_row, int mi_col, int segment_id) {
   const int mi_offset = mi_row * cm->mi_cols + mi_col;
   const int bw = 1 << mi_width_log2(bsize);
   const int bh = 1 << mi_height_log2(bsize);
   const int xmis = MIN(cm->mi_cols - mi_col, bw);
   const int ymis = MIN(cm->mi_rows - mi_row, bh);
   int x, y;
 
   assert(segment_id >= 0 && segment_id < MAX_SEGMENTS);
 
   for (y = 0; y < ymis; y++)
     for (x = 0; x < xmis; x++)
       cm->last_frame_seg_map[mi_offset + y * cm->mi_cols + x] = segment_id;
 }
 
 static int read_intra_segment_id(VP9D_COMP *pbi, int mi_row, int mi_col,
                                  vp9_reader *r) {
   MACROBLOCKD *const xd = &pbi->mb;
-  struct segmentation *const seg = &xd->seg;
-  const BLOCK_SIZE_TYPE bsize = xd->mode_info_context->mbmi.sb_type;
+  struct segmentation *const seg = &pbi->common.seg;
+  const BLOCK_SIZE bsize = xd->mode_info_context->mbmi.sb_type;
   int segment_id;
 
   if (!seg->enabled)
     return 0;  // Default for disabled segmentation
 
   if (!seg->update_map)
     return 0;
 
   segment_id = read_segment_id(r, seg);
   set_segment_id(&pbi->common, bsize, mi_row, mi_col, segment_id);
   return segment_id;
 }
 
 static int read_inter_segment_id(VP9D_COMP *pbi, int mi_row, int mi_col,
                                  vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
-  struct segmentation *const seg = &xd->seg;
-  const BLOCK_SIZE_TYPE bsize = xd->mode_info_context->mbmi.sb_type;
+  struct segmentation *const seg = &cm->seg;
+  const BLOCK_SIZE bsize = xd->mode_info_context->mbmi.sb_type;
   int pred_segment_id, segment_id;
 
   if (!seg->enabled)
     return 0;  // Default for disabled segmentation
 
   pred_segment_id = vp9_get_segment_id(cm, cm->last_frame_seg_map,
                                        bsize, mi_row, mi_col);
   if (!seg->update_map)
     return pred_segment_id;
 
   if (seg->temporal_update) {
-    const vp9_prob pred_prob = vp9_get_pred_prob_seg_id(xd);
+    const vp9_prob pred_prob = vp9_get_pred_prob_seg_id(seg, xd);
     const int pred_flag = vp9_read(r, pred_prob);
     vp9_set_pred_flag_seg_id(cm, bsize, mi_row, mi_col, pred_flag);
     segment_id = pred_flag ? pred_segment_id
                            : read_segment_id(r, seg);
   } else {
     segment_id = read_segment_id(r, seg);
   }
   set_segment_id(cm, bsize, mi_row, mi_col, segment_id);
   return segment_id;
 }
 
 static uint8_t read_skip_coeff(VP9D_COMP *pbi, int segment_id, vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
-  int skip_coeff = vp9_segfeature_active(&xd->seg, segment_id, SEG_LVL_SKIP);
+  int skip_coeff = vp9_segfeature_active(&cm->seg, segment_id, SEG_LVL_SKIP);
   if (!skip_coeff) {
     const int ctx = vp9_get_pred_context_mbskip(xd);
     skip_coeff = vp9_read(r, vp9_get_pred_prob_mbskip(cm, xd));
     cm->counts.mbskip[ctx][skip_coeff]++;
   }
   return skip_coeff;
 }
 
-static void read_intra_mode_info(VP9D_COMP *pbi, MODE_INFO *m,
-                                 int mi_row, int mi_col, vp9_reader *r) {
+static void read_intra_frame_mode_info(VP9D_COMP *pbi, MODE_INFO *m,
+                                       int mi_row, int mi_col, vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
   MB_MODE_INFO *const mbmi = &m->mbmi;
-  const BLOCK_SIZE_TYPE bsize = mbmi->sb_type;
+  const BLOCK_SIZE bsize = mbmi->sb_type;
   const int mis = cm->mode_info_stride;
 
   mbmi->segment_id = read_intra_segment_id(pbi, mi_row, mi_col, r);
-  mbmi->mb_skip_coeff = read_skip_coeff(pbi, mbmi->segment_id, r);
+  mbmi->skip_coeff = read_skip_coeff(pbi, mbmi->segment_id, r);
   mbmi->txfm_size = read_tx_size(pbi, cm->tx_mode, bsize, 1, r);
   mbmi->ref_frame[0] = INTRA_FRAME;
+  mbmi->ref_frame[1] = NONE;
 
-  if (bsize >= BLOCK_SIZE_SB8X8) {
+  if (bsize >= BLOCK_8X8) {
     const MB_PREDICTION_MODE A = above_block_mode(m, 0, mis);
     const MB_PREDICTION_MODE L = xd->left_available ?
                                   left_block_mode(m, 0) : DC_PRED;
     mbmi->mode = read_intra_mode(r, vp9_kf_y_mode_prob[A][L]);
   } else {
     // Only 4x4, 4x8, 8x4 blocks
-    const int bw = 1 << b_width_log2(bsize);
-    const int bh = 1 << b_height_log2(bsize);
+    const int num_4x4_w = num_4x4_blocks_wide_lookup[bsize];  // 1 or 2
+    const int num_4x4_h = num_4x4_blocks_high_lookup[bsize];  // 1 or 2
     int idx, idy;
 
