From 2fe81791ef7426adc3124d62e2d7761891e61e8b Mon Sep 17 00:00:00 2001
From: EkeEke <ekeeke31@gmail.com>
Date: Mon, 21 Oct 2013 00:20:28 +0200
Subject: [PATCH] [Core/MCD] improved Sub-CPU synchronization with Main-CPU
 (fixes "Soul Star")

---
 core/mem68k.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/core/mem68k.c b/core/mem68k.c
index 0004d03..60f0763 100644
--- a/core/mem68k.c
+++ b/core/mem68k.c
@@ -498,6 +498,15 @@ unsigned int ctrl_io_read_word(unsigned int address)
         /* default registers */
         if (index < 0x30)
         {
+          /* relative SUB-CPU cycle counter */
+          unsigned int cycles = (m68k.cycles * SCYCLES_PER_LINE) / MCYCLES_PER_LINE;
+
+          /* sync SUB-CPU with MAIN-CPU (Soul Star) */
+          if (!s68k.stopped && (s68k.cycles < cycles))
+          {
+            s68k_run(cycles);
+          }
+
           /* SUB-CPU communication words */
           if (index >= 0x20)
           {