From 4ca0c9b62507462a8a9f47dbf68c2002d2227208 Mon Sep 17 00:00:00 2001
From: transistor <trans@jabberwocky.ca>
Date: Mon, 20 Dec 2021 20:08:11 -0800
Subject: [PATCH] Fixed bug in genesis controllers with incorrect counter

The TH counter in the genesis controller code was increasing each
time the TH bit changed state instead of only in one direction.
Surprisingly it worked before, and fixing it made it not work in
Sonic 2, but after adding the 1.5ms timer to reset the TH counter,
it worked again.  I guess Sonic2 only reads the 3 buttons instead
of all 6.  It should now work with both 3 and 6 button games
---
 src/peripherals/genesis/controllers.rs | 44 +++++++++++++-------------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/src/peripherals/genesis/controllers.rs b/src/peripherals/genesis/controllers.rs
index d56d9e5..238889b 100644
--- a/src/peripherals/genesis/controllers.rs
+++ b/src/peripherals/genesis/controllers.rs
@@ -1,6 +1,7 @@
 
 use crate::error::Error;
-use crate::devices::{Address, Addressable, Transmutable};
+use crate::system::System;
+use crate::devices::{Clock, ClockElapsed, Address, Addressable, Steppable, Transmutable};
 use crate::host::controllers::{ControllerDevice, ControllerEvent};
 use crate::host::traits::{Host, ControllerUpdater, HostData};
 
@@ -64,7 +65,7 @@ impl GenesisControllerPort {
         let prev_th = self.outputs & 0x40;
         self.outputs = outputs;
 
-        if ((outputs & 0x40) ^ prev_th) != 0 {
+        if ((outputs & 0x40) ^ prev_th) != 0 && (outputs & 0x40) == 0 {
             // TH bit was toggled
 
             self.th_count += 1;
@@ -116,8 +117,7 @@ pub struct GenesisController {
     port_2: GenesisControllerPort,
     expansion: GenesisControllerPort,
     interrupt: HostData<bool>,
-    //last_clock: Clock,
-    //last_write: Clock,
+    reset_timer: Clock,
 }
 
 impl GenesisController {
@@ -127,8 +127,7 @@ impl GenesisController {
             port_2: GenesisControllerPort::new(),
             expansion: GenesisControllerPort::new(),
             interrupt: HostData::new(false),
-            //last_clock: 0,
-            //last_write: 0,
+            reset_timer: 0,
         }
     }
 
@@ -179,13 +178,7 @@ impl Addressable for GenesisController {
     }
 
     fn write(&mut self, addr: Address, data: &[u8]) -> Result<(), Error> {
-        // TODO this causes sonic2 to read incorrect inputs, but works without the reset
-        //if self.last_clock - self.last_write >= 1_500_000 {
-        //    self.port_1.reset_count();
-        //    self.port_2.reset_count();
-        //    self.expansion.reset_count();
-        //}
-        //self.last_write = self.last_clock; 
+        self.reset_timer = 0;
 
         debug!("{}: write to register {:x} with {:x}", DEV_NAME, addr, data[0]);
         match addr {
@@ -204,21 +197,28 @@ impl Addressable for GenesisController {
     }
 }
 
-//impl Steppable for GenesisController {
-//    fn step(&mut self, system: &System) -> Result<ClockElapsed, Error> {
-//        self.last_clock = system.clock;
-//        Ok(100_000)     // Update every 100us
-//    }
-//}
+impl Steppable for GenesisController {
+    fn step(&mut self, system: &System) -> Result<ClockElapsed, Error> {
+        let duration = 100_00;     // Update every 100us
+
+        self.reset_timer += duration;
+        if self.reset_timer >= 1_500_000 {
+            self.port_1.reset_count();
+            self.port_2.reset_count();
+            self.expansion.reset_count();
+        }
+        Ok(duration)
+    }
+}
 
 impl Transmutable for GenesisController {
     fn as_addressable(&mut self) -> Option<&mut dyn Addressable> {
         Some(self)
     }
 
-    //fn as_steppable(&mut self) -> Option<&mut dyn Steppable> {
-    //    Some(self)
-    //}
+    fn as_steppable(&mut self) -> Option<&mut dyn Steppable> {
+        Some(self)
+    }
 }