-    for (idy = 0; idy < 2; idy += bh) {
-      for (idx = 0; idx < 2; idx += bw) {
+    for (idy = 0; idy < 2; idy += num_4x4_h) {
+      for (idx = 0; idx < 2; idx += num_4x4_w) {
         const int ib = idy * 2 + idx;
         const MB_PREDICTION_MODE A = above_block_mode(m, ib, mis);
         const MB_PREDICTION_MODE L = (xd->left_available || idx) ?
                                       left_block_mode(m, ib) : DC_PRED;
         const MB_PREDICTION_MODE b_mode = read_intra_mode(r,
                                               vp9_kf_y_mode_prob[A][L]);
         m->bmi[ib].as_mode = b_mode;
-        if (bh == 2)
+        if (num_4x4_h == 2)
           m->bmi[ib + 2].as_mode = b_mode;
-        if (bw == 2)
+        if (num_4x4_w == 2)
           m->bmi[ib + 1].as_mode = b_mode;
       }
     }
 
     mbmi->mode = m->bmi[3].as_mode;
   }
 
   mbmi->uv_mode = read_intra_mode(r, vp9_kf_uv_mode_prob[mbmi->mode]);
 }
 
@@ skipping 26 matching lines @@
   hp = usehp ? vp9_read(r, class0 ? mvcomp->class0_hp : mvcomp->hp)
              : 1;
 
   // Result
   mag = vp9_get_mv_mag(mv_class, (d << 3) | (fr << 1) | hp) + 1;
   return sign ? -mag : mag;
 }
 
 static INLINE void read_mv(vp9_reader *r, MV *mv, const MV *ref,
                            const nmv_context *ctx,
-                           nmv_context_counts *counts, int usehp) {
+                           nmv_context_counts *counts, int allow_hp) {
   const MV_JOINT_TYPE j = treed_read(r, vp9_mv_joint_tree, ctx->joints);
+  const int use_hp = allow_hp && vp9_use_mv_hp(ref);
   MV diff = {0, 0};
 
-  usehp = usehp && vp9_use_mv_hp(ref);
   if (mv_joint_vertical(j))
-    diff.row = read_mv_component(r, &ctx->comps[0], usehp);
+    diff.row = read_mv_component(r, &ctx->comps[0], use_hp);
 
   if (mv_joint_horizontal(j))
-    diff.col = read_mv_component(r, &ctx->comps[1], usehp);
+    diff.col = read_mv_component(r, &ctx->comps[1], use_hp);
 
   vp9_inc_mv(&diff, counts);
 
   mv->row = ref->row + diff.row;
   mv->col = ref->col + diff.col;
 }
 
-static void update_mv(vp9_reader *r, vp9_prob *p, vp9_prob upd_p) {
-  if (vp9_read(r, upd_p))
+static void update_mv(vp9_reader *r, vp9_prob *p) {
+  if (vp9_read(r, NMV_UPDATE_PROB))
     *p = (vp9_read_literal(r, 7) << 1) | 1;
 }
 
-static void read_mv_probs(vp9_reader *r, nmv_context *mvc, int usehp) {
+static void read_mv_probs(vp9_reader *r, nmv_context *mvc, int allow_hp) {
   int i, j, k;
 
   for (j = 0; j < MV_JOINTS - 1; ++j)
-    update_mv(r, &mvc->joints[j], VP9_NMV_UPDATE_PROB);
+    update_mv(r, &mvc->joints[j]);
 
   for (i = 0; i < 2; ++i) {
     nmv_component *const comp = &mvc->comps[i];
 
-    update_mv(r, &comp->sign, VP9_NMV_UPDATE_PROB);
+    update_mv(r, &comp->sign);
+
     for (j = 0; j < MV_CLASSES - 1; ++j)
-      update_mv(r, &comp->classes[j], VP9_NMV_UPDATE_PROB);
+      update_mv(r, &comp->classes[j]);
 
     for (j = 0; j < CLASS0_SIZE - 1; ++j)
-      update_mv(r, &comp->class0[j], VP9_NMV_UPDATE_PROB);
+      update_mv(r, &comp->class0[j]);
 
     for (j = 0; j < MV_OFFSET_BITS; ++j)
-      update_mv(r, &comp->bits[j], VP9_NMV_UPDATE_PROB);
+      update_mv(r, &comp->bits[j]);
   }
 
   for (i = 0; i < 2; ++i) {
     nmv_component *const comp = &mvc->comps[i];
 
     for (j = 0; j < CLASS0_SIZE; ++j)
       for (k = 0; k < 3; ++k)
-        update_mv(r, &comp->class0_fp[j][k], VP9_NMV_UPDATE_PROB);
+        update_mv(r, &comp->class0_fp[j][k]);
 
     for (j = 0; j < 3; ++j)
-      update_mv(r, &comp->fp[j], VP9_NMV_UPDATE_PROB);
+      update_mv(r, &comp->fp[j]);
   }
 
