From e55d3e6d1bc346200bb9694de31518b3770a4c0d Mon Sep 17 00:00:00 2001
From: Dmitry Kovalev <dkovalev@google.com>
Date: Tue, 19 Nov 2013 14:59:12 -0800
Subject: [PATCH] Cleaning up probability/cost functions.

Change-Id: Ifad4b0e6355ce49fcc6f470becc080e8069452ee
---
 vp9/encoder/vp9_encodemv.c   | 21 ++++++++-------------
 vp9/encoder/vp9_subexp.c     |  1 -
 vp9/encoder/vp9_treewriter.h | 19 ++++---------------
 3 files changed, 12 insertions(+), 29 deletions(-)

diff --git a/vp9/encoder/vp9_encodemv.c b/vp9/encoder/vp9_encodemv.c
index 030ca6413..7e838c901 100644
--- a/vp9/encoder/vp9_encodemv.c
+++ b/vp9/encoder/vp9_encodemv.c
@@ -126,20 +126,15 @@ static void build_nmv_component_cost_table(int *mvcost,
 
 static int update_mv(vp9_writer *w, const unsigned int ct[2], vp9_prob *cur_p,
                      vp9_prob upd_p) {
-  const vp9_prob new_p = get_binary_prob(ct[0], ct[1]);
-  vp9_prob mod_p = new_p | 1;
-  const int cur_b = cost_branch256(ct, *cur_p);
-  const int mod_b = cost_branch256(ct, mod_p);
-  const int cost = 7 * 256 + (vp9_cost_one(upd_p) - vp9_cost_zero(upd_p));
-  if (cur_b - mod_b > cost) {
-    *cur_p = mod_p;
-    vp9_write(w, 1, upd_p);
-    vp9_write_literal(w, mod_p >> 1, 7);
-    return 1;
-  } else {
-    vp9_write(w, 0, upd_p);
-    return 0;
+  const vp9_prob new_p = get_binary_prob(ct[0], ct[1]) | 1;
+  const int update = cost_branch256(ct, *cur_p) + vp9_cost_zero(upd_p) >
+                     cost_branch256(ct, new_p) + vp9_cost_one(upd_p) + 7 * 256;
+  vp9_write(w, update, upd_p);
+  if (update) {
+    *cur_p = new_p;
+    vp9_write_literal(w, new_p >> 1, 7);
   }
+  return update;
 }
 
 static void counts_to_nmv_context(
diff --git a/vp9/encoder/vp9_subexp.c b/vp9/encoder/vp9_subexp.c
index 387fc9056..f31e568b7 100644
--- a/vp9/encoder/vp9_subexp.c
+++ b/vp9/encoder/vp9_subexp.c
@@ -14,7 +14,6 @@
 #include "vp9/encoder/vp9_boolhuff.h"
 #include "vp9/encoder/vp9_treewriter.h"
 
-#define vp9_cost_upd  ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)) >> 8)
 #define vp9_cost_upd256  ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)))
 
 static int update_bits[255];
diff --git a/vp9/encoder/vp9_treewriter.h b/vp9/encoder/vp9_treewriter.h
index eeda5cda7..41d1bfb83 100644
--- a/vp9/encoder/vp9_treewriter.h
+++ b/vp9/encoder/vp9_treewriter.h
@@ -19,31 +19,20 @@
 
 #include "vp9/encoder/vp9_boolhuff.h"       /* for now */
 
-
 #define vp9_write_prob(w, v) vp9_write_literal((w), (v), 8)
 
-/* Approximate length of an encoded bool in 256ths of a bit at given prob */
+#define vp9_cost_zero(prob) (vp9_prob_cost[prob])
 
-#define vp9_cost_zero(x) (vp9_prob_cost[x])
-#define vp9_cost_one(x) vp9_cost_zero(vp9_complement(x))
+#define vp9_cost_one(prob) vp9_cost_zero(vp9_complement(prob))
 
-#define vp9_cost_bit(x, b) vp9_cost_zero((b) ? vp9_complement(x) : (x))
+#define vp9_cost_bit(prob, bit) vp9_cost_zero((bit) ? vp9_complement(prob) \
+                                                    : (prob))
 
-/* VP8BC version is scaled by 2^20 rather than 2^8; see bool_coder.h */
-
-
-/* Both of these return bits, not scaled bits. */
 static INLINE unsigned int cost_branch256(const unsigned int ct[2],
                                           vp9_prob p) {
   return ct[0] * vp9_cost_zero(p) + ct[1] * vp9_cost_one(p);
 }
 
-static INLINE unsigned int cost_branch(const unsigned int ct[2],
-                                       vp9_prob p) {
-  return cost_branch256(ct, p) >> 8;
-}
-
-
 static INLINE void treed_write(vp9_writer *w,
                                vp9_tree tree, const vp9_prob *probs,
                                int bits, int len) {