Pre-store the pred_diff for nmv context

Replace the int_mv storage in the ref_mv_stack struct with unit8_t
integer to indicate the prediction difference level.

Change-Id: I0bfbcab350a46ecdd5bc47bd918cce9614365227

av1/common/mv.h

@@ -165,7 +165,7 @@ static INLINE void set_default_gmparams(WarpedMotionParams *wm) {
 typedef struct candidate_mv {
   int_mv this_mv;
   int_mv comp_mv;
-  int_mv pred_mv[2];
+  uint8_t pred_diff[2];
   int weight;
 } CANDIDATE_MV;
 #endif

av1/common/mvref_common.c

@@ -35,8 +35,8 @@ static uint8_t add_ref_mv_candidate(
         // Add a new item to the list.
         if (index == *refmv_count) {
           ref_mv_stack[index].this_mv = this_refmv;
-          ref_mv_stack[index].pred_mv[0] =
-              get_sub_block_pred_mv(candidate_mi, ref, col, block);
+          ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+              get_sub_block_pred_mv(candidate_mi, ref, col, block), this_refmv);
           ref_mv_stack[index].weight = 2 * len;
           ++(*refmv_count);
 
@@ -61,8 +61,9 @@ static uint8_t add_ref_mv_candidate(
           // Add a new item to the list.
           if (index == *refmv_count) {
             ref_mv_stack[index].this_mv = this_refmv;
-            ref_mv_stack[index].pred_mv[0] =
-                get_sub_block_pred_mv(candidate_mi, ref, col, alt_block);
+            ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+                get_sub_block_pred_mv(candidate_mi, ref, col, alt_block),
+                this_refmv);
             ref_mv_stack[index].weight = len;
             ++(*refmv_count);
 
@@ -97,10 +98,10 @@ static uint8_t add_ref_mv_candidate(
       if (index == *refmv_count) {
         ref_mv_stack[index].this_mv = this_refmv[0];
         ref_mv_stack[index].comp_mv = this_refmv[1];
-        ref_mv_stack[index].pred_mv[0] =
-            get_sub_block_pred_mv(candidate_mi, 0, col, block);
-        ref_mv_stack[index].pred_mv[1] =
-            get_sub_block_pred_mv(candidate_mi, 1, col, block);
+        ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+            get_sub_block_pred_mv(candidate_mi, 0, col, block), this_refmv[0]);
+        ref_mv_stack[index].pred_diff[1] = av1_get_pred_diff_ctx(
+            get_sub_block_pred_mv(candidate_mi, 1, col, block), this_refmv[1]);
         ref_mv_stack[index].weight = 2 * len;
         ++(*refmv_count);
 
@@ -131,10 +132,12 @@ static uint8_t add_ref_mv_candidate(
         if (index == *refmv_count) {
           ref_mv_stack[index].this_mv = this_refmv[0];
           ref_mv_stack[index].comp_mv = this_refmv[1];
-          ref_mv_stack[index].pred_mv[0] =
-              get_sub_block_pred_mv(candidate_mi, 0, col, block);
-          ref_mv_stack[index].pred_mv[1] =
-              get_sub_block_pred_mv(candidate_mi, 1, col, block);
+          ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+              get_sub_block_pred_mv(candidate_mi, 0, col, block),
+              this_refmv[0]);
+          ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+              get_sub_block_pred_mv(candidate_mi, 1, col, block),
+              this_refmv[1]);
           ref_mv_stack[index].weight = len;
           ++(*refmv_count);
 
@@ -356,7 +359,8 @@ static int add_col_ref_mv(const AV1_COMMON *cm,
 #if CONFIG_SIMP_MV_PRED
         ref_mv_stack[idx].pred_mv[0] = prev_frame_mvs->mv[ref];
 #else
-        ref_mv_stack[idx].pred_mv[0] = prev_frame_mvs->pred_mv[ref];
+        ref_mv_stack[idx].pred_diff[0] =
+            av1_get_pred_diff_ctx(prev_frame_mvs->pred_mv[ref], this_refmv);
 #endif
         ref_mv_stack[idx].weight = 2;
         ++(*refmv_count);

av1/common/mvref_common.h

@@ -362,24 +362,24 @@ static INLINE void lower_mv_precision(MV *mv, int allow_hp) {
 }
 
 #if CONFIG_REF_MV
+static INLINE uint8_t av1_get_pred_diff_ctx(const int_mv pred_mv,
+                                            const int_mv this_mv) {
+  if (abs(this_mv.as_mv.row - pred_mv.as_mv.row) <= 4 &&
+      abs(this_mv.as_mv.col - pred_mv.as_mv.col) <= 4)
+    return 2;
+  else
+    return 1;
+}
+
 static INLINE int av1_nmv_ctx(const uint8_t ref_mv_count,
                               const CANDIDATE_MV *ref_mv_stack, int ref,
                               int ref_mv_idx) {
-  int_mv this_mv = (ref == 0) ? ref_mv_stack[ref_mv_idx].this_mv
-                              : ref_mv_stack[ref_mv_idx].comp_mv;
 #if CONFIG_EXT_INTER
   return 0;
 #endif
 
-  if (ref_mv_stack[ref_mv_idx].weight >= REF_CAT_LEVEL && ref_mv_count > 0) {
-    if (abs(this_mv.as_mv.row -
-            ref_mv_stack[ref_mv_idx].pred_mv[ref].as_mv.row) <= 4 &&
-        abs(this_mv.as_mv.col -
-            ref_mv_stack[ref_mv_idx].pred_mv[ref].as_mv.col) <= 4)
-      return 2;
-    else
-      return 1;
-  }
+  if (ref_mv_stack[ref_mv_idx].weight >= REF_CAT_LEVEL && ref_mv_count > 0)
+    return ref_mv_stack[ref_mv_idx].pred_diff[ref];
 
   return 0;
 }