-  if (usehp) {
+  if (allow_hp) {
     for (i = 0; i < 2; ++i) {
-      update_mv(r, &mvc->comps[i].class0_hp, VP9_NMV_UPDATE_PROB);
-      update_mv(r, &mvc->comps[i].hp, VP9_NMV_UPDATE_PROB);
+      update_mv(r, &mvc->comps[i].class0_hp);
+      update_mv(r, &mvc->comps[i].hp);
     }
   }
 }
 
 // Read the referncence frame
-static void read_ref_frame(VP9D_COMP *pbi, vp9_reader *r,
-                           int segment_id, MV_REFERENCE_FRAME ref_frame[2]) {
+static void read_ref_frames(VP9D_COMP *pbi, vp9_reader *r,
+                            int segment_id, MV_REFERENCE_FRAME ref_frame[2]) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
   FRAME_CONTEXT *const fc = &cm->fc;
   FRAME_COUNTS *const counts = &cm->counts;
 
-  if (vp9_segfeature_active(&xd->seg, segment_id, SEG_LVL_REF_FRAME)) {
-    ref_frame[0] = vp9_get_segdata(&xd->seg, segment_id, SEG_LVL_REF_FRAME);
+  if (vp9_segfeature_active(&cm->seg, segment_id, SEG_LVL_REF_FRAME)) {
+    ref_frame[0] = vp9_get_segdata(&cm->seg, segment_id, SEG_LVL_REF_FRAME);
     ref_frame[1] = NONE;
   } else {
     const int comp_ctx = vp9_get_pred_context_comp_inter_inter(cm, xd);
     int is_comp;
 
     if (cm->comp_pred_mode == HYBRID_PREDICTION) {
       is_comp = vp9_read(r, fc->comp_inter_prob[comp_ctx]);
       counts->comp_inter[comp_ctx][is_comp]++;
     } else {
       is_comp = cm->comp_pred_mode == COMP_PREDICTION_ONLY;
     }
 
     // FIXME(rbultje) I'm pretty sure this breaks segmentation ref frame coding
     if (is_comp) {
       const int fix_ref_idx = cm->ref_frame_sign_bias[cm->comp_fixed_ref];
       const int ref_ctx = vp9_get_pred_context_comp_ref_p(cm, xd);
       const int b = vp9_read(r, fc->comp_ref_prob[ref_ctx]);
       counts->comp_ref[ref_ctx][b]++;
       ref_frame[fix_ref_idx] = cm->comp_fixed_ref;
       ref_frame[!fix_ref_idx] = cm->comp_var_ref[b];
     } else {
-      const int ref1_ctx = vp9_get_pred_context_single_ref_p1(xd);
-      ref_frame[1] = NONE;
-      if (vp9_read(r, fc->single_ref_prob[ref1_ctx][0])) {
-        const int ref2_ctx = vp9_get_pred_context_single_ref_p2(xd);
-        const int b = vp9_read(r, fc->single_ref_prob[ref2_ctx][1]);
-        ref_frame[0] = b ? ALTREF_FRAME : GOLDEN_FRAME;
-        counts->single_ref[ref1_ctx][0][1]++;
-        counts->single_ref[ref2_ctx][1][b]++;
+      const int ctx0 = vp9_get_pred_context_single_ref_p1(xd);
+      const int bit0 = vp9_read(r, fc->single_ref_prob[ctx0][0]);
+      ++counts->single_ref[ctx0][0][bit0];
+      if (bit0) {
+        const int ctx1 = vp9_get_pred_context_single_ref_p2(xd);
+        const int bit1 = vp9_read(r, fc->single_ref_prob[ctx1][1]);
+        ref_frame[0] = bit1 ? ALTREF_FRAME : GOLDEN_FRAME;
+        ++counts->single_ref[ctx1][1][bit1];
       } else {
         ref_frame[0] = LAST_FRAME;
-        counts->single_ref[ref1_ctx][0][0]++;
       }
+
+      ref_frame[1] = NONE;
     }
   }
 }
 
 static void read_switchable_interp_probs(FRAME_CONTEXT *fc, vp9_reader *r) {
   int i, j;
-  for (j = 0; j < VP9_SWITCHABLE_FILTERS + 1; ++j)
-    for (i = 0; i < VP9_SWITCHABLE_FILTERS - 1; ++i)
-      if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+  for (j = 0; j < SWITCHABLE_FILTERS + 1; ++j)
+    for (i = 0; i < SWITCHABLE_FILTERS - 1; ++i)
+      if (vp9_read(r, MODE_UPDATE_PROB))
         vp9_diff_update_prob(r, &fc->switchable_interp_prob[j][i]);
 }
 
 static void read_inter_mode_probs(FRAME_CONTEXT *fc, vp9_reader *r) {
   int i, j;
   for (i = 0; i < INTER_MODE_CONTEXTS; ++i)
-    for (j = 0; j < VP9_INTER_MODES - 1; ++j)
-      if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+    for (j = 0; j < INTER_MODES - 1; ++j)
+      if (vp9_read(r, MODE_UPDATE_PROB))
         vp9_diff_update_prob(r, &fc->inter_mode_probs[i][j]);
 }
 
 static INLINE COMPPREDMODE_TYPE read_comp_pred_mode(vp9_reader *r) {
   COMPPREDMODE_TYPE mode = vp9_read_bit(r);
   if (mode)
     mode += vp9_read_bit(r);
   return mode;
 }
 
