Simplify flow of control

Avoid switch warning regarding fallthrough, add consts.

Change-Id: Ie3a03e60420d962941abc4e144648f29401916b9

av1/encoder/bitstream.c

@@ -3819,9 +3819,7 @@ static void write_global_motion_params(const WarpedMotionParams *params,
                                        const WarpedMotionParams *ref_params,
                                        struct aom_write_bit_buffer *wb,
                                        int allow_hp) {
-  TransformationType type = params->wmtype;
-  int trans_bits;
-  int trans_prec_diff;
+  const TransformationType type = params->wmtype;
 
   aom_wb_write_bit(wb, type != IDENTITY);
   if (type != IDENTITY) {
@@ -3833,9 +3831,7 @@ static void write_global_motion_params(const WarpedMotionParams *params,
 #endif  // GLOBAL_TRANS_TYPES > 4
   }
 
-  switch (type) {
-    case AFFINE:
-    case ROTZOOM:
+  if (type >= ROTZOOM) {
     aom_wb_write_signed_primitive_refsubexpfin(
         wb, GM_ALPHA_MAX + 1, SUBEXPFIN_K,
         (ref_params->wmmat[2] >> GM_ALPHA_PREC_DIFF) -
@@ -3845,6 +3841,8 @@ static void write_global_motion_params(const WarpedMotionParams *params,
         wb, GM_ALPHA_MAX + 1, SUBEXPFIN_K,
         (ref_params->wmmat[3] >> GM_ALPHA_PREC_DIFF),
         (params->wmmat[3] >> GM_ALPHA_PREC_DIFF));
+  }
+
   if (type >= AFFINE) {
     aom_wb_write_signed_primitive_refsubexpfin(
         wb, GM_ALPHA_MAX + 1, SUBEXPFIN_K,
@@ -3854,14 +3852,14 @@ static void write_global_motion_params(const WarpedMotionParams *params,
         wb, GM_ALPHA_MAX + 1, SUBEXPFIN_K,
         (ref_params->wmmat[5] >> GM_ALPHA_PREC_DIFF) -
             (1 << GM_ALPHA_PREC_BITS),
-            (params->wmmat[5] >> GM_ALPHA_PREC_DIFF) -
-                (1 << GM_ALPHA_PREC_BITS));
+        (params->wmmat[5] >> GM_ALPHA_PREC_DIFF) - (1 << GM_ALPHA_PREC_BITS));
   }
-    // fallthrough intended
-    case TRANSLATION:
-      trans_bits = (type == TRANSLATION) ? GM_ABS_TRANS_ONLY_BITS - !allow_hp
+
+  if (type >= TRANSLATION) {
+    const int trans_bits = (type == TRANSLATION)
+                               ? GM_ABS_TRANS_ONLY_BITS - !allow_hp
                                : GM_ABS_TRANS_BITS;
-      trans_prec_diff = (type == TRANSLATION)
+    const int trans_prec_diff = (type == TRANSLATION)
                                     ? GM_TRANS_ONLY_PREC_DIFF + !allow_hp
                                     : GM_TRANS_PREC_DIFF;
     aom_wb_write_signed_primitive_refsubexpfin(
@@ -3872,9 +3870,6 @@ static void write_global_motion_params(const WarpedMotionParams *params,
         wb, (1 << trans_bits) + 1, SUBEXPFIN_K,
         (ref_params->wmmat[1] >> trans_prec_diff),
         (params->wmmat[1] >> trans_prec_diff));
-      break;
-    case IDENTITY: break;
-    default: assert(0);
   }
 }