From f467b6a4544e2d4f60327693b734eea5f86e492a Mon Sep 17 00:00:00 2001
From: Dennis Ranke <dennis.ranke@gmail.com>
Date: Wed, 14 Sep 2022 23:49:43 +0200
Subject: [PATCH] z80 branch, but with original (slightly more accurate) prob
 update

---
 src/context_state.rs | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/context_state.rs b/src/context_state.rs
index b7a75f2..447c93b 100644
--- a/src/context_state.rs
+++ b/src/context_state.rs
@@ -33,13 +33,12 @@ impl<'a> Context<'a> {
 
     pub fn update(&mut self, bit: bool) {
         let old = self.state.contexts[self.index];
-        let offset = if !bit {
-            ONE_PROB as i32 >> UPDATE_RATE
+        if bit {
+            self.state.contexts[self.index] =
+                old - ((old as i32 + UPDATE_ADD) >> UPDATE_RATE) as u8;
         } else {
-            0
-        };
-
-        self.state.contexts[self.index] =
-            (offset + old as i32 - ((old as i32 + UPDATE_ADD) >> UPDATE_RATE)) as u8;
+            self.state.contexts[self.index] =
+                old + (((ONE_PROB as i32 - old as i32) + UPDATE_ADD) >> UPDATE_RATE) as u8;
+        }
     }
 }