-static INLINE void assign_and_clamp_mv(int_mv *dst, const int_mv *src,
-                                       int mb_to_left_edge,
-                                       int mb_to_right_edge,
-                                       int mb_to_top_edge,
-                                       int mb_to_bottom_edge) {
-  dst->as_int = src->as_int;
-  clamp_mv(dst, mb_to_left_edge, mb_to_right_edge, mb_to_top_edge,
-           mb_to_bottom_edge);
-}
-
 static INLINE INTERPOLATIONFILTERTYPE read_switchable_filter_type(
     VP9D_COMP *pbi, vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
-  const vp9_prob *probs = vp9_get_pred_probs_switchable_interp(cm, xd);
-  const int index = treed_read(r, vp9_switchable_interp_tree, probs);
   const int ctx = vp9_get_pred_context_switchable_interp(xd);
-  ++cm->counts.switchable_interp[ctx][index];
-  return vp9_switchable_interp[index];
+  const int type = treed_read(r, vp9_switchable_interp_tree,
+                              cm->fc.switchable_interp_prob[ctx]);
+  ++cm->counts.switchable_interp[ctx][type];
+  return type;
 }
 
-static void read_intra_block_modes(VP9D_COMP *pbi, MODE_INFO *mi,
-                                   vp9_reader *r) {
+static void read_intra_block_mode_info(VP9D_COMP *pbi, MODE_INFO *mi,
+                                  vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MB_MODE_INFO *const mbmi = &mi->mbmi;
-  const BLOCK_SIZE_TYPE bsize = mi->mbmi.sb_type;
-  const int bwl = b_width_log2(bsize), bhl = b_height_log2(bsize);
+  const BLOCK_SIZE bsize = mi->mbmi.sb_type;
 
-  if (bsize >= BLOCK_SIZE_SB8X8) {
-    const int size_group = MIN(3, MIN(bwl, bhl));
+  mbmi->ref_frame[0] = INTRA_FRAME;
+  mbmi->ref_frame[1] = NONE;
+
+  if (bsize >= BLOCK_8X8) {
+    const int size_group = size_group_lookup[bsize];
     mbmi->mode = read_intra_mode(r, cm->fc.y_mode_prob[size_group]);
     cm->counts.y_mode[size_group][mbmi->mode]++;
   } else {
      // Only 4x4, 4x8, 8x4 blocks
-     const int bw = 1 << bwl, bh = 1 << bhl;
+     const int num_4x4_w = num_4x4_blocks_wide_lookup[bsize];  // 1 or 2
+     const int num_4x4_h = num_4x4_blocks_high_lookup[bsize];  // 1 or 2
      int idx, idy;
 
-     for (idy = 0; idy < 2; idy += bh) {
-       for (idx = 0; idx < 2; idx += bw) {
+     for (idy = 0; idy < 2; idy += num_4x4_h) {
+       for (idx = 0; idx < 2; idx += num_4x4_w) {
          const int ib = idy * 2 + idx;
          const int b_mode = read_intra_mode(r, cm->fc.y_mode_prob[0]);
          mi->bmi[ib].as_mode = b_mode;
          cm->counts.y_mode[0][b_mode]++;
 
-         if (bh == 2)
+         if (num_4x4_h == 2)
            mi->bmi[ib + 2].as_mode = b_mode;
-         if (bw == 2)
+         if (num_4x4_w == 2)
            mi->bmi[ib + 1].as_mode = b_mode;
       }
     }
     mbmi->mode = mi->bmi[3].as_mode;
   }
 
   mbmi->uv_mode = read_intra_mode(r, cm->fc.uv_mode_prob[mbmi->mode]);
   cm->counts.uv_mode[mbmi->mode][mbmi->uv_mode]++;
 }
 
-static MV_REFERENCE_FRAME read_reference_frame(VP9D_COMP *pbi, int segment_id,
-                                               vp9_reader *r) {
+static int read_is_inter_block(VP9D_COMP *pbi, int segment_id, vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
 
-  MV_REFERENCE_FRAME ref;
-  if (!vp9_segfeature_active(&xd->seg, segment_id, SEG_LVL_REF_FRAME)) {
+  if (vp9_segfeature_active(&cm->seg, segment_id, SEG_LVL_REF_FRAME)) {
+    return vp9_get_segdata(&cm->seg, segment_id, SEG_LVL_REF_FRAME) !=
+           INTRA_FRAME;
+  } else {
     const int ctx = vp9_get_pred_context_intra_inter(xd);
-    ref = (MV_REFERENCE_FRAME)
-              vp9_read(r, vp9_get_pred_prob_intra_inter(cm, xd));
-    cm->counts.intra_inter[ctx][ref != INTRA_FRAME]++;
-  } else {
-    ref = (MV_REFERENCE_FRAME) vp9_get_segdata(&xd->seg, segment_id,
-                                   SEG_LVL_REF_FRAME) != INTRA_FRAME;
+    const int is_inter = vp9_read(r, vp9_get_pred_prob_intra_inter(cm, xd));
+    ++cm->counts.intra_inter[ctx][is_inter];
+    return is_inter;
   }
-  return ref;
 }
 
-static void read_inter_mode_info(VP9D_COMP *pbi, MODE_INFO *mi,
-                                 int mi_row, int mi_col, vp9_reader *r) {
+static void read_inter_block_mode_info(VP9D_COMP *pbi, MODE_INFO *mi,
+                                       int mi_row, int mi_col, vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
   nmv_context *const nmvc = &cm->fc.nmvc;
   MB_MODE_INFO *const mbmi = &mi->mbmi;
-
   int_mv *const mv0 = &mbmi->mv[0];
   int_mv *const mv1 = &mbmi->mv[1];
-  const BLOCK_SIZE_TYPE bsize = mi->mbmi.sb_type;
-  const int bw = 1 << b_width_log2(bsize);
-  const int bh = 1 << b_height_log2(bsize);
+  const BLOCK_SIZE bsize = mbmi->sb_type;
+  const int allow_hp = xd->allow_high_precision_mv;
 
-  int idx, idy;
+  int_mv nearest, nearby, best_mv;
+  int_mv nearest_second, nearby_second, best_mv_second;
+  uint8_t inter_mode_ctx;
+  MV_REFERENCE_FRAME ref0;
+  int is_compound;
 
-  mbmi->segment_id = read_inter_segment_id(pbi, mi_row, mi_col, r);
-  mbmi->mb_skip_coeff = read_skip_coeff(pbi, mbmi->segment_id, r);
-  mbmi->ref_frame[0] = read_reference_frame(pbi, mbmi->segment_id, r);
-  mbmi->ref_frame[1] = NONE;
-  mbmi->txfm_size = read_tx_size(pbi, cm->tx_mode, bsize,
-     (!mbmi->mb_skip_coeff || mbmi->ref_frame[0] == INTRA_FRAME), r);
+  mbmi->uv_mode = DC_PRED;
+  read_ref_frames(pbi, r, mbmi->segment_id, mbmi->ref_frame);
+  ref0 = mbmi->ref_frame[0];
+  is_compound = has_second_ref(mbmi);
 
-  if (mbmi->ref_frame[0] != INTRA_FRAME) {
-    int_mv nearest, nearby, best_mv;
-    int_mv nearest_second, nearby_second, best_mv_second;
-    vp9_prob *mv_ref_p;
-    MV_REFERENCE_FRAME ref0, ref1;
+  vp9_find_mv_refs(cm, xd, mi, xd->prev_mode_info_context,
+                   ref0, mbmi->ref_mvs[ref0], mi_row, mi_col);
 
-    read_ref_frame(pbi, r, mbmi->segment_id, mbmi->ref_frame);
-    ref0 = mbmi->ref_frame[0];
-    ref1 = mbmi->ref_frame[1];
+  inter_mode_ctx = mbmi->mode_context[ref0];
 
+  if (vp9_segfeature_active(&cm->seg, mbmi->segment_id, SEG_LVL_SKIP)) {
+    mbmi->mode = ZEROMV;
+  } else {
+    if (bsize >= BLOCK_8X8)
+      mbmi->mode = read_inter_mode(cm, r, inter_mode_ctx);
+  }
+
+  // nearest, nearby
+  if (bsize < BLOCK_8X8 || mbmi->mode != ZEROMV) {
+    vp9_find_best_ref_mvs(xd, mbmi->ref_mvs[ref0], &nearest, &nearby);
+    best_mv.as_int = mbmi->ref_mvs[ref0][0].as_int;
+  }
+
+  if (is_compound) {
+    const MV_REFERENCE_FRAME ref1 = mbmi->ref_frame[1];
     vp9_find_mv_refs(cm, xd, mi, xd->prev_mode_info_context,
-                     ref0, mbmi->ref_mvs[ref0], cm->ref_frame_sign_bias);
+                     ref1, mbmi->ref_mvs[ref1], mi_row, mi_col);
 
-    mv_ref_p = cm->fc.inter_mode_probs[mbmi->mb_mode_context[ref0]];
+    if (bsize < BLOCK_8X8 || mbmi->mode != ZEROMV) {
+      vp9_find_best_ref_mvs(xd, mbmi->ref_mvs[ref1],
+                            &nearest_second, &nearby_second);
+      best_mv_second.as_int = mbmi->ref_mvs[ref1][0].as_int;
+    }
+  }
 
-    if (vp9_segfeature_active(&xd->seg, mbmi->segment_id, SEG_LVL_SKIP)) {
-      mbmi->mode = ZEROMV;
-    } else if (bsize >= BLOCK_SIZE_SB8X8) {
-      mbmi->mode = read_inter_mode(r, mv_ref_p);
-      vp9_accum_mv_refs(cm, mbmi->mode, mbmi->mb_mode_context[ref0]);
-    }
-    mbmi->uv_mode = DC_PRED;
-
-    // nearest, nearby
-    if (bsize < BLOCK_SIZE_SB8X8 || mbmi->mode != ZEROMV) {
-      vp9_find_best_ref_mvs(xd, mbmi->ref_mvs[ref0], &nearest, &nearby);
-      best_mv.as_int = mbmi->ref_mvs[ref0][0].as_int;
-    }
-
-    mbmi->interp_filter = cm->mcomp_filter_type == SWITCHABLE
+  mbmi->interp_filter = cm->mcomp_filter_type == SWITCHABLE
                               ? read_switchable_filter_type(pbi, r)
                               : cm->mcomp_filter_type;
 
-    if (ref1 > INTRA_FRAME) {
-      vp9_find_mv_refs(cm, xd, mi, xd->prev_mode_info_context,
-                       ref1, mbmi->ref_mvs[ref1], cm->ref_frame_sign_bias);
+  if (bsize < BLOCK_8X8) {
+    const int num_4x4_w = num_4x4_blocks_wide_lookup[bsize];  // 1 or 2
+    const int num_4x4_h = num_4x4_blocks_high_lookup[bsize];  // 1 or 2
+    int idx, idy;
+    for (idy = 0; idy < 2; idy += num_4x4_h) {
+      for (idx = 0; idx < 2; idx += num_4x4_w) {
+        int_mv blockmv, secondmv;
+        const int j = idy * 2 + idx;
+        const int b_mode = read_inter_mode(cm, r, inter_mode_ctx);
 
-      if (bsize < BLOCK_SIZE_SB8X8 || mbmi->mode != ZEROMV) {
-        vp9_find_best_ref_mvs(xd, mbmi->ref_mvs[ref1],
-                              &nearest_second, &nearby_second);
-        best_mv_second.as_int = mbmi->ref_mvs[ref1][0].as_int;
+        if (b_mode == NEARESTMV || b_mode == NEARMV) {
+          vp9_append_sub8x8_mvs_for_idx(cm, xd, &nearest, &nearby, j, 0,
+                                        mi_row, mi_col);
+
+          if (is_compound)
+            vp9_append_sub8x8_mvs_for_idx(cm, xd,  &nearest_second,
+                                         &nearby_second, j, 1,
+                                         mi_row, mi_col);
+        }
+
+        switch (b_mode) {
+          case NEWMV:
+            read_mv(r, &blockmv.as_mv, &best_mv.as_mv, nmvc,
+                    &cm->counts.mv, allow_hp);
+
+            if (is_compound)
+              read_mv(r, &secondmv.as_mv, &best_mv_second.as_mv, nmvc,
+                      &cm->counts.mv, allow_hp);
+            break;
+          case NEARESTMV:
+            blockmv.as_int = nearest.as_int;
+            if (is_compound)
+              secondmv.as_int = nearest_second.as_int;
+            break;
+          case NEARMV:
+            blockmv.as_int = nearby.as_int;
+            if (is_compound)
+              secondmv.as_int = nearby_second.as_int;
+            break;
+          case ZEROMV:
+            blockmv.as_int = 0;
+            if (is_compound)
+              secondmv.as_int = 0;
+            break;
+          default:
+            assert(!"Invalid inter mode value");
+        }
+        mi->bmi[j].as_mv[0].as_int = blockmv.as_int;
+        if (is_compound)
+          mi->bmi[j].as_mv[1].as_int = secondmv.as_int;
+
+        if (num_4x4_h == 2)
+          mi->bmi[j + 2] = mi->bmi[j];
+        if (num_4x4_w == 2)
+          mi->bmi[j + 1] = mi->bmi[j];
+        mi->mbmi.mode = b_mode;
       }
     }
 
+    mv0->as_int = mi->bmi[3].as_mv[0].as_int;
+    mv1->as_int = mi->bmi[3].as_mv[1].as_int;
+  } else {
+    switch (mbmi->mode) {
+      case NEARMV:
+        mv0->as_int = nearby.as_int;
+        if (is_compound)
+          mv1->as_int = nearby_second.as_int;
+        break;
 
-    if (mbmi->sb_type < BLOCK_SIZE_SB8X8) {
-      for (idy = 0; idy < 2; idy += bh) {
-        for (idx = 0; idx < 2; idx += bw) {
-          int_mv blockmv, secondmv;
-          const int j = idy * 2 + idx;
-          const int blockmode = read_inter_mode(r, mv_ref_p);
+      case NEARESTMV:
+        mv0->as_int = nearest.as_int;
+        if (is_compound)
+          mv1->as_int = nearest_second.as_int;
+        break;
 
-          vp9_accum_mv_refs(cm, blockmode, mbmi->mb_mode_context[ref0]);
-          if (blockmode == NEARESTMV || blockmode == NEARMV) {
-            vp9_append_sub8x8_mvs_for_idx(cm, xd, &nearest, &nearby, j, 0);
-            if (ref1 > 0)
-              vp9_append_sub8x8_mvs_for_idx(cm, xd,  &nearest_second,
-                                            &nearby_second, j, 1);
-          }
+      case ZEROMV:
+        mv0->as_int = 0;
+        if (is_compound)
+          mv1->as_int = 0;
+        break;
 
-          switch (blockmode) {
-            case NEWMV:
-              read_mv(r, &blockmv.as_mv, &best_mv.as_mv, nmvc,
-                      &cm->counts.mv, xd->allow_high_precision_mv);
+      case NEWMV:
+        read_mv(r, &mv0->as_mv, &best_mv.as_mv, nmvc, &cm->counts.mv, allow_hp);
+        if (is_compound)
+          read_mv(r, &mv1->as_mv, &best_mv_second.as_mv, nmvc, &cm->counts.mv,
+                  allow_hp);
+        break;
+      default:
+        assert(!"Invalid inter mode value");
+    }
+  }
+}
 
-              if (ref1 > 0)
-                read_mv(r, &secondmv.as_mv, &best_mv_second.as_mv, nmvc,
-                        &cm->counts.mv, xd->allow_high_precision_mv);
-              break;
-            case NEARESTMV:
-              blockmv.as_int = nearest.as_int;
-              if (ref1 > 0)
-                secondmv.as_int = nearest_second.as_int;
-              break;
-            case NEARMV:
-              blockmv.as_int = nearby.as_int;
-              if (ref1 > 0)
-                secondmv.as_int = nearby_second.as_int;
-              break;
-            case ZEROMV:
-              blockmv.as_int = 0;
-              if (ref1 > 0)
-                secondmv.as_int = 0;
-              break;
-            default:
-              assert(!"Invalid inter mode value");
-          }
-          mi->bmi[j].as_mv[0].as_int = blockmv.as_int;
-          if (ref1 > 0)
-            mi->bmi[j].as_mv[1].as_int = secondmv.as_int;
+static void read_inter_frame_mode_info(VP9D_COMP *pbi, MODE_INFO *mi,
+                                       int mi_row, int mi_col, vp9_reader *r) {
+  VP9_COMMON *const cm = &pbi->common;
+  MB_MODE_INFO *const mbmi = &mi->mbmi;
+  int inter_block;
 
-          if (bh == 2)
-            mi->bmi[j + 2] = mi->bmi[j];
-          if (bw == 2)
-            mi->bmi[j + 1] = mi->bmi[j];
-          mi->mbmi.mode = blockmode;
-        }
-      }
+  mbmi->mv[0].as_int = 0;
+  mbmi->mv[1].as_int = 0;
+  mbmi->segment_id = read_inter_segment_id(pbi, mi_row, mi_col, r);
+  mbmi->skip_coeff = read_skip_coeff(pbi, mbmi->segment_id, r);
+  inter_block = read_is_inter_block(pbi, mbmi->segment_id, r);
+  mbmi->txfm_size = read_tx_size(pbi, cm->tx_mode, mbmi->sb_type,
+                                 !mbmi->skip_coeff || !inter_block, r);
 
-      mv0->as_int = mi->bmi[3].as_mv[0].as_int;
-      mv1->as_int = mi->bmi[3].as_mv[1].as_int;
-    } else {
-      const int mb_to_top_edge = xd->mb_to_top_edge - LEFT_TOP_MARGIN;
-      const int mb_to_bottom_edge = xd->mb_to_bottom_edge + RIGHT_BOTTOM_MARGIN;
-      const int mb_to_left_edge = xd->mb_to_left_edge - LEFT_TOP_MARGIN;
-      const int mb_to_right_edge = xd->mb_to_right_edge + RIGHT_BOTTOM_MARGIN;
-
-      switch (mbmi->mode) {
-        case NEARMV:
-          // Clip "next_nearest" so that it does not extend to far out of image
-          assign_and_clamp_mv(mv0, &nearby, mb_to_left_edge,
-                                            mb_to_right_edge,
-                                            mb_to_top_edge,
-                                            mb_to_bottom_edge);
-          if (ref1 > 0)
-            assign_and_clamp_mv(mv1, &nearby_second, mb_to_left_edge,
-                                                     mb_to_right_edge,
-                                                     mb_to_top_edge,
-                                                     mb_to_bottom_edge);
-          break;
-
-        case NEARESTMV:
-          // Clip "next_nearest" so that it does not extend to far out of image
-          assign_and_clamp_mv(mv0, &nearest, mb_to_left_edge,
-                                             mb_to_right_edge,
-                                             mb_to_top_edge,
-                                             mb_to_bottom_edge);
-          if (ref1 > 0)
-            assign_and_clamp_mv(mv1, &nearest_second, mb_to_left_edge,
-                                                      mb_to_right_edge,
-                                                      mb_to_top_edge,
-                                                      mb_to_bottom_edge);
-          break;
-
-        case ZEROMV:
-          mv0->as_int = 0;
-          if (ref1 > 0)
-            mv1->as_int = 0;
-          break;
-
-        case NEWMV:
-          read_mv(r, &mv0->as_mv, &best_mv.as_mv, nmvc, &cm->counts.mv,
-                  xd->allow_high_precision_mv);
-          if (ref1 > 0)
-            read_mv(r, &mv1->as_mv, &best_mv_second.as_mv, nmvc,
-                    &cm->counts.mv, xd->allow_high_precision_mv);
-          break;
-        default:
-          assert(!"Invalid inter mode value");
-      }
-    }
-  } else {
-    mv0->as_int = 0;  // required for left and above block mv
-    read_intra_block_modes(pbi, mi, r);
-  }
+  if (inter_block)
+    read_inter_block_mode_info(pbi, mi, mi_row, mi_col, r);
+  else
+    read_intra_block_mode_info(pbi, mi, r);
 }
 
 static void read_comp_pred(VP9_COMMON *cm, vp9_reader *r) {
   int i;
 
   cm->comp_pred_mode = cm->allow_comp_inter_inter ? read_comp_pred_mode(r)
                                                   : SINGLE_PREDICTION_ONLY;
 
   if (cm->comp_pred_mode == HYBRID_PREDICTION)
     for (i = 0; i < COMP_INTER_CONTEXTS; i++)
-      if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+      if (vp9_read(r, MODE_UPDATE_PROB))
         vp9_diff_update_prob(r, &cm->fc.comp_inter_prob[i]);
 
   if (cm->comp_pred_mode != COMP_PREDICTION_ONLY)
     for (i = 0; i < REF_CONTEXTS; i++) {
-      if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+      if (vp9_read(r, MODE_UPDATE_PROB))
         vp9_diff_update_prob(r, &cm->fc.single_ref_prob[i][0]);
-      if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+      if (vp9_read(r, MODE_UPDATE_PROB))
         vp9_diff_update_prob(r, &cm->fc.single_ref_prob[i][1]);
     }
 
   if (cm->comp_pred_mode != SINGLE_PREDICTION_ONLY)
     for (i = 0; i < REF_CONTEXTS; i++)
-      if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+      if (vp9_read(r, MODE_UPDATE_PROB))
         vp9_diff_update_prob(r, &cm->fc.comp_ref_prob[i]);
 }
 
 void vp9_prepare_read_mode_info(VP9D_COMP* pbi, vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   int k;
 
   // TODO(jkoleszar): does this clear more than MBSKIP_CONTEXTS? Maybe remove.
   // vpx_memset(cm->fc.mbskip_probs, 0, sizeof(cm->fc.mbskip_probs));
   for (k = 0; k < MBSKIP_CONTEXTS; ++k)
-    if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+    if (vp9_read(r, MODE_UPDATE_PROB))
       vp9_diff_update_prob(r, &cm->fc.mbskip_probs[k]);
 
   if (cm->frame_type != KEY_FRAME && !cm->intra_only) {
     nmv_context *const nmvc = &pbi->common.fc.nmvc;
     MACROBLOCKD *const xd = &pbi->mb;
     int i, j;
 
     read_inter_mode_probs(&cm->fc, r);
 
     if (cm->mcomp_filter_type == SWITCHABLE)
       read_switchable_interp_probs(&cm->fc, r);
 
     for (i = 0; i < INTRA_INTER_CONTEXTS; i++)
-      if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+      if (vp9_read(r, MODE_UPDATE_PROB))
         vp9_diff_update_prob(r, &cm->fc.intra_inter_prob[i]);
 
     read_comp_pred(cm, r);
 
     for (j = 0; j < BLOCK_SIZE_GROUPS; j++)
-      for (i = 0; i < VP9_INTRA_MODES - 1; ++i)
-        if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+      for (i = 0; i < INTRA_MODES - 1; ++i)
+        if (vp9_read(r, MODE_UPDATE_PROB))
           vp9_diff_update_prob(r, &cm->fc.y_mode_prob[j][i]);
 
     for (j = 0; j < NUM_PARTITION_CONTEXTS; ++j)
       for (i = 0; i < PARTITION_TYPES - 1; ++i)
-        if (vp9_read(r, VP9_MODE_UPDATE_PROB))
+        if (vp9_read(r, MODE_UPDATE_PROB))
           vp9_diff_update_prob(r, &cm->fc.partition_prob[INTER_FRAME][j][i]);
 
     read_mv_probs(r, nmvc, xd->allow_high_precision_mv);
   }
 }
 
 void vp9_read_mode_info(VP9D_COMP* pbi, int mi_row, int mi_col, vp9_reader *r) {
   VP9_COMMON *const cm = &pbi->common;
   MACROBLOCKD *const xd = &pbi->mb;
   MODE_INFO *mi = xd->mode_info_context;
-  const BLOCK_SIZE_TYPE bsize = mi->mbmi.sb_type;
+  const BLOCK_SIZE bsize = mi->mbmi.sb_type;
   const int bw = 1 << mi_width_log2(bsize);
   const int bh = 1 << mi_height_log2(bsize);
   const int y_mis = MIN(bh, cm->mi_rows - mi_row);
   const int x_mis = MIN(bw, cm->mi_cols - mi_col);
   int x, y;
 
   if (cm->frame_type == KEY_FRAME || cm->intra_only)
-    read_intra_mode_info(pbi, mi, mi_row, mi_col, r);
+    read_intra_frame_mode_info(pbi, mi, mi_row, mi_col, r);
   else
-    read_inter_mode_info(pbi, mi, mi_row, mi_col, r);
+    read_inter_frame_mode_info(pbi, mi, mi_row, mi_col, r);
 
   for (y = 0; y < y_mis; y++)
     for (x = !y; x < x_mis; x++)
       mi[y * cm->mode_info_stride + x] = *mi;